Yocto-servo : user's guide

Yocto-Servo : User's guide

1. Introduction
1.1 Prerequisites
1.2 Optional accessories
2. Presentation
2.1 Common elements
2.2 Specific elements
3. First steps
3.1 Localization
3.2 Test of the module
3.3 Configuration
4. Assembly and connections
4.1 Fixing
4.2 Polarity
4.3 Using a controller for RC-models
4.4 USB power distribution
5. Programming, general concepts
5.1 Programming paradigm
5.2 The Yocto-Servo module
5.3 Module control interface
5.4 External power supply control interface
5.5 Servo function interface
5.6 What interface: Native, DLL or Service ?
5.7 Programming, where to start?
6. Using the Yocto-Servo in command line
6.1 Installing
6.2 Use: general description
6.3 Control of the Servo function
6.4 Control of the module part
6.5 Limitations
7. Using Yocto-Servo with Javascript
7.1 Getting ready
7.2 Control of the Servo function
7.3 Control of the module part
7.4 Error handling
8. Using Yocto-Servo with PHP
8.1 Getting ready
8.2 Control of the Servo function
8.3 Control of the module part
8.4 HTTP callback API and NAT filters
8.5 Error handling
9. Using Yocto-Servo with C++
9.1 Control of the Servo function
9.2 Control of the module part
9.3 Error handling
9.4 Integration variants for the C++ Yoctopuce library
10. Using Yocto-Servo with Objective-C
10.1 Control of the Servo function
10.2 Control of the module part
10.3 Error handling
11. Using Yocto-Servo with Visual Basic .NET
11.1 Installation
11.2 Using the Yoctopuce API in a Visual Basic project
11.3 Control of the Servo function
11.4 Control of the module part
11.5 Error handling
12. Using Yocto-Servo with C#
12.1 Installation
12.2 Using the Yoctopuce API in a Visual C# project
12.3 Control of the Servo function
12.4 Control of the module part
12.5 Error handling
13. Using Yocto-Servo with Delphi
13.1 Preparation
13.2 Control of the Servo function
13.3 Control of the module part
13.4 Error handling
14. Using the Yocto-Servo with Python
14.1 Source files
14.2 Dynamic library
14.3 Control of the Servo function
14.4 Control of the module part
14.5 Error handling
15. Using the Yocto-Servo with Java
15.1 Getting ready
15.2 Control of the Servo function
15.3 Control of the module part
15.4 Error handling
16. Using the Yocto-Servo with Android
16.1 Native access and VirtualHub
16.2 Getting ready
16.3 Compatibility
16.4 Activating the USB port under Android
16.5 Control of the Servo function
16.6 Control of the module part
16.7 Error handling
17. Advanced programming
17.1 Event programming
18. Using with unsupported languages
18.1 Command line
18.2 VirtualHub and HTTP GET
18.3 Using dynamic libraries
18.4 Porting the high level library
19. High-level API Reference
19.1 General functions
19.2 Module control interface
19.3 Servo function interface
19.4 External power supply control interface
20. Troubleshooting
20.1 Linux and USB
20.2 ARM Platforms: HF and EL
21. Troubleshooting
21.1 Linux and USB
21.2 ARM Platforms: HF and EL
22. Characteristics
23. Index

1. Introduction

The Yocto-Servo module is a 45x20mm module which allows you to pilot up to five servo-motors for RC-models. The power supply of the module can be external, but the module can also function with the USB bus only, which allows the module to pilot a small servo without any additional connection. The module is able to measure the voltage provided by the external power supply and to automatically shut it down if it detects that the voltage becomes too low. This guide mainly describes how to pilot servo-motors for RC-models with your Yocto-Servo module, but you can naturally use your module to pilot other devices currently used for RC-models, such as speed controllers, light controllers, etc.


The Yocto-Servo module

Yoctopuce thanks you for buying this Yocto-Servo and sincerely hopes that you will be satisfied with it. The Yoctopuce engineers have put a large amount of effort to ensure that your Yocto-Servo is easy to install anywhere and easy to drive from a maximum of programming languages. If you are nevertheless disappointed with this module, do not hesitate to contact Yoctopuce support1.

By design, all Yoctopuce modules are driven the same way. Therefore, user's guides for all the modules of the range are very similar. If you have already carefully read through the user's guide of another Yoctopuce module, you can jump directly to the description of the module functions.

1.1. Prerequisites

In order to use your Yocto-Servo module, you should have the following items at hand.

A computer

Yoctopuce modules are intended to be driven by a computer (or possibly an embedded microprocessor). You will write the control software yourself, according to your needs, using the information provided in this manual.

Yoctopuce provides software libraries to drive its modules for the following operating systems: Windows, Mac OS X, Linux, and Android. Yoctopuce modules do not require installing any specific system driver, as they leverage the standard HID driver2 provided with every operating system.

Windows versions currently supported are: Windows XP, Windows 2003, Windows Vista, and Windows 7. Both 32 bit and 64 bit versions are supported. Yoctopuce is frequently testing its modules on Windows XP and Windows 7.

Mac OS X versions currently supported are: 10.6 (Snow Leopard), Mac OS X 10.7 (Lion), and 10.8 (Mountain Lion). Yoctopuce is frequently testing its modules on Mac OS X 10.6 and 10.7.

Linux kernels currently supported are the 2.6 branch and the 3.0 branch. Other versions of the Linux kernel, and even other UNIX variants, are very likely to work as well, as Linux support is implemented through the standard libusb API. Yoctopuce is frequently testing its modules on Linux kernel 2.6.

Android versions currently supported are: Android 3.1 and later. Moreover, it is necessary for the tablet or phone to support the Host USB mode. Yoctopuce is frequently testing its modules on Android 4.x on a Nexus 7 and a Samsung Galaxy S3 with the Java for Android library.

A USB cable, type A-micro B

USB connectors exist in three sizes: the "standard" size that you probably use to connect your printer, the very common mini size to connect small devices, and finally the micro size often used to connect mobile phones, as long as they do not exhibit an apple logo. All USB modules manufactured by Yoctopuce use micro size connectors.


The most common USB 2 connectors: A, B, Mini B, Micro A, Micro B.3

To connect your Yocto-Servo module to a computer, you need a USB cable of type A-micro B. The price of this cable may vary a lot depending on the source, look for it under the name USB A to micro B Data cable. Make sure not to buy a simple USB charging cable without data connectivity. The correct type of cable is available on the Yoctopuce shop.


You must plug in your Yocto-Servo module with a USB cable of type A - micro B.

If you insert a USB hub between the computer and the Yocto-Servo module, make sure to take into account the USB current limits. If you do not, be prepared to face unstable behaviors and unpredictable failures. You can find more details on this topic in the chapter about assembly and connections.

1.2. Optional accessories

The accessories below are not necessary to use the Yocto-Servo module but might be useful depending on your project. These are mostly common products that you can buy from your favourite hacking store. To save you the tedious job of looking for them, most of them are also available on the Yoctopuce shop.

Screws and spacers

In order to mount the Yocto-Servo module, you can put small screws in the 2.5mm assembly holes, with a screw head no larger than 4.5mm. The best way is to use threaded spacers, which you can then mount wherever you want. You can find more details on this topic in the chapter about assembly and connections.

Micro-USB hub

If you intend to put several Yoctopuce modules in a very small space, you can connect them directly to a micro-USB hub. Yoctopuce builds a USB hub particularly small for this purpose (down to 20mmx36mm), on which you can directly solder a USB cable instead of using a USB plug. For more details, see the micro-USB hub information sheet.

YoctoHub-Ethernet and YoctoHub-Wireless

You can add network connectivity to your Yocto-Servo, thanks to the YoctoHub-Ethernet and the YoctoHub-Wireless. The YoctoHub-Ethernet provides Ethernet connectivity and the YoctoHub-Wireless provides WiFi connectivity. Both can drive up to three devices and behave exactly like a regular computer running a VirtualHub.

Solid copper ribbon cable

If you wish to solder the Yocto-Servo module directly to a micro-USB hub to save on the space used by USB cables, consider using solid copper ribbon cable: it is much easier to solder. In any case, you will need cable with 4 wires with 1.27mm pitch.

External power supply terminal

The module is designed so that you can solder an external power supply cable directly on it. However, you can also use a terminal4 to make you project somewhat easier to disassemble.


Use of a terminal for the external power supply.

Enclosures

Your Yocto-Servo has been designed to be installed as is in your project. Nevertheless, Yoctopuce sells enclosures specifically designed for Yoctopuce devices. These enclosures have removable mounting brackets and magnets allowing them to stick on ferromagnetic surfaces. More details are available on the Yoctopuce web site 5. The suggested enclosure model for your Yocto-Servo is the YoctoBox-Short-Thick-Black.


You can install your Yocto-Servo in an optional enclosure

2. Presentation


1:Micro-B USB socket 6:Channel servo 3
2:Yocto-button 7:Channel servo 4
3:Yocto-led 8:Channel servo 5
4:Channel servo 1 9:USB power supply led
5:Channel servo 2 10:External power supply led
11: External power supply connector

2.1. Common elements

All Yocto-modules share a number of common functionalities.

USB connector

Yoctopuce modules all come with a micro-B USB socket. The corresponding cables are not the most common, but the sockets are the smallest available.

Warning: the USB connector is simply soldered in surface and can be pulled out if the USB plug acts as a lever. In this case, if the tracks stayed in position, the connector can be soldered back with a good iron and using flux to avoid bridges. Alternatively, you can solder a USB cable directly in the 1.27mm-spaced holes near the connector.

Yocto-button

The Yocto-button has two functionalities. First, it can activate the Yocto-beacon mode (see below under Yocto-led). Second, if you plug in a Yocto-module while keeping this button pressed, you can then reprogram its firmware with a new version. Note that there is a simpler UI-based method to update the firmware, but this one works even in case of severely damaged firmware.

Yocto-led

Normally, the Yocto-led is used to indicate that the module is working smoothly. The Yocto-led then emits a low blue light which varies slowly, mimicking breathing. The Yocto-led stops breathing when the module is not communicating any more, as for instance when powered by a USB hub which is disconnected from any active computer.

When you press the Yocto-button, the Yocto-led switches to Yocto-beacon mode. It starts flashing faster with a stronger light, in order to facilitate the localization of a module when you have several identical ones. It is indeed possible to trigger off the Yocto-beacon by software, as it is possible to detect by software that a Yocto-beacon is on.

The Yocto-led has a third functionality, which is less pleasant: when the internal software which controls the module encounters a fatal error, the Yocto-led starts emitting an SOS in morse 6. If this happens, unplug and re-plug the module. If it happens again, check that the module contains the latest version of the firmware, and, if it is the case, contact Yoctopuce support7.

Current sensor

Each Yocto-module is able to measure its own current consumption on the USB bus. Current supply on a USB bus being quite critical, this functionality can be of great help. You can only view the current consumption of a module by software.

Serial number

Each Yocto-module has a unique serial number assigned to it at the factory. For Yocto-Servo modules, this number starts with SERVORC1. The module can be software driven using this serial number. The serial number cannot be modified.

Logical name

The logical name is similar to the serial number: it is a supposedly unique character string which allows you to reference your module by software. However, in the opposite of the serial number, the logical name can be modified at will. The benefit is to enable you to build several copies of the same project without needing to modify the driving software. You only need to program the same logical name in each copy. Warning: the behavior of a project becomes unpredictable when it contains several modules with the same logical name and when the driving software tries to access one of these modules through its logical name. When leaving the factory, modules do not have an assigned logical name. It is yours to define.

2.2. Specific elements

Five channels

The Yocto-Servo module possesses five outputs, each one able to pilot a servo. These outputs can use the USB bus as power supply, or use an external power supply.


It is possible to connect up to five servos

The module is mainly designed to drive servo-motors for RC-models, but is can very well drive other devices: actually, if you can make a device work by plugging it to an RC-model receptor, you can also drive it with the Yocto-Servo module. This includes speed controllers, whether brushless or not.

As the USB port can officially provide no more than 500mA, and in any case no more than 2 amps, you can only drive very small servos when using only the USB port. Therefore, the Yocto-Servo module can have an external power supply.

The external power supply port

You can connect an external power supply to your module. This power supply is used to supply the servos. The voltage applied to the external power supply connector is directly transmitted to the servos. This means that if you apply 5V, the servos are supplied with 5V, if you apply 6V, the servos are supplied with 6V, and so on. Check that you use a voltage which is compatible with your servos.

The module supports four supply modes

Off

In this mode, the logic of the module works, but the servos are simply not supplied and therefore cannot function.

USB

In this mode, the servos are supplied only by the USB port. It means that they have only 500mA, if one decides to comply with the USB specifications, 2A if you are ready to gamble. In any case, it is not much for a servo, but quite enough to pilot a controller, for example. Remember that if more than 2 amps are taken from a USB port, either the computer controlling it is well designed and it deactivates the port, or it is not and the electronics controlling the port risks burning out.

In practice, this means that if your Yocto-Servo module is powered only through the USB port, you can probably not have several servos working at the same time, otherwise the module might get disconnected. It is difficult to predict with certainty how the module will behave with several servos if it is powered only by USB, because it depends in part on the servo models, and in part on you computer USB power supply. The easiest is to try it out. Note that the peak consumption of a servo-motor can be much higher than its average consumption. These consumption peaks appear when the servo starts moving or when it forces.

External

In this mode, the servo are supplied only if there is an external power supply with a voltage above 4V.

Automatic

In this mode, the servos are normally supplied by USB. If the external power supply goes from 0V to more that 5V, the external power supply is selected. If the voltage of the external power supply goes down below 4V, the servos are not supplied any more: the supply is not automatically switched back to USB.

Power supply leds

The logical state of the module power supply is indicated by two leds located close to the servo connector. When the servos are supplied by the USB port, the internal led is on, when the servos are supplied by the external power supply, the external led is on. If the later starts blinking, it mean that the voltage of the external power supply is becoming abnormally low (<4.5v) and that the power supply will soon be shut down.

3. First steps

When reading this chapter, your Yocto-Servo should be connected to your computer, which should have recognized it. It is time to make it work.

Go to the Yoctopuce web site and download the Virtual Hub software8. It is available for Windows, Linux, and Mac OS X. Normally, the Virtual Hub software serves as an abstraction layer for languages which cannot access the hardware layers of your computer. However, it also offers a succinct interface to configure your modules and to test their basic functions. You access this interface with a simple web browser9. Start the Virtual Hub software in a command line, open your preferred web browser and enter the URL http://127.0.0.1:4444. The list of the Yoctopuce modules connected to your computer is displayed.


Module list as displayed in your web bowser.

3.1. Localization

You can then physically localize each of the displayed modules by clicking on the beacon button. This puts the Yocto-led of the corresponding module in Yocto-beacon mode. It starts flashing, which allows you to easily localize it. The second effect is to display a little blue circle on the screen. You obtain the same behavior when pressing the Yocto-button of the module.

3.2. Test of the module

The first item to check is that your module is working well: click on the serial number corresponding to your module. This displays a window summarizing the properties of your Yocto-Servo.


Properties of the Yocto-Servo module.

This windows allows you, among other things, to play with your Yocto-Servo module and to check that it is in working order. You can move the cursors corresponding to the different channels, which has the effect of moving the corresponding servos. Note that the power consumption of the module increases greatly when a servo moves when the module uses the USB power supply, while the consumption stays stable when the modules uses an external power supply.

3.3. Configuration

When, in the module list, you click on the configure button corresponding to your module, the configuration window is displayed.


Yocto-Servo module configuration.

Firmware

The module firmware can easily be updated with the help of the interface. To do so, you must beforehand have the adequate firmware on your local disk. Firmware destined for Yoctopuce modules are available as .byn files and can be downloaded from the Yoctopuce web site.

To update a firmware, simply click on the upgrade button on the configuration window and follow the instructions. If the update fails for one reason or another, unplug and re-plug the module and start the update process again. This solves the issue in most cases. If the module was unplugged while it was being reprogrammed, it does probably not work anymore and is not listed in the interface. However, it is always possible to reprogram the module correctly by using the Virtual Hub software 10 in command line 11.

Logical name of the module

The logical name is a name that you choose, which allows you to access your module, in the same way a file name allows you to access its content. A logical name has a maximum length of 19 characters. Authorized characters are A..Z, a..z, 0..9, _, and -. If you assign the same logical name to two modules connected to the same computer and you try to access one of them through this logical name, behavior is undetermined: you have no way of knowing which of the two modules answers.

Luminosity

This parameter allows you to act on the maximal intensity of the leds of the module. This enables you, if necessary, to make it a little more discreet, while limiting its power consumption. Note that this parameter acts on all the signposting leds of the module, including the Yocto-led. If you connect a module and no led turns on, it may mean that its luminosity was set to zero.

Logical names of functions

Each Yoctopuce module has a serial number and a logical name. In the same way, each function on each Yoctopuce module has a hardware name and a logical name, the latter can be freely chosen by the user. Using logical names for functions provides a greater flexibility when programming modules.

The Yocto-Servo module provides two functions: Servo, for which there are five instances: servo1..servo5, and dualPower, for which there is only one instance.

Servo1..Servo5

It allows you to pilot the servo-motors. You can assign them a logical name by clicking on the rename button.

Dual power

It allows you to pilot the double USB/external power supply. You can assign a logical name to this function and select its working mode: off, USB, external, or automatic.

4. Assembly and connections

This chapter provides important information regarding the use of the Yocto-Servo module in real-world situations. Make sure to read it carefully before going too far into your project if you want to avoid pitfalls.

4.1. Fixing

While developing your project, you can simply let the module hang at the end of its cable. Check only that it does not come in contact with any conducting material (such as your tools). When your project is almost at an end, you need to find a way for your modules to stop moving around.


Examples of assembly on supports

The Yocto-Servo module contains 2.5mm assembly holes. You can use these holes for screws. The screw head diameter must not be larger than 4.5mm or they will damage the module circuits. Make sure that the lower surface of the module is not in contact with the support. We recommend using spacers, but other methods are possible. Nothing prevents you from fixing the module with a glue gun; it will not be good-looking, but it will hold.

If your intend to screw your module directly against a conducting part, for example a metallic frame, insert an isolating layer in between. Otherwise you are bound to induce a short circuit: there are naked pads under your module. Simple packaging tape should be enough for electric insulation.

4.2. Polarity

You must connect the plug so that the signal wire is connected to the upper pin. Note that if you connect the servo pins the other way round, you do not risk much: your device will simply not work.


Way to connect the servos.

Servo cable colors vary from one brand to another. You will find below the most common color codes:

Brand Signal (+) (-)
Multiplex yellow redblack
Futaba / Robbe white redblack
JR / Hitec / Graupnerorangeredbrown

4.3. Using a controller for RC-models

You can very well use the Yocto-Servo module to pilot a motor controller, but this requires you to take a small precaution. Most controllers used for RC-models are designed to provide power to the receptor through the red wire. If you connect a controller on the Yocto-Servo module, you must noramally cut this wire, the controller should certainly not inject power into the module through the servo connectors. On the other hand, you can very well connect this red wired to the positive pole of the external power supply: the controller then serves as an external power supply.


If you want to pilot a controller, you must either cut the red wire, or use it as an external power supply.

4.4. USB power distribution

Although USB means Universal Serial BUS, USB devices are not physically organized as a flat bus but as a tree, using point-to-point connections. This has consequences on power distribution: to make it simple, every USB port must supply power to all devices directly or indirectly connected to it. And USB puts some limits.

In theory, a USB port provides 100mA, and may provide up to 500mA if available and requested by the device. In the case of a hub without external power supply, 100mA are available for the hub itself, and the hub should distribute no more than 100mA to each of its ports. This is it, and this is not much. In particular, it means that in theory, it is not possible to connect USB devices through two cascaded hubs without external power supply. In order to cascade hubs, it is necessary to use self-powered USB hubs, that provide a full 500mA to each subport.

In practice, USB would not have been as successful if it was really so picky about power distribution. As it happens, most USB hub manufacturers have been doing savings by not implementing current limitation on ports: they simply connect the computer power supply to every port, and declare themselves as self-powered hub even when they are taking all their power from the USB bus (in order to prevent any power consumption check in the operating system). This looks a bit dirty, but given the fact that computer USB ports are usually well protected by a hardware current limitation around 2000mA, it actually works in every day life, and seldom makes hardware damage.

What you should remember: if you connect Yoctopuce modules through one, or more, USB hub without external power supply, you have no safe-guard and you depend entirely on your computer manufacturer attention to provide as much current as possible on the USB ports, and to detect overloads before they lead to problems or to hardware damages. When modules are not provided enough current, they may work erratically and create unpredictable bugs. If you want to prevent any risk, do not cascade hubs without external power supply, and do not connect peripherals requiring more than 100mA behind a bus-powered hub.

In order to help controlling and planning overall power consumption for your project, all Yoctopuce modules include a built-in current sensor that tells (with 5mA precision) the consumption of the module on the USB bus.

5. Programming, general concepts

The Yoctopuce API was designed to be at the same time simple to use and sufficiently generic for the concepts used to be valid for all the modules in the Yoctopuce range, and this in all the available programming languages. Therefore, when you have understood how to drive your Yocto-Servo with your favorite programming language, learning to use another module, even with a different language, will most likely take you only a minimum of time.

5.1. Programming paradigm

The Yoctopuce API is object oriented. However, for simplicity's sake, only the basics of object programming were used. Even if you are not familiar with object programming, it is unlikely that this will be a hinderance for using Yoctopuce products. Note that you will never need to allocate or deallocate an object linked to the Yoctopuce API: it is automatically managed.

There is one class per Yoctopuce function type. The name of these classes always starts with a Y followed by the name of the function, for example YTemperature, YRelay, YPressure, etc.. There is also a YModule class, dedicated to managing the modules themselves, and finally there is the static YAPI class, that supervises the global workings of the API and manages low level communications.


Structure of the Yoctopuce API.

In the Yoctopuce API, priority was put on the ease of access to the module functions by offering the possibility to make abstractions of the modules implementing them. Therefore, it is quite possible to work with a set of functions without ever knowing exactly which module are hosting them at the hardware level. This tremendously simplifies programming projects with a large number of modules.

From the programming stand point, your Yocto-Servo is viewed as a module hosting a given number of functions. In the API, these functions are objects which can be found independently, in several ways.

Access to the functions of a module

Access by logical name

Each function can be assigned an arbitrary and persistent logical name: this logical name is stored in the flash memory of the module, even if this module is disconnected. An object corresponding to an Xxx function to which a logical name has been assigned can then be directly found with this logical name and the YXxx.FindXxx method. Note however that a logical name must be unique among all the connected modules.

Access by enumeration

You can enumerate all the functions of the same type on all the connected modules with the help of the classic enumeration functions FirstXxx and nextXxxx available for each YXxx class.

Access by hardware name

Each module function has a hardware name, assigned at the factory and which cannot be modified. The functions of a module can also be found directly with this hardware name and the YXxx.FindXxx function of the corresponding class.

Difference between Find and First

The YXxx.FindXxxx and YXxx.FirstXxxx methods do not work exactly the same way. If there is no available module, YXxx.FirstXxxx returns a null value. On the opposite, even if there is no corresponding module, YXxx.FindXxxx returns a valid object, which is not online but which could become so if the corresponding module is later connected.

Function handling

When the object corresponding to a function is found, its methods are available in a classic way. Note that most of these subfunctions require the module hosting the function to be connected in order to be handled. This is generally not guaranteed, as a USB module can be disconnected after the control software has started. The isOnline method, available in all the classes, is then very helpful.

Access to the modules

Even if it is perfectly possible to build a complete project while making a total abstraction of which function is hosted on which module, the modules themselves are also accessible from the API. In fact, they can be handled in a way quite similar to the functions. They are assigned a serial number at the factory which allows you to find the corresponding object with YModule.Find(). You can also assign arbitrary logical names to the modules to make finding them easier. Finally, the YModule class contains the YModule.FirstModule() and nextModule() enumeration methods allowing you to list the connected modules.

Functions/Module interaction

From the API standpoint, the modules and their functions are strongly uncorrelated by design. Nevertheless, the API provides the possibility to go from one to the other. Thus, the get_module() method, available for each function class, allows you to find the object corresponding to the module hosting this function. Inversely, the YModule class provides several methods allowing you to enumerate the functions available on a module.

5.2. The Yocto-Servo module

The Yocto-Servo module provides one power supply control interface, and five instances of the Servo function, corresponding to the five servo-motor controllers of the module.

module : Module

attributetypemodifiable ?
productName  String  read-only
serialNumber  String  read-only
logicalName  String  modifiable
productId  Hexadecimal number  read-only
productRelease  Hexadecimal number  read-only
firmwareRelease  String  read-only
persistentSettings  Enumerated  modifiable
luminosity  0..100%  modifiable
beacon  On/Off  modifiable
upTime  Time  read-only
usbCurrent  Used current (mA)  read-only
rebootCountdown  Integer  modifiable
usbBandwidth  Enumerated  modifiable

dualPower : DualPower
attributetypemodifiable ?
logicalName  String  modifiable
advertisedValue  String  read-only
powerState  Enumerated  read-only
powerControl  Enumerated  modifiable
extVoltage  Integer  read-only

servo1 : Servo
servo2 : Servo
servo3 : Servo
servo4 : Servo
servo5 : Servo
attributetypemodifiable ?
logicalName  String  modifiable
advertisedValue  String  read-only
position  Integer  modifiable
range  0..100%  modifiable
neutral  0..65000 [us]  modifiable
move  Aggregate  modifiable

5.3. Module control interface

This interface is identical for all Yoctopuce USB modules. It can be used to control the module global parameters, and to enumerate the functions provided by each module.

productName

Character string containing the commercial name of the module, as set by the factory.

serialNumber

Character string containing the serial number, unique and programmed at the factory. For a Yocto-Servo module, this serial number always starts with SERVORC1. You can use the serial number to access a given module by software.

logicalName

Character string containing the logical name of the module, initially empty. This attribute can be modified at will by the user. Once initialized to an non-empty value, it can be used to access a given module. If two modules with the same logical name are in the same project, there is no way to determine which one answers when one tries accessing by logical name. The logical name is limited to 19 characters among A..Z,a..z,0..9,_, and -.

productId

USB device identifier of the module, preprogrammed to 18 at the factory.

productRelease

Release number of the module hardware, preprogrammed at the factory.

firmwareRelease

Release version of the embedded firmware, changes each time the embedded software is updated.

persistentSettings

State of persistent module settings: loaded from flash memory, modified by the user or saved to flash memory.

luminosity

Lighting strength of the informative leds (e.g. the Yocto-Led) contained in the module. It is an integer value which varies between 0 (leds turned off) and 100 (maximum led intensity). The default value is 50. To change the strength of the module leds, or to turn them off completely, you only need to change this value.

beacon

Activity of the localization beacon of the module.

upTime

Time elapsed since the last time the module was powered on.

usbCurrent

Current consumed by the module on the USB bus, in milli-amps.

rebootCountdown

Countdown to use for triggering a reboot of the module.

usbBandwidth

Number of USB interfaces used by the device. If this parameter is set to DOUBLE, the device can send twice as much data, but this may saturate the USB hub. Remember to call the saveToFlash() method and then to reboot the module to apply this setting.

5.4. External power supply control interface

Yoctopuce application programming interface allows you to control the power source to use for module functions that require high current. The module can also automatically disconnect the external power when a voltage drop is observed on the external power source (external battery running out of power).

logicalName

Character string containing the logical name of the power control, initially empty. This attribute can be modified at will by the user. Once initialized to an non-empty value, it can be used to access the power control directly. If two dual power controls with the same logical name are used in the same project, there is no way to determine which one answers when one tries accessing by logical name. The logical name is limited to 19 characters among A..Z,a..z,0..9,_, and -.

advertisedValue

Short character string summarizing the current state of the power control, that will be automatically advertised up to the parent hub. For a dual power control, the advertised value is the current power source: OFF, FROM_USB, FROM_EXT.

powerState

Current power source for module functions that require lots of current: OFF (when no power is provided), FROM_USB (when USB current is used) and FROM_EXT (when an external power supply is used). This attribute is automatically updated when automated power supply control is active.

powerControl

Selected power source for module functions that require lots of current: OFF to disable power, FROM_USB to force the use of USB power, FROM_EXT to force the use of external power supply and AUTO to enable automated power supply control.

extVoltage

Measured voltage on the external power source, in millivolts.

5.5. Servo function interface

Yoctopuce application programming interface allows you not only to move a servo to a given position, but also to specify the time interval in which the move should be performed. This makes it possible to synchronize two servos involved in a same move.

logicalName

Character string containing the logical name of the servo, initially empty. This attribute can be modified at will by the user. Once initialized to an non-empty value, it can be used to access the servo directly. If two servos with the same logical name are used in the same project, there is no way to determine which one answers when one tries accessing by logical name. The logical name is limited to 19 characters among A..Z,a..z,0..9,_, and -.

advertisedValue

Short character string summarizing the current state of the servo, that will be automatically advertised up to the parent hub. For a servo, the advertised value is its current position (a number between -1000 and 1000 included).

position

Current servo position, as a number between -1000 and 1000 included. The value 0 corresponds to the median position.

range

Range of use of the servo. A range of 100% corresponds to a standard control signal, that varies from 1 [ms] to 2 [ms], When using a servo that supports a double range, from 0.5 [ms] to 2.5 [ms], you can select a range of 200%. Be aware that using a range higher than what is supported by the servo is likely to damage the servo.

neutral

Duration in microseconds of a neutral pulse for the servo. The standard value is 1500 [us], but some servos use a different value to use a broader signal range. Be aware that using an improper neutral position is likely to damage the servo.

move

Allows you to move the servo from one position to another, in a given time. The value is an aggregate including the target position (an integer) and a duration in milliseconds.

5.6. What interface: Native, DLL or Service ?

There are several methods to control you Yoctopuce module by software.

Native control

In this case, the software driving your project is compiled directly with a library which provides control of the modules. Objectively, it is the simplest and most elegant solution for the end user. The end user then only needs to plug the USB cable and run your software for everything to work. Unfortunately, this method is not always available or even possible.


The application uses the native library to control the locally connected module

Native control by DLL

Here, the main part of the code controlling the modules is located in a DLL. The software is compiled with a small library which provides control of the DLL. It is the fastest method to code module support in a given language. Indeed, the "useful" part of the control code is located in the DLL which is the same for all languages: the effort to support a new language is limited to coding the small library which controls the DLL. From the end user stand point, there are few differences: one must simply make sure that the DLL is installed on the end user's computer at the same time as the main software.


The application uses the DLL to natively control the locally connected module

Control by service

Some languages do simply not allow you to easily gain access to the hardware layers of the machine. It is the case for Javascript, for instance. To deal with this case, Yoctopuce provides a solution in the form of a small piece of software called Virtual Hub12. It can access the modules, and your application only needs to use a library which offers all necessary functions to control the modules via this virtual hub. The end users will have to start the virtual hub before running the project control software itself, unless they decide to install the hub as a service/deamon, in which case the virtual hub starts automatically when the machine starts up.


The application connects itself to the virtual hub to gain access to the module

The service control method comes with a non-negligible advantage: the application does not need to run on the machine on which the modules are connected. The application can very well be located on another machine which connects itself to the service to drive the modules. Moreover, the native libraries and DLL mentioned above are also able to connect themselves remotely to one or several virtual hubs.


When a virtual hub is used, the control application does not need to reside on the same machine as the module.

Whatever the selected programming language and the control paradigm used, programming itself stays strictly identical. From one language to another, functions bear exactly the same name, and have the same parameters. The only differences are linked to the constraints of the languages themselves.

Language Native  Native with DLL  Virtual hub 
C++
Objective-C -
Delphi -
Python -
VisualBasic .Net -
C# .Net -
Javascript - -
Node.js - -
PHP - -
Java - -
Java for Android -
Command line -

Support methods for different languages

Limitations of the Yoctopuce libraries

Natives et DLL libraries have a technical limitation. On the same computer, you cannot concurrently run several applications accessing Yoctopuce devices directly. If you want to run several projects on the same computer, make sure your control applications use Yoctopuce devices through a VirtualHub software. The modification is trivial: it is just a matter of parameter change in the yRegisterHub() call.

5.7. Programming, where to start?

At this point of the user's guide, you should know the main theoretical points of your Yocto-Servo. It is now time to practice. You must download the Yoctopuce library for your favorite programming language from the Yoctopuce web site13. Then skip directly to the chapter corresponding to the chosen programming language.

All the examples described in this guide are available in the programming libraries. For some languages, the libraries also include some complete graphical applications, with their source code.

When you have mastered the basic programming of your module, you can turn to the chapter on advanced programming that describes some techniques that will help you make the most of your Yocto-Servo.

6. Using the Yocto-Servo in command line

When you want to perform a punctual operation on your Yocto-Servo, such as reading a value, assigning a logical name, and so on, you can obviously use the Virtual Hub, but there is a simpler, faster, and more efficient method: the command line API.

The command line API is a set of executables, one by type of functionality offered by the range of Yoctopuce products. These executables are provided pre-compiled for all the Yoctopuce officially supported platforms/OS. Naturally, the executable sources are also provided14.

6.1. Installing

Download the command line API15. You do not need to run any setup, simply copy the executables corresponding to your platform/OS in a directory of your choice. You may add this directory to your PATH variable to be able to access these executables from anywhere. You are all set, you only need to connect your Yocto-Servo, open a shell, and start working by typing for example:

C:\>YServo any move 1000 2000

To use the command API on Linux, you need either have root privileges or to define an udev rule for your system. See the Troubleshooting chapter for more details.

6.2. Use: general description

All the command line API executables work on the same principle. They must be called the following way


C:\>Executable [options] [target] command [parameter]

[options] manage the global workings of the commands, they allow you, for instance, to pilot a module remotely through the network, or to force the module to save its configuration after executing the command.

[target] is the name of the module or of the function to which the command applies. Some very generic commands do not need a target. You can also use the aliases "any" and "all", or a list of names separated by comas without space.

command is the command you want to run. Almost all the functions available in the classic programming APIs are available as commands. You need to respect neither the case nor the underlined characters in the command name.

[parameters] logically are the parameters needed by the command.

At any time, the command line API executables can provide a rather detailed help. Use for instance:


C:\>executable /help

to know the list of available commands for a given command line API executable, or even:


C:\>executable command /help

to obtain a detailed description of the parameters of a command.

6.3. Control of the Servo function

To control the Servo function of your Yocto-Servo, you need the YServo executable file.

For instance, you can launch:

C:\>YServo any move 1000 2000

This example uses the "any" target to indicate that we want to work on the first Servo function found among all those available on the connected Yoctopuce modules when running. This prevents you from having to know the exact names of your function and of your module.

But you can use logical names as well, as long as you have configured them beforehand. Let us imagine a Yocto-Servo module with the SERVORC1-123456 serial number which you have called "MyModule", and its servo1 function which you have renamed "MyFunction". The five following calls are strictly equivalent (as long as MyFunction is defined only once, to avoid any ambiguity).


C:\>YServo SERVORC1-123456.servo1 describe

C:\>YServo SERVORC1-123456.MyFunction describe

C:\>YServo MyModule.servo1 describe

C:\>YServo MyModule.MyFunction describe

C:\>YServo MyFunction describe

To work on all the Servo functions at the same time, use the "all" target.


C:\>YServo all describe

For more details on the possibilities of the YServo executable, use:


C:\>YServo /help

6.4. Control of the module part

Each module can be controlled in a similar way with the help of the YModule executable. For example, to obtain the list of all the connected modules, use:


C:\>YModule inventory

You can also use the following command to obtain an even more detailed list of the connected modules:


C:\>YModule all describe

Each xxx property of the module can be obtained thanks to a command of the get_xxxx() type, and the properties which are not read only can be modified with the set_xxx() command. For example:


C:\>YModule SERVORC1-12346 set_logicalName MonPremierModule

C:\>YModule SERVORC1-12346 get_logicalName

Changing the settings of the module

When you want to change the settings of a module, simply use the corresponding set_xxx command. However, this change happens only in the module RAM: if the module restarts, the changes are lost. To store them permanently, you must tell the module to save its current configuration in its nonvolatile memory. To do so, use the saveToFlash command. Inversely, it is possible to force the module to forget its current settings by using the revertFromFlash method. For example:


C:\>YModule SERVORC1-12346 set_logicalName MonPremierModule
C:\>YModule SERVORC1-12346 saveToFlash

Note that you can do the same thing in a single command with the -s option.


C:\>YModule -s  SERVORC1-12346 set_logicalName MonPremierModule

Warning: the number of write cycles of the nonvolatile memory of the module is limited. When this limit is reached, nothing guaranties that the saving process is performed correctly. This limit, linked to the technology employed by the module micro-processor, is located at about 100000 cycles. In short, you can use the saveToFlash() function only 100000 times in the life of the module. Make sure you do not call this function within a loop.

6.5. Limitations

The command line API has the same limitation than the other APIs: there can be only one application at a given time which can access the modules natively. By default, the command line API works in native mode.

You can easily work around this limitation by using a Virtual Hub: run the VirtualHub16 on the concerned machine, and use the executables of the command line API with the -r option. For example, if you use:


C:\>YModule  inventory

you obtain a list of the modules connected by USB, using a native access. If another command which accesses the modules natively is already running, this does not work. But if you run a Virtual Hub, and you give your command in the form:


C:\>YModule -r 127.0.0.1 inventory

it works because the command is not executed natively anymore, but through the Virtual Hub. Note that the Virtual Hub counts as a native application.

7. Using Yocto-Servo with Javascript

Javascript is probably not the first language that comes to mind to control hardware, but its ease of use is a great advantage: with Javascript, you only need a text editor and a web browser to realize your first tests.

At the time of writing, the Javascript library functions with any recent browser ... except Opera. It is likely that Opera will end up working with the Yoctopuce library one of these days17, but it is not the case right now.

Javascript is one of those languages which do not allow you to directly access the hardware layers of your computer. Therefore you need to run the Yoctopuce TCP/IP to USB gateway, named VirtualHub, on the machine on which your modules are connected.

7.1. Getting ready

Go to the Yoctopuce web site and download the following items:

Decompress the library files in a folder of your choice, connect your modules, run the VirtualHub software, and you are ready to start your first tests. You do not need to install any driver.

7.2. Control of the Servo function

A few lines of code are enough to use a Yocto-Servo. Here is the skeleton of a JavaScript code snipplet to use the Servo function.


<SCRIPT type="text/javascript" src="yocto_api.js"></SCRIPT>
<SCRIPT type="text/javascript" src="yocto_servo.js"></SCRIPT>

// Get access to your device, through the VirtualHub running locally
yRegisterHub('http://127.0.0.1:4444/');
var servo = yFindServo("SERVORC1-123456.servo1");

// Check that the module is online to handle hot-plug
if(servo.isOnline())
{
    // Use servo.set_position(), ...
}

Let us look at these lines in more details.

yocto_api.js and yocto_servo.js

These two Javascript includes provide access to functions allowing you to manage Yoctopuce modules. yocto_api.js must always be included, yocto_servo.js is necessary to manage modules containing a servo, such as Yocto-Servo.

yRegisterHub

The yRegisterHub function allows you to indicate on which machine the Yoctopuce modules are located, more precisely on which machine the VirtualHub software is running. In our case, the 127.0.0.1:4444 address indicates the local machine, port 4444 (the standard port used by Yoctopuce). You can very well modify this address, and enter the address of another machine on which the VirtualHub software is running.

yFindServo

The yFindServo function allows you to find a servo from the serial number of the module on which it resides and from its function name. You can also use logical names, as long as you have initialized them. Let us imagine a Yocto-Servo module with serial number SERVORC1-123456 which you have named "MyModule", and for which you have given the servo1 function the name "MyFunction". The following five calls are strictly equivalent, as long as "MyFunction" is defined only once.


var servo = yFindServo("SERVORC1-123456.servo1");
var servo = yFindServo("SERVORC1-123456.MyFunction");
var servo = yFindServo("MyModule.servo1");
var servo = yFindServo("MyModule.MyFunction");
var servo = yFindServo("MyFunction");

yFindServo returns an object which you can then use at will to control the servo.

isOnline

The isOnline() method of the object returned by yFindServo allows you to know if the corresponding module is present and in working order.

set_position

The set_position() method of the objet returned by yFindServo moves the servo position as quickly as possible to the specified target. The central position is 0, and the two extremities are -1000 and 1000.

move

The move() method of the objet returned by yFindServo moves the servo at a controlled speed to a desired position, within a time interval specified in milliseconds.

A real example

Open your preferred text editor20, copy the code sample below, save it in the same directory as the Yoctopuce library files and then use your preferred web browser to access this page. The code is also provided in the directory Examples/Doc-GettingStarted-Yocto-Servo of the Yoctopuce library.

In this example, you will recognize the functions explained above, but this time used with all side materials needed to make it work nicely as a small demo.

The example is coded to be used either from a web server, or directly by opening the file on the local machine. Note that this latest solution does not work with some versions of Internet Explorer, in particular IE 9 on Windows 7, which is not able to open network connections when working on a local file. In order to use Internet Explorer, you should load the example from a web server. No such problem exists with Chrome, Firefox or Safari.

If your Yocto-Servo is not connected on the host running the browser, replace in the example the address 127.0.0.1 by the IP address of the host on which the Yocto-Servo is connected and where you run the VirtualHub.

<HTML>
<HEAD>
 <TITLE>Hello World</TITLE>
 <SCRIPT type="text/javascript" src="yocto_api.js"></SCRIPT>
 <SCRIPT type="text/javascript" src="yocto_servo.js"></SCRIPT>
 <SCRIPT language='javascript1.5' type='text/JavaScript'>
 <!--

 // Setup the API to use the VirtualHub on local machine
 if(yRegisterHub('http://127.0.0.1:4444/') != YAPI_SUCCESS) {
     alert("Cannot contact VirtualHub on 127.0.0.1");
 }

 var s1, s5;

 function refresh()
 {
     var serial = document.getElementById('serial').value;
     if(serial == '') {
         // Detect any conected module suitable for the demo
         s1 = yFirstServo();
         if(s1) {
             serial = s1.module().get_serialNumber();
             document.getElementById('serial').value = serial;
         }
     }

     s1 = yFindServo(serial+".servo1");
     s5 = yFindServo(serial+".servo5");
     if(s1.isOnline()) {
         document.getElementById('msg').value = '';
     } else {
         document.getElementById('msg').value = 'Module not connected';        
     }
     setTimeout('refresh()',500);
 }

 function moveTo(pos)
 {
     // Show two different types of move
     s1.set_position(pos); // move as fast as possible
     s5.move(pos,3000);    // move in 3 seconds
 }
 -->
 </SCRIPT>
</HEAD>  
<BODY onload='refresh();'>
 Module to use: <input id='serial'>
 <input id='msg' style='color:red;border:none;' readonly><br>
 <a href='javascript:moveTo(-1000);'>Move to position -1000</a><br>
 <a href='javascript:moveTo(-500);' >Move to position -500</a><br>
 <a href='javascript:moveTo(0);'    >Move to center position</a><br>
 <a href='javascript:moveTo(500);'  >Move to position +500</a><br>
 <a href='javascript:moveTo(1000);' >Move to position +1000</a><br>
</BODY>
</HTML>
 

7.3. Control of the module part

Each module can be controlled in a similar manner, you can find below a simple sample program displaying the main parameters of the module and enabling you to activate the localization beacon.

<HTML>
<HEAD>
 <TITLE>Module Control</TITLE>
 <SCRIPT type="text/javascript" src="yocto_api.js"></SCRIPT>
 <SCRIPT language='javascript1.5'  type='text/JavaScript'>
 <!--
 // Use explicit error handling rather than exceptions
 yDisableExceptions();

 // Setup the API to use the VirtualHub on local machine
 if(yRegisterHub('http://127.0.0.1:4444/') != YAPI_SUCCESS) {
     alert("Cannot contact VirtualHub on 127.0.0.1");
 }

 var module;

 function refresh()
 {
     var serial = document.getElementById('serial').value;
     if(serial == '') {
         // Detect any conected module suitable for the demo
         module = yFirstModule().nextModule();
         if(module) {
             serial = module.get_serialNumber();
             document.getElementById('serial').value = serial;
         }
     }

     module = yFindModule(serial);
     if(module.isOnline()) {
         document.getElementById('msg').value = '';
         var html = 'serial: '+module.get_serialNumber()+'<br>';
         html += 'logical name: '+module.get_logicalName()+'<br>';
         html += 'luminosity:'+module.get_luminosity()+'%<br>';
         html += 'beacon:';
         if (module.get_beacon()==Y_BEACON_ON)  
             html+="ON <a href='javascript:beacon(Y_BEACON_OFF)'>switch off</a><br>";
         else  
             html+="OFF <a href='javascript:beacon(Y_BEACON_ON)'>switch on</a><br>";        
         html += 'upTime: '+parseInt(module.get_upTime()/1000)+' sec<br>';
         html += 'USB current: '+module.get_usbCurrent()+' mA<br>';
         html += 'logs:<br><pre>'+module.get_lastLogs()+'</pre><br>';
         document.getElementById('data').innerHTML = html;
     } else {
         document.getElementById('msg').value = 'Module not connected';        
     }
     setTimeout('refresh()',1000);
 }

 function beacon(state)
 {
     module.set_beacon(state);
     refresh();
 }
 -->
 </SCRIPT>
</HEAD>  
<BODY onload='refresh();'>
 Module to use: <input id='serial'>
 <input id='msg' style='color:red;border:none;' readonly><br>
 <span id='data'></span>
</BODY>
</HTML>
 

Each property xxx of the module can be read thanks to a method of type get_xxxx(), and properties which are not read-only can be modified with the help of the set_xxx() method. For more details regarding the used functions, refer to the API chapters.

Changing the module settings

When you want to modify the settings of a module, you only need to call the corresponding set_xxx() function. However, this modification is performed only in the random access memory (RAM) of the module: if the module is restarted, the modifications are lost. To memorize them persistently, it is necessary to ask the module to save its current configuration in its permanent memory. To do so, use the saveToFlash() method. Inversely, it is possible to force the module to forget its current settings by using the revertFromFlash() method. The short example below allows you to modify the logical name of a module.

<HTML>
<HEAD>
 <TITLE>Change module settings</TITLE>
 <SCRIPT type="text/javascript" src="yocto_api.js"></SCRIPT>
 <SCRIPT language='javascript1.5'  type='text/JavaScript'>
 <!--
 // Use explicit error handling rather than exceptions
 yDisableExceptions();

 // Setup the API to use the VirtualHub on local machine
 if(yRegisterHub('http://127.0.0.1:4444/') != YAPI_SUCCESS) {
     alert("Cannot contact VirtualHub on 127.0.0.1");
 }

 var module;

 function refresh()
 {
     var serial = document.getElementById('serial').value;
     if(serial == '') {
         // Detect any conected module suitable for the demo
         module = yFirstModule().nextModule();
         if(module) {
             serial = module.get_serialNumber();
             document.getElementById('serial').value = serial;
         }
     }

     module = yFindModule(serial);
     if(module.isOnline()) {
         document.getElementById('msg').value = '';
         document.getElementById('curName').value = module.get_logicalName();
     } else {
         document.getElementById('msg').value = 'Module not connected';        
     }
     setTimeout('refresh()',1000);
 }

 function save()
 {
     var newname = document.getElementById('newName').value;
     if (!yCheckLogicalName(newname)) {
         alert('invalid logical name');
         return;
     }
     module.set_logicalName(newname);
     module.saveToFlash();
 }  
 -->
 </SCRIPT>
</HEAD>  
<BODY onload='refresh();'>
 Module to use: <input id='serial'>
 <input id='msg' style='color:red;border:none;' readonly><br>
 Current name: <input id='curName' readonly><br>
 New logical name: <input id='newName'>
 <a href='javascript:save();'>Save</a>
</BODY>
</HTML>
 

Warning: the number of write cycles of the nonvolatile memory of the module is limited. When this limit is reached, nothing guaranties that the saving process is performed correctly. This limit, linked to the technology employed by the module micro-processor, is located at about 100000 cycles. In short, you can use the saveToFlash() function only 100000 times in the life of the module. Make sure you do not call this function within a loop.

Listing the modules

Obtaining the list of the connected modules is performed with the yFirstModule() function which returns the first module found. Then, you only need to call the nextModule() function of this object to find the following modules, and this as long as the returned value is not NULL. Below a short example listing the connected modules.

<HTML>
<HEAD>
 <TITLE>Modules inventory</TITLE>
 <SCRIPT type="text/javascript" src="yocto_api.js"></SCRIPT>
 <SCRIPT language='javascript1.5'  type='text/JavaScript'>
 <!--
 // Use explicit error handling rather than exceptions
 yDisableExceptions();

 // Setup the API to use the VirtualHub on local machine
 if(yRegisterHub('http://127.0.0.1:4444/') != YAPI_SUCCESS) {
     alert("Cannot contact VirtualHub on 127.0.0.1");
 }

 function refresh()
 {
     yUpdateDeviceList();

     var htmlcode = '';
     var module = yFirstModule();
     while(module) {
         htmlcode += module.get_serialNumber()
                     +'('+module.get_productName()+")<br>";
         module = module.nextModule();
     }
     document.getElementById('list').innerHTML=htmlcode;
     setTimeout('refresh()',500);
 }
 -->
 </SCRIPT>
</HEAD>  
<BODY onload='refresh();'>
 <H1>Device list</H1>
 <tt><span id='list'></span></tt>
</BODY>
</HTML>
 

7.4. Error handling

When you implement a program which must interact with USB modules, you cannot disregard error handling. Inevitably, there will be a time when a user will have unplugged the device, either before running the software, or even while the software is running. The Yoctopuce library is designed to help you support this kind of behavior, but your code must nevertheless be conceived to interpret in the best possible way the errors indicated by the library.

The simplest way to work around the problem is the one used in the short examples provided in this chapter: before accessing a module, check that it is online with the isOnline function, and then hope that it will stay so during the fraction of a second necessary for the following code lines to run. This method is not perfect, but it can be sufficient in some cases. You must however be aware that you cannot completely exclude an error which would occur after the call to isOnline and which could crash the software. The only way to prevent this is to implement one of the two error handling techniques described below.

The method recommended by most programming languages for unpredictable error handling is the use of exceptions. By default, it is the behavior of the Yoctopuce library. If an error happens while you try to access a module, the library throws an exception. In this case, there are three possibilities:

As this latest situation is not the most desirable, the Yoctopuce library offers another possibility for error handling, allowing you to create a robust program without needing to catch exceptions at every line of code. You simply need to call the yDisableExceptions() function to commute the library to a mode where exceptions for all the functions are systematically replaced by specific return values, which can be tested by the caller when necessary. For each function, the name of each return value in case of error is systematically documented in the library reference. The name always follows the same logic: a get_state() method returns a Y_STATE_INVALID value, a get_currentValue method returns a Y_CURRENTVALUE_INVALID value, and so on. In any case, the returned value is of the expected type and is not a null pointer which would risk crashing your program. At worst, if you display the value without testing it, it will be outside the expected bounds for the returned value. In the case of functions which do not normally return information, the return value is YAPI_SUCCESS if everything went well, and a different error code in case of failure.

When you work without exceptions, you can obtain an error code and an error message explaining the source of the error. You can request them from the object which returned the error, calling the errType() and errMessage() methods. Their returned values contain the same information as in the exceptions when they are active.

8. Using Yocto-Servo with PHP

PHP is, like Javascript, an atypical language when interfacing with hardware is at stakes. Nevertheless, using PHP with Yoctopuce modules provides you with the opportunity to very easily create web sites which are able to interact with their physical environment, and this is not available to every web server. This technique has a direct application in home automation: a few Yoctopuce modules, a PHP server, and you can interact with your home from anywhere on the planet, as long as you have an internet connection.

PHP is one of those languages which do not allow you to directly access the hardware layers of your computer. Therefore you need to run a virtual hub on the machine on which your modules are connected.

To start your tests with PHP, you need a PHP 5.3 (or more) server21, preferably locally on you machine. If you wish to use the PHP server of your internet provider, it is possible, but you will probably need to configure your ADSL router for it to accept and forward TCP request on the 4444 port.

8.1. Getting ready

Go to the Yoctopuce web site and download the following items:

Decompress the library files in a folder of your choice accessible to your web server, connect your modules, run the VirtualHub software, and you are ready to start your first tests. You do not need to install any driver.

8.2. Control of the Servo function

A few lines of code are enough to use a Yocto-Servo. Here is the skeleton of a PHP code snipplet to use the Servo function.


include('yocto_api.php');
include('yocto_servo.php');

// Get access to your device, through the VirtualHub running locally
yRegisterHub('http://127.0.0.1:4444/',$errmsg);
$servo = yFindServo("SERVORC1-123456.servo1");

// Check that the module is online to handle hot-plug
if(servo->isOnline())
{
    // Use servo->set_position(), ...
}

Let's look at these lines in more details.

yocto_api.php and yocto_servo.php

These two PHP includes provides access to the functions allowing you to manage Yoctopuce modules. yocto_api.php must always be included, yocto_servo.php is necessary to manage modules containing a servo, such as Yocto-Servo.

yRegisterHub

The yRegisterHub function allows you to indicate on which machine the Yoctopuce modules are located, more precisely on which machine the VirtualHub software is running. In our case, the 127.0.0.1:4444 address indicates the local machine, port 4444 (the standard port used by Yoctopuce). You can very well modify this address, and enter the address of another machine on which the VirtualHub software is running.

yFindServo

The yFindServo function allows you to find a servo from the serial number of the module on which it resides and from its function name. You can use logical names as well, as long as you have initialized them. Let us imagine a Yocto-Servo module with serial number SERVORC1-123456 which you have named "MyModule", and for which you have given the servo1 function the name "MyFunction". The following five calls are strictly equivalent, as long as "MyFunction" is defined only once.


$servo = yFindServo("SERVORC1-123456.servo1");
$servo = yFindServo("SERVORC1-123456.MyFunction");
$servo = yFindServo("MyModule.servo1");
$servo = yFindServo("MyModule.MyFunction");
$servo = yFindServo("MyFunction");

yFindServo returns an object which you can then use at will to control the servo.

isOnline

The isOnline() method of the object returned by yFindServo allows you to know if the corresponding module is present and in working order.

set_position

The set_position() method of the objet returned by yFindServo moves the servo position as quickly as possible to the specified target. The central position is 0, and the two extremities are -1000 and 1000.

move

The move() method of the objet returned by yFindServo moves the servo at a controlled speed to a desired position, within a time interval specified in milliseconds.

A real example

Open your preferred text editor24, copy the code sample below, save it with the Yoctopuce library files in a location which is accessible to you web server, then use your preferred web browser to access this page. The code is also provided in the directory Examples/Doc-GettingStarted-Yocto-Servo of the Yoctopuce library.

In this example, you will recognize the functions explained above, but this time used with all side materials needed to make it work nicely as a small demo.

<HTML>
<HEAD>
 <TITLE>Hello World</TITLE>
</HEAD>  
<BODY>
<FORM method='get'>
<?php
  include('yocto_api.php');
  include('yocto_servo.php');

  // Use explicit error handling rather than exceptions
  yDisableExceptions();

  // Setup the API to use the VirtualHub on local machine
  if(yRegisterHub('http://127.0.0.1:4444/',$errmsg) != YAPI_SUCCESS) {
      die("Cannot contact VirtualHub on 127.0.0.1");
  }

  @$serial = $_GET['serial'];
  if ($serial != '') {
      // Check if a specified module is available online
      $servo1 = yFindServo("$serial.servo1");
      $servo5 = yFindServo("$serial.servo5");
      if (!$servo1->isOnline()) {
          die("Module not connected (check serial and USB cable)");
      }
  } else {
      // or use any connected module suitable for the demo
      $servo1 = yFirstServo();
      if(is_null($servo1)) {
          die("No module connected (check USB cable)");
      } else {
          $serial = $servo1->module()->get_serialnumber();
          $servo1 = yFindServo("$serial.servo1");
          $servo5 = yFindServo("$serial.servo5");
      }
  }
  Print("Module to use: <input name='serial' value='$serial'><br>");

  if(isset($_GET['pos'])) {
      $pos = $_GET['pos'];
      $servo1->set_position($pos); // move as fast as possible
      $servo5->move($pos,3000);    // move in 3 seconds
   }      
?>  
<input type='radio' name='pos' value='-1000'>Move to -1000<br>
<input type='radio' name='pos' value='-500'>Move to -500<br>
<input type='radio' name='pos' value='0'>Move to center<br>
<input type='radio' name='pos' value='500'>Move to 500<br>
<input type='radio' name='pos' value='1000'>Move to 1000<br>
<input type='submit'>
</FORM>
</BODY>
</HTML>
 

8.3. Control of the module part

Each module can be controlled in a similar manner, you can find below a simple sample program displaying the main parameters of the module and enabling you to activate the localization beacon.

<HTML>
<HEAD>
 <TITLE>Module Control</TITLE>
</HEAD>
<BODY>
<FORM method='get'>
<?php
  include('yocto_api.php');

  // Use explicit error handling rather than exceptions
  yDisableExceptions();

  // Setup the API to use the VirtualHub on local machine
  if(yRegisterHub('http://127.0.0.1:4444/',$errmsg) != YAPI_SUCCESS) {
      die("Cannot contact VirtualHub on 127.0.0.1 : ".$errmsg);
  }

  @$serial = $_GET['serial'];
  if ($serial != '') {
      // Check if a specified module is available online
      $module = yFindModule("$serial");  
      if (!$module->isOnline()) {
          die("Module not connected (check serial and USB cable)");
      }
  } else {
      // or use any connected module suitable for the demo
      $module = yFirstModule();
      if($module) { // skip VirtualHub
          $module = $module->nextModule();
      }
      if(is_null($module)) {
          die("No module connected (check USB cable)");
      } else {
          $serial = $module->get_serialnumber();
      }
  }
  Print("Module to use: <input name='serial' value='$serial'><br>");

  if (isset($_GET['beacon'])) {
      if ($_GET['beacon']=='ON')
          $module->set_beacon(Y_BEACON_ON);
      else  
          $module->set_beacon(Y_BEACON_OFF);
  }          
  printf('serial: %s<br>',$module->get_serialNumber());
  printf('logical name: %s<br>',$module->get_logicalName());
  printf('luminosity: %s<br>',$module->get_luminosity());
  print('beacon: ');
  if($module->get_beacon() == Y_BEACON_ON) {
      printf("<input type='radio' name='beacon' value='ON' checked>ON ");
      printf("<input type='radio' name='beacon' value='OFF'>OFF<br>");
  } else {
      printf("<input type='radio' name='beacon' value='ON'>ON ");
      printf("<input type='radio' name='beacon' value='OFF' checked>OFF<br>");
  }
  printf('upTime: %s sec<br>',intVal($module->get_upTime()/1000));
  printf('USB current: %smA<br>',$module->get_usbCurrent());
  printf('logs:<br><pre>%s</pre>',$module->get_lastLogs());
?>  
<input type='submit' value='refresh'>
</FORM>
</BODY>
</HTML>
 

Each property xxx of the module can be read thanks to a method of type get_xxxx(), and properties which are not read-only can be modified with the help of the set_xxx() method. For more details regarding the used functions, refer to the API chapters.

Changing the module settings

When you want to modify the settings of a module, you only need to call the corresponding set_xxx() function. However, this modification is performed only in the random access memory (RAM) of the module: if the module is restarted, the modifications are lost. To memorize them persistently, it is necessary to ask the module to save its current configuration in its permanent memory. To do so, use the saveToFlash() method. Inversely, it is possible to force the module to forget its current settings by using the revertFromFlash() method. The short example below allows you to modify the logical name of a module.

<HTML>
<HEAD>
 <TITLE>save settings</TITLE>
<BODY>
<FORM method='get'>
<?php
  include('yocto_api.php');
 
  // Use explicit error handling rather than exceptions
  yDisableExceptions();

  // Setup the API to use the VirtualHub on local machine
  if(yRegisterHub('http://127.0.0.1:4444/',$errmsg) != YAPI_SUCCESS) {
      die("Cannot contact VirtualHub on 127.0.0.1");
  }

  @$serial = $_GET['serial'];
  if ($serial != '') {
      // Check if a specified module is available online
      $module = yFindModule("$serial");  
      if (!$module->isOnline()) {
          die("Module not connected (check serial and USB cable)");
      }
  } else {
      // or use any connected module suitable for the demo
      $module = yFirstModule();
      if($module) { // skip VirtualHub
          $module = $module->nextModule();
      }
      if(is_null($module)) {
          die("No module connected (check USB cable)");
      } else {
          $serial = $module->get_serialnumber();
      }
  }
  Print("Module to use: <input name='serial' value='$serial'><br>");

  if (isset($_GET['newname'])){
      $newname = $_GET['newname'];
      if (!yCheckLogicalName($newname))
          die('Invalid name');
      $module->set_logicalName($newname);
      $module->saveToFlash();
  }
  printf("Current name: %s<br>", $module->get_logicalName());
  print("New name: <input name='newname' value='' maxlength=19><br>");
?>
<input type='submit'>
</FORM>
</BODY>
</HTML>
 

Warning: the number of write cycles of the nonvolatile memory of the module is limited. When this limit is reached, nothing guaranties that the saving process is performed correctly. This limit, linked to the technology employed by the module micro-processor, is located at about 100000 cycles. In short, you can use the saveToFlash() function only 100000 times in the life of the module. Make sure you do not call this function within a loop.

Listing the modules

Obtaining the list of the connected modules is performed with the yFirstModule() function which returns the first module found. Then, you only need to call the nextModule() function of this object to find the following modules, and this as long as the returned value is not NULL. Below a short example listing the connected modules.

<HTML>
<HEAD>
 <TITLE>inventory</TITLE>
</HEAD>
<BODY>
<H1>Device list</H1>
<TT>
<?php
    include('yocto_api.php');
    yRegisterHub("http://127.0.0.1:4444/");
    $module   = yFirstModule();
    while (!is_null($module)) {
        printf("%s (%s)<br>", $module->get_serialNumber(),
               $module->get_productName());
        $module=$module->nextModule();
    }
?>
</TT>
</BODY>
</HTML>
 

8.4. HTTP callback API and NAT filters

The PHP library is able to work in a specific mode called HTTP callback Yocto-API. With this mode, you can control Yoctopuce devices installed behind a NAT filter, such as a DSL router for example, and this without needing to open a port. The typical application is to control Yoctopuce devices, located on a private network, from a public web site.

The NAT filter: advantages and disadvantages

A DSL router which translates network addresses (NAT) works somewhat like a private phone switchboard (a PBX): internal extensions can call each other and call the outside; but seen from the outside, there is only one official phone number, that of the switchboard itself. You cannot reach the internal extensions from the outside.


Typical DSL configuration: LAN machines are isolated from the outside by the DSL router

Transposed to the network, we have the following: appliances connected to your home automation network can communicate with one another using a local IP address (of the 192.168.xxx.yyy type), and contact Internet servers through their public address. However, seen from the outside, you have only one official IP address, assigned to the DSL router only, and you cannot reach your network appliances directly from the outside. It is rather restrictive, but it is a relatively efficient protection against intrusions.


Responses from request from LAN machines are routed.


But requests from the outside are blocked.

Seeing Internet without being seen provides an enormous security advantage. However, this signifies that you cannot, a priori, set up your own web server at home to control a home automation installation from the outside. A solution to this problem, advised by numerous home automation system dealers, consists in providing outside visibility to your home automation server itself, by adding a routing rule in the NAT configuration of the DSL router. The issue of this solution is that it exposes the home automation server to external attacks.

The HTTP callback API solves this issue without having to modify the DSL router configuration. The module control script is located on an external site, and it is the VirtualHub which is in charge of calling it a regular intervals.


The HTTP callback API uses the VirtualHub which initiates the requests.

Configuration

The callback API thus uses the VirtualHub as a gateway. All the communications are initiated by the VirtualHub. They are thus outgoing communications and therefore perfectly authorized by the DSL router.

You must configure the VirtualHub so that it calls the PHP script on a regular basis. To do so:

  1. Launch a VirtualHub
  2. Access its interface, usually 127.0.0.1:4444
  3. Click on the configure button of the line corresponding to the VirtualHub itself
  4. Click on the edit button of the Outgoing callbacks section


Click on the "configure" button on the first line


Click on the "edit" button of the "Outgoing callbacks" section


And select "Yocto-API callback".

You then only need to define the URL of the PHP script and, if need be, the user name and password to access this URL. Supported authentication methods are basic and digest. The second method is safer than the first one because it does not allow transfer of the password on the network.

Usage

From the programmer standpoint, the only difference is at the level of the yRegisterHub function call. Instead of using an IP address, you must use the callback string (or http://callback which is equivalent).


include("yocto_api.php");
yRegisterHub("callback");

The remainder of the code stays strictly identical. On the VirtualHub interface, at the bottom of the configuration window for the HTTP callback API , there is a button allowing you to test the call to the PHP script.

Be aware that the PHP script controlling the modules remotely through the HTTP callback API can be called only by the VirtualHub. Indeed, it requires the information posted by the VirtualHub to function. To code a web site which controls Yoctopuce modules interactively, you must create a user interface which stores in a file or in a database the actions to be performed on the Yoctopuce modules. These actions are then read and run by the control script.

Common issues

For the HTTP callback API to work, the PHP option allow_url_fopen must be set. Some web site hosts do not set it by default. The problem then manifests itself with the following error:

error: URL file-access is disabled in the server configuration

To set this option, you must create, in the repertory where the control PHP script is located, an .htaccess file containing the following line:
php_flag "allow_url_fopen" "On"
Depending on the security policies of the host, it is sometimes impossible to authorize this option at the root of the web site, or even to install PHP scripts receiving data from a POST HTTP. In this case, place the PHP script in a subdirectory.

Limitations

This method that allows you to go through NAT filters cheaply has nevertheless a price. Communications being initiated by the VirtualHub at a more or less regular interval, reaction time to an event is clearly longer than if the Yoctopuce modules were driven directly. You can configure the reaction time in the specific window of the VirtualHub, but it is at least of a few seconds in the best case.

The HTTP callback Yocto-API mode is currently available in PHP and Node.JS only.

8.5. Error handling

When you implement a program which must interact with USB modules, you cannot disregard error handling. Inevitably, there will be a time when a user will have unplugged the device, either before running the software, or even while the software is running. The Yoctopuce library is designed to help you support this kind of behavior, but your code must nevertheless be conceived to interpret in the best possible way the errors indicated by the library.

The simplest way to work around the problem is the one used in the short examples provided in this chapter: before accessing a module, check that it is online with the isOnline function, and then hope that it will stay so during the fraction of a second necessary for the following code lines to run. This method is not perfect, but it can be sufficient in some cases. You must however be aware that you cannot completely exclude an error which would occur after the call to isOnline and which could crash the software. The only way to prevent this is to implement one of the two error handling techniques described below.

The method recommended by most programming languages for unpredictable error handling is the use of exceptions. By default, it is the behavior of the Yoctopuce library. If an error happens while you try to access a module, the library throws an exception. In this case, there are three possibilities:

As this latest situation is not the most desirable, the Yoctopuce library offers another possibility for error handling, allowing you to create a robust program without needing to catch exceptions at every line of code. You simply need to call the yDisableExceptions() function to commute the library to a mode where exceptions for all the functions are systematically replaced by specific return values, which can be tested by the caller when necessary. For each function, the name of each return value in case of error is systematically documented in the library reference. The name always follows the same logic: a get_state() method returns a Y_STATE_INVALID value, a get_currentValue method returns a Y_CURRENTVALUE_INVALID value, and so on. In any case, the returned value is of the expected type and is not a null pointer which would risk crashing your program. At worst, if you display the value without testing it, it will be outside the expected bounds for the returned value. In the case of functions which do not normally return information, the return value is YAPI_SUCCESS if everything went well, and a different error code in case of failure.

When you work without exceptions, you can obtain an error code and an error message explaining the source of the error. You can request them from the object which returned the error, calling the errType() and errMessage() methods. Their returned values contain the same information as in the exceptions when they are active.

9. Using Yocto-Servo with C++

C++ is not the simplest language to master. However, if you take care to limit yourself to its essential functionalities, this language can very well be used for short programs quickly coded, and it has the advantage of being easily ported from one operating system to another. Under Windows, all the examples and the project models are tested with Microsoft Visual Studio 2010 Express, freely available on the Microsoft web site25. Under Mac OS X, all the examples and project models are tested with XCode 4, available on the App Store. Moreover, under Max OS X and under Linux, you can compile the examples using a command line with GCC using the provided GNUmakefile. In the same manner under Windows, a Makefile allows you to compile examples using a command line, fully knowing the compilation and linking arguments.

Yoctopuce C++ libraries26 are integrally provided as source files. A section of the low-level library is written in pure C, but you should not need to interact directly with it: everything was done to ensure the simplest possible interaction from C++. The library is naturally also available as binary files, so that you can link it directly if you prefer.

You will soon notice that the C++ API defines many functions which return objects. You do not need to deallocate these objects yourself, the API does it automatically at the end of the application.

In order to keep them simple, all the examples provided in this documentation are console applications. Naturally, the libraries function in a strictly identical manner if you integrate them in an application with a graphical interface. You will find in the last section of this chapter all the information needed to create a wholly new project linked with the Yoctopuce libraries.

9.1. Control of the Servo function

A few lines of code are enough to use a Yocto-Servo. Here is the skeleton of a C++ code snipplet to use the Servo function.


#include "yocto_api.h"
#include "yocto_servo.h"

[...]
String  errmsg;
YServo *servo;

// Get access to your device, connected locally on USB for instance
yRegisterHub("usb", errmsg);
servo = yFindServo("SERVORC1-123456.servo1");

// Hot-plug is easy: just check that the device is online
if(servo->isOnline())
{
    // Use servo->set_position(), ...
}

Let's look at these lines in more details.

yocto_api.h et yocto_servo.h

These two include files provide access to the functions allowing you to manage Yoctopuce modules. yocto_api.h must always be used, yocto_servo.h is necessary to manage modules containing a servo, such as Yocto-Servo.

yRegisterHub

The yRegisterHub function initializes the Yoctopuce API and indicates where the modules should be looked for. When used with the parameter "usb", it will use the modules locally connected to the computer running the library. If the initialization does not succeed, this function returns a value different from YAPI_SUCCESS and errmsg contains the error message.

yFindServo

The yFindServo function allows you to find a servo from the serial number of the module on which it resides and from its function name. You can use logical names as well, as long as you have initialized them. Let us imagine a Yocto-Servo module with serial number SERVORC1-123456 which you have named "MyModule", and for which you have given the servo1 function the name "MyFunction". The following five calls are strictly equivalent, as long as "MyFunction" is defined only once.


YServo *servo = yFindServo("SERVORC1-123456.servo1");
YServo *servo = yFindServo("SERVORC1-123456.MyFunction");
YServo *servo = yFindServo("MyModule.servo1");
YServo *servo = yFindServo("MyModule.MyFunction");
YServo *servo = yFindServo("MyFunction");

yFindServo returns an object which you can then use at will to control the servo.

isOnline

The isOnline() method of the object returned by yFindServo allows you to know if the corresponding module is present and in working order.

set_position

The set_position() method of the objet returned by yFindServo moves the servo position as quickly as possible to the specified target. The central position is 0, and the two extremities are -1000 and 1000.

move

The move() method of the objet returned by yFindServo moves the servo at a controlled speed to a desired position, within a time interval specified in milliseconds.

A real example

Launch your C++ environment and open the corresponding sample project provided in the directory Examples/Doc-GettingStarted-Yocto-Servo of the Yoctopuce library. If you prefer to work with your favorite text editor, open the file main.cpp, and type make to build the example when you are done.

In this example, you will recognize the functions explained above, but this time used with all side materials needed to make it work nicely as a small demo.

#include "yocto_api.h"
#include "yocto_servo.h"
#include <iostream>
#include <stdlib.h>

using namespace std;

static void usage(void)
{
    cout << "usage: demo <serial_number>  [ -1000 | ... | 1000 ]" << endl;
    cout << "       demo <logical_name> [ -1000 | ... | 1000 ]" << endl;
    cout << "       demo any  [ -1000 | ... | 1000 ]                (use any discovered device)" << endl;
    u64 now = yGetTickCount();    // dirty active wait loop
        while (yGetTickCount()-now<3000);
    exit(1);
}

int main(int argc, const char * argv[])
{
    string errmsg;
    string target;
    YServo *servo1;
    YServo *servo5;
    int    pos;

    if (argc < 3) {
        usage();
    }
    target = (string) argv[1];
    pos = (int) atol(argv[2]);
   
    // Setup the API to use local USB devices
    if (yRegisterHub("usb", errmsg) != YAPI_SUCCESS) {
        cerr << "RegisterHub error: " << errmsg << endl;
        return 1;
    }

    if (target == "any") {
        YServo *servo = yFirstServo();
        if (servo==NULL) {
            cout << "No module connected (check USB cable)" << endl;
            return 1;
        }
        target = servo->module()->get_serialNumber();
    }  
    servo1 =  yFindServo(target + ".servo1");
    servo5 =  yFindServo(target + ".servo5");
   
    if (servo1->isOnline()) {
        servo1->set_position(pos);  // immediate switch
        servo5->move(pos,3000);     // smooth transition  
    } else {
        cout << "Module not connected (check identification and USB cable)" << endl;
    }
       
    return 0;
}
 

9.2. Control of the module part

Each module can be controlled in a similar manner, you can find below a simple sample program displaying the main parameters of the module and enabling you to activate the localization beacon.

#include <iostream>
#include <stdlib.h>

#include "yocto_api.h"

using namespace std;

static void usage(const char *exe)
{
    cout << "usage: " << exe << " <serial or logical name> [ON/OFF]" << endl;
    exit(1);
}


int main(int argc, const char * argv[])
{
    string      errmsg;

    // Setup the API to use local USB devices
    if(yRegisterHub("usb", errmsg) != YAPI_SUCCESS) {
        cerr << "RegisterHub error: " << errmsg << endl;
        return 1;
    }

    if(argc < 2)
        usage(argv[0]);

    YModule *module = yFindModule(argv[1]);  // use serial or logical name
 
    if (module->isOnline()) {
        if (argc > 2) {
            if (string(argv[2]) == "ON")
                module->set_beacon(Y_BEACON_ON);
            else  
                module->set_beacon(Y_BEACON_OFF);
        }          
        cout << "serial:       " << module->get_serialNumber() << endl;
        cout << "logical name: " << module->get_logicalName() << endl;
        cout << "luminosity:   " << module->get_luminosity() << endl;
        cout << "beacon:       ";
        if (module->get_beacon()==Y_BEACON_ON)  
           cout << "ON" << endl;
        else  
           cout << "OFF" << endl;
        cout << "upTime:       " << module->get_upTime()/1000 << " sec" << endl;
        cout << "USB current:  " << module->get_usbCurrent() << " mA" << endl;
        cout << "Logs:"<< endl << module->get_lastLogs() << endl;
    } else {
        cout << argv[1] << " not connected (check identification and USB cable)"
             << endl;
    }
    return 0;
}
 

Each property xxx of the module can be read thanks to a method of type get_xxxx(), and properties which are not read-only can be modified with the help of the set_xxx() method. For more details regarding the used functions, refer to the API chapters.

Changing the module settings

When you want to modify the settings of a module, you only need to call the corresponding set_xxx() function. However, this modification is performed only in the random access memory (RAM) of the module: if the module is restarted, the modifications are lost. To memorize them persistently, it is necessary to ask the module to save its current configuration in its permanent memory. To do so, use the saveToFlash() method. Inversely, it is possible to force the module to forget its current settings by using the revertFromFlash() method. The short example below allows you to modify the logical name of a module.

#include <iostream>
#include <stdlib.h>

#include "yocto_api.h"

using namespace std;

static void usage(const char *exe)
{
    cerr << "usage: " << exe << " <serial> <newLogicalName>" << endl;
    exit(1);
}

int main(int argc, const char * argv[])
{
    string      errmsg;

    // Setup the API to use local USB devices
    if(yRegisterHub("usb", errmsg) != YAPI_SUCCESS) {
        cerr << "RegisterHub error: " << errmsg << endl;
        return 1;
    }

    if(argc < 2)
        usage(argv[0]);

    YModule *module = yFindModule(argv[1]);  // use serial or logical name
 
    if (module->isOnline()) {
        if (argc >= 3){
            string newname =  argv[2];
            if (!yCheckLogicalName(newname)){
                cerr << "Invalid name (" << newname << ")" << endl;
                usage(argv[0]);
            }
            module->set_logicalName(newname);
            module->saveToFlash();
        }
        cout << "Current name: " << module->get_logicalName() << endl;
    } else {
        cout << argv[1] << " not connected (check identification and USB cable)"
             << endl;
    }
    return 0;
}
 

Warning: the number of write cycles of the nonvolatile memory of the module is limited. When this limit is reached, nothing guaranties that the saving process is performed correctly. This limit, linked to the technology employed by the module micro-processor, is located at about 100000 cycles. In short, you can use the saveToFlash() function only 100000 times in the life of the module. Make sure you do not call this function within a loop.

Listing the modules

Obtaining the list of the connected modules is performed with the yFirstModule() function which returns the first module found. Then, you only need to call the nextModule() function of this object to find the following modules, and this as long as the returned value is not NULL. Below a short example listing the connected modules.

#include <iostream>

#include "yocto_api.h"

using namespace std;

int main(int argc, const char * argv[])
{
    string      errmsg;

    // Setup the API to use local USB devices
    if(yRegisterHub("usb", errmsg) != YAPI_SUCCESS) {
        cerr << "RegisterHub error: " << errmsg << endl;
        return 1;
    }

    cout << "Device list: " << endl;

    YModule *module = yFirstModule();
    while (module != NULL) {
        cout << module->get_serialNumber() << " ";
        cout << module->get_productName()  << endl;
        module = module->nextModule();
    }
    return 0;
}
 

9.3. Error handling

When you implement a program which must interact with USB modules, you cannot disregard error handling. Inevitably, there will be a time when a user will have unplugged the device, either before running the software, or even while the software is running. The Yoctopuce library is designed to help you support this kind of behavior, but your code must nevertheless be conceived to interpret in the best possible way the errors indicated by the library.

The simplest way to work around the problem is the one used in the short examples provided in this chapter: before accessing a module, check that it is online with the isOnline function, and then hope that it will stay so during the fraction of a second necessary for the following code lines to run. This method is not perfect, but it can be sufficient in some cases. You must however be aware that you cannot completely exclude an error which would occur after the call to isOnline and which could crash the software. The only way to prevent this is to implement one of the two error handling techniques described below.

The method recommended by most programming languages for unpredictable error handling is the use of exceptions. By default, it is the behavior of the Yoctopuce library. If an error happens while you try to access a module, the library throws an exception. In this case, there are three possibilities:

As this latest situation is not the most desirable, the Yoctopuce library offers another possibility for error handling, allowing you to create a robust program without needing to catch exceptions at every line of code. You simply need to call the yDisableExceptions() function to commute the library to a mode where exceptions for all the functions are systematically replaced by specific return values, which can be tested by the caller when necessary. For each function, the name of each return value in case of error is systematically documented in the library reference. The name always follows the same logic: a get_state() method returns a Y_STATE_INVALID value, a get_currentValue method returns a Y_CURRENTVALUE_INVALID value, and so on. In any case, the returned value is of the expected type and is not a null pointer which would risk crashing your program. At worst, if you display the value without testing it, it will be outside the expected bounds for the returned value. In the case of functions which do not normally return information, the return value is YAPI_SUCCESS if everything went well, and a different error code in case of failure.

When you work without exceptions, you can obtain an error code and an error message explaining the source of the error. You can request them from the object which returned the error, calling the errType() and errMessage() methods. Their returned values contain the same information as in the exceptions when they are active.

9.4. Integration variants for the C++ Yoctopuce library

Depending on your needs and on your preferences, you can integrate the library into your projects in several distinct manners. This section explains how to implement the different options.

Integration in source format

Integrating all the sources of the library into your projects has several advantages:

To integrate the source code, the easiest way is to simply include the Sources directory of your Yoctopuce library into your IncludePath, and to add all the files of this directory (including the sub-directory yapi) to your project.

For your project to build correctly, you need to link with your project the prerequisite system libraries, that is:

Integration as a static library

Integration of the Yoctopuce library as a static library is a simpler manner to build a small executable which uses Yoctopuce modules. You can quickly compile the program with a single command. You do not need to install a dynamic library specific to Yoctopuce, everything is in the executable.

To integrate the static Yoctopuce library to your project, you must include the Sources directory of the Yoctopuce library into your IncludePath, and add the sub-directory Binaries/... corresponding to your operating system into your libPath.

Then, for you project to build correctly, you need to link with your project the Yoctopuce library and the prerequisite system libraries:

Note, under Linux, if you wish to compile in command line with GCC, it is generally advisable to link system libraries as dynamic libraries, rather than as static ones. To mix static and dynamic libraries on the same command line, you must pass the following arguments:

gcc (...) -Wl,-Bstatic -lyocto-static -Wl,-Bdynamic -lm -lpthread -lusb-1.0 -lstdc++

Integration as a dynamic library

Integration of the Yoctopuce library as a dynamic library allows you to produce an executable smaller than with the two previous methods, and to possibly update this library, if a patch reveals itself necessary, without needing to recompile the source code of the application. On the other hand, it is an integration mode which systematically requires you to copy the dynamic library on the target machine where the application will run (yocto.dll for Windows, libyocto.so.1.0.1 for Mac OS X and Linux).

To integrate the dynamic Yoctopuce library to your project, you must include the Sources directory of the Yoctopuce library into your IncludePath, and add the sub-directory Binaries/... corresponding to your operating system into your LibPath.

Then, for you project to build correctly, you need to link with your project the dynamic Yoctopuce library and the prerequisite system libraries:

With GCC, the command line to compile is simply:

gcc (...) -lyocto -lm -lpthread -lusb-1.0 -lstdc++

10. Using Yocto-Servo with Objective-C

Objective-C is language of choice for programming on Mac OS X, due to its integration with the Cocoa framework. In order to use the Objective-C library, you need XCode version 4.2 (earlier versions will not work), available freely when you run Lion. If you are still under Snow Leopard, you need to be registered as Apple developer to be able to download XCode 4.2. The Yoctopuce library is ARC compatible. You can therefore implement your projects either using the traditional retain / release method, or using the Automatic Reference Counting.

Yoctopuce Objective-C libraries27 are integrally provided as source files. A section of the low-level library is written in pure C, but you should not need to interact directly with it: everything was done to ensure the simplest possible interaction from Objective-C.

You will soon notice that the Objective-C API defines many functions which return objects. You do not need to deallocate these objects yourself, the API does it automatically at the end of the application.

In order to keep them simple, all the examples provided in this documentation are console applications. Naturally, the libraries function in a strictly identical manner if you integrate them in an application with a graphical interface. You can find on Yoctopuce blog a detailed example28 with video shots showing how to integrate the library into your projects.

10.1. Control of the Servo function

Launch Xcode 4.2 and open the corresponding sample project provided in the directory Examples/Doc-GettingStarted-Yocto-Servo of the Yoctopuce library.

#import <Foundation/Foundation.h>
#import "yocto_api.h"
#import "yocto_servo.h"


static void usage(void)
{
    NSLog(@"usage: demo <serial_number>  [ -1000 | ... | 1000 ]");
    NSLog(@"       demo <logical_name> [ -1000 | ... | 1000 ]");
    NSLog(@"       demo any  [ -1000 | ... | 1000 ]                (use any discovered device)");
    exit(1);
}


int main(int argc, const char * argv[])
{
    NSError *error;
   
    if (argc < 3) {
        usage();
    }
   
    @autoreleasepool{
        // Setup the API to use local USB devices
        if([YAPI RegisterHub:@"usb": &error] != YAPI_SUCCESS) {
            NSLog(@"RegisterHub error: %@", [error localizedDescription]);
            return 1;
        }
        NSString *target = [NSString stringWithUTF8String:argv[1]];
       
        if ([target isEqualToString:@"any"]) {
            YServo *servo = [YServo FirstServo];
            if (servo==NULL) {
                NSLog(@"No module connected (check USB cable)");
                return 1;
            }
            target = [[servo module] serialNumber];
        }  
        YServo   *servo1 =  [YServo FindServo:[target stringByAppendingString:@".servo1"]];
        YServo   *servo5 =  [YServo FindServo:[target stringByAppendingString:@".servo5"]];
               
        int pos = (int) atol(argv[2]);
       
        if ([servo1 isOnline]) {
            [servo1 set_position:pos];  // immediate switch
            [servo5 move:pos:3000];     // smooth transition  
        } else {
            NSLog(@"Module not connected (check identification and USB cable)\n");
        }
    }
    return 0;
}
 

There are only a few really important lines in this example. We will look at them in details.

yocto_api.h et yocto_servo.h

These two import files provide access to the functions allowing you to manage Yoctopuce modules. yocto_api.h must always be used, yocto_servo.h is necessary to manage modules containing a servo, such as Yocto-Servo.

yRegisterHub

The yRegisterHub function initializes the Yoctopuce API and indicates where the modules should be looked for. When used with the parameter @"usb", it will use the modules locally connected to the computer running the library. If the initialization does not succeed, this function returns a value different from YAPI_SUCCESS and errmsg contains the error message.

yFindServo

The yFindServo function allows you to find a servo from the serial number of the module on which it resides and from its function name. You can use logical names as well, as long as you have initialized them. Let us imagine a Yocto-Servo module with serial number SERVORC1-123456 which you have named "MyModule", and for which you have given the servo1 function the name "MyFunction". The following five calls are strictly equivalent, as long as "MyFunction" is defined only once.


YServo *servo = yFindServo(@"SERVORC1-123456.servo1");
YServo *servo = yFindServo(@"SERVORC1-123456.MyFunction");
YServo *servo = yFindServo(@"MyModule.servo1");
YServo *servo = yFindServo(@"MyModule.MyFunction");
YServo *servo = yFindServo(@"MyFunction");

yFindServo returns an object which you can then use at will to control the servo.

isOnline

The isOnline() method of the object returned by yFindServo allows you to know if the corresponding module is present and in working order.

set_position

The set_position() method of the objet returned by yFindServo moves the servo position as quickly as possible to the specified target. The central position is 0, and the two extremities are -1000 and 1000.

move

The move() method of the objet returned by yFindServo moves the servo at a controlled speed to a desired position, within a time interval specified in milliseconds.

10.2. Control of the module part

Each module can be controlled in a similar manner, you can find below a simple sample program displaying the main parameters of the module and enabling you to activate the localization beacon.

#import <Foundation/Foundation.h>
#import "yocto_api.h"

static void usage(const char *exe)
{
    NSLog(@"usage: %s <serial or logical name> [ON/OFF]\n",exe);
    exit(1);
}


int main (int argc, const char * argv[])
{
    NSError *error;
   
    @autoreleasepool {
        // Setup the API to use local USB devices
        if([YAPI RegisterHub:@"usb": &error] != YAPI_SUCCESS) {
            NSLog(@"RegisterHub error: %@", [error localizedDescription]);
            return 1;
        }
        if(argc < 2)
            usage(argv[0]);
        NSString *serial_or_name =[NSString stringWithUTF8String:argv[1]];
        YModule *module = [YModule FindModule:serial_or_name];  // use serial or logical name
        if ([module isOnline]) {
            if (argc > 2) {
                if (strcmp(argv[2], "ON")==0)
                    [module setBeacon:Y_BEACON_ON];
                else  
                    [module setBeacon:Y_BEACON_OFF];
            }        
            NSLog(@"serial:       %@\n", [module serialNumber]);
            NSLog(@"logical name: %@\n", [module logicalName]);
            NSLog(@"luminosity:   %d\n", [module luminosity]);
            NSLog(@"beacon:       ");
            if ([module beacon] == Y_BEACON_ON)
               NSLog(@"ON\n");
            else  
               NSLog(@"OFF\n");
            NSLog(@"upTime:       %d sec\n", [module upTime]/1000);
            NSLog(@"USB current:  %d mA\n",  [module usbCurrent]);
            NSLog(@"logs:  %@\n",  [module get_lastLogs]);
        } else {
            NSLog(@"%@ not connected (check identification and USB cable)\n",serial_or_name);
        }
    }
    return 0;
}
 

Each property xxx of the module can be read thanks to a method of type get_xxxx, and properties which are not read-only can be modified with the help of the set_xxx: method. For more details regarding the used functions, refer to the API chapters.

Changing the module settings

When you want to modify the settings of a module, you only need to call the corresponding set_xxx: function. However, this modification is performed only in the random access memory (RAM) of the module: if the module is restarted, the modifications are lost. To memorize them persistently, it is necessary to ask the module to save its current configuration in its permanent memory. To do so, use the saveToFlash method. Inversely, it is possible to force the module to forget its current settings by using the revertFromFlash method. The short example below allows you to modify the logical name of a module.

#import <Foundation/Foundation.h>
#import "yocto_api.h"

static void usage(const char *exe)
{
    NSLog(@"usage: %s <serial> <newLogicalName>\n",exe);
    exit(1);
}


int main (int argc, const char * argv[])
{
    NSError *error;

    @autoreleasepool {
        // Setup the API to use local USB devices
        if(yRegisterHub(@"usb", &error) != YAPI_SUCCESS) {
            NSLog(@"RegisterHub error: %@", [error localizedDescription]);
            return 1;
        }

        if(argc < 2)
            usage(argv[0]);

        NSString *serial_or_name =[NSString stringWithUTF8String:argv[1]];
        YModule *module = yFindModule(serial_or_name);  // use serial or logical name
     
        if (module.isOnline) {
            if (argc >= 3){
                NSString *newname =  [NSString stringWithUTF8String:argv[2]];
                if (!yCheckLogicalName(newname)){
                    NSLog(@"Invalid name (%@)\n", newname);
                    usage(argv[0]);
                }
                module.logicalName = newname;
                [module saveToFlash];
            }
            NSLog(@"Current name: %@\n", module.logicalName);
        } else {
            NSLog(@"%@ not connected (check identification and USB cable)\n",serial_or_name);
        }
    }
    return 0;
}
 

Warning: the number of write cycles of the nonvolatile memory of the module is limited. When this limit is reached, nothing guaranties that the saving process is performed correctly. This limit, linked to the technology employed by the module micro-processor, is located at about 100000 cycles. In short, you can use the saveToFlash function only 100000 times in the life of the module. Make sure you do not call this function within a loop.

Listing the modules

Obtaining the list of the connected modules is performed with the yFirstModule() function which returns the first module found. Then, you only need to call the nextModule() function of this object to find the following modules, and this as long as the returned value is not NULL. Below a short example listing the connected modules.

#import <Foundation/Foundation.h>
#import "yocto_api.h"

int main (int argc, const char * argv[])
{
    NSError *error;
   
    @autoreleasepool {
        // Setup the API to use local USB devices
        if(yRegisterHub(@"usb", &error) != YAPI_SUCCESS) {
            NSLog(@"RegisterHub error: %@\n", [error localizedDescription]);
            return 1;
        }

        NSLog(@"Device list:\n");

        YModule *module = yFirstModule();
        while (module != nil) {
            NSLog(@"%@ %@",module.serialNumber, module.productName);
            module = [module nextModule];
        }
    }
    return 0;
}
 

10.3. Error handling

When you implement a program which must interact with USB modules, you cannot disregard error handling. Inevitably, there will be a time when a user will have unplugged the device, either before running the software, or even while the software is running. The Yoctopuce library is designed to help you support this kind of behavior, but your code must nevertheless be conceived to interpret in the best possible way the errors indicated by the library.

The simplest way to work around the problem is the one used in the short examples provided in this chapter: before accessing a module, check that it is online with the isOnline function, and then hope that it will stay so during the fraction of a second necessary for the following code lines to run. This method is not perfect, but it can be sufficient in some cases. You must however be aware that you cannot completely exclude an error which would occur after the call to isOnline and which could crash the software. The only way to prevent this is to implement one of the two error handling techniques described below.

The method recommended by most programming languages for unpredictable error handling is the use of exceptions. By default, it is the behavior of the Yoctopuce library. If an error happens while you try to access a module, the library throws an exception. In this case, there are three possibilities:

As this latest situation is not the most desirable, the Yoctopuce library offers another possibility for error handling, allowing you to create a robust program without needing to catch exceptions at every line of code. You simply need to call the yDisableExceptions() function to commute the library to a mode where exceptions for all the functions are systematically replaced by specific return values, which can be tested by the caller when necessary. For each function, the name of each return value in case of error is systematically documented in the library reference. The name always follows the same logic: a get_state() method returns a Y_STATE_INVALID value, a get_currentValue method returns a Y_CURRENTVALUE_INVALID value, and so on. In any case, the returned value is of the expected type and is not a null pointer which would risk crashing your program. At worst, if you display the value without testing it, it will be outside the expected bounds for the returned value. In the case of functions which do not normally return information, the return value is YAPI_SUCCESS if everything went well, and a different error code in case of failure.

When you work without exceptions, you can obtain an error code and an error message explaining the source of the error. You can request them from the object which returned the error, calling the errType() and errMessage() methods. Their returned values contain the same information as in the exceptions when they are active.

11. Using Yocto-Servo with Visual Basic .NET

VisualBasic has long been the most favored entrance path to the Microsoft world. Therefore, we had to provide our library for this language, even if the new trend is shifting to C#. All the examples and the project models are tested with Microsoft VisualBasic 2010 Express, freely available on the Microsoft web site29.

11.1. Installation

Download the Visual Basic Yoctopuce library from the Yoctopuce web site30. There is no setup program, simply copy the content of the zip file into the directory of your choice. You mostly need the content of the Sources directory. The other directories contain the documentation and a few sample programs. All sample projects are Visual Basic 2010, projects, if you are using a previous version, you may have to recreate the projects structure from scratch.

11.2. Using the Yoctopuce API in a Visual Basic project

The Visual Basic.NET Yoctopuce library is composed of a DLL and of source files in Visual Basic. The DLL is not a .NET DLL, but a classic DLL, written in C, which manages the low level communications with the modules31. The source files in Visual Basic manage the high level part of the API. Therefore, your need both this DLL and the .vb files of the sources directory to create a project managing Yoctopuce modules.

Configuring a Visual Basic project

The following indications are provided for Visual Studio Express 2010, but the process is similar for other versions. Start by creating your project. Then, on the Solution Explorer panel, right click on your project, and select "Add" and then "Add an existing item".

A file selection window opens. Select the yocto_api.vb file and the files corresponding to the functions of the Yoctopuce modules that your project is going to manage. If in doubt, select all the files.

You then have the choice between simply adding these files to your project, or to add them as links (the Add button is in fact a scroll-down menu). In the first case, Visual Studio copies the selected files into your project. In the second case, Visual Studio simply keeps a link on the original files. We recommend you to use links, which makes updates of the library much easier.

Then add in the same manner the yapi.dll DLL, located in the Sources/dll directory32. Then, from the Solution Explorer window, right click on the DLL, select Properties and in the Properties panel, set the Copy to output folder to always. You are now ready to use your Yoctopuce modules from Visual Studio.

In order to keep them simple, all the examples provided in this documentation are console applications. Naturally, the libraries function in a strictly identical manner if you integrate them in an application with a graphical interface.

11.3. Control of the Servo function

A few lines of code are enough to use a Yocto-Servo. Here is the skeleton of a Visual Basic code snipplet to use the Servo function.


[...]
Dim errmsg As String errmsg
Dim servo As YServo
 
REM Get access to your device, connected locally on USB for instance
yRegisterHub("usb", errmsg)
servo = yFindServo("SERVORC1-123456.servo1")

REM Hot-plug is easy: just check that the device is online
If (servo.isOnline()) Then
   REM Use servo.set_position(), ...
End If

Let's look at these lines in more details.

yRegisterHub

The yRegisterHub function initializes the Yoctopuce API and indicates where the modules should be looked for. When used with the parameter "usb", it will use the modules locally connected to the computer running the library. If the initialization does not succeed, this function returns a value different from YAPI_SUCCESS and errmsg contains the error message.

yFindServo

The yFindServo function allows you to find a servo from the serial number of the module on which it resides and from its function name. You can use logical names as well, as long as you have initialized them. Let us imagine a Yocto-Servo module with serial number SERVORC1-123456 which you have named "MyModule", and for which you have given the servo1 function the name "MyFunction". The following five calls are strictly equivalent, as long as "MyFunction" is defined only once.


servo = yFindServo("SERVORC1-123456.servo1")
servo = yFindServo("SERVORC1-123456.MyFunction")
servo = yFindServo("MyModule.servo1")
servo = yFindServo("MyModule.MyFunction")
servo = yFindServo("MyFunction")

yFindServo returns an object which you can then use at will to control the servo.

isOnline

The isOnline() method of the object returned by yFindServo allows you to know if the corresponding module is present and in working order.

set_position

The set_position() method of the objet returned by yFindServo moves the servo position as quickly as possible to the specified target. The central position is 0, and the two extremities are -1000 and 1000.

move

The move() method of the objet returned by yFindServo moves the servo at a controlled speed to a desired position, within a time interval specified in milliseconds.

A real example

Launch Microsoft VisualBasic and open the corresponding sample project provided in the directory Examples/Doc-GettingStarted-Yocto-Servo of the Yoctopuce library.

In this example, you will recognize the functions explained above, but this time used with all side materials needed to make it work nicely as a small demo.

Module Module1

  Private Sub Usage()
    Dim execname = System.AppDomain.CurrentDomain.FriendlyName
    Console.WriteLine("Usage:")
    Console.WriteLine(execname+" <serial_number>  [ -1000 | ... | 1000 ]")
    Console.WriteLine(execname+" <logical_name> [ -1000 | ... | 1000 ]")
    Console.WriteLine(execname+" any [ -1000 | ... | 1000 ]")
    System.Threading.Thread.Sleep(2500)
    End
  End Sub


  Sub Main()
    Dim argv() As String = System.Environment.GetCommandLineArgs()
    Dim errmsg As String = ""
    Dim target As String
    Dim servo1 As YServo
    Dim servo5 As YServo
    Dim pos As Integer

    If argv.Length < 3 Then Usage()

    target = argv(1)
    pos = CInt(argv(2))

    REM Setup the API to use local USB devices
    If (yRegisterHub("usb", errmsg) <> YAPI_SUCCESS) Then
      Console.WriteLine("RegisterHub error: " + errmsg)
      End
    End If

    If target = "any" Then
      servo1 = yFirstServo()
      If servo1 Is Nothing Then
        Console.WriteLine("No module connected (check USB cable) ")
        End
      End If
      target = servo1.get_Module().get_serialNumber()
    End If
    servo1 = yFindServo(target + ".servo1")
    servo5 = yFindServo(target + ".servo5")

    If (servo1.isOnline()) Then
      servo1.set_position(pos)
      servo5.move(pos, 3000)
    Else
      Console.WriteLine("Module not connected (check identification and USB cable)")
    End If
  End Sub

End Module
 

11.4. Control of the module part

Each module can be controlled in a similar manner, you can find below a simple sample program displaying the main parameters of the module and enabling you to activate the localization beacon.


Imports System.IO
Imports System.Environment

Module Module1

  Sub usage()
    Console.WriteLine("usage: demo <serial or logical name> [ON/OFF]")  
    End
  End Sub

  Sub Main()
    Dim argv() As String = System.Environment.GetCommandLineArgs()
    Dim errmsg As String = ""
    Dim m As ymodule

    If (yRegisterHub("usb", errmsg) <> YAPI_SUCCESS) Then
      Console.WriteLine("RegisterHub error:" + errmsg)
      End
    End If

    If argv.Length < 2 Then usage()

    m = yFindModule(argv(1)) REM use serial or logical name

    If (m.isOnline()) Then
      If argv.Length > 2 Then
        If argv(2) = "ON" Then m.set_beacon(Y_BEACON_ON)
        If argv(2) = "OFF" Then m.set_beacon(Y_BEACON_OFF)
      End If
      Console.WriteLine("serial:       " + m.get_serialNumber())
      Console.WriteLine("logical name: " + m.get_logicalName())
      Console.WriteLine("luminosity:   " + Str(m.get_luminosity()))
      Console.Write("beacon:       ")
      If (m.get_beacon() = Y_BEACON_ON) Then
        Console.WriteLine("ON")
      Else
        Console.WriteLine("OFF")
      End If
      Console.WriteLine("upTime:       " + Str(m.get_upTime() / 1000) + " sec")
      Console.WriteLine("USB current:  " + Str(m.get_usbCurrent()) + " mA")
      Console.WriteLine("Logs:")
      Console.WriteLine(m.get_lastLogs())
    Else
      Console.WriteLine(argv(1) + " not connected (check identification and USB cable)")
    End If



  End Sub

End Module
 

Each property xxx of the module can be read thanks to a method of type get_xxxx(), and properties which are not read-only can be modified with the help of the set_xxx() method. For more details regarding the used functions, refer to the API chapters.

Changing the module settings

When you want to modify the settings of a module, you only need to call the corresponding set_xxx() function. However, this modification is performed only in the random access memory (RAM) of the module: if the module is restarted, the modifications are lost. To memorize them persistently, it is necessary to ask the module to save its current configuration in its permanent memory. To do so, use the saveToFlash() method. Inversely, it is possible to force the module to forget its current settings by using the revertFromFlash() method. The short example below allows you to modify the logical name of a module.

Module Module1


  Sub usage()

    Console.WriteLine("usage: demo <serial or logical name> <new logical name>")
    End
  End Sub

  Sub Main()
    Dim argv() As String = System.Environment.GetCommandLineArgs()
    Dim errmsg As String = ""
    Dim newname As String
    Dim m As YModule

    If (argv.Length <> 3) Then usage()

    REM Setup the API to use local USB devices
    If yRegisterHub("usb", errmsg) <> YAPI_SUCCESS Then
      Console.WriteLine("RegisterHub error: " + errmsg)
      End
    End If

    m = yFindModule(argv(1)) REM use serial or logical name
    If m.isOnline() Then

      newname = argv(2)
      If (Not yCheckLogicalName(newname)) Then
        Console.WriteLine("Invalid name (" + newname + ")")
        End
      End If
      m.set_logicalName(newname)
      m.saveToFlash() REM do not forget this

      Console.Write("Module: serial= " + m.get_serialNumber)
      Console.Write(" / name= " + m.get_logicalName())
    Else
      Console.Write("not connected (check identification and USB cable")
    End If

  End Sub

End Module
 

Warning: the number of write cycles of the nonvolatile memory of the module is limited. When this limit is reached, nothing guaranties that the saving process is performed correctly. This limit, linked to the technology employed by the module micro-processor, is located at about 100000 cycles. In short, you can use the saveToFlash() function only 100000 times in the life of the module. Make sure you do not call this function within a loop.

Listing the modules

Obtaining the list of the connected modules is performed with the yFirstModule() function which returns the first module found. Then, you only need to call the nextModule() function of this object to find the following modules, and this as long as the returned value is not Nothing. Below a short example listing the connected modules.

Module Module1

  Sub Main()
    Dim M As ymodule
    Dim errmsg As String = ""

    REM Setup the API to use local USB devices
    If yRegisterHub("usb", errmsg) <> YAPI_SUCCESS Then
      Console.WriteLine("RegisterHub error: " + errmsg)
      End
    End If

    Console.WriteLine("Device list")
    M = yFirstModule()
    While M IsNot Nothing
      Console.WriteLine(M.get_serialNumber() + " (" + M.get_productName() + ")")
      M = M.nextModule()
    End While

  End Sub

    End Module
 

11.5. Error handling

When you implement a program which must interact with USB modules, you cannot disregard error handling. Inevitably, there will be a time when a user will have unplugged the device, either before running the software, or even while the software is running. The Yoctopuce library is designed to help you support this kind of behavior, but your code must nevertheless be conceived to interpret in the best possible way the errors indicated by the library.

The simplest way to work around the problem is the one used in the short examples provided in this chapter: before accessing a module, check that it is online with the isOnline function, and then hope that it will stay so during the fraction of a second necessary for the following code lines to run. This method is not perfect, but it can be sufficient in some cases. You must however be aware that you cannot completely exclude an error which would occur after the call to isOnline and which could crash the software. The only way to prevent this is to implement one of the two error handling techniques described below.

The method recommended by most programming languages for unpredictable error handling is the use of exceptions. By default, it is the behavior of the Yoctopuce library. If an error happens while you try to access a module, the library throws an exception. In this case, there are three possibilities:

As this latest situation is not the most desirable, the Yoctopuce library offers another possibility for error handling, allowing you to create a robust program without needing to catch exceptions at every line of code. You simply need to call the yDisableExceptions() function to commute the library to a mode where exceptions for all the functions are systematically replaced by specific return values, which can be tested by the caller when necessary. For each function, the name of each return value in case of error is systematically documented in the library reference. The name always follows the same logic: a get_state() method returns a Y_STATE_INVALID value, a get_currentValue method returns a Y_CURRENTVALUE_INVALID value, and so on. In any case, the returned value is of the expected type and is not a null pointer which would risk crashing your program. At worst, if you display the value without testing it, it will be outside the expected bounds for the returned value. In the case of functions which do not normally return information, the return value is YAPI_SUCCESS if everything went well, and a different error code in case of failure.

When you work without exceptions, you can obtain an error code and an error message explaining the source of the error. You can request them from the object which returned the error, calling the errType() and errMessage() methods. Their returned values contain the same information as in the exceptions when they are active.

12. Using Yocto-Servo with C#

C# (pronounced C-Sharp) is an object-oriented programming language promoted by Microsoft, it is somewhat similar to Java. Like Visual-Basic and Delphi, it allows you to create Windows applications quite easily. All the examples and the project models are tested with Microsoft C# 2010 Express, freely available on the Microsoft web site33.

12.1. Installation

Download the Visual C# Yoctopuce library from the Yoctopuce web site34. There is no setup program, simply copy the content of the zip file into the directory of your choice. You mostly need the content of the Sources directory. The other directories contain the documentation and a few sample programs. All sample projects are Visual C# 2010, projects, if you are using a previous version, you may have to recreate the projects structure from scratch.

12.2. Using the Yoctopuce API in a Visual C# project

The Visual C#.NET Yoctopuce library is composed of a DLL and of source files in Visual C#. The DLL is not a .NET DLL, but a classic DLL, written in C, which manages the low level communications with the modules35. The source files in Visual C# manage the high level part of the API. Therefore, your need both this DLL and the .cs files of the sources directory to create a project managing Yoctopuce modules.

Configuring a Visual C# project

The following indications are provided for Visual Studio Express 2010, but the process is similar for other versions. Start by creating your project. Then, on the Solution Explorer panel, right click on your project, and select "Add" and then "Add an existing item".

A file selection window opens. Select the yocto_api.cs file and the files corresponding to the functions of the Yoctopuce modules that your project is going to manage. If in doubt, select all the files.

You then have the choice between simply adding these files to your project, or to add them as links (the Add button is in fact a scroll-down menu). In the first case, Visual Studio copies the selected files into your project. In the second case, Visual Studio simply keeps a link on the original files. We recommend you to use links, which makes updates of the library much easier.

Then add in the same manner the yapi.dll DLL, located in the Sources/dll directory36. Then, from the Solution Explorer window, right click on the DLL, select Properties and in the Properties panel, set the Copy to output folder to always. You are now ready to use your Yoctopuce modules from Visual Studio.

In order to keep them simple, all the examples provided in this documentation are console applications. Naturally, the libraries function in a strictly identical manner if you integrate them in an application with a graphical interface.

12.3. Control of the Servo function

A few lines of code are enough to use a Yocto-Servo. Here is the skeleton of a C# code snipplet to use the Servo function.


[...]
string errmsg ="";
YServo servo;
 
// Get access to your device, connected locally on USB for instance
YAPI.RegisterHub("usb", errmsg);
servo = YServo.FindServo("SERVORC1-123456.servo1");

// Hot-plug is easy: just check that the device is online
if (servo.isOnline())
 {  // Use servo.set_position(); ...
 }

Let's look at these lines in more details.

YAPI.RegisterHub

The YAPI.RegisterHub function initializes the Yoctopuce API and indicates where the modules should be looked for. When used with the parameter "usb", it will use the modules locally connected to the computer running the library. If the initialization does not succeed, this function returns a value different from YAPI.SUCCESS and errmsg contains the error message.

YServo.FindServo

The YServo.FindServo function allows you to find a servo from the serial number of the module on which it resides and from its function name. You can use logical names as well, as long as you have initialized them. Let us imagine a Yocto-Servo module with serial number SERVORC1-123456 which you have named "MyModule", and for which you have given the servo1 function the name "MyFunction". The following five calls are strictly equivalent, as long as "MyFunction" is defined only once.


servo = YServo.FindServo("SERVORC1-123456.servo1");
servo = YServo.FindServo("SERVORC1-123456.MyFunction");
servo = YServo.FindServo("MyModule.servo1");
servo = YServo.FindServo("MyModule.MyFunction");
servo = YServo.FindServo("MyFunction");

YServo.FindServo returns an object which you can then use at will to control the servo.

isOnline

The isOnline() method of the object returned by YServo.FindServo allows you to know if the corresponding module is present and in working order.

set_position

The set_position() method of the objet returned by YServo.FindServo moves the servo position as quickly as possible to the specified target. The central position is 0, and the two extremities are -1000 and 1000.

move

The move() method of the objet returned by YServo.FindServo moves the servo at a controlled speed to a desired position, within a time interval specified in milliseconds.

A real example

Launch Microsoft Visual C# and open the corresponding sample project provided in the directory Examples/Doc-GettingStarted-Yocto-Servo of the Yoctopuce library.

In this example, you will recognize the functions explained above, but this time used with all side materials needed to make it work nicely as a small demo.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
  class Program
  {
    static void usage()
    { string execname = System.AppDomain.CurrentDomain.FriendlyName;
      Console.WriteLine("Usage");
      Console.WriteLine(execname+" <serial_number>  [ -1000 | ... | 1000 ]");
      Console.WriteLine(execname+" <logical_name> [ -1000 | ... | 1000 ]");
      Console.WriteLine(execname+" any [ -1000 | ... | 1000 ]");
      System.Threading.Thread.Sleep(2500);
      Environment.Exit(0);
    }

    static void Main(string[] args)
    {
      string errmsg = "";
      string target;
      YServo servo1;
      YServo servo5;
      int pos;

      if (args.Length < 2) usage();
      target = args[0].ToUpper();
      pos = Convert.ToInt32(args[1]);

      if (YAPI.RegisterHub("usb", ref errmsg) != YAPI.SUCCESS)
      {
        Console.WriteLine("RegisterHub error: " + errmsg);
        Environment.Exit(0);
      }

      if (target == "ANY")
      {
        servo1 = YServo.FirstServo();
        if (servo1 == null)
        {
          Console.WriteLine("No module connected (check USB cable) ");
          Environment.Exit(0);
        }
        target = servo1.get_module().get_serialNumber();
      }

      servo1 = YServo.FindServo(target + ".servo1");
      servo5 = YServo.FindServo(target + ".servo5");

      if (servo1.isOnline())
      {
        servo1.set_position(pos);
        servo5.move(pos, 3000);
      }
      else
        Console.WriteLine("Module not connected (check identification and USB cable)");
    }
  }
}
 

12.4. Control of the module part

Each module can be controlled in a similar manner, you can find below a simple sample program displaying the main parameters of the module and enabling you to activate the localization beacon.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;


namespace ConsoleApplication1
{
  class Program
  {
    static void usage()
    { string execname = System.AppDomain.CurrentDomain.FriendlyName;
      Console.WriteLine("Usage:");
      Console.WriteLine(execname+" <serial or logical name> [ON/OFF]");
      System.Threading.Thread.Sleep(2500);
      Environment.Exit(0);
    }

    static void Main(string[] args)
    {
      YModule m;
      string errmsg = "";

      if (YAPI.RegisterHub("usb", ref errmsg) !=  YAPI.SUCCESS)
      {
        Console.WriteLine("RegisterHub error: " + errmsg);
        Environment.Exit(0);
      }

     
      if (args.Length < 1)  usage();

      m = YModule.FindModule(args[0]); // use serial or logical name

      if (m.isOnline())
      {
        if (args.Length >= 2)
        {
          if (args[1].ToUpper() == "ON") { m.set_beacon(YModule.BEACON_ON); }
          if (args[1].ToUpper() == "OFF") { m.set_beacon(YModule.BEACON_OFF); }
        }
     
        Console.WriteLine("serial:       " + m.get_serialNumber());
        Console.WriteLine("logical name: " + m.get_logicalName());
        Console.WriteLine("luminosity:   " + m.get_luminosity().ToString());
        Console.Write("beacon:       ");
        if (m.get_beacon() == YModule.BEACON_ON)
          Console.WriteLine("ON");
        else
          Console.WriteLine("OFF");
        Console.WriteLine("upTime:       " + (m.get_upTime() / 1000 ).ToString()+ " sec");
        Console.WriteLine("USB current:  " + m.get_usbCurrent().ToString() + " mA");
        Console.WriteLine("Logs:\r\n"+ m.get_lastLogs());

      }
    else
      Console.WriteLine(args[0] + " not connected (check identification and USB cable)");
   
   }
  }
}
 

Each property xxx of the module can be read thanks to a method of type YModule.get_xxxx(), and properties which are not read-only can be modified with the help of the YModule.set_xxx() method. For more details regarding the used functions, refer to the API chapters.

Changing the module settings

When you want to modify the settings of a module, you only need to call the corresponding YModule.set_xxx() function. However, this modification is performed only in the random access memory (RAM) of the module: if the module is restarted, the modifications are lost. To memorize them persistently, it is necessary to ask the module to save its current configuration in its permanent memory. To do so, use the YModule.saveToFlash() method. Inversely, it is possible to force the module to forget its current settings by using the YModule.revertFromFlash() method. The short example below allows you to modify the logical name of a module.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
  class Program
  {
    static void usage()
    { string execname = System.AppDomain.CurrentDomain.FriendlyName;
      Console.WriteLine("Usage:");
      Console.WriteLine("usage: demo <serial or logical name> <new logical name>");
      System.Threading.Thread.Sleep(2500);
      Environment.Exit(0);
    }

    static void Main(string[] args)
    {
      YModule m;
      string errmsg = "";
      string newname;

      if (args.Length != 2) usage();

      if (YAPI.RegisterHub("usb", ref errmsg) !=  YAPI.SUCCESS)
      {
        Console.WriteLine("RegisterHub error: " + errmsg);
        Environment.Exit(0);
      }

      m = YModule.FindModule(args[0]); // use serial or logical name

      if (m.isOnline())
      {
        newname = args[1];
        if (!YAPI.CheckLogicalName(newname))
        {
          Console.WriteLine("Invalid name (" + newname + ")");
          Environment.Exit(0);
        }

        m.set_logicalName(newname);
        m.saveToFlash(); // do not forget this

        Console.Write("Module: serial= " + m.get_serialNumber());
        Console.WriteLine(" / name= " + m.get_logicalName());
      }
      else
        Console.Write("not connected (check identification and USB cable");
    }
  }
}
 

Warning: the number of write cycles of the nonvolatile memory of the module is limited. When this limit is reached, nothing guaranties that the saving process is performed correctly. This limit, linked to the technology employed by the module micro-processor, is located at about 100000 cycles. In short, you can use the YModule.saveToFlash() function only 100000 times in the life of the module. Make sure you do not call this function within a loop.

Listing the modules

Obtaining the list of the connected modules is performed with the YModule.yFirstModule() function which returns the first module found. Then, you only need to call the nextModule() function of this object to find the following modules, and this as long as the returned value is not null. Below a short example listing the connected modules.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
  class Program
  {
    static void Main(string[] args)
    {
      YModule m;
      string errmsg = "";

      if (YAPI.RegisterHub("usb", ref errmsg) !=  YAPI.SUCCESS)
      {
        Console.WriteLine("RegisterHub error: " + errmsg);
        Environment.Exit(0);
      }

      Console.WriteLine("Device list");
      m = YModule.FirstModule();
      while (m!=null)
      { Console.WriteLine(m.get_serialNumber() + " (" + m.get_productName() + ")");
       m = m.nextModule();
      }

    }
  }
}
 

12.5. Error handling

When you implement a program which must interact with USB modules, you cannot disregard error handling. Inevitably, there will be a time when a user will have unplugged the device, either before running the software, or even while the software is running. The Yoctopuce library is designed to help you support this kind of behavior, but your code must nevertheless be conceived to interpret in the best possible way the errors indicated by the library.

The simplest way to work around the problem is the one used in the short examples provided in this chapter: before accessing a module, check that it is online with the isOnline function, and then hope that it will stay so during the fraction of a second necessary for the following code lines to run. This method is not perfect, but it can be sufficient in some cases. You must however be aware that you cannot completely exclude an error which would occur after the call to isOnline and which could crash the software. The only way to prevent this is to implement one of the two error handling techniques described below.

The method recommended by most programming languages for unpredictable error handling is the use of exceptions. By default, it is the behavior of the Yoctopuce library. If an error happens while you try to access a module, the library throws an exception. In this case, there are three possibilities:

As this latest situation is not the most desirable, the Yoctopuce library offers another possibility for error handling, allowing you to create a robust program without needing to catch exceptions at every line of code. You simply need to call the yDisableExceptions() function to commute the library to a mode where exceptions for all the functions are systematically replaced by specific return values, which can be tested by the caller when necessary. For each function, the name of each return value in case of error is systematically documented in the library reference. The name always follows the same logic: a get_state() method returns a Y_STATE_INVALID value, a get_currentValue method returns a Y_CURRENTVALUE_INVALID value, and so on. In any case, the returned value is of the expected type and is not a null pointer which would risk crashing your program. At worst, if you display the value without testing it, it will be outside the expected bounds for the returned value. In the case of functions which do not normally return information, the return value is YAPI_SUCCESS if everything went well, and a different error code in case of failure.

When you work without exceptions, you can obtain an error code and an error message explaining the source of the error. You can request them from the object which returned the error, calling the errType() and errMessage() methods. Their returned values contain the same information as in the exceptions when they are active.

13. Using Yocto-Servo with Delphi

Delphi is a descendent of Turbo-Pascal. Originally, Delphi was produced by Borland, Embarcadero now edits it. The strength of this language resides in its ease of use, as anyone with some notions of the Pascal language can develop a Windows application in next to no time. Its only disadvantage is to cost something37.

Delphi libraries are provided not as VCL components, but directly as source files. These files are compatible with most Delphi versions. 38

To keep them simple, all the examples provided in this documentation are console applications. Obviously, the libraries work in a strictly identical way with VCL applications.

You will soon notice that the Delphi API defines many functions which return objects. You do not need to deallocate these objects yourself, the API does it automatically at the end of the application.

13.1. Preparation

Go to the Yoctopuce web site and download the Yoctopuce Delphi libraries39. Uncompress everything in a directory of your choice, add the subdirectory sources in the list of directories of Delphi libraries.40

By default, the Yoctopuce Delphi library uses the yapi.dll DLL, all the applications you will create with Delphi must have access to this DLL. The simplest way to ensure this is to make sure yapi.dll is located in the same directory as the executable file of your application.

13.2. Control of the Servo function

Launch your Delphi environment, copy the yapi.dll DLL in a directory, create a new console application in the same directory, and copy-paste the piece of code below:

program helloworld;
{$APPTYPE CONSOLE}
uses
  SysUtils,
  yocto_api,
  yocto_servo;

procedure usage();
  var
    execname:string;
  begin
    execname := ExtractFileName(paramstr(0));
    WriteLn('Usage:');
    WriteLn(execname + ' <serial_number> <channel> position');
    WriteLn(execname + ' <logical_name> <channel> position');
    WriteLn(execname + ' any <channel> position');
    WriteLn('Example:');
    WriteLn(execname + ' any 2 1000');
    sleep(2500);
    halt;
  end;

var
 errmsg,target,channel:string;
 position:integer;
 servo:TYservo;
 m : TYModule;

begin
  if (paramcount<3) then usage();

  target   :=  UpperCase(paramstr(1));
  channel  :=  paramstr(2);
  position :=  StrToInt(paramstr(3));

  if (YRegisterHub('usb', errmsg) <> YAPI_SUCCESS)  then
    begin
      writeln('RegisterHub error: ' + errmsg);
      halt;
    end;

  if (target='ANY') then
    begin
      servo :=  YFirstServo();
      if (servo =nil) then
       begin
         writeln('No module connected (check USB cable)');
         halt;
       end;
      m :=  servo.get_module();
      target := m. get_serialNumber();
     end;

  Writeln('using ' + target);
  servo := YFindServo(target + '.servo'+channel);

  if (servo.isOnline()) then servo.move(position,1500)
  else writeln('Module not connected (check identification and USB cable)');

end.
 

There are only a few really important lines in this sample example. We will look at them in details.

yocto_api and yocto_servo

These two units provide access to the functions allowing you to manage Yoctopuce modules. yocto_api must always be used, yocto_servo is necessary to manage modules containing a servo, such as Yocto-Servo.

yRegisterHub

The yRegisterHub function initializes the Yoctopuce API and specifies where the modules should be looked for. When used with the parameter 'usb', it will use the modules locally connected to the computer running the library. If the initialization does not succeed, this function returns a value different from YAPI_SUCCESS and errmsg contains the error message.

yFindServo

The yFindServo function allows you to find a servo from the serial number of the module on which it resides and from its function name. You can also use logical names, as long as you have initialized them. Let us imagine a Yocto-Servo module with serial number SERVORC1-123456 which you have named "MyModule", and for which you have given the servo1 function the name "MyFunction". The following five calls are strictly equivalent, as long as "MyFunction" is defined only once.


servo := yFindServo("SERVORC1-123456.servo1");
servo := yFindServo("SERVORC1-123456.MyFunction");
servo := yFindServo("MyModule.servo1");
servo := yFindServo("MyModule.MyFunction");
servo := yFindServo("MyFunction");

yFindServo returns an object which you can then use at will to control the servo.

isOnline

The isOnline() method of the object returned by yFindServo allows you to know if the corresponding module is present and in working order.

set_position

The set_position() method of the objet returned by yFindServo moves the servo position as quickly as possible to the specified target. The central position is 0, and the two extremities are -1000 and 1000.

move

The move() method of the objet returned by yFindServo moves the servo at a controlled speed to a desired position, within a time interval specified in milliseconds.

13.3. Control of the module part

Each module can be controlled in a similar manner, you can find below a simple sample program displaying the main parameters of the module and enabling you to activate the localization beacon.

program modulecontrol;
{$APPTYPE CONSOLE}
uses
  SysUtils,
  yocto_api;

const
  serial = 'SERVORC1-123456'; // use serial number or logical name

procedure refresh(module:Tymodule) ;
  begin
    if (module.isOnline())  then
     begin
       Writeln('');
       Writeln('Serial       : ' + module.get_serialNumber());
       Writeln('Logical name : ' + module.get_logicalName());
       Writeln('Luminosity   : ' + intToStr(module.get_luminosity()));
       Write('Beacon    :');
       if  (module.get_beacon()=Y_BEACON_ON) then Writeln('on')
                                             else Writeln('off');
       Writeln('uptime       : ' + intToStr(module.get_upTime() div 1000)+'s');
       Writeln('USB current  : ' + intToStr(module.get_usbCurrent())+'mA');
       Writeln('Logs         : ');
       Writeln(module.get_lastlogs());
       Writeln('');
       Writeln('r : refresh / b:beacon ON / space : beacon off');
     end
    else Writeln('Module not connected (check identification and USB cable)');
  end;


procedure beacon(module:Tymodule;state:integer);
  begin
    module.set_beacon(state);
    refresh(module);
  end;

var
  module : TYModule;
  c      : char;
  errmsg : string;

begin
  // Setup the API to use local USB devices
  if yRegisterHub('usb', errmsg)<>YAPI_SUCCESS then
  begin
    Write('RegisterHub error: '+errmsg);
    exit;
  end;

  module := yFindModule(serial);
  refresh(module);

  repeat
    read(c);
    case c of
     'r': refresh(module);
     'b': beacon(module,Y_BEACON_ON);
     ' ': beacon(module,Y_BEACON_OFF);
    end;
  until  c = 'x';
end.

Each property xxx of the module can be read thanks to a method of type get_xxxx(), and properties which are not read-only can be modified with the help of the set_xxx() method. For more details regarding the used functions, refer to the API chapters.

Changing the module settings

When you want to modify the settings of a module, you only need to call the corresponding set_xxx() function. However, this modification is performed only in the random access memory (RAM) of the module: if the module is restarted, the modifications are lost. To memorize them persistently, it is necessary to ask the module to save its current configuration in its permanent memory. To do so, use the saveToFlash() method. Inversely, it is possible to force the module to forget its current settings by using the revertFromFlash() method. The short example below allows you to modify the logical name of a module.

program savesettings;
{$APPTYPE CONSOLE}
uses
  SysUtils,
  yocto_api;

const
  serial = 'SERVORC1-123456'; // use serial number or logical name

var
  module  : TYModule;
  errmsg  : string;
  newname : string;
 
begin
  // Setup the API to use local USB devices
  if yRegisterHub('usb', errmsg)<>YAPI_SUCCESS then
  begin
    Write('RegisterHub error: '+errmsg);
    exit;
  end;

  module := yFindModule(serial);
  if (not(module.isOnline)) then
   begin
     writeln('Module not connected (check identification and USB cable)');
     exit;
   end;

  Writeln('Current logical name : '+module.get_logicalName());
  Write('Enter new name : ');
  Readln(newname);
  if (not(yCheckLogicalName(newname))) then
   begin
     Writeln('invalid logical name');
     exit;
   end;
  module.set_logicalName(newname);
  module.saveToFlash();
 
  Writeln('logical name is now : '+module.get_logicalName());
end.
 

Warning: the number of write cycles of the nonvolatile memory of the module is limited. When this limit is reached, nothing guaranties that the saving process is performed correctly. This limit, linked to the technology employed by the module micro-processor, is located at about 100000 cycles. In short, you can use the saveToFlash() function only 100000 times in the life of the module. Make sure you do not call this function within a loop.

Listing the modules

Obtaining the list of the connected modules is performed with the yFirstModule() function which returns the first module found. Then, you only need to call the nextModule() function of this object to find the following modules, and this as long as the returned value is not nil. Below a short example listing the connected modules.

program inventory;
{$APPTYPE CONSOLE}
uses
  SysUtils,
  yocto_api;

var
  module : TYModule;
  errmsg : string;

begin
  // Setup the API to use local USB devices
  if yRegisterHub('usb', errmsg)<>YAPI_SUCCESS then
  begin
    Write('RegisterHub error: '+errmsg);
    exit;
  end;

  Writeln('Device list');

  module := yFirstModule();
  while module<>nil  do
   begin
     Writeln( module.get_serialNumber()+' ('+module.get_productName()+')');
     module := module.nextModule();
   end;

end.

13.4. Error handling

When you implement a program which must interact with USB modules, you cannot disregard error handling. Inevitably, there will be a time when a user will have unplugged the device, either before running the software, or even while the software is running. The Yoctopuce library is designed to help you support this kind of behavior, but your code must nevertheless be conceived to interpret in the best possible way the errors indicated by the library.

The simplest way to work around the problem is the one used in the short examples provided in this chapter: before accessing a module, check that it is online with the isOnline function, and then hope that it will stay so during the fraction of a second necessary for the following code lines to run. This method is not perfect, but it can be sufficient in some cases. You must however be aware that you cannot completely exclude an error which would occur after the call to isOnline and which could crash the software. The only way to prevent this is to implement one of the two error handling techniques described below.

The method recommended by most programming languages for unpredictable error handling is the use of exceptions. By default, it is the behavior of the Yoctopuce library. If an error happens while you try to access a module, the library throws an exception. In this case, there are three possibilities:

As this latest situation is not the most desirable, the Yoctopuce library offers another possibility for error handling, allowing you to create a robust program without needing to catch exceptions at every line of code. You simply need to call the yDisableExceptions() function to commute the library to a mode where exceptions for all the functions are systematically replaced by specific return values, which can be tested by the caller when necessary. For each function, the name of each return value in case of error is systematically documented in the library reference. The name always follows the same logic: a get_state() method returns a Y_STATE_INVALID value, a get_currentValue method returns a Y_CURRENTVALUE_INVALID value, and so on. In any case, the returned value is of the expected type and is not a null pointer which would risk crashing your program. At worst, if you display the value without testing it, it will be outside the expected bounds for the returned value. In the case of functions which do not normally return information, the return value is YAPI_SUCCESS if everything went well, and a different error code in case of failure.

When you work without exceptions, you can obtain an error code and an error message explaining the source of the error. You can request them from the object which returned the error, calling the errType() and errMessage() methods. Their returned values contain the same information as in the exceptions when they are active.

14. Using the Yocto-Servo with Python

Python is an interpreted object oriented language developed by Guido van Rossum. Among its advantages is the fact that it is free, and the fact that it is available for most platforms, Windows as well as UNIX. It is an ideal language to write small scripts on a napkin. The Yoctopuce library is compatible with Python 2.6+ and 3+. It works under Windows, Mac OS X, and Linux, Intel as well as ARM. The library was tested with Python 2.6 and Python 3.2. Python interpreters are available on the Python web site41.

14.1. Source files

The Yoctopuce library classes42 for Python that you will use are provided as source files. Copy all the content of the Sources directory in the directory of your choice and add this directory to the PYTHONPATH environment variable. If you use an IDE to program in Python, refer to its documentation to configure it so that it automatically finds the API source files.

14.2. Dynamic library

A section of the low-level library is written in C, but you should not need to interact directly with it: it is provided as a DLL under Windows, as a .so files under UNIX, and as a .dylib file under Mac OS X. Everything was done to ensure the simplest possible interaction from Python: the distinct versions of the dynamic library corresponding to the distinct operating systems and architectures are stored in the cdll directory. The API automatically loads the correct file during its initialization. You should not have to worry about it.

If you ever need to recompile the dynamic library, its complete source code is located in the Yoctopuce C++ library.

In order to keep them simple, all the examples provided in this documentation are console applications. Naturally, the libraries function in a strictly identical manner if you integrate them in an application with a graphical interface.

14.3. Control of the Servo function

A few lines of code are enough to use a Yocto-Servo. Here is the skeleton of a Python code snipplet to use the Servo function.


[...]

errmsg=YRefParam()
#Get access to your device, connected locally on USB for instance
YAPI.RegisterHub("usb",errmsg)
servo = YServo.FindServo("SERVORC1-123456.servo1")

# Hot-plug is easy: just check that the device is online
if servo.isOnline():
    #Use servo.set_position()
    ...
   
[...]    

Let's look at these lines in more details.

YAPI.RegisterHub

The yAPI.RegisterHub function initializes the Yoctopuce API and indicates where the modules should be looked for. When used with the parameter "usb", it will use the modules locally connected to the computer running the library. If the initialization does not succeed, this function returns a value different from YAPI.SUCCESS and errmsg contains the error message.

YServo.FindServo

The YServo.FindServo function allows you to find a servo from the serial number of the module on which it resides and from its function name. You can use logical names as well, as long as you have initialized them. Let us imagine a Yocto-Servo module with serial number SERVORC1-123456 which you have named "MyModule", and for which you have given the servo1 function the name "MyFunction". The following five calls are strictly equivalent, as long as "MyFunction" is defined only once.


servo = YServo.FindServo("SERVORC1-123456.servo1")
servo = YServo.FindServo("SERVORC1-123456.MyFunction")
servo = YServo.FindServo("MyModule.servo1")
servo = YServo.FindServo("MyModule.MyFunction")
servo = YServo.FindServo("MyFunction")

YServo.FindServo returns an object which you can then use at will to control the servo.

isOnline

The isOnline() method of the object returned by YServo.FindServo allows you to know if the corresponding module is present and in working order.

set_position

The set_position() method of the objet returned by YServo.FindServo moves the servo position as quickly as possible to the specified target. The central position is 0, and the two extremities are -1000 and 1000.

move

The move() method of the objet returned by YServo.FindServo moves the servo at a controlled speed to a desired position, within a time interval specified in milliseconds.

A real example

Launch Python and open the corresponding sample script provided in the directory Examples/Doc-GettingStarted-Yocto-Servo of the Yoctopuce library.

In this example, you will recognize the functions explained above, but this time used with all side materials needed to make it work nicely as a small demo.

#!/usr/bin/python
# -*- coding: utf-8 -*-
import os,sys
from yocto_api import *
from yocto_servo import *

def usage():
    scriptname = os.path.basename(sys.argv[0])
    print("Usage:")
    print(scriptname + ' <serial_number> <channel> position')
    print(scriptname + ' <logical_name> <channel> position')
    print(scriptname + ' any <channel> position')
    print('Example:')
    print(scriptname + ' any 2 500')
    sys.exit()

def die(msg):
    sys.exit(msg+' (check USB cable)')

if len(sys.argv)<3 :  usage()

target=sys.argv[1].upper()
channel=sys.argv[2]
position=int(sys.argv[3])

# Setup the API to use local USB devices
errmsg=YRefParam()
if YAPI.RegisterHub("usb", errmsg)!= YAPI.SUCCESS:
    sys.exit("init error"+errmsg.value)

if target=='ANY':
    # retreive any servo then find its serial #
    servo = YServo.FirstServo()
    if servo is None : die('No module connected')
    m=servo.get_module()
    target = m.get_serialNumber()

print('using ' + target)
servo = YServo.FindServo(target + '.servo'+channel)

if not(servo.isOnline()):die('device not connected')

servo.move(position,1000)

 

14.4. Control of the module part

Each module can be controlled in a similar manner, you can find below a simple sample program displaying the main parameters of the module and enabling you to activate the localization beacon.

#!/usr/bin/python
# -*- coding: utf-8 -*-
import os,sys
from yocto_api import *


def usage():
    sys.exit("usage: demo <serial or logical name> [ON/OFF]")

errmsg =YRefParam()
if YAPI.RegisterHub("usb", errmsg) !=  YAPI.SUCCESS:
    sys.exit("RegisterHub error: " + str(errmsg))

if len(sys.argv)<2 : usage()

m = YModule.FindModule(sys.argv[1]) ## use serial or logical name

if m.isOnline():
    if len(sys.argv) > 2:
        if sys.argv[2].upper() == "ON" :  m.set_beacon(YModule.BEACON_ON)
        if sys.argv[2].upper() == "OFF" : m.set_beacon(YModule.BEACON_OFF)

    print("serial:       " + m.get_serialNumber())
    print("logical name: " + m.get_logicalName())
    print("luminosity:   " + str(m.get_luminosity()))
    if m.get_beacon() == YModule.BEACON_ON:
        print("beacon:       ON")
    else:
        print("beacon:       OFF")
    print("upTime:       " + str(m.get_upTime()/1000)+" sec")
    print("USB current:  " + str(m.get_usbCurrent())+" mA")
    print("logs:\n" + m.get_lastLogs())    
else:
    print(sys.argv[1] + " not connected (check identification and USB cable)")



 

Each property xxx of the module can be read thanks to a method of type YModule.get_xxxx(), and properties which are not read-only can be modified with the help of the YModule.set_xxx() method. For more details regarding the used functions, refer to the API chapters.

Changing the module settings

When you want to modify the settings of a module, you only need to call the corresponding YModule.set_xxx() function. However, this modification is performed only in the random access memory (RAM) of the module: if the module is restarted, the modifications are lost. To memorize them persistently, it is necessary to ask the module to save its current configuration in its permanent memory. To do so, use the YModule.saveToFlash() method. Inversely, it is possible to force the module to forget its current settings by using the YModule.revertFromFlash() method. The short example below allows you to modify the logical name of a module.

#!/usr/bin/python
# -*- coding: utf-8 -*-
import os,sys
from yocto_api import *

def usage():
    sys.exit("usage: demo <serial or logical name> <new logical name>")

if len(sys.argv) != 3 :  usage()

errmsg =YRefParam()
if YAPI.RegisterHub("usb", errmsg) !=  YAPI.SUCCESS:
    sys.exit("RegisterHub error: " + str(errmsg))

m = YModule.FindModule(sys.argv[1]) # use serial or logical name

if m.isOnline():
    newname = sys.argv[2]
    if not YAPI.CheckLogicalName(newname):
        sys.exit("Invalid name (" + newname + ")")
    m.set_logicalName(newname)
    m.saveToFlash()  # do not forget this
    print ("Module: serial= " + m.get_serialNumber()+" / name= " + m.get_logicalName())
else:
    sys.exit("not connected (check identification and USB cable")

 

Warning: the number of write cycles of the nonvolatile memory of the module is limited. When this limit is reached, nothing guaranties that the saving process is performed correctly. This limit, linked to the technology employed by the module micro-processor, is located at about 100000 cycles. In short, you can use the YModule.saveToFlash() function only 100000 times in the life of the module. Make sure you do not call this function within a loop.

Listing the modules

Obtaining the list of the connected modules is performed with the YModule.yFirstModule() function which returns the first module found. Then, you only need to call the nextModule() function of this object to find the following modules, and this as long as the returned value is not null. Below a short example listing the connected modules.

#!/usr/bin/python
# -*- coding: utf-8 -*-
import os,sys

from yocto_api import *

errmsg=YRefParam()

# Setup the API to use local USB devices
if YAPI.RegisterHub("usb", errmsg)!= YAPI.SUCCESS:
    sys.exit("init error"+str(errmsg))

print('Device list')

module = YModule.FirstModule()
while module is not None:
     print(module.get_serialNumber()+' ('+module.get_productName()+')')
     module = module.nextModule()
 

14.5. Error handling

When you implement a program which must interact with USB modules, you cannot disregard error handling. Inevitably, there will be a time when a user will have unplugged the device, either before running the software, or even while the software is running. The Yoctopuce library is designed to help you support this kind of behavior, but your code must nevertheless be conceived to interpret in the best possible way the errors indicated by the library.

The simplest way to work around the problem is the one used in the short examples provided in this chapter: before accessing a module, check that it is online with the isOnline function, and then hope that it will stay so during the fraction of a second necessary for the following code lines to run. This method is not perfect, but it can be sufficient in some cases. You must however be aware that you cannot completely exclude an error which would occur after the call to isOnline and which could crash the software. The only way to prevent this is to implement one of the two error handling techniques described below.

The method recommended by most programming languages for unpredictable error handling is the use of exceptions. By default, it is the behavior of the Yoctopuce library. If an error happens while you try to access a module, the library throws an exception. In this case, there are three possibilities:

As this latest situation is not the most desirable, the Yoctopuce library offers another possibility for error handling, allowing you to create a robust program without needing to catch exceptions at every line of code. You simply need to call the yDisableExceptions() function to commute the library to a mode where exceptions for all the functions are systematically replaced by specific return values, which can be tested by the caller when necessary. For each function, the name of each return value in case of error is systematically documented in the library reference. The name always follows the same logic: a get_state() method returns a Y_STATE_INVALID value, a get_currentValue method returns a Y_CURRENTVALUE_INVALID value, and so on. In any case, the returned value is of the expected type and is not a null pointer which would risk crashing your program. At worst, if you display the value without testing it, it will be outside the expected bounds for the returned value. In the case of functions which do not normally return information, the return value is YAPI_SUCCESS if everything went well, and a different error code in case of failure.

When you work without exceptions, you can obtain an error code and an error message explaining the source of the error. You can request them from the object which returned the error, calling the errType() and errMessage() methods. Their returned values contain the same information as in the exceptions when they are active.

15. Using the Yocto-Servo with Java

Java is an object oriented language created by Sun Microsystem. Beside being free, its main strength is its portability. Unfortunately, this portability has an excruciating price. In Java, hardware abstraction is so high that it is almost impossible to work directly with the hardware. Therefore, the Yoctopuce API does not support native mode in regular Java. The Java API needs a Virtual Hub to communicate with Yoctopuce devices.

15.1. Getting ready

Go to the Yoctopuce web site and download the following items:

The library is available as source files as well as a jar file. Decompress the library files in a folder of your choice, connect your modules, run the VirtualHub software, and you are ready to start your first tests. You do not need to install any driver.

In order to keep them simple, all the examples provided in this documentation are console applications. Naturally, the libraries function in a strictly identical manner if you integrate them in an application with a graphical interface.

15.2. Control of the Servo function

A few lines of code are enough to use a Yocto-Servo. Here is the skeleton of a Java code snippet to use the Servo function.


[...]

// Get access to your device, connected locally on USB for instance
YAPI.RegisterHub("127.0.0.1");
servo = YServo.FindServo("SERVORC1-123456.servo1");

// Hot-plug is easy: just check that the device is online
if (servo.isOnline())
   { //Use servo.set_position()
     ...
   }

[...]

Let us look at these lines in more details.

YAPI.RegisterHub

The yAPI.RegisterHub function initializes the Yoctopuce API and indicates where the modules should be looked for. The parameter is the address of the Virtual Hub able to see the devices. If the initialization does not succeed, an exception is thrown.

YServo.FindServo

The YServo.FindServo function allows you to find a servo from the serial number of the module on which it resides and from its function name. You can use logical names as well, as long as you have initialized them. Let us imagine a Yocto-Servo module with serial number SERVORC1-123456 which you have named "MyModule", and for which you have given the servo1 function the name "MyFunction". The following five calls are strictly equivalent, as long as "MyFunction" is defined only once.


servo = YServo.FindServo("SERVORC1-123456.servo1")
servo = YServo.FindServo("SERVORC1-123456.MyFunction")
servo = YServo.FindServo("MyModule.servo1")
servo = YServo.FindServo("MyModule.MyFunction")
servo = YServo.FindServo("MyFunction")

YServo.FindServo returns an object which you can then use at will to control the servo.

isOnline

The isOnline() method of the object returned by YServo.FindServo allows you to know if the corresponding module is present and in working order.

set_position

The set_position() method of the objet returned by YServo.FindServo moves the servo position as quickly as possible to the specified target. The central position is 0, and the two extremities are -1000 and 1000.

move

The move() method of the objet returned by YServo.FindServo moves the servo at a controlled speed to a desired position, within a time interval specified in milliseconds.

A real example

Launch you Java environment and open the corresponding sample project provided in the directory Examples/Doc-GettingStarted-Yocto-Servo of the Yoctopuce library.

In this example, you will recognize the functions explained above, but this time used with all the side materials needed to make it work nicely as a small demo.

import com.yoctopuce.YoctoAPI.*;

public class Demo {

    public static void main(String[] args)   {
        try {
            // setup the API to use local VirtualHub
            YAPI.RegisterHub("127.0.0.1");
        } catch (YAPI_Exception ex) {
            System.out.println("Cannot contact VirtualHub on 127.0.0.1 (" + ex.getLocalizedMessage() + ")");
            System.out.println("Ensure that the VirtualHub application is running");
            System.exit(1);
        }

        String serial = "";
        if (args.length > 0) {
            serial = args[0];
        } else {
            YServo tmp = YServo.FirstServo();
            if (tmp == null) {
                System.out.println("No module connected (check USB cable)");
                System.exit(1);
            }
            try {
                serial = tmp.module().get_serialNumber();
            } catch (YAPI_Exception ex) {
                System.out.println("No module connected (check USB cable)");
                System.exit(1);
            }
        }
        YServo servo1 = YServo.FindServo(serial + ".servo1");
        YServo servo5 = YServo.FindServo(serial + ".servo5");



        int pos[] = {-1000,1000,0};
        for(int p : pos) {
            try {
                System.out.println(String.format("Change postition to %d", p));
                servo1.set_position(p);//imediat transition
                servo5.move(p, 1000); // smooth transition
                YAPI.Sleep(1000);
            } catch (YAPI_Exception ex) {
                System.out.println("Module not connected (check identification and USB cable)");
                break;
            }
        }

        YAPI.FreeAPI();
    }
}
 

15.3. Control of the module part

Each module can be controlled in a similar manner, you can find below a simple sample program displaying the main parameters of the module and enabling you to activate the localization beacon.


import com.yoctopuce.YoctoAPI.*;
import java.util.logging.Level;
import java.util.logging.Logger;

public class Demo {

    public static void main(String[] args)
    {
        try {
            // setup the API to use local VirtualHub
            YAPI.RegisterHub("127.0.0.1");
        } catch (YAPI_Exception ex) {
            System.out.println("Cannot contact VirtualHub on 127.0.0.1 (" + ex.getLocalizedMessage() + ")");
            System.out.println("Ensure that the VirtualHub application is running");
            System.exit(1);
        }
        System.out.println("usage: demo [serial or logical name] [ON/OFF]");

        YModule module;
        if (args.length == 0) {
            module = YModule.FirstModule();
            if (module == null) {
                System.out.println("No module connected (check USB cable)");
                System.exit(1);
            }
        } else {
            module = YModule.FindModule(args[0]);  // use serial or logical name
        }

        try {
            if (args.length > 1) {
                if (args[1].equalsIgnoreCase("ON")) {
                    module.setBeacon(YModule.BEACON_ON);
                } else {
                    module.setBeacon(YModule.BEACON_OFF);
                }
            }
            System.out.println("serial:       " + module.get_serialNumber());
            System.out.println("logical name: " + module.get_logicalName());
            System.out.println("luminosity:   " + module.get_luminosity());
            if (module.get_beacon() == YModule.BEACON_ON) {
                System.out.println("beacon:       ON");
            } else {
                System.out.println("beacon:       OFF");
            }
            System.out.println("upTime:       " + module.get_upTime() / 1000 + " sec");
            System.out.println("USB current:  " + module.get_usbCurrent() + " mA");
            System.out.println("logs:\n" + module.get_lastLogs());
        } catch (YAPI_Exception ex) {
            System.out.println(args[1] + " not connected (check identification and USB cable)");
        }
        YAPI.FreeAPI();
    }
}
 

Each property xxx of the module can be read thanks to a method of type YModule.get_xxxx(), and properties which are not read-only can be modified with the help of the YModule.set_xxx() method. For more details regarding the used functions, refer to the API chapters.

Changing the module settings

When you want to modify the settings of a module, you only need to call the corresponding YModule.set_xxx() function. However, this modification is performed only in the random access memory (RAM) of the module: if the module is restarted, the modifications are lost. To memorize them persistently, it is necessary to ask the module to save its current configuration in its permanent memory. To do so, use the YModule.saveToFlash() method. Inversely, it is possible to force the module to forget its current settings by using the YModule.revertFromFlash() method. The short example below allows you to modify the logical name of a module.

import com.yoctopuce.YoctoAPI.*;

public class Demo {

    public static void main(String[] args)
    {
        try {
            // setup the API to use local VirtualHub
            YAPI.RegisterHub("127.0.0.1");
        } catch (YAPI_Exception ex) {
            System.out.println("Cannot contact VirtualHub on 127.0.0.1 (" + ex.getLocalizedMessage() + ")");
            System.out.println("Ensure that the VirtualHub application is running");
            System.exit(1);
        }

        if (args.length != 2) {
            System.out.println("usage: demo <serial or logical name> <new logical name>");
            System.exit(1);
        }

        YModule m;
        String newname;

        m = YModule.FindModule(args[0]); // use serial or logical name

        try {
            newname = args[1];
            if (!YAPI.CheckLogicalName(newname))
                {
                    System.out.println("Invalid name (" + newname + ")");
                    System.exit(1);
                }

            m.set_logicalName(newname);
            m.saveToFlash(); // do not forget this

            System.out.println("Module: serial= " + m.get_serialNumber());
            System.out.println(" / name= " + m.get_logicalName());
        } catch (YAPI_Exception ex) {
            System.out.println("Module " + args[0] + "not connected (check identification and USB cable)");
            System.out.println(ex.getMessage());
            System.exit(1);
        }

        YAPI.FreeAPI();
    }
}
 

Warning: the number of write cycles of the nonvolatile memory of the module is limited. When this limit is reached, nothing guaranties that the saving process is performed correctly. This limit, linked to the technology employed by the module micro-processor, is located at about 100000 cycles. In short, you can use the YModule.saveToFlash() function only 100000 times in the life of the module. Make sure you do not call this function within a loop.

Listing the modules

Obtaining the list of the connected modules is performed with the YModule.yFirstModule() function which returns the first module found. Then, you only need to call the nextModule() function of this object to find the following modules, and this as long as the returned value is not null. Below a short example listing the connected modules.

import com.yoctopuce.YoctoAPI.*;

public class Demo {

    public static void main(String[] args)
    {
        try {
            // setup the API to use local VirtualHub
            YAPI.RegisterHub("127.0.0.1");
        } catch (YAPI_Exception ex) {
            System.out.println("Cannot contact VirtualHub on 127.0.0.1 (" + ex.getLocalizedMessage() + ")");
            System.out.println("Ensure that the VirtualHub application is running");
            System.exit(1);
        }

        System.out.println("Device list");
        YModule module = YModule.FirstModule();
        while (module != null) {
            try {
                System.out.println(module.get_serialNumber() + " (" + module.get_productName() + ")");
            } catch (YAPI_Exception ex) {
                break;
            }
            module = module.nextModule();
        }

        YAPI.FreeAPI();
    }
}
 

15.4. Error handling

When you implement a program which must interact with USB modules, you cannot disregard error handling. Inevitably, there will be a time when a user will have unplugged the device, either before running the software, or even while the software is running. The Yoctopuce library is designed to help you support this kind of behavior, but your code must nevertheless be conceived to interpret in the best possible way the errors indicated by the library.

The simplest way to work around the problem is the one used in the short examples provided in this chapter: before accessing a module, check that it is online with the isOnline function, and then hope that it will stay so during the fraction of a second necessary for the following code lines to run. This method is not perfect, but it can be sufficient in some cases. You must however be aware that you cannot completely exclude an error which would occur after the call to isOnline and which could crash the software.

In the Java API, error handling is implemented with exceptions. Therefore you must catch and handle correctly all exceptions that might be thrown by the API if you do not want your software to crash as soon as you unplug a device.

16. Using the Yocto-Servo with Android

To tell the truth, Android is not a programming language, it is an operating system developed by Google for mobile appliances such as smart phones and tablets. But it so happens that under Android everything is programmed with the same programming language: Java. Nevertheless, the programming paradigms and the possibilities to access the hardware are slightly different from classical Java, and this justifies a separate chapter on Android programming.

16.1. Native access and VirtualHub

In the opposite to the classical Java API, the Java for Android API can access USB modules natively. However, as there is no VirtualHub running under Android, it is not possible to remotely control Yoctopuce modules connected to a machine under Android. Naturally, the Java for Android API remains perfectly able to connect itself to a VirtualHub running on another OS.

16.2. Getting ready

Go to the Yoctopuce web site and download the Java for Android programming library45. The library is available as source files, and also as a jar file. Connect your modules, decompress the library files in the directory of your choice, and configure your Android programming environment so that it can find them.

To keep them simple, all the examples provided in this documentation are snippets of Android applications. You must integrate them in your own Android applications to make them work. However, your can find complete applications in the examples provided with the Java for Android library.

16.3. Compatibility

In an ideal world, you would only need to have a smart phone running under Android to be able to make Yoctopuce modules work. Unfortunately, it is not quite so in the real world. A machine running under Android must fulfil to a few requirements to be able to manage Yoctopuce USB modules natively.

Android 4.x

Android 4.0 (api 14) and following are officially supported. Theoretically, support of USB host functions since Android 3.1. But be aware that the Yoctopuce Java for Android API is regularly tested only from Android 4 onwards.

USB host support

Naturally, not only must your machine have a USB port, this port must also be able to run in host mode. In host mode, the machine literally takes control of the devices which are connected to it. The USB ports of a desktop computer, for example, work in host mode. The opposite of the host mode is the device mode. USB keys, for instance, work in device mode: they must be controlled by a host. Some USB ports are able to work in both modes, they are OTG (On The Go) ports. It so happens that many mobile devices can only work in device mode: they are designed to be connected to a charger or a desktop computer, and nothing else. It is therefore highly recommended to pay careful attention to the technical specifications of a product working under Android before hoping to make Yoctopuce modules work with it.

Unfortunately, having a correct version of Android and USB ports working in host mode is not enough to guaranty that Yoctopuce modules will work well under Android. Indeed, some manufacturers configure their Android image so that devices other than keyboard and mass storage are ignored, and this configuration is hard to detect. As things currently stand, the best way to know if a given Android machine works with Yoctopuce modules consists in trying.

Supported hardware

The library is tested and validated on the following machines:

If your Android machine is not able to control Yoctopuce modules natively, you still have the possibility to remotely control modules driven by a VirtualHub on another OS, or a YoctoHub 46.

16.4. Activating the USB port under Android

By default, Android does not allow an application to access the devices connected to the USB port. To enable your application to interact with a Yoctopuce module directly connected on your tablet on a USB port, a few additional steps are required. If you intend to interact only with modules connected on another machine through the network, you can ignore this section.

In your AndroidManifest.xml, you must declare using the "USB Host" functionality by adding the <uses-feature android:name="android.hardware.usb.host" /> tag in the manifest section.


<manifest ...>
    ...
    <uses-feature android:name="android.hardware.usb.host" />;
    ...
</manifest>

When first accessing a Yoctopuce module, Android opens a window to inform the user that the application is going to access the connected module. The user can deny or authorize access to the device. If the user authorizes the access, the application can access the connected device as long as it stays connected. To enable the Yoctopuce library to correctly manage these authorizations, your must provide a pointer on the application context by calling the EnableUSBHost method of the YAPI class before the first USB access. This function takes as arguments an object of the android.content.Context class (or of a subclass). As the Activity class is a subclass of Context, it is simpler to call YAPI.EnableUSBHost(this); in the method onCreate of your application. If the object passed as parameter is not of the correct type, a YAPI_Exception exception is generated.


...
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    try {
                // Pass the application Context to the Yoctopuce Library
        YAPI.EnableUSBHost(this);
        } catch (YAPI_Exception e) {
                Log.e("Yocto",e.getLocalizedMessage());
        }
}
...

Autorun

It is possible to register your application as a default application for a USB module. In this case, as soon as a module is connected to the system, the application is automatically launched. You must add <action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED"/> in the section <intent-filter> of the main activity. The section <activity> must have a pointer to an XML file containing the list of USB modules which can run the application.


<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    ...
    <uses-feature android:name="android.hardware.usb.host" />
    ...
    <application ... >
        <activity
            android:name=".MainActivity" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>

            <meta-data
                android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED"
                android:resource="@xml/device_filter" />
        </activity>
    </application>

</manifest>

The XML file containing the list of modules allowed to run the application must be saved in the res/xml directory. This file contains a list of USB vendorId and deviceID in decimal. The following example runs the application as soon as a Yocto-Relay or a YoctoPowerRelay is connected. You can find the vendorID and the deviceID of Yoctopuce modules in the characteristics section of the documentation.


<?xml version="1.0" encoding="utf-8"?>

<resources>
    <usb-device vendor-id="9440" product-id="12" />
    <usb-device vendor-id="9440" product-id="13" />
</resources>

16.5. Control of the Servo function

A few lines of code are enough to use a Yocto-Servo. Here is the skeleton of a Java code snippet to use the Servo function.


[...]

// Retrieving the object representing the module (connected here locally by USB)
YAPI.EnableUSBHost(this);
YAPI.RegisterHub("usb");
servo = YServo.FindServo("SERVORC1-123456.servo1");

// Hot-plug is easy: just check that the device is online
if (servo.isOnline())
   { //Use servo.set_position()
     ...
   }

[...]

Let us look at these lines in more details.

YAPI.EnableUSBHost

The YAPI.EnableUSBHost function initializes the API with the Context of the current application. This function takes as argument an object of the android.content.Context class (or of a subclass). If you intend to connect your application only to other machines through the network, this function is facultative.

YAPI.RegisterHub

The yAPI.RegisterHub function initializes the Yoctopuce API and indicates where the modules should be looked for. The parameter is the address of the virtual hub able to see the devices. If the string "usb" is passed as parameter, the API works with modules locally connected to the machine. If the initialization does not succeed, an exception is thrown.

YServo.FindServo

The YServo.FindServo function allows you to find a servo from the serial number of the module on which it resides and from its function name. You can use logical names as well, as long as you have initialized them. Let us imagine a Yocto-Servo module with serial number SERVORC1-123456 which you have named "MyModule", and for which you have given the servo1 function the name "MyFunction". The following five calls are strictly equivalent, as long as "MyFunction" is defined only once.


servo = YServo.FindServo("SERVORC1-123456.servo1")
servo = YServo.FindServo("SERVORC1-123456.MyFunction")
servo = YServo.FindServo("MyModule.servo1")
servo = YServo.FindServo("MyModule.MyFunction")
servo = YServo.FindServo("MyFunction")

YServo.FindServo returns an object which you can then use at will to control the servo.

isOnline

The isOnline() method of the object returned by YServo.FindServo allows you to know if the corresponding module is present and in working order.

set_position

The set_position() method of the objet returned by YServo.FindServo moves the servo position as quickly as possible to the specified target. The central position is 0, and the two extremities are -1000 and 1000.

move

The move() method of the objet returned by YServo.FindServo moves the servo at a controlled speed to a desired position, within a time interval specified in milliseconds.

A real example

Launch you Java environment and open the corresponding sample project provided in the directory Examples//Doc-Examples of the Yoctopuce library.

In this example, you can recognize the functions explained above, but this time used with all the side materials needed to make it work nicely as a small demo.

package com.yoctopuce.doc_examples;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.ArrayAdapter;
import android.widget.SeekBar;
import android.widget.Spinner;

import com.yoctopuce.YoctoAPI.YAPI;
import com.yoctopuce.YoctoAPI.YAPI_Exception;
import com.yoctopuce.YoctoAPI.YServo;

public class GettingStarted_Yocto_Servo extends Activity implements OnItemSelectedListener
{

    private YServo servo = null;
    private ArrayAdapter<String> aa;

    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.gettingstarted_yocto_servo);
        Spinner my_spin = (Spinner) findViewById(R.id.spinner1);
        my_spin.setOnItemSelectedListener(this);
        aa = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item);
        aa.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        my_spin.setAdapter(aa);
    }

    @Override
    protected void onStart()
    {
        super.onStart();
        aa.clear();
        try {
            YAPI.EnableUSBHost(this);
            YAPI.RegisterHub("usb");
            YServo s = YServo.FirstServo();
            while (s != null) {
                String hwid = s.get_hardwareId();
                aa.add(hwid);
                s = s.nextServo();
            }
        } catch (YAPI_Exception e) {
            e.printStackTrace();
        }
        aa.notifyDataSetChanged();
    }

    @Override
    protected void onStop()
    {
        super.onStop();
        YAPI.FreeAPI();
    }

    @Override
    public void onItemSelected(AdapterView<?> parent, View view, int pos, long id)
    {
        String hwid = parent.getItemAtPosition(pos).toString();
        servo = YServo.FindServo(hwid);
    }

    @Override
    public void onNothingSelected(AdapterView<?> arg0)
    {
    }

    /** Called when the user touches the button State A */
    public void updatePos(View view)
    {
        if (servo == null)
            return;

        SeekBar bar = (SeekBar) findViewById(R.id.seekBarPos);
        int newpow = bar.getProgress() * 2000 / bar.getMax() - 1000;
        switch (view.getId()) {
        case R.id.movePosButton:
            try {
                servo.move(newpow, 1000);
            } catch (YAPI_Exception e) {
                e.printStackTrace();
            }
            break;
        case R.id.setPosButton:
            try {
                servo.set_position(newpow);
            } catch (YAPI_Exception e) {
                e.printStackTrace();
            }
            break;
        }

    }

}
 

16.6. Control of the module part

Each module can be controlled in a similar manner, you can find below a simple sample program displaying the main parameters of the module and enabling you to activate the localization beacon.

package com.yoctopuce.doc_examples;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.ArrayAdapter;
import android.widget.Spinner;
import android.widget.Switch;
import android.widget.TextView;

import com.yoctopuce.YoctoAPI.YAPI;
import com.yoctopuce.YoctoAPI.YAPI_Exception;
import com.yoctopuce.YoctoAPI.YModule;

public class ModuleControl extends Activity implements OnItemSelectedListener
{

    private ArrayAdapter<String> aa;
    private YModule module = null;

    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.modulecontrol);
        Spinner my_spin = (Spinner) findViewById(R.id.spinner1);
        my_spin.setOnItemSelectedListener(this);
        aa = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item);
        aa.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        my_spin.setAdapter(aa);
    }

    @Override
    protected void onStart()
    {
        super.onStart();

        try {
            aa.clear();
            YAPI.EnableUSBHost(this);
            YAPI.RegisterHub("usb");
            YModule r = YModule.FirstModule();
            while (r != null) {
                String hwid = r.get_hardwareId();
                aa.add(hwid);
                r = r.nextModule();
            }
        } catch (YAPI_Exception e) {
            e.printStackTrace();
        }
        // refresh Spinner with detected relay
        aa.notifyDataSetChanged();
    }

    @Override
    protected void onStop()
    {
        super.onStop();
        YAPI.FreeAPI();
    }

    private void DisplayModuleInfo()
    {
        TextView field;
        if (module == null)
            return;
        try {
            field = (TextView) findViewById(R.id.serialfield);
            field.setText(module.getSerialNumber());
            field = (TextView) findViewById(R.id.logicalnamefield);
            field.setText(module.getLogicalName());
            field = (TextView) findViewById(R.id.luminosityfield);
            field.setText(String.format("%d%%", module.getLuminosity()));
            field = (TextView) findViewById(R.id.uptimefield);
            field.setText(module.getUpTime() / 1000 + " sec");
            field = (TextView) findViewById(R.id.usbcurrentfield);
            field.setText(module.getUsbCurrent() + " mA");
            Switch sw = (Switch) findViewById(R.id.beaconswitch);
            Log.d("switch", "beacon" + module.get_beacon());
            sw.setChecked(module.getBeacon() == YModule.BEACON_ON);
            field = (TextView) findViewById(R.id.logs);
            field.setText(module.get_lastLogs());

        } catch (YAPI_Exception e) {
            e.printStackTrace();
        }
    }

    @Override
    public void onItemSelected(AdapterView<?> parent, View view, int pos, long id)
    {
        String hwid = parent.getItemAtPosition(pos).toString();
        module = YModule.FindModule(hwid);
        DisplayModuleInfo();
    }

    @Override
    public void onNothingSelected(AdapterView<?> arg0)
    {
    }

    public void refreshInfo(View view)
    {
        DisplayModuleInfo();
    }

    public void toggleBeacon(View view)
    {
        if (module == null)
            return;
        boolean on = ((Switch) view).isChecked();

        try {
            if (on) {
                module.setBeacon(YModule.BEACON_ON);
            } else {
                module.setBeacon(YModule.BEACON_OFF);
            }
        } catch (YAPI_Exception e) {
            e.printStackTrace();
        }
    }
}
 

Each property xxx of the module can be read thanks to a method of type YModule.get_xxxx(), and properties which are not read-only can be modified with the help of the YModule.set_xxx() method. For more details regarding the used functions, refer to the API chapters.

Changing the module settings

When you want to modify the settings of a module, you only need to call the corresponding YModule.set_xxx() function. However, this modification is performed only in the random access memory (RAM) of the module: if the module is restarted, the modifications are lost. To memorize them persistently, it is necessary to ask the module to save its current configuration in its permanent memory. To do so, use the YModule.saveToFlash() method. Inversely, it is possible to force the module to forget its current settings by using the YModule.revertFromFlash() method. The short example below allows you to modify the logical name of a module.

package com.yoctopuce.doc_examples;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;

import com.yoctopuce.YoctoAPI.YAPI;
import com.yoctopuce.YoctoAPI.YAPI_Exception;
import com.yoctopuce.YoctoAPI.YModule;

public class SaveSettings extends Activity implements OnItemSelectedListener
{

    private ArrayAdapter<String> aa;
    private YModule module = null;

    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.savesettings);
        Spinner my_spin = (Spinner) findViewById(R.id.spinner1);
        my_spin.setOnItemSelectedListener(this);
        aa = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item);
        aa.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        my_spin.setAdapter(aa);
    }

    @Override
    protected void onStart()
    {
        super.onStart();

        try {
            aa.clear();
            YAPI.EnableUSBHost(this);
            YAPI.RegisterHub("usb");
            YModule r = YModule.FirstModule();
            while (r != null) {
                String hwid = r.get_hardwareId();
                aa.add(hwid);
                r = r.nextModule();
            }
        } catch (YAPI_Exception e) {
            e.printStackTrace();
        }
        // refresh Spinner with detected relay
        aa.notifyDataSetChanged();
    }

    @Override
    protected void onStop()
    {
        super.onStop();
        YAPI.FreeAPI();
    }

    private void DisplayModuleInfo()
    {
        TextView field;
        if (module == null)
            return;
        try {
            YAPI.UpdateDeviceList();// fixme
            field = (TextView) findViewById(R.id.logicalnamefield);
            field.setText(module.getLogicalName());
        } catch (YAPI_Exception e) {
            e.printStackTrace();
        }
    }

    @Override
    public void onItemSelected(AdapterView<?> parent, View view, int pos, long id)
    {
        String hwid = parent.getItemAtPosition(pos).toString();
        module = YModule.FindModule(hwid);
        DisplayModuleInfo();
    }

    @Override
    public void onNothingSelected(AdapterView<?> arg0)
    {
    }

    public void saveName(View view)
    {
        if (module == null)
            return;

        EditText edit = (EditText) findViewById(R.id.newname);
        String newname = edit.getText().toString();
        try {
            if (!YAPI.CheckLogicalName(newname)) {
                Toast.makeText(getApplicationContext(), "Invalid name (" + newname + ")", Toast.LENGTH_LONG).show();
                return;
            }
            module.set_logicalName(newname);
            module.saveToFlash(); // do not forget this
            edit.setText("");
        } catch (YAPI_Exception ex) {
            ex.printStackTrace();
        }
        DisplayModuleInfo();
    }

}
 

Warning: the number of write cycles of the nonvolatile memory of the module is limited. When this limit is reached, nothing guaranties that the saving process is performed correctly. This limit, linked to the technology employed by the module micro-processor, is located at about 100000 cycles. In short, you can use the YModule.saveToFlash() function only 100000 times in the life of the module. Make sure you do not call this function within a loop.

Listing the modules

Obtaining the list of the connected modules is performed with the YModule.yFirstModule() function which returns the first module found. Then, you only need to call the nextModule() function of this object to find the following modules, and this as long as the returned value is not null. Below a short example listing the connected modules.

package com.yoctopuce.doc_examples;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.LinearLayout;
import android.widget.TextView;

import com.yoctopuce.YoctoAPI.YAPI;
import com.yoctopuce.YoctoAPI.YAPI_Exception;
import com.yoctopuce.YoctoAPI.YModule;

public class Inventory extends Activity
{

    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.inventory);
    }

    public void refreshInventory(View view)
    {
        LinearLayout layout = (LinearLayout) findViewById(R.id.inventoryList);
        layout.removeAllViews();

        try {
            YAPI.UpdateDeviceList();
            YModule module = YModule.FirstModule();
            while (module != null) {
                String line = module.get_serialNumber() + " (" + module.get_productName() + ")";
                TextView tx = new TextView(this);
                tx.setText(line);
                layout.addView(tx);
                module = module.nextModule();
            }
        } catch (YAPI_Exception e) {
            e.printStackTrace();
        }
    }

    @Override
    protected void onStart()
    {
        super.onStart();
        try {
            YAPI.EnableUSBHost(this);
            YAPI.RegisterHub("usb");
        } catch (YAPI_Exception e) {
            e.printStackTrace();
        }
        refreshInventory(null);
    }

    @Override
    protected void onStop()
    {
        super.onStop();
        YAPI.FreeAPI();
    }

}
 

16.7. Error handling

When you implement a program which must interact with USB modules, you cannot disregard error handling. Inevitably, there will be a time when a user will have unplugged the device, either before running the software, or even while the software is running. The Yoctopuce library is designed to help you support this kind of behavior, but your code must nevertheless be conceived to interpret in the best possible way the errors indicated by the library.

The simplest way to work around the problem is the one used in the short examples provided in this chapter: before accessing a module, check that it is online with the isOnline function, and then hope that it will stay so during the fraction of a second necessary for the following code lines to run. This method is not perfect, but it can be sufficient in some cases. You must however be aware that you cannot completely exclude an error which would occur after the call to isOnline and which could crash the software.

In the Java API for Android, error handling is implemented with exceptions. Therefore you must catch and handle correctly all exceptions that might be thrown by the API if you do not want your software to crash soon as you unplug a device.

17. Advanced programming

The preceding chapters have introduced, in each available language, the basic programming functions which can be used with your Yocto-Servo module. This chapter presents in a more generic manner a more advanced use of your module. Examples are provided in the language which is the most popular among Yoctopuce customers, that is C#. Nevertheless, you can find complete examples illustrating the concepts presented here in the programming libraries of each language.

To remain as concise as possible, examples provided in this chapter do not perform any error handling. Do not copy them "as is" in a production application.

17.1. Event programming

The methods to manage Yoctopuce modules which we presented to you in preceding chapters were polling functions, consisting in permanently asking the API if something had changed. While easy to understand, this programming technique is not the most efficient, nor the most reactive. Therefore, the Yoctopuce programming API also provides an event programming model. This technique consists in asking the API to signal by itself the important changes as soon as they are detected. Each time a key parameter is modified, the API calls a callback function which you have defined in advance.

Detecting module arrival and departure

Hot-plug management is important when you work with USB modules because, sooner or later, you will have to connect or disconnect a module when your application is running. The API is designed to manage module unexpected arrival or departure in a transparent way. But your application must take this into account if it wants to avoid pretending to use a disconnected module.

Event programming is particularly useful to detect module connection/disconnection. Indeed, it is simpler to be told of new connections rather than to have to permanently list the connected modules to deduce which ones just arrived and which ones left. To be warned as soon as a module is connected, you need three pieces of code.

The callback

The callback is the function which is called each time a new Yoctopuce module is connected. It takes as parameter the relevant module.


 static void deviceArrival(YModule m)
{
  Console.WriteLine("New module  : " + m.get_serialNumber());
}

Initialization

You must then tell the API that it must call the callback when a new module is connected.


YAPI.RegisterDeviceArrivalCallback(deviceArrival);

Note that if modules are already connected when the callback is registered, the callback is called for each of the already connected modules.

Triggering callbacks

A classis issue of callback programming is that these callbacks can be triggered at any time, including at times when the main program is not ready to receive them. This can have undesired side effects, such as dead-locks and other race conditions. Therefore, in the Yoctopuce API, module arrival/departure callbacks are called only when the UpdateDeviceList() function is running. You only need to call UpdateDeviceList() at regular intervals from a timer or from a specific thread to precisely control when the calls to these callbacks happen:


// waiting loop managing callbacks
while (true)
{
    // module arrival / departure callback
    YAPI.UpdateDeviceList(ref errmsg);
    // non active waiting time managing other callbacks
    YAPI.Sleep(500, ref errmsg);
}

In a similar way, it is possible to have a callback when a module is disconnected. You can find a complete example implemented in your favorite programming language in the Examples/Prog-EventBased directory of the corresponding library.

Be aware that in most programming languages, callbacks must be global procedures, and not methods. If you wish for the callback to call the method of an object, define your callback as a global procedure which then calls your method.

18. Using with unsupported languages

Yoctopuce modules can be driven from most common programming languages. New languages are regularly added, depending on the interest expressed by Yoctopuce product users. Nevertheless, some languages are not, and will never be, supported by Yoctopuce. There can be several reasons for this: compilers which are not available anymore, unadapted environments, etc.

However, there are alternative methods to access Yoctopuce modules from an unsupported programming language.

18.1. Command line

The easiest method to drive Yoctopuce modules from an unsupported programming language is to use the command line API through system calls. The command line API is in fact made of a group of small executables which are easy to call. Their output is also easy to analyze. As most programming languages allow you to make system calls, the issue is solved with a few lines of code.

However, if the command line API is the easiest solution, it is neither the fastest nor the most efficient. For each call, the executable must initialize its own API and make an inventory of USB connected modules. This requires about one second per call.

18.2. VirtualHub and HTTP GET

The VirtualHub is available on almost all current platforms. It is generally used as a gateway to provide access to Yoctopuce modules from languages which prevent direct access to hardware layers of a computer (JavaScript, PHP, Java, ...).

In fact, the VirtualHub is a small web server able to route HTTP requests to Yoctopuce modules. This means that if you can make an HTTP request from your programming language, you can drive Yoctopuce modules, even if this language is not officially supported.

REST interface

At a low level, the modules are driven through a REST API. Thus, to control a module, you only need to perform appropriate requests on the VirtualHub. By default, the VirtualHub HTTP port is 4444.

An important advantage of this technique is that preliminary tests are very easy to implement. You only need a VirtualHub and a simple web browser. If you copy the following URL in your preferred browser, while the VirtualHub is running, you obtain the list of the connected modules.


http://127.0.0.1:4444/api/services/whitePages.txt

Note that the result is displayed as text, but if you request whitePages.xml, you obtain an XML result. Likewise, whitePages.json allows you to obtain a JSON result. The html extension even allows you to display a rough interface where you can modify values in real time. The whole REST API is available in these different formats.

Driving a module through the REST interface

Each Yoctopuce module has its own REST interface, available in several variants. Let us imagine a Yocto-Servo with the SERVORC1-12345 serial number and the myModule logical name. The following URL allows you to know the state of the module.


http://127.0.0.1:4444/bySerial/SERVORC1-12345/api/module.txt

You can naturally also use the module logical name rather than its serial number.


http://127.0.0.1:4444/byName/myModule/api/module.txt

To retrieve the value of a module property, simply add the name of the property below module. For example, if you want to know the signposting led luminosity, send the following request:


http://127.0.0.1:4444/bySerial/SERVORC1-12345/api/module/luminosity

To change the value of a property, modify the corresponding attribute. Thus, to modify the luminosity, send the following request:


http://127.0.0.1:4444/bySerial/SERVORC1-12345/api/module?luminosity=100

Driving the module functions through the REST interface

The module functions can be manipulated in the same way. To know the state of the servo function, build the following URL:


http://127.0.0.1:4444/bySerial/SERVORC1-12345/api/servo.txt

Note that if you can use logical names for the modules instead of their serial number, you cannot use logical names for functions. Only hardware names are authorized to access functions.

You can retrieve a module function attribute in a way rather similar to that used with the modules. For example:


http://127.0.0.1:4444/bySerial/SERVORC1-12345/api/servo/logicalName

Rather logically, attributes can be modified in the same manner.


http://127.0.0.1:4444/bySerial/SERVORC1-12345/api/servo?logicalName=myFunction

You can find the list of available attributes for your Yocto-Servo at the beginning of the Programming chapter.

Accessing Yoctopuce data logger through the REST interface

This section only applies to devices with a built-in data logger.

The preview of all recorded data streams can be retrieved in JSON format using the following URL:


http://127.0.0.1:4444/bySerial/SERVORC1-12345/dataLogger.json

Individual measures for any given stream can be obtained by appending the desired function identifier as well as start time of the stream:


http://127.0.0.1:4444/bySerial/SERVORC1-12345/dataLogger.json?id=servo&utc=1389801080

18.3. Using dynamic libraries

The low level Yoctopuce API is available under several formats of dynamic libraries written in C. The sources are available with the C++ API. If you use one of these low level libraries, you do not need the VirtualHub anymore.

FilenamePlatform
libyapi.dylibMax OS X
libyapi-amd64.soLinux Intel (64 bits)
libyapi-armel.soLinux ARM EL
libyapi-armhf.soLinux ARM HL
libyapi-i386.soLinux Intel (32 bits)
yapi64.dllWindows (64 bits)
yapi.dllWindows (32 bits)

These dynamic libraries contain all the functions necessary to completely rebuild the whole high level API in any language able to integrate these libraries. This chapter nevertheless restrains itself to describing basic use of the modules.

Driving a module

The three essential functions of the low level API are the following:


int yapiInitAPI(int connection_type, char *errmsg);
int yapiUpdateDeviceList(int forceupdate, char *errmsg);
int yapiHTTPRequest(char *device, char *request, char* buffer,int buffsize,int *fullsize, char *errmsg);

The yapiInitAPI function initializes the API and must be called once at the beginning of the program. For a USB type connection, the connection_type parameter takes value 1. The errmsg parameter must point to a 255 character buffer to retrieve a potential error message. This pointer can also point to null. The function returns a negative integer in case of error, zero otherwise.

The yapiUpdateDeviceList manages the inventory of connected Yoctopuce modules. It must be called at least once. To manage hot plug and detect potential newly connected modules, this function must be called at regular intervals. The forceupdate parameter must take value 1 to force a hardware scan. The errmsg parameter must point to a 255 character buffer to retrieve a potential error message. This pointer can also point to null. The function returns a negative integer in case of error, zero otherwise.

Finally, the yapiHTTPRequest function sends HTTP requests to the module REST API. The device parameter contains the serial number or the logical name of the module which you want to reach. The request parameter contains the full HTTP request (including terminal line breaks). buffer points to a character buffer long enough to contain the answer. buffsize is the size of the buffer. fullsize is a pointer to an integer to which will be assigned the actual size of the answer. The errmsg parameter must point to a 255 character buffer to retrieve a potential error message. This pointer can also point to null. The function returns a negative integer in case of error, zero otherwise.

The format of the requests is the same as the one described in the VirtualHub et HTTP GET section. All the character strings used by the API are strings made of 8-bit characters: Unicode and UTF8 are not supported.

The resutlt returned in the buffer variable respects the HTTP protocol. It therefore includes an HTTP header. This header ends with two empty lines, that is a sequence of four ASCII characters 13, 10, 13, 10.

Here is a sample program written in pascal using the yapi.dll DLL to read and then update the luminosity of a module.


// Dll functions import
function  yapiInitAPI(mode:integer;
                      errmsg : pansichar):integer;cdecl;
                      external 'yapi.dll' name 'yapiInitAPI';
function  yapiUpdateDeviceList(force:integer;errmsg : pansichar):integer;cdecl;
                      external 'yapi.dll' name 'yapiUpdateDeviceList';
function  yapiHTTPRequest(device:pansichar;url:pansichar; buffer:pansichar;
                      buffsize:integer;var fullsize:integer;
                      errmsg : pansichar):integer;cdecl;
                      external 'yapi.dll' name 'yapiHTTPRequest';

var
 errmsgBuffer  : array [0..256] of ansichar;
 dataBuffer    : array [0..1024] of ansichar;
 errmsg,data   : pansichar;
 fullsize,p    : integer;

const
  serial      = 'SERVORC1-12345';
  getValue = 'GET /api/module/luminosity HTTP/1.1'#13#10#13#10;
  setValue = 'GET /api/module?luminosity=100 HTTP/1.1'#13#10#13#10;

begin
  errmsg  :=  @errmsgBuffer;
  data    :=  @dataBuffer;
  // API  initialization
  if(yapiInitAPI(1,errmsg)<0) then
   begin
    writeln(errmsg);
    halt;
  end;

  // forces a device inventory
  if( yapiUpdateDeviceList(1,errmsg)<0) then
    begin
     writeln(errmsg);
     halt;
   end;

  // requests the  module luminosity
  if (yapiHTTPRequest(serial,getValue,data,sizeof(dataBuffer),fullsize,errmsg)<0) then
   begin
     writeln(errmsg);
     halt;
   end;

  // searches for the HTTP header end
  p := pos(#13#10#13#10,data);

  // displays the response minus the HTTP header
  writeln(copy(data,p+4,length(data)-p-3));

  // changes the luminosity
  if (yapiHTTPRequest(serial,setValue,data,sizeof(dataBuffer),fullsize,errmsg)<0) then
   begin
     writeln(errmsg);
     halt;
   end;

end.

Module inventory

To perform an inventory of Yoctopuce modules, you need two functions from the dynamic library:


 int yapiGetAllDevices(int *buffer,int maxsize,int *neededsize,char *errmsg);
 int yapiGetDeviceInfo(int devdesc,yDeviceSt *infos, char *errmsg);

The yapiGetAllDevices function retrieves the list of all connected modules as a list of handles. buffer points to a 32-bit integer array which contains the returned handles. maxsize is the size in bytes of the buffer. To neededsize is assigned the necessary size to store all the handles. From this, you can deduce either the number of connected modules or that the input buffer is too small. The errmsg parameter must point to a 255 character buffer to retrieve a potential error message. This pointer can also point to null. The function returns a negative integer in case of error, zero otherwise.

The yapiGetDeviceInfo function retrieves the information related to a module from its handle. devdesc is a 32-bit integer representing the module and which was obtained through yapiGetAllDevices. infos points to a data structure in which the result is stored. This data structure has the following format:

Name TypeSize (bytes)Description
vendorid int4Yoctopuce USB ID
deviceid int4Module USB ID
devrelease int4Module version
nbinbterfaces int4Number of USB interfaces used by the module
manufacturer char[]20Yoctopuce (null terminated)
productname char[]28Model (null terminated)
serial char[]20Serial number (null terminated)
logicalname char[]20Logical name (null terminated)
firmware char[]22Firmware version (null terminated)
beacon byte1Beacon state (0/1)

The errmsg parameter must point to a 255 character buffer to retrieve a potential error message.

Here is a sample program written in pascal using the yapi.dll DLL to list the connected modules.


// device description structure
type yDeviceSt = packed record
   vendorid        : word;
   deviceid        : word;
   devrelease      : word;
   nbinbterfaces   : word;
   manufacturer    : array [0..19] of ansichar;
   productname     : array [0..27] of ansichar;
   serial          : array [0..19] of ansichar;
   logicalname     : array [0..19] of ansichar;
   firmware        : array [0..21] of ansichar;
   beacon          : byte;
 end;

// Dll function import
function  yapiInitAPI(mode:integer;
                      errmsg : pansichar):integer;cdecl;
                      external 'yapi.dll' name 'yapiInitAPI';

function  yapiUpdateDeviceList(force:integer;errmsg : pansichar):integer;cdecl;
                      external 'yapi.dll' name 'yapiUpdateDeviceList';

function  yapiGetAllDevices( buffer:pointer;
                             maxsize:integer;
                             var neededsize:integer;
                             errmsg : pansichar):integer; cdecl;
                             external 'yapi.dll' name 'yapiGetAllDevices';

function  apiGetDeviceInfo(d:integer; var infos:yDeviceSt;
                             errmsg : pansichar):integer;  cdecl;
                             external 'yapi.dll' name 'yapiGetDeviceInfo';


var
 errmsgBuffer  : array [0..256] of ansichar;
 dataBuffer    : array [0..127] of integer;   // max of 128 USB devices
 errmsg,data   : pansichar;
 neededsize,i  : integer;
 devinfos      : yDeviceSt;

begin
  errmsg  :=  @errmsgBuffer;

  // API  initialization
  if(yapiInitAPI(1,errmsg)<0) then
   begin
    writeln(errmsg);
    halt;
  end;

   // forces a device inventory
  if( yapiUpdateDeviceList(1,errmsg)<0) then
    begin
     writeln(errmsg);
     halt;
   end;

  // loads all device handles into dataBuffer
  if yapiGetAllDevices(@dataBuffer,sizeof(dataBuffer),neededsize,errmsg)<0 then
    begin
     writeln(errmsg);
     halt;
    end;

  // gets device info from each handle
  for i:=0 to  neededsize div sizeof(integer)-1 do
   begin
     if (apiGetDeviceInfo(dataBuffer[i], devinfos, errmsg)<0) then
       begin
         writeln(errmsg);
         halt;
       end;
     writeln(pansichar(@devinfos.serial)+' ('+pansichar(@devinfos.productname)+')');
   end;

end.

18.4. Porting the high level library

As all the sources of the Yoctopuce API are fully provided, you can very well port the whole API in the language of your choice. Note, however, that a large portion of the API source code is automatically generated.

Therefore, it is not necessary for you to port the complete API. You only need to port the yocto_api file and one file corresponding to a function, for example yocto_relay. After a little additional work, Yoctopuce is then able to generate all other files. Therefore, we highly recommend that you contact Yoctopuce support before undertaking to port the Yoctopuce library in another language. Collaborative work is advantageous to both parties.

19. High-level API Reference

This chapter summarizes the high-level API functions to drive your Yocto-Servo. Syntax and exact type names may vary from one language to another, but, unless otherwise stated, all the functions are available in every language. For detailed information regarding the types of arguments and return values for a given language, refer to the definition file for this language (yocto_api.* as well as the other yocto_* files that define the function interfaces).

For languages which support exceptions, all of these functions throw exceptions in case of error by default, rather than returning the documented error value for each function. This is by design, to facilitate debugging. It is however possible to disable the use of exceptions using the yDisableExceptions() function, in case you prefer to work with functions that return error values.

This chapter does not repeat the programming concepts described earlier, in order to stay as concise as possible. In case of doubt, do not hesitate to go back to the chapter describing in details all configurable attributes.

19.1. General functions

These general functions should be used to initialize and configure the Yoctopuce library. In most cases, a simple call to function yRegisterHub() should be enough. The module-specific functions yFind...() or yFirst...() should then be used to retrieve an object that provides interaction with the module.

In order to use the functions described here, you should include:

js
<script type='text/javascript' src='yocto_api.js'></script>
nodejs
var yoctolib = require('yoctolib');
var YAPI = yoctolib.YAPI;
var YModule = yoctolib.YModule;
php
require_once('yocto_api.php');
cpp
#include "yocto_api.h"
m
#import "yocto_api.h"
pas
uses yocto_api;
vb
yocto_api.vb
cs
yocto_api.cs
java
import com.yoctopuce.YoctoAPI.YModule;
py
from yocto_api import *
Global functions
yCheckLogicalName(name)

Checks if a given string is valid as logical name for a module or a function.

yDisableExceptions()

Disables the use of exceptions to report runtime errors.

yEnableExceptions()

Re-enables the use of exceptions for runtime error handling.

yEnableUSBHost(osContext)

This function is used only on Android.

yFreeAPI()

Frees dynamically allocated memory blocks used by the Yoctopuce library.

yGetAPIVersion()

Returns the version identifier for the Yoctopuce library in use.

yGetTickCount()

Returns the current value of a monotone millisecond-based time counter.

yHandleEvents(errmsg)

Maintains the device-to-library communication channel.

yInitAPI(mode, errmsg)

Initializes the Yoctopuce programming library explicitly.

yPreregisterHub(url, errmsg)

Fault-tolerant alternative to RegisterHub().

yRegisterDeviceArrivalCallback(arrivalCallback)

Register a callback function, to be called each time a device is pluged.

yRegisterDeviceRemovalCallback(removalCallback)

Register a callback function, to be called each time a device is unpluged.

yRegisterHub(url, errmsg)

Setup the Yoctopuce library to use modules connected on a given machine.

yRegisterHubDiscoveryCallback(callback)

Register a callback function, to be called each time a network hub or a VirtualHub is detected on the local network.

yRegisterLogFunction(logfun)

Registers a log callback function.

ySelectArchitecture(arch)

Select the architecture or the library to be loaded to access to USB.

ySetDelegate(object)

(Objective-C only) Register an object that must follow the procol YDeviceHotPlug.

ySetTimeout(callback, ms_timeout, arguments)

Invoke the specified callback function after a given timeout.

ySleep(ms_duration, errmsg)

Pauses the execution flow for a specified duration.

yUnregisterHub(url)

Setup the Yoctopuce library to no more use modules connected on a previously registered machine with RegisterHub.

yUpdateDeviceList(errmsg)

Triggers a (re)detection of connected Yoctopuce modules.

yUpdateDeviceList_async(callback, context)

Triggers a (re)detection of connected Yoctopuce modules.

YAPI.CheckLogicalName()
yCheckLogicalName()
yCheckLogicalName()YAPI.CheckLogicalName()yCheckLogicalName()yCheckLogicalName()yCheckLogicalName()yCheckLogicalName()yCheckLogicalName()YAPI.CheckLogicalName()YAPI.CheckLogicalName()YAPI.CheckLogicalName()

Checks if a given string is valid as logical name for a module or a function.

js
function yCheckLogicalName(name)
nodejs
function CheckLogicalName(name)
php
function yCheckLogicalName($name)
cpp
bool yCheckLogicalName(const string& name)
m
BOOL yCheckLogicalName(NSString * name)
pas
function yCheckLogicalName(name: string): boolean
vb
function yCheckLogicalName(ByVal name As String) As Boolean
cs
bool CheckLogicalName(string name)
java
boolean CheckLogicalName(String name)
py
def CheckLogicalName(name)

A valid logical name has a maximum of 19 characters, all among A..Z, a..z, 0..9, _, and -. If you try to configure a logical name with an incorrect string, the invalid characters are ignored.

Parameters :

namea string containing the name to check.

Returns :

true if the name is valid, false otherwise.

YAPI.DisableExceptions()
yDisableExceptions()
yDisableExceptions()YAPI.DisableExceptions()yDisableExceptions()yDisableExceptions()yDisableExceptions()yDisableExceptions()yDisableExceptions()YAPI.DisableExceptions()YAPI.DisableExceptions()

Disables the use of exceptions to report runtime errors.

js
function yDisableExceptions()
nodejs
function DisableExceptions()
php
function yDisableExceptions()
cpp
void yDisableExceptions()
m
void yDisableExceptions()
pas
procedure yDisableExceptions()
vb
procedure yDisableExceptions()
cs
void DisableExceptions()
py
def DisableExceptions()

When exceptions are disabled, every function returns a specific error value which depends on its type and which is documented in this reference manual.

YAPI.EnableExceptions()
yEnableExceptions()
yEnableExceptions()YAPI.EnableExceptions()yEnableExceptions()yEnableExceptions()yEnableExceptions()yEnableExceptions()yEnableExceptions()YAPI.EnableExceptions()YAPI.EnableExceptions()

Re-enables the use of exceptions for runtime error handling.

js
function yEnableExceptions()
nodejs
function EnableExceptions()
php
function yEnableExceptions()
cpp
void yEnableExceptions()
m
void yEnableExceptions()
pas
procedure yEnableExceptions()
vb
procedure yEnableExceptions()
cs
void EnableExceptions()
py
def EnableExceptions()

Be aware than when exceptions are enabled, every function that fails triggers an exception. If the exception is not caught by the user code, it either fires the debugger or aborts (i.e. crash) the program. On failure, throws an exception or returns a negative error code.

YAPI.EnableUSBHost()
yEnableUSBHost()
YAPI.EnableUSBHost()

This function is used only on Android.

java
synchronized static void EnableUSBHost(Object osContext)

Before calling yRegisterHub("usb") you need to activate the USB host port of the system. This function takes as argument, an object of class android.content.Context (or any subclasee). It is not necessary to call this function to reach modules through the network.

Parameters :

On failure, throws an exception.
osContextan object of class android.content.Context (or any subclass).

YAPI.FreeAPI()
yFreeAPI()
yFreeAPI()YAPI.FreeAPI()yFreeAPI()yFreeAPI()yFreeAPI()yFreeAPI()yFreeAPI()YAPI.FreeAPI()YAPI.FreeAPI()YAPI.FreeAPI()

Frees dynamically allocated memory blocks used by the Yoctopuce library.

js
function yFreeAPI()
nodejs
function FreeAPI()
php
function yFreeAPI()
cpp
void yFreeAPI()
m
void yFreeAPI()
pas
procedure yFreeAPI()
vb
procedure yFreeAPI()
cs
void FreeAPI()
java
synchronized static void FreeAPI()
py
def FreeAPI()

It is generally not required to call this function, unless you want to free all dynamically allocated memory blocks in order to track a memory leak for instance. You should not call any other library function after calling yFreeAPI(), or your program will crash.

YAPI.GetAPIVersion()
yGetAPIVersion()
yGetAPIVersion()YAPI.GetAPIVersion()yGetAPIVersion()yGetAPIVersion()yGetAPIVersion()yGetAPIVersion()yGetAPIVersion()YAPI.GetAPIVersion()YAPI.GetAPIVersion()YAPI.GetAPIVersion()

Returns the version identifier for the Yoctopuce library in use.

js
function yGetAPIVersion()
nodejs
function GetAPIVersion()
php
function yGetAPIVersion()
cpp
string yGetAPIVersion()
m
NSString* yGetAPIVersion()
pas
function yGetAPIVersion(): string
vb
function yGetAPIVersion() As String
cs
String GetAPIVersion()
java
String GetAPIVersion()
py
def GetAPIVersion()

The version is a string in the form "Major.Minor.Build", for instance "1.01.5535". For languages using an external DLL (for instance C#, VisualBasic or Delphi), the character string includes as well the DLL version, for instance "1.01.5535 (1.01.5439)".

If you want to verify in your code that the library version is compatible with the version that you have used during development, verify that the major number is strictly equal and that the minor number is greater or equal. The build number is not relevant with respect to the library compatibility.

Returns :

a character string describing the library version.

YAPI.GetTickCount()
yGetTickCount()
yGetTickCount()YAPI.GetTickCount()yGetTickCount()yGetTickCount()yGetTickCount()yGetTickCount()yGetTickCount()YAPI.GetTickCount()YAPI.GetTickCount()YAPI.GetTickCount()

Returns the current value of a monotone millisecond-based time counter.

js
function yGetTickCount()
nodejs
function GetTickCount()
php
function yGetTickCount()
cpp
u64 yGetTickCount()
m
u64 yGetTickCount()
pas
function yGetTickCount(): u64
vb
function yGetTickCount() As Long
cs
ulong GetTickCount()
java
long GetTickCount()
py
def GetTickCount()

This counter can be used to compute delays in relation with Yoctopuce devices, which also uses the millisecond as timebase.

Returns :

a long integer corresponding to the millisecond counter.

YAPI.HandleEvents()
yHandleEvents()
yHandleEvents()YAPI.HandleEvents()yHandleEvents()yHandleEvents()yHandleEvents()yHandleEvents()yHandleEvents()YAPI.HandleEvents()YAPI.HandleEvents()YAPI.HandleEvents()

Maintains the device-to-library communication channel.

js
function yHandleEvents(errmsg)
nodejs
function HandleEvents(errmsg)
php
function yHandleEvents(&$errmsg)
cpp
YRETCODE yHandleEvents(string& errmsg)
m
YRETCODE yHandleEvents(NSError** errmsg)
pas
function yHandleEvents(var errmsg: string): integer
vb
function yHandleEvents(ByRef errmsg As String) As YRETCODE
cs
YRETCODE HandleEvents(ref string errmsg)
java
int HandleEvents()
py
def HandleEvents(errmsg=None)

If your program includes significant loops, you may want to include a call to this function to make sure that the library takes care of the information pushed by the modules on the communication channels. This is not strictly necessary, but it may improve the reactivity of the library for the following commands.

This function may signal an error in case there is a communication problem while contacting a module.

Parameters :

errmsga string passed by reference to receive any error message.

Returns :

YAPI_SUCCESS when the call succeeds. On failure, throws an exception or returns a negative error code.

YAPI.InitAPI()
yInitAPI()
yInitAPI()YAPI.InitAPI()yInitAPI()yInitAPI()yInitAPI()yInitAPI()yInitAPI()YAPI.InitAPI()YAPI.InitAPI()YAPI.InitAPI()

Initializes the Yoctopuce programming library explicitly.

js
function yInitAPI(mode, errmsg)
nodejs
function InitAPI(mode, errmsg)
php
function yInitAPI($mode, &$errmsg)
cpp
YRETCODE yInitAPI(int mode, string& errmsg)
m
YRETCODE yInitAPI(int mode, NSError** errmsg)
pas
function yInitAPI(mode: integer, var errmsg: string): integer
vb
function yInitAPI(ByVal mode As Integer, ByRef errmsg As String) As Integer
cs
int InitAPI(int mode, ref string errmsg)
java
synchronized static int InitAPI(int mode)
py
def InitAPI(mode, errmsg=None)

It is not strictly needed to call yInitAPI(), as the library is automatically initialized when calling yRegisterHub() for the first time.

When Y_DETECT_NONE is used as detection mode, you must explicitly use yRegisterHub() to point the API to the VirtualHub on which your devices are connected before trying to access them.

Parameters :

modean integer corresponding to the type of automatic device detection to use. Possible values are Y_DETECT_NONE, Y_DETECT_USB, Y_DETECT_NET, and Y_DETECT_ALL.
errmsga string passed by reference to receive any error message.

Returns :

YAPI_SUCCESS when the call succeeds. On failure, throws an exception or returns a negative error code.

YAPI.PreregisterHub()
yPreregisterHub()
yPreregisterHub()YAPI.PreregisterHub()yPreregisterHub()yPreregisterHub()yPreregisterHub()yPreregisterHub()yPreregisterHub()YAPI.PreregisterHub()YAPI.PreregisterHub()YAPI.PreregisterHub()

Fault-tolerant alternative to RegisterHub().

js
function yPreregisterHub(url, errmsg)
nodejs
function PreregisterHub(url, errmsg)
php
function yPreregisterHub($url, &$errmsg)
cpp
YRETCODE yPreregisterHub(const string& url, string& errmsg)
m
YRETCODE yPreregisterHub(NSString * url, NSError** errmsg)
pas
function yPreregisterHub(url: string, var errmsg: string): integer
vb
function yPreregisterHub(ByVal url As String,
  ByRef errmsg As String) As Integer
cs
int PreregisterHub(string url, ref string errmsg)
java
synchronized static int PreregisterHub(String url)
py
def PreregisterHub(url, errmsg=None)

This function has the same purpose and same arguments as RegisterHub(), but does not trigger an error when the selected hub is not available at the time of the function call. This makes it possible to register a network hub independently of the current connectivity, and to try to contact it only when a device is actively needed.

Parameters :

urla string containing either "usb","callback" or the root URL of the hub to monitor
errmsga string passed by reference to receive any error message.

Returns :

YAPI_SUCCESS when the call succeeds.

On failure, throws an exception or returns a negative error code.

YAPI.RegisterDeviceArrivalCallback()
yRegisterDeviceArrivalCallback()
yRegisterDeviceArrivalCallback()YAPI.RegisterDeviceArrivalCallback()yRegisterDeviceArrivalCallback()yRegisterDeviceArrivalCallback()yRegisterDeviceArrivalCallback()yRegisterDeviceArrivalCallback()yRegisterDeviceArrivalCallback()YAPI.RegisterDeviceArrivalCallback()YAPI.RegisterDeviceArrivalCallback()YAPI.RegisterDeviceArrivalCallback()

Register a callback function, to be called each time a device is pluged.

js
function yRegisterDeviceArrivalCallback(arrivalCallback)
nodejs
function RegisterDeviceArrivalCallback(arrivalCallback)
php
function yRegisterDeviceArrivalCallback($arrivalCallback)
cpp
void yRegisterDeviceArrivalCallback(yDeviceUpdateCallback arrivalCallback)
m
void yRegisterDeviceArrivalCallback(yDeviceUpdateCallback arrivalCallback)
pas
procedure yRegisterDeviceArrivalCallback(arrivalCallback: yDeviceUpdateFunc)
vb
procedure yRegisterDeviceArrivalCallback(ByVal arrivalCallback As yDeviceUpdateFunc)
cs
void RegisterDeviceArrivalCallback(yDeviceUpdateFunc arrivalCallback)
java
synchronized static void RegisterDeviceArrivalCallback(DeviceArrivalCallback arrivalCallback)
py
def RegisterDeviceArrivalCallback(arrivalCallback)

This callback will be invoked while yUpdateDeviceList is running. You will have to call this function on a regular basis.

Parameters :

to unregister a previously registered callback.
arrivalCallbacka procedure taking a YModule parameter, or null

YAPI.RegisterDeviceRemovalCallback()
yRegisterDeviceRemovalCallback()
yRegisterDeviceRemovalCallback()YAPI.RegisterDeviceRemovalCallback()yRegisterDeviceRemovalCallback()yRegisterDeviceRemovalCallback()yRegisterDeviceRemovalCallback()yRegisterDeviceRemovalCallback()yRegisterDeviceRemovalCallback()YAPI.RegisterDeviceRemovalCallback()YAPI.RegisterDeviceRemovalCallback()YAPI.RegisterDeviceRemovalCallback()

Register a callback function, to be called each time a device is unpluged.

js
function yRegisterDeviceRemovalCallback(removalCallback)
nodejs
function RegisterDeviceRemovalCallback(removalCallback)
php
function yRegisterDeviceRemovalCallback($removalCallback)
cpp
void yRegisterDeviceRemovalCallback(yDeviceUpdateCallback removalCallback)
m
void yRegisterDeviceRemovalCallback(yDeviceUpdateCallback removalCallback)
pas
procedure yRegisterDeviceRemovalCallback(removalCallback: yDeviceUpdateFunc)
vb
procedure yRegisterDeviceRemovalCallback(ByVal removalCallback As yDeviceUpdateFunc)
cs
void RegisterDeviceRemovalCallback(yDeviceUpdateFunc removalCallback)
java
synchronized static void RegisterDeviceRemovalCallback(DeviceRemovalCallback removalCallback)
py
def RegisterDeviceRemovalCallback(removalCallback)

This callback will be invoked while yUpdateDeviceList is running. You will have to call this function on a regular basis.

Parameters :

to unregister a previously registered callback.
removalCallbacka procedure taking a YModule parameter, or null

YAPI.RegisterHub()
yRegisterHub()
yRegisterHub()YAPI.RegisterHub()yRegisterHub()yRegisterHub()yRegisterHub()yRegisterHub()yRegisterHub()YAPI.RegisterHub()YAPI.RegisterHub()YAPI.RegisterHub()

Setup the Yoctopuce library to use modules connected on a given machine.

js
function yRegisterHub(url, errmsg)
nodejs
function RegisterHub(url, errmsg)
php
function yRegisterHub($url, &$errmsg)
cpp
YRETCODE yRegisterHub(const string& url, string& errmsg)
m
YRETCODE yRegisterHub(NSString * url, NSError** errmsg)
pas
function yRegisterHub(url: string, var errmsg: string): integer
vb
function yRegisterHub(ByVal url As String,
  ByRef errmsg As String) As Integer
cs
int RegisterHub(string url, ref string errmsg)
java
synchronized static int RegisterHub(String url)
py
def RegisterHub(url, errmsg=None)

The parameter will determine how the API will work. Use the follwing values:

usb: When the usb keyword is used, the API will work with devices connected directly to the USB bus. Some programming languages such a Javascript, PHP, and Java don't provide direct access to USB harware, so usb will not work with these. In this case, use a VirtualHub or a networked YoctoHub (see below).

x.x.x.x or hostname: The API will use the devices connected to the host with the given IP address or hostname. That host can be a regular computer running a VirtualHub, or a networked YoctoHub such as YoctoHub-Ethernet or YoctoHub-Wireless. If you want to use the VirtualHub running on you local computer, use the IP address 127.0.0.1.

callback: that keywork make the API run in "HTTP Callback" mode. This a special mode allowing to take control of Yoctopuce devices through a NAT filter when using a VirtualHub ou a networked YoctoHub. You only need to configure your hub to call your server script on a regular basis. This mode is currently available for PHP and Node.JS only.

Be aware that only one application can use direct USB access at a given time on a machine. Multiple access would cause conflicts while trying to access the USB modules. In particular, this means that you must stop the VirtualHub software before starting an application that uses direct USB access. The workaround for this limitation is to setup the library to use the VirtualHub rather than direct USB access.

If acces control has been activated on the hub, virtual or not, you want to reach, the URL parameter should look like:

http://username:password@adresse:port

You can call RegisterHub several times to connect to several machines.

Parameters :

urla string containing either "usb","callback" or the root URL of the hub to monitor
errmsga string passed by reference to receive any error message.

Returns :

YAPI_SUCCESS when the call succeeds.

On failure, throws an exception or returns a negative error code.

YAPI.RegisterHubDiscoveryCallback()
yRegisterHubDiscoveryCallback()
YAPI.RegisterHubDiscoveryCallback()

Register a callback function, to be called each time a network hub or a VirtualHub is detected on the local network.

java
void RegisterHubDiscoveryCallback(NewHubCallback callback)

Parameters :

to unregister a previously registered callback.
callbacka procedure taking a two string as parameter, or null

YAPI.RegisterLogFunction()
yRegisterLogFunction()
yRegisterLogFunction()yRegisterLogFunction()yRegisterLogFunction()yRegisterLogFunction()YAPI.RegisterLogFunction()YAPI.RegisterLogFunction()YAPI.RegisterLogFunction()

Registers a log callback function.

cpp
void yRegisterLogFunction(yLogFunction logfun)
m
void yRegisterLogFunction(yLogCallback logfun)
pas
procedure yRegisterLogFunction(logfun: yLogFunc)
vb
procedure yRegisterLogFunction(ByVal logfun As yLogFunc)
cs
void RegisterLogFunction(yLogFunc logfun)
java
void RegisterLogFunction(LogCallback logfun)
py
def RegisterLogFunction(logfun)

This callback will be called each time the API have something to say. Quite usefull to debug the API.

Parameters :

to unregister a previously registered callback.
logfuna procedure taking a string parameter, or null

YAPI.SelectArchitecture()
ySelectArchitecture()
YAPI.SelectArchitecture()

Select the architecture or the library to be loaded to access to USB.

py
def SelectArchitecture(arch)

By default, the Python library automatically detects the appropriate library to use. However, for Linux ARM, it not possible to reliably distinguish between a Hard Float (armhf) and a Soft Float (armel) install. For in this case, it is therefore recommended to manually select the proper architecture by calling SelectArchitecture() before any other call to the library.

Parameters :

archA string containing the architecture to use. Possibles value are: "armhf","armel", "i386","x86_64","32bit", "64bit"

Returns :

nothing.

On failure, throws an exception.

YAPI.SetDelegate()
ySetDelegate()
ySetDelegate()

(Objective-C only) Register an object that must follow the procol YDeviceHotPlug.

m
void ySetDelegate(id object)

The methodes yDeviceArrival and yDeviceRemoval will be invoked while yUpdateDeviceList is running. You will have to call this function on a regular basis.

Parameters :

to unregister a previously registered object.
objectan object that must follow the procol YAPIDelegate, or nil

YAPI.SetTimeout()
ySetTimeout()
ySetTimeout()YAPI.SetTimeout()

Invoke the specified callback function after a given timeout.

js
function ySetTimeout(callback, ms_timeout, arguments)
nodejs
function SetTimeout(callback, ms_timeout, arguments)

This function behaves more or less like Javascript setTimeout, but during the waiting time, it will call yHandleEvents and yUpdateDeviceList periodically, in order to keep the API up-to-date with current devices.

Parameters :

callbackthe function to call after the timeout occurs. On Microsoft Internet Explorer, the callback must be provided as a string to be evaluated.
ms_timeoutan integer corresponding to the duration of the timeout, in milliseconds.
argumentsadditional arguments to be passed to the callback function can be provided, if needed (not supported on Microsoft Internet Explorer).

Returns :

YAPI_SUCCESS when the call succeeds. On failure, throws an exception or returns a negative error code.

YAPI.Sleep()
ySleep()
ySleep()YAPI.Sleep()ySleep()ySleep()ySleep()ySleep()ySleep()YAPI.Sleep()YAPI.Sleep()YAPI.Sleep()

Pauses the execution flow for a specified duration.

js
function ySleep(ms_duration, errmsg)
nodejs
function Sleep(ms_duration, errmsg)
php
function ySleep($ms_duration, &$errmsg)
cpp
YRETCODE ySleep(unsigned ms_duration, string& errmsg)
m
YRETCODE ySleep(unsigned ms_duration, NSError ** errmsg)
pas
function ySleep(ms_duration: integer, var errmsg: string): integer
vb
function ySleep(ByVal ms_duration As Integer,
  ByRef errmsg As String) As Integer
cs
int Sleep(int ms_duration, ref string errmsg)
java
int Sleep(long ms_duration)
py
def Sleep(ms_duration, errmsg=None)

This function implements a passive waiting loop, meaning that it does not consume CPU cycles significatively. The processor is left available for other threads and processes. During the pause, the library nevertheless reads from time to time information from the Yoctopuce modules by calling yHandleEvents(), in order to stay up-to-date.

This function may signal an error in case there is a communication problem while contacting a module.

Parameters :

ms_durationan integer corresponding to the duration of the pause, in milliseconds.
errmsga string passed by reference to receive any error message.

Returns :

YAPI_SUCCESS when the call succeeds. On failure, throws an exception or returns a negative error code.

YAPI.UnregisterHub()
yUnregisterHub()
yUnregisterHub()YAPI.UnregisterHub()yUnregisterHub()yUnregisterHub()yUnregisterHub()yUnregisterHub()yUnregisterHub()YAPI.UnregisterHub()YAPI.UnregisterHub()YAPI.UnregisterHub()

Setup the Yoctopuce library to no more use modules connected on a previously registered machine with RegisterHub.

js
function yUnregisterHub(url)
nodejs
function UnregisterHub(url)
php
function yUnregisterHub($url)
cpp
void yUnregisterHub(const string& url)
m
void yUnregisterHub(NSString * url)
pas
procedure yUnregisterHub(url: string)
vb
procedure yUnregisterHub(ByVal url As String)
cs
void UnregisterHub(string url)
java
synchronized static void UnregisterHub(String url)
py
def UnregisterHub(url)

Parameters :

root URL of the hub to monitor
urla string containing either "usb" or the

YAPI.UpdateDeviceList()
yUpdateDeviceList()
yUpdateDeviceList()YAPI.UpdateDeviceList()yUpdateDeviceList()yUpdateDeviceList()yUpdateDeviceList()yUpdateDeviceList()yUpdateDeviceList()YAPI.UpdateDeviceList()YAPI.UpdateDeviceList()YAPI.UpdateDeviceList()

Triggers a (re)detection of connected Yoctopuce modules.

js
function yUpdateDeviceList(errmsg)
nodejs
function UpdateDeviceList(errmsg)
php
function yUpdateDeviceList(&$errmsg)
cpp
YRETCODE yUpdateDeviceList(string& errmsg)
m
YRETCODE yUpdateDeviceList(NSError** errmsg)
pas
function yUpdateDeviceList(var errmsg: string): integer
vb
function yUpdateDeviceList(ByRef errmsg As String) As YRETCODE
cs
YRETCODE UpdateDeviceList(ref string errmsg)
java
int UpdateDeviceList()
py
def UpdateDeviceList(errmsg=None)

The library searches the machines or USB ports previously registered using yRegisterHub(), and invokes any user-defined callback function in case a change in the list of connected devices is detected.

This function can be called as frequently as desired to refresh the device list and to make the application aware of hot-plug events.

Parameters :

errmsga string passed by reference to receive any error message.

Returns :

YAPI_SUCCESS when the call succeeds. On failure, throws an exception or returns a negative error code.

YAPI.UpdateDeviceList_async()
yUpdateDeviceList_async()
yUpdateDeviceList_async()YAPI.UpdateDeviceList_async()

Triggers a (re)detection of connected Yoctopuce modules.

js
function yUpdateDeviceList_async(callback, context)
nodejs
function UpdateDeviceList_async(callback, context)

The library searches the machines or USB ports previously registered using yRegisterHub(), and invokes any user-defined callback function in case a change in the list of connected devices is detected.

This function can be called as frequently as desired to refresh the device list and to make the application aware of hot-plug events.

This asynchronous version exists only in Javascript. It uses a callback instead of a return value in order to avoid blocking Firefox Javascript VM that does not implement context switching during blocking I/O calls.

Parameters :

callbackcallback function that is invoked when the result is known. The callback function receives three arguments: the caller-specific context object, the result code (YAPI_SUCCESS if the operation completes successfully) and the error message.
contextcaller-specific object that is passed as-is to the callback function

Returns :

nothing : the result is provided to the callback.

19.2. Module control interface

This interface is identical for all Yoctopuce USB modules. It can be used to control the module global parameters, and to enumerate the functions provided by each module.

In order to use the functions described here, you should include:

js
<script type='text/javascript' src='yocto_api.js'></script>
nodejs
var yoctolib = require('yoctolib');
var YAPI = yoctolib.YAPI;
var YModule = yoctolib.YModule;
php
require_once('yocto_api.php');
cpp
#include "yocto_api.h"
m
#import "yocto_api.h"
pas
uses yocto_api;
vb
yocto_api.vb
cs
yocto_api.cs
java
import com.yoctopuce.YoctoAPI.YModule;
py
from yocto_api import *
Global functions
yFindModule(func)

Allows you to find a module from its serial number or from its logical name.

yFirstModule()

Starts the enumeration of modules currently accessible.

YModule methods
module→describe()

Returns a descriptive text that identifies the module.

module→download(pathname)

Downloads the specified built-in file and returns a binary buffer with its content.

module→functionCount()

Returns the number of functions (beside the "module" interface) available on the module.

module→functionId(functionIndex)

Retrieves the hardware identifier of the nth function on the module.

module→functionName(functionIndex)

Retrieves the logical name of the nth function on the module.

module→functionValue(functionIndex)

Retrieves the advertised value of the nth function on the module.

module→get_beacon()

Returns the state of the localization beacon.

module→get_errorMessage()

Returns the error message of the latest error with this module object.

module→get_errorType()

Returns the numerical error code of the latest error with this module object.

module→get_firmwareRelease()

Returns the version of the firmware embedded in the module.

module→get_hardwareId()

Returns the unique hardware identifier of the module.

module→get_icon2d()

Returns the icon of the module.

module→get_lastLogs()

Returns a string with last logs of the module.

module→get_logicalName()

Returns the logical name of the module.

module→get_luminosity()

Returns the luminosity of the module informative leds (from 0 to 100).

module→get_persistentSettings()

Returns the current state of persistent module settings.

module→get_productId()

Returns the USB device identifier of the module.

module→get_productName()

Returns the commercial name of the module, as set by the factory.

module→get_productRelease()

Returns the hardware release version of the module.

module→get_rebootCountdown()

Returns the remaining number of seconds before the module restarts, or zero when no reboot has been scheduled.

module→get_serialNumber()

Returns the serial number of the module, as set by the factory.

module→get_upTime()

Returns the number of milliseconds spent since the module was powered on.

module→get_usbBandwidth()

Returns the number of USB interfaces used by the module.

module→get_usbCurrent()

Returns the current consumed by the module on the USB bus, in milli-amps.

module→get_userData()

Returns the value of the userData attribute, as previously stored using method set_userData.

module→isOnline()

Checks if the module is currently reachable, without raising any error.

module→isOnline_async(callback, context)

Checks if the module is currently reachable, without raising any error.

module→load(msValidity)

Preloads the module cache with a specified validity duration.

module→load_async(msValidity, callback, context)

Preloads the module cache with a specified validity duration (asynchronous version).

module→nextModule()

Continues the module enumeration started using yFirstModule().

module→reboot(secBeforeReboot)

Schedules a simple module reboot after the given number of seconds.

module→revertFromFlash()

Reloads the settings stored in the nonvolatile memory, as when the module is powered on.

module→saveToFlash()

Saves current settings in the nonvolatile memory of the module.

module→set_beacon(newval)

Turns on or off the module localization beacon.

module→set_logicalName(newval)

Changes the logical name of the module.

module→set_luminosity(newval)

Changes the luminosity of the module informative leds.

module→set_usbBandwidth(newval)

Changes the number of USB interfaces used by the module.

module→set_userData(data)

Stores a user context provided as argument in the userData attribute of the function.

module→triggerFirmwareUpdate(secBeforeReboot)

Schedules a module reboot into special firmware update mode.

module→wait_async(callback, context)

Waits for all pending asynchronous commands on the module to complete, and invoke the user-provided callback function.

YModule.FindModule()
yFindModule()
yFindModule()YModule.FindModule()yFindModule()yFindModule()yFindModule()yFindModule()yFindModule()YModule.FindModule()YModule.FindModule()YModule.FindModule()

Allows you to find a module from its serial number or from its logical name.

js
function yFindModule(func)
nodejs
function FindModule(func)
php
function yFindModule($func)
cpp
YModule* yFindModule(string func)
m
+(YModule*) yFindModule: (NSString*) func
pas
function yFindModule(func: string): TYModule
vb
function yFindModule(ByVal func As String) As YModule
cs
YModule FindModule(string func)
java
YModule FindModule(String func)
py
def FindModule(func)

This function does not require that the module is online at the time it is invoked. The returned object is nevertheless valid. Use the method YModule.isOnline() to test if the module is indeed online at a given time. In case of ambiguity when looking for a module by logical name, no error is notified: the first instance found is returned. The search is performed first by hardware name, then by logical name.

Parameters :

funca string containing either the serial number or the logical name of the desired module

Returns :

a YModule object allowing you to drive the module or get additional information on the module.

YModule.FirstModule()
yFirstModule()
yFirstModule()YModule.FirstModule()yFirstModule()yFirstModule()yFirstModule()yFirstModule()yFirstModule()YModule.FirstModule()YModule.FirstModule()YModule.FirstModule()

Starts the enumeration of modules currently accessible.

js
function yFirstModule()
nodejs
function FirstModule()
php
function yFirstModule()
cpp
YModule* yFirstModule()
m
YModule* yFirstModule()
pas
function yFirstModule(): TYModule
vb
function yFirstModule() As YModule
cs
YModule FirstModule()
java
YModule FirstModule()
py
def FirstModule()

Use the method YModule.nextModule() to iterate on the next modules.

Returns :

a pointer to a YModule object, corresponding to the first module currently online, or a null pointer if there are none.

module→describe()module.describe()module.describe()module→describe()module→describe()[module describe]module.describe()module.describe()module.describe()module.describe()module.describe()

Returns a descriptive text that identifies the module.

js
function describe()
nodejs
function describe()
php
function describe()
cpp
string describe()
m
-(NSString*) describe
pas
function describe(): string
vb
function describe() As String
cs
string describe()
java
String describe()
py
def describe()

The text may include either the logical name or the serial number of the module.

Returns :

a string that describes the module

module→download()module.download()module.download()module→download()module→download()[module download: ]module.download()module.download()module.download()YModule download

Downloads the specified built-in file and returns a binary buffer with its content.

js
function download(pathname)
nodejs
function download(pathname)
php
function download($pathname)
cpp
string download(string pathname)
m
-(NSData*) download: (NSString*) pathname
pas
function download(pathname: string): TByteArray
vb
function download() As Byte
py
def download(pathname)
cmd
YModule target download pathname

Parameters :

pathnamename of the new file to load

Returns :

a binary buffer with the file content

On failure, throws an exception or returns an empty content.

module→functionCount()module.functionCount()module.functionCount()module→functionCount()module→functionCount()[module functionCount]module.functionCount()module.functionCount()module.functionCount()module.functionCount()

Returns the number of functions (beside the "module" interface) available on the module.

js
function functionCount()
nodejs
function functionCount()
php
function functionCount()
cpp
int functionCount()
m
-(int) functionCount
pas
function functionCount(): integer
vb
function functionCount() As Integer
cs
int functionCount()
py
def functionCount()

Returns :

the number of functions on the module

On failure, throws an exception or returns a negative error code.

module→functionId()module.functionId()module.functionId()module→functionId()module→functionId()[module functionId: ]module.functionId()module.functionId()module.functionId()module.functionId()

Retrieves the hardware identifier of the nth function on the module.

js
function functionId(functionIndex)
nodejs
function functionId(functionIndex)
php
function functionId($functionIndex)
cpp
string functionId(int functionIndex)
m
-(NSString*) functionId: (int) functionIndex
pas
function functionId(functionIndex: integer): string
vb
function functionId(ByVal functionIndex As Integer) As String
cs
string functionId(int functionIndex)
py
def functionId(functionIndex)

Parameters :

functionIndexthe index of the function for which the information is desired, starting at 0 for the first function.

Returns :

a string corresponding to the unambiguous hardware identifier of the requested module function

On failure, throws an exception or returns an empty string.

module→functionName()module.functionName()module.functionName()module→functionName()module→functionName()[module functionName: ]module.functionName()module.functionName()module.functionName()module.functionName()

Retrieves the logical name of the nth function on the module.

js
function functionName(functionIndex)
nodejs
function functionName(functionIndex)
php
function functionName($functionIndex)
cpp
string functionName(int functionIndex)
m
-(NSString*) functionName: (int) functionIndex
pas
function functionName(functionIndex: integer): string
vb
function functionName(ByVal functionIndex As Integer) As String
cs
string functionName(int functionIndex)
py
def functionName(functionIndex)

Parameters :

functionIndexthe index of the function for which the information is desired, starting at 0 for the first function.

Returns :

a string corresponding to the logical name of the requested module function

On failure, throws an exception or returns an empty string.

module→functionValue()module.functionValue()module.functionValue()module→functionValue()module→functionValue()[module functionValue: ]module.functionValue()module.functionValue()module.functionValue()module.functionValue()

Retrieves the advertised value of the nth function on the module.

js
function functionValue(functionIndex)
nodejs
function functionValue(functionIndex)
php
function functionValue($functionIndex)
cpp
string functionValue(int functionIndex)
m
-(NSString*) functionValue: (int) functionIndex
pas
function functionValue(functionIndex: integer): string
vb
function functionValue(ByVal functionIndex As Integer) As String
cs
string functionValue(int functionIndex)
py
def functionValue(functionIndex)

Parameters :

functionIndexthe index of the function for which the information is desired, starting at 0 for the first function.

Returns :

a short string (up to 6 characters) corresponding to the advertised value of the requested module function

On failure, throws an exception or returns an empty string.

module→get_beacon()
module→beacon()
module.get_beacon()module.get_beacon()module→get_beacon()module→get_beacon()[module beacon]module.get_beacon()module.get_beacon()module.get_beacon()module.get_beacon()module.get_beacon()YModule get_beacon

Returns the state of the localization beacon.

js
function get_beacon()
nodejs
function get_beacon()
php
function get_beacon()
cpp
Y_BEACON_enum get_beacon()
m
-(Y_BEACON_enum) beacon
pas
function get_beacon(): Integer
vb
function get_beacon() As Integer
cs
int get_beacon()
java
int get_beacon()
py
def get_beacon()
cmd
YModule target get_beacon

Returns :

either Y_BEACON_OFF or Y_BEACON_ON, according to the state of the localization beacon

On failure, throws an exception or returns Y_BEACON_INVALID.

module→get_errorMessage()
module→errorMessage()
module.get_errorMessage()module.get_errorMessage()module→get_errorMessage()module→get_errorMessage()[module errorMessage]module.get_errorMessage()module.get_errorMessage()module.get_errorMessage()module.get_errorMessage()module.get_errorMessage()

Returns the error message of the latest error with this module object.

js
function get_errorMessage()
nodejs
function get_errorMessage()
php
function get_errorMessage()
cpp
string get_errorMessage()
m
-(NSString*) errorMessage
pas
function get_errorMessage(): string
vb
function get_errorMessage() As String
cs
string get_errorMessage()
java
String get_errorMessage()
py
def get_errorMessage()

This method is mostly useful when using the Yoctopuce library with exceptions disabled.

Returns :

a string corresponding to the latest error message that occured while using this module object

module→get_errorType()
module→errorType()
module.get_errorType()module.get_errorType()module→get_errorType()module→get_errorType()module.get_errorType()module.get_errorType()module.get_errorType()module.get_errorType()module.get_errorType()

Returns the numerical error code of the latest error with this module object.

js
function get_errorType()
nodejs
function get_errorType()
php
function get_errorType()
cpp
YRETCODE get_errorType()
pas
function get_errorType(): YRETCODE
vb
function get_errorType() As YRETCODE
cs
YRETCODE get_errorType()
java
int get_errorType()
py
def get_errorType()

This method is mostly useful when using the Yoctopuce library with exceptions disabled.

Returns :

a number corresponding to the code of the latest error that occured while using this module object

module→get_firmwareRelease()
module→firmwareRelease()
module.get_firmwareRelease()module.get_firmwareRelease()module→get_firmwareRelease()module→get_firmwareRelease()[module firmwareRelease]module.get_firmwareRelease()module.get_firmwareRelease()module.get_firmwareRelease()module.get_firmwareRelease()module.get_firmwareRelease()YModule get_firmwareRelease

Returns the version of the firmware embedded in the module.

js
function get_firmwareRelease()
nodejs
function get_firmwareRelease()
php
function get_firmwareRelease()
cpp
string get_firmwareRelease()
m
-(NSString*) firmwareRelease
pas
function get_firmwareRelease(): string
vb
function get_firmwareRelease() As String
cs
string get_firmwareRelease()
java
String get_firmwareRelease()
py
def get_firmwareRelease()
cmd
YModule target get_firmwareRelease

Returns :

a string corresponding to the version of the firmware embedded in the module

On failure, throws an exception or returns Y_FIRMWARERELEASE_INVALID.

module→get_hardwareId()
module→hardwareId()
module.get_hardwareId()module.get_hardwareId()module→get_hardwareId()module→get_hardwareId()[module hardwareId]module.get_hardwareId()module.get_hardwareId()module.get_hardwareId()module.get_hardwareId()

Returns the unique hardware identifier of the module.

js
function get_hardwareId()
nodejs
function get_hardwareId()
php
function get_hardwareId()
cpp
string get_hardwareId()
m
-(NSString*) hardwareId
vb
function get_hardwareId() As String
cs
string get_hardwareId()
java
String get_hardwareId()
py
def get_hardwareId()

The unique hardware identifier is made of the device serial number followed by string ".module".

Returns :

a string that uniquely identifies the module

module→get_icon2d()
module→icon2d()
module.get_icon2d()module.get_icon2d()module→get_icon2d()module→get_icon2d()[module icon2d]module.get_icon2d()module.get_icon2d()module.get_icon2d()YModule get_icon2d

Returns the icon of the module.

js
function get_icon2d()
nodejs
function get_icon2d()
php
function get_icon2d()
cpp
string get_icon2d()
m
-(NSData*) icon2d
pas
function get_icon2d(): TByteArray
vb
function get_icon2d() As Byte
py
def get_icon2d()
cmd
YModule target get_icon2d

The icon is a PNG image and does not exceeds 1536 bytes.

Returns :

a binary buffer with module icon, in png format.

module→get_lastLogs()
module→lastLogs()
module.get_lastLogs()module.get_lastLogs()module→get_lastLogs()module→get_lastLogs()[module lastLogs]module.get_lastLogs()module.get_lastLogs()module.get_lastLogs()module.get_lastLogs()module.get_lastLogs()YModule get_lastLogs

Returns a string with last logs of the module.

js
function get_lastLogs()
nodejs
function get_lastLogs()
php
function get_lastLogs()
cpp
string get_lastLogs()
m
-(NSString*) lastLogs
pas
function get_lastLogs(): string
vb
function get_lastLogs() As String
cs
string get_lastLogs()
java
String get_lastLogs()
py
def get_lastLogs()
cmd
YModule target get_lastLogs

This method return only logs that are still in the module.

Returns :

a string with last logs of the module.

module→get_logicalName()
module→logicalName()
module.get_logicalName()module.get_logicalName()module→get_logicalName()module→get_logicalName()[module logicalName]module.get_logicalName()module.get_logicalName()module.get_logicalName()module.get_logicalName()module.get_logicalName()YModule get_logicalName

Returns the logical name of the module.

js
function get_logicalName()
nodejs
function get_logicalName()
php
function get_logicalName()
cpp
string get_logicalName()
m
-(NSString*) logicalName
pas
function get_logicalName(): string
vb
function get_logicalName() As String
cs
string get_logicalName()
java
String get_logicalName()
py
def get_logicalName()
cmd
YModule target get_logicalName

Returns :

a string corresponding to the logical name of the module

On failure, throws an exception or returns Y_LOGICALNAME_INVALID.

module→get_luminosity()
module→luminosity()
module.get_luminosity()module.get_luminosity()module→get_luminosity()module→get_luminosity()[module luminosity]module.get_luminosity()module.get_luminosity()module.get_luminosity()module.get_luminosity()module.get_luminosity()YModule get_luminosity

Returns the luminosity of the module informative leds (from 0 to 100).

js
function get_luminosity()
nodejs
function get_luminosity()
php
function get_luminosity()
cpp
int get_luminosity()
m
-(int) luminosity
pas
function get_luminosity(): LongInt
vb
function get_luminosity() As Integer
cs
int get_luminosity()
java
int get_luminosity()
py
def get_luminosity()
cmd
YModule target get_luminosity

Returns :

an integer corresponding to the luminosity of the module informative leds (from 0 to 100)

On failure, throws an exception or returns Y_LUMINOSITY_INVALID.

module→get_persistentSettings()
module→persistentSettings()
module.get_persistentSettings()module.get_persistentSettings()module→get_persistentSettings()module→get_persistentSettings()[module persistentSettings]module.get_persistentSettings()module.get_persistentSettings()module.get_persistentSettings()module.get_persistentSettings()module.get_persistentSettings()YModule get_persistentSettings

Returns the current state of persistent module settings.

js
function get_persistentSettings()
nodejs
function get_persistentSettings()
php
function get_persistentSettings()
cpp
Y_PERSISTENTSETTINGS_enum get_persistentSettings()
m
-(Y_PERSISTENTSETTINGS_enum) persistentSettings
pas
function get_persistentSettings(): Integer
vb
function get_persistentSettings() As Integer
cs
int get_persistentSettings()
java
int get_persistentSettings()
py
def get_persistentSettings()
cmd
YModule target get_persistentSettings

Returns :

a value among Y_PERSISTENTSETTINGS_LOADED, Y_PERSISTENTSETTINGS_SAVED and Y_PERSISTENTSETTINGS_MODIFIED corresponding to the current state of persistent module settings

On failure, throws an exception or returns Y_PERSISTENTSETTINGS_INVALID.

module→get_productId()
module→productId()
module.get_productId()module.get_productId()module→get_productId()module→get_productId()[module productId]module.get_productId()module.get_productId()module.get_productId()module.get_productId()module.get_productId()YModule get_productId

Returns the USB device identifier of the module.

js
function get_productId()
nodejs
function get_productId()
php
function get_productId()
cpp
int get_productId()
m
-(int) productId
pas
function get_productId(): LongInt
vb
function get_productId() As Integer
cs
int get_productId()
java
int get_productId()
py
def get_productId()
cmd
YModule target get_productId

Returns :

an integer corresponding to the USB device identifier of the module

On failure, throws an exception or returns Y_PRODUCTID_INVALID.

module→get_productName()
module→productName()
module.get_productName()module.get_productName()module→get_productName()module→get_productName()[module productName]module.get_productName()module.get_productName()module.get_productName()module.get_productName()module.get_productName()YModule get_productName

Returns the commercial name of the module, as set by the factory.

js
function get_productName()
nodejs
function get_productName()
php
function get_productName()
cpp
string get_productName()
m
-(NSString*) productName
pas
function get_productName(): string
vb
function get_productName() As String
cs
string get_productName()
java
String get_productName()
py
def get_productName()
cmd
YModule target get_productName

Returns :

a string corresponding to the commercial name of the module, as set by the factory

On failure, throws an exception or returns Y_PRODUCTNAME_INVALID.

module→get_productRelease()
module→productRelease()
module.get_productRelease()module.get_productRelease()module→get_productRelease()module→get_productRelease()[module productRelease]module.get_productRelease()module.get_productRelease()module.get_productRelease()module.get_productRelease()module.get_productRelease()YModule get_productRelease

Returns the hardware release version of the module.

js
function get_productRelease()
nodejs
function get_productRelease()
php
function get_productRelease()
cpp
int get_productRelease()
m
-(int) productRelease
pas
function get_productRelease(): LongInt
vb
function get_productRelease() As Integer
cs
int get_productRelease()
java
int get_productRelease()
py
def get_productRelease()
cmd
YModule target get_productRelease

Returns :

an integer corresponding to the hardware release version of the module

On failure, throws an exception or returns Y_PRODUCTRELEASE_INVALID.

module→get_rebootCountdown()
module→rebootCountdown()
module.get_rebootCountdown()module.get_rebootCountdown()module→get_rebootCountdown()module→get_rebootCountdown()[module rebootCountdown]module.get_rebootCountdown()module.get_rebootCountdown()module.get_rebootCountdown()module.get_rebootCountdown()module.get_rebootCountdown()YModule get_rebootCountdown

Returns the remaining number of seconds before the module restarts, or zero when no reboot has been scheduled.

js
function get_rebootCountdown()
nodejs
function get_rebootCountdown()
php
function get_rebootCountdown()
cpp
int get_rebootCountdown()
m
-(int) rebootCountdown
pas
function get_rebootCountdown(): LongInt
vb
function get_rebootCountdown() As Integer
cs
int get_rebootCountdown()
java
int get_rebootCountdown()
py
def get_rebootCountdown()
cmd
YModule target get_rebootCountdown

Returns :

an integer corresponding to the remaining number of seconds before the module restarts, or zero when no reboot has been scheduled

On failure, throws an exception or returns Y_REBOOTCOUNTDOWN_INVALID.

module→get_serialNumber()
module→serialNumber()
module.get_serialNumber()module.get_serialNumber()module→get_serialNumber()module→get_serialNumber()[module serialNumber]module.get_serialNumber()module.get_serialNumber()module.get_serialNumber()module.get_serialNumber()module.get_serialNumber()YModule get_serialNumber

Returns the serial number of the module, as set by the factory.

js
function get_serialNumber()
nodejs
function get_serialNumber()
php
function get_serialNumber()
cpp
string get_serialNumber()
m
-(NSString*) serialNumber
pas
function get_serialNumber(): string
vb
function get_serialNumber() As String
cs
string get_serialNumber()
java
String get_serialNumber()
py
def get_serialNumber()
cmd
YModule target get_serialNumber

Returns :

a string corresponding to the serial number of the module, as set by the factory

On failure, throws an exception or returns Y_SERIALNUMBER_INVALID.

module→get_upTime()
module→upTime()
module.get_upTime()module.get_upTime()module→get_upTime()module→get_upTime()[module upTime]module.get_upTime()module.get_upTime()module.get_upTime()module.get_upTime()module.get_upTime()YModule get_upTime

Returns the number of milliseconds spent since the module was powered on.

js
function get_upTime()
nodejs
function get_upTime()
php
function get_upTime()
cpp
s64 get_upTime()
m
-(s64) upTime
pas
function get_upTime(): int64
vb
function get_upTime() As Long
cs
long get_upTime()
java
long get_upTime()
py
def get_upTime()
cmd
YModule target get_upTime

Returns :

an integer corresponding to the number of milliseconds spent since the module was powered on

On failure, throws an exception or returns Y_UPTIME_INVALID.

module→get_usbBandwidth()
module→usbBandwidth()
module.get_usbBandwidth()module.get_usbBandwidth()module→get_usbBandwidth()module→get_usbBandwidth()[module usbBandwidth]module.get_usbBandwidth()module.get_usbBandwidth()module.get_usbBandwidth()module.get_usbBandwidth()module.get_usbBandwidth()YModule get_usbBandwidth

Returns the number of USB interfaces used by the module.

js
function get_usbBandwidth()
nodejs
function get_usbBandwidth()
php
function get_usbBandwidth()
cpp
Y_USBBANDWIDTH_enum get_usbBandwidth()
m
-(Y_USBBANDWIDTH_enum) usbBandwidth
pas
function get_usbBandwidth(): Integer
vb
function get_usbBandwidth() As Integer
cs
int get_usbBandwidth()
java
int get_usbBandwidth()
py
def get_usbBandwidth()
cmd
YModule target get_usbBandwidth

Returns :

either Y_USBBANDWIDTH_SIMPLE or Y_USBBANDWIDTH_DOUBLE, according to the number of USB interfaces used by the module

On failure, throws an exception or returns Y_USBBANDWIDTH_INVALID.

module→get_usbCurrent()
module→usbCurrent()
module.get_usbCurrent()module.get_usbCurrent()module→get_usbCurrent()module→get_usbCurrent()[module usbCurrent]module.get_usbCurrent()module.get_usbCurrent()module.get_usbCurrent()module.get_usbCurrent()module.get_usbCurrent()YModule get_usbCurrent

Returns the current consumed by the module on the USB bus, in milli-amps.

js
function get_usbCurrent()
nodejs
function get_usbCurrent()
php
function get_usbCurrent()
cpp
int get_usbCurrent()
m
-(int) usbCurrent
pas
function get_usbCurrent(): LongInt
vb
function get_usbCurrent() As Integer
cs
int get_usbCurrent()
java
int get_usbCurrent()
py
def get_usbCurrent()
cmd
YModule target get_usbCurrent

Returns :

an integer corresponding to the current consumed by the module on the USB bus, in milli-amps

On failure, throws an exception or returns Y_USBCURRENT_INVALID.

module→get_userData()
module→userData()
module.get_userData()module.get_userData()module→get_userData()module→get_userData()[module userData]module.get_userData()module.get_userData()module.get_userData()module.get_userData()module.get_userData()

Returns the value of the userData attribute, as previously stored using method set_userData.

js
function get_userData()
nodejs
function get_userData()
php
function get_userData()
cpp
void * get_userData()
m
-(void*) userData
pas
function get_userData(): Tobject
vb
function get_userData() As Object
cs
object get_userData()
java
Object get_userData()
py
def get_userData()

This attribute is never touched directly by the API, and is at disposal of the caller to store a context.

Returns :

the object stored previously by the caller.

module→isOnline()module.isOnline()module.isOnline()module→isOnline()module→isOnline()[module isOnline]module.isOnline()module.isOnline()module.isOnline()module.isOnline()module.isOnline()

Checks if the module is currently reachable, without raising any error.

js
function isOnline()
nodejs
function isOnline()
php
function isOnline()
cpp
bool isOnline()
m
-(BOOL) isOnline
pas
function isOnline(): boolean
vb
function isOnline() As Boolean
cs
bool isOnline()
java
boolean isOnline()
py
def isOnline()

If there are valid cached values for the module, that have not yet expired, the device is considered reachable. No exception is raised if there is an error while trying to contact the requested module.

Returns :

true if the module can be reached, and false otherwise

module→isOnline_async()module.isOnline_async()module.isOnline_async()

Checks if the module is currently reachable, without raising any error.

js
function isOnline_async(callback, context)
nodejs
function isOnline_async(callback, context)

If there are valid cached values for the module, that have not yet expired, the device is considered reachable. No exception is raised if there is an error while trying to contact the requested module.

This asynchronous version exists only in Javascript. It uses a callback instead of a return value in order to avoid blocking Firefox Javascript VM that does not implement context switching during blocking I/O calls.

Parameters :

callbackcallback function that is invoked when the result is known. The callback function receives three arguments: the caller-specific context object, the receiving module object and the boolean result
contextcaller-specific object that is passed as-is to the callback function

Returns :

nothing : the result is provided to the callback.

module→load()module.load()module.load()module→load()module→load()[module load: ]module.load()module.load()module.load()module.load()module.load()

Preloads the module cache with a specified validity duration.

js
function load(msValidity)
nodejs
function load(msValidity)
php
function load($msValidity)
cpp
YRETCODE load(int msValidity)
m
-(YRETCODE) load: (int) msValidity
pas
function load(msValidity: integer): YRETCODE
vb
function load(ByVal msValidity As Integer) As YRETCODE
cs
YRETCODE load(int msValidity)
java
int load(long msValidity)
py
def load(msValidity)

By default, whenever accessing a device, all module attributes are kept in cache for the standard duration (5 ms). This method can be used to temporarily mark the cache as valid for a longer period, in order to reduce network trafic for instance.

Parameters :

msValidityan integer corresponding to the validity attributed to the loaded module parameters, in milliseconds

Returns :

YAPI_SUCCESS when the call succeeds. On failure, throws an exception or returns a negative error code.

module→load_async()module.load_async()module.load_async()

Preloads the module cache with a specified validity duration (asynchronous version).

js
function load_async(msValidity, callback, context)
nodejs
function load_async(msValidity, callback, context)

By default, whenever accessing a device, all module attributes are kept in cache for the standard duration (5 ms). This method can be used to temporarily mark the cache as valid for a longer period, in order to reduce network trafic for instance. This asynchronous version exists only in Javascript. It uses a callback instead of a return value in order to avoid blocking Firefox javascript VM that does not implement context switching during blocking I/O calls. See the documentation section on asynchronous Javascript calls for more details.

Parameters :

msValidityan integer corresponding to the validity of the loaded module parameters, in milliseconds
callbackcallback function that is invoked when the result is known. The callback function receives three arguments: the caller-specific context object, the receiving module object and the error code (or YAPI_SUCCESS)
contextcaller-specific object that is passed as-is to the callback function

Returns :

nothing : the result is provided to the callback.

module→nextModule()module.nextModule()module.nextModule()module→nextModule()module→nextModule()[module nextModule]module.nextModule()module.nextModule()module.nextModule()module.nextModule()module.nextModule()

Continues the module enumeration started using yFirstModule().

js
function nextModule()
nodejs
function nextModule()
php
function nextModule()
cpp
YModule * nextModule()
m
-(YModule*) nextModule
pas
function nextModule(): TYModule
vb
function nextModule() As YModule
cs
YModule nextModule()
java
YModule nextModule()
py
def nextModule()

Returns :

a pointer to a YModule object, corresponding to the next module found, or a null pointer if there are no more modules to enumerate.

module→reboot()module.reboot()module.reboot()module→reboot()module→reboot()[module reboot: ]module.reboot()module.reboot()module.reboot()module.reboot()module.reboot()YModule reboot

Schedules a simple module reboot after the given number of seconds.

js
function reboot(secBeforeReboot)
nodejs
function reboot(secBeforeReboot)
php
function reboot($secBeforeReboot)
cpp
int reboot(int secBeforeReboot)
m
-(int) reboot: (int) secBeforeReboot
pas
function reboot(secBeforeReboot: LongInt): LongInt
vb
function reboot() As Integer
cs
int reboot(int secBeforeReboot)
java
int reboot(int secBeforeReboot)
py
def reboot(secBeforeReboot)
cmd
YModule target reboot secBeforeReboot

Parameters :

secBeforeRebootnumber of seconds before rebooting

Returns :

YAPI_SUCCESS when the call succeeds. On failure, throws an exception or returns a negative error code.

module→revertFromFlash()module.revertFromFlash()module.revertFromFlash()module→revertFromFlash()module→revertFromFlash()[module revertFromFlash]module.revertFromFlash()module.revertFromFlash()module.revertFromFlash()module.revertFromFlash()module.revertFromFlash()YModule revertFromFlash

Reloads the settings stored in the nonvolatile memory, as when the module is powered on.

js
function revertFromFlash()
nodejs
function revertFromFlash()
php
function revertFromFlash()
cpp
int revertFromFlash()
m
-(int) revertFromFlash
pas
function revertFromFlash(): LongInt
vb
function revertFromFlash() As Integer
cs
int revertFromFlash()
java
int revertFromFlash()
py
def revertFromFlash()
cmd
YModule target revertFromFlash

Returns :

YAPI_SUCCESS when the call succeeds. On failure, throws an exception or returns a negative error code.

module→saveToFlash()module.saveToFlash()module.saveToFlash()module→saveToFlash()module→saveToFlash()[module saveToFlash]module.saveToFlash()module.saveToFlash()module.saveToFlash()module.saveToFlash()module.saveToFlash()YModule saveToFlash

Saves current settings in the nonvolatile memory of the module.

js
function saveToFlash()
nodejs
function saveToFlash()
php
function saveToFlash()
cpp
int saveToFlash()
m
-(int) saveToFlash
pas
function saveToFlash(): LongInt
vb
function saveToFlash() As Integer
cs
int saveToFlash()
java
int saveToFlash()
py
def saveToFlash()
cmd
YModule target saveToFlash

Warning: the number of allowed save operations during a module life is limited (about 100000 cycles). Do not call this function within a loop.

Returns :

YAPI_SUCCESS when the call succeeds. On failure, throws an exception or returns a negative error code.

module→set_beacon()
module→setBeacon()
module.set_beacon()module.set_beacon()module→set_beacon()module→set_beacon()[module setBeacon: ]module.set_beacon()module.set_beacon()module.set_beacon()module.set_beacon()module.set_beacon()YModule set_beacon

Turns on or off the module localization beacon.

js
function set_beacon(newval)
nodejs
function set_beacon(newval)
php
function set_beacon($newval)
cpp
int set_beacon(Y_BEACON_enum newval)
m
-(int) setBeacon: (Y_BEACON_enum) newval
pas
function set_beacon(newval: Integer): integer
vb
function set_beacon(ByVal newval As Integer) As Integer
cs
int set_beacon(int newval)
java
int set_beacon(int newval)
py
def set_beacon(newval)
cmd
YModule target set_beacon newval

Parameters :

newvaleither Y_BEACON_OFF or Y_BEACON_ON

Returns :

YAPI_SUCCESS if the call succeeds.

On failure, throws an exception or returns a negative error code.

module→set_logicalName()
module→setLogicalName()
module.set_logicalName()module.set_logicalName()module→set_logicalName()module→set_logicalName()[module setLogicalName: ]module.set_logicalName()module.set_logicalName()module.set_logicalName()module.set_logicalName()module.set_logicalName()YModule set_logicalName

Changes the logical name of the module.

js
function set_logicalName(newval)
nodejs
function set_logicalName(newval)
php
function set_logicalName($newval)
cpp
int set_logicalName(const string& newval)
m
-(int) setLogicalName: (NSString*) newval
pas
function set_logicalName(newval: string): integer
vb
function set_logicalName(ByVal newval As String) As Integer
cs
int set_logicalName(string newval)
java
int set_logicalName(String newval)
py
def set_logicalName(newval)
cmd
YModule target set_logicalName newval

You can use yCheckLogicalName() prior to this call to make sure that your parameter is valid. Remember to call the saveToFlash() method of the module if the modification must be kept.

Parameters :

newvala string corresponding to the logical name of the module

Returns :

YAPI_SUCCESS if the call succeeds.

On failure, throws an exception or returns a negative error code.

module→set_luminosity()
module→setLuminosity()
module.set_luminosity()module.set_luminosity()module→set_luminosity()module→set_luminosity()[module setLuminosity: ]module.set_luminosity()module.set_luminosity()module.set_luminosity()module.set_luminosity()module.set_luminosity()YModule set_luminosity

Changes the luminosity of the module informative leds.

js
function set_luminosity(newval)
nodejs
function set_luminosity(newval)
php
function set_luminosity($newval)
cpp
int set_luminosity(int newval)
m
-(int) setLuminosity: (int) newval
pas
function set_luminosity(newval: LongInt): integer
vb
function set_luminosity(ByVal newval As Integer) As Integer
cs
int set_luminosity(int newval)
java
int set_luminosity(int newval)
py
def set_luminosity(newval)
cmd
YModule target set_luminosity newval

The parameter is a value between 0 and 100. Remember to call the saveToFlash() method of the module if the modification must be kept.

Parameters :

newvalan integer corresponding to the luminosity of the module informative leds

Returns :

YAPI_SUCCESS if the call succeeds.

On failure, throws an exception or returns a negative error code.

module→set_usbBandwidth()
module→setUsbBandwidth()
module.set_usbBandwidth()module.set_usbBandwidth()module→set_usbBandwidth()module→set_usbBandwidth()[module setUsbBandwidth: ]module.set_usbBandwidth()module.set_usbBandwidth()module.set_usbBandwidth()module.set_usbBandwidth()module.set_usbBandwidth()YModule set_usbBandwidth

Changes the number of USB interfaces used by the module.

js
function set_usbBandwidth(newval)
nodejs
function set_usbBandwidth(newval)
php
function set_usbBandwidth($newval)
cpp
int set_usbBandwidth(Y_USBBANDWIDTH_enum newval)
m
-(int) setUsbBandwidth: (Y_USBBANDWIDTH_enum) newval
pas
function set_usbBandwidth(newval: Integer): integer
vb
function set_usbBandwidth(ByVal newval As Integer) As Integer
cs
int set_usbBandwidth(int newval)
java
int set_usbBandwidth(int newval)
py
def set_usbBandwidth(newval)
cmd
YModule target set_usbBandwidth newval

You must reboot the module after changing this setting.

Parameters :

newvaleither Y_USBBANDWIDTH_SIMPLE or Y_USBBANDWIDTH_DOUBLE, according to the number of USB interfaces used by the module

Returns :

YAPI_SUCCESS if the call succeeds.

On failure, throws an exception or returns a negative error code.

module→set_userData()
module→setUserData()
module.set_userData()module.set_userData()module→set_userData()module→set_userData()[module setUserData: ]module.set_userData()module.set_userData()module.set_userData()module.set_userData()module.set_userData()

Stores a user context provided as argument in the userData attribute of the function.

js
function set_userData(data)
nodejs
function set_userData(data)
php
function set_userData($data)
cpp
void set_userData(void* data)
m
-(void) setUserData: (void*) data
pas
procedure set_userData(data: Tobject)
vb
procedure set_userData(ByVal data As Object)
cs
void set_userData(object data)
java
void set_userData(Object data)
py
def set_userData(data)

This attribute is never touched by the API, and is at disposal of the caller to store a context.

Parameters :

dataany kind of object to be stored

module→triggerFirmwareUpdate()module.triggerFirmwareUpdate()module.triggerFirmwareUpdate()module→triggerFirmwareUpdate()module→triggerFirmwareUpdate()[module triggerFirmwareUpdate: ]module.triggerFirmwareUpdate()module.triggerFirmwareUpdate()module.triggerFirmwareUpdate()module.triggerFirmwareUpdate()module.triggerFirmwareUpdate()YModule triggerFirmwareUpdate

Schedules a module reboot into special firmware update mode.

js
function triggerFirmwareUpdate(secBeforeReboot)
nodejs
function triggerFirmwareUpdate(secBeforeReboot)
php
function triggerFirmwareUpdate($secBeforeReboot)
cpp
int triggerFirmwareUpdate(int secBeforeReboot)
m
-(int) triggerFirmwareUpdate: (int) secBeforeReboot
pas
function triggerFirmwareUpdate(secBeforeReboot: LongInt): LongInt
vb
function triggerFirmwareUpdate() As Integer
cs
int triggerFirmwareUpdate(int secBeforeReboot)
java
int triggerFirmwareUpdate(int secBeforeReboot)
py
def triggerFirmwareUpdate(secBeforeReboot)
cmd
YModule target triggerFirmwareUpdate secBeforeReboot

Parameters :

secBeforeRebootnumber of seconds before rebooting

Returns :

YAPI_SUCCESS when the call succeeds. On failure, throws an exception or returns a negative error code.

module→wait_async()module.wait_async()module.wait_async()

Waits for all pending asynchronous commands on the module to complete, and invoke the user-provided callback function.

js
function wait_async(callback, context)
nodejs
function wait_async(callback, context)

The callback function can therefore freely issue synchronous or asynchronous commands, without risking to block the Javascript VM.

Parameters :

callbackcallback function that is invoked when all pending commands on the module are completed. The callback function receives two arguments: the caller-specific context object and the receiving function object.
contextcaller-specific object that is passed as-is to the callback function

Returns :

nothing.

19.3. Servo function interface

Yoctopuce application programming interface allows you not only to move a servo to a given position, but also to specify the time interval in which the move should be performed. This makes it possible to synchronize two servos involved in a same move.

In order to use the functions described here, you should include:

js
<script type='text/javascript' src='yocto_servo.js'></script>
nodejs
var yoctolib = require('yoctolib');
var YServo = yoctolib.YServo;
php
require_once('yocto_servo.php');
cpp
#include "yocto_servo.h"
m
#import "yocto_servo.h"
pas
uses yocto_servo;
vb
yocto_servo.vb
cs
yocto_servo.cs
java
import com.yoctopuce.YoctoAPI.YServo;
py
from yocto_servo import *
Global functions
yFindServo(func)

Retrieves a servo for a given identifier.

yFirstServo()

Starts the enumeration of servos currently accessible.

YServo methods
servo→describe()

Returns a short text that describes the servo in the form TYPE(NAME)=SERIAL.FUNCTIONID.

servo→get_advertisedValue()

Returns the current value of the servo (no more than 6 characters).

servo→get_errorMessage()

Returns the error message of the latest error with the servo.

servo→get_errorType()

Returns the numerical error code of the latest error with the servo.

servo→get_friendlyName()

Returns a global identifier of the servo in the format MODULE_NAME.FUNCTION_NAME.

servo→get_functionDescriptor()

Returns a unique identifier of type YFUN_DESCR corresponding to the function.

servo→get_functionId()

Returns the hardware identifier of the servo, without reference to the module.

servo→get_hardwareId()

Returns the unique hardware identifier of the servo in the form SERIAL.FUNCTIONID.

servo→get_logicalName()

Returns the logical name of the servo.

servo→get_module()

Gets the YModule object for the device on which the function is located.

servo→get_module_async(callback, context)

Gets the YModule object for the device on which the function is located (asynchronous version).

servo→get_neutral()

Returns the duration in microseconds of a neutral pulse for the servo.

servo→get_position()

Returns the current servo position.

servo→get_range()

Returns the current range of use of the servo.

servo→get_userData()

Returns the value of the userData attribute, as previously stored using method set_userData.

servo→isOnline()

Checks if the servo is currently reachable, without raising any error.

servo→isOnline_async(callback, context)

Checks if the servo is currently reachable, without raising any error (asynchronous version).

servo→load(msValidity)

Preloads the servo cache with a specified validity duration.

servo→load_async(msValidity, callback, context)

Preloads the servo cache with a specified validity duration (asynchronous version).

servo→move(target, ms_duration)

Performs a smooth move at constant speed toward a given position.

servo→nextServo()

Continues the enumeration of servos started using yFirstServo().

servo→registerValueCallback(callback)

Registers the callback function that is invoked on every change of advertised value.

servo→set_logicalName(newval)

Changes the logical name of the servo.

servo→set_neutral(newval)

Changes the duration of the pulse corresponding to the neutral position of the servo.

servo→set_position(newval)

Changes immediately the servo driving position.

servo→set_range(newval)

Changes the range of use of the servo, specified in per cents.

servo→set_userData(data)

Stores a user context provided as argument in the userData attribute of the function.

servo→wait_async(callback, context)

Waits for all pending asynchronous commands on the module to complete, and invoke the user-provided callback function.

YServo.FindServo()
yFindServo()
yFindServo()YServo.FindServo()yFindServo()yFindServo()yFindServo()yFindServo()yFindServo()YServo.FindServo()YServo.FindServo()YServo.FindServo()

Retrieves a servo for a given identifier.

js
function yFindServo(func)
nodejs
function FindServo(func)
php
function yFindServo($func)
cpp
YServo* yFindServo(const string& func)
m
YServo* yFindServo(NSString* func)
pas
function yFindServo(func: string): TYServo
vb
function yFindServo(ByVal func As String) As YServo
cs
YServo FindServo(string func)
java
YServo FindServo(String func)
py
def FindServo(func)

The identifier can be specified using several formats:

This function does not require that the servo is online at the time it is invoked. The returned object is nevertheless valid. Use the method YServo.isOnline() to test if the servo is indeed online at a given time. In case of ambiguity when looking for a servo by logical name, no error is notified: the first instance found is returned. The search is performed first by hardware name, then by logical name.

Parameters :

funca string that uniquely characterizes the servo

Returns :

a YServo object allowing you to drive the servo.

YServo.FirstServo()
yFirstServo()
yFirstServo()YServo.FirstServo()yFirstServo()yFirstServo()yFirstServo()yFirstServo()yFirstServo()YServo.FirstServo()YServo.FirstServo()YServo.FirstServo()

Starts the enumeration of servos currently accessible.

js
function yFirstServo()
nodejs
function FirstServo()
php
function yFirstServo()
cpp
YServo* yFirstServo()
m
YServo* yFirstServo()
pas
function yFirstServo(): TYServo
vb
function yFirstServo() As YServo
cs
YServo FirstServo()
java
YServo FirstServo()
py
def FirstServo()

Use the method YServo.nextServo() to iterate on next servos.

Returns :

a pointer to a YServo object, corresponding to the first servo currently online, or a null pointer if there are none.

servo→describe()servo.describe()servo.describe()servo→describe()servo→describe()[servo describe]servo.describe()servo.describe()servo.describe()servo.describe()servo.describe()

Returns a short text that describes the servo in the form TYPE(NAME)=SERIAL.FUNCTIONID.

js
function describe()
nodejs
function describe()
php
function describe()
cpp
string describe()
m
-(NSString*) describe
pas
function describe(): string
vb
function describe() As String
cs
string describe()
java
String describe()
py
def describe()

More precisely, TYPE is the type of the function, NAME it the name used for the first access to the function, SERIAL is the serial number of the module if the module is connected or "unresolved", and FUNCTIONID is the hardware identifier of the function if the module is connected. For example, this method returns Relay(MyCustomName.relay1)=RELAYLO1-123456.relay1 if the module is already connected or Relay(BadCustomeName.relay1)=unresolved if the module has not yet been connected. This method does not trigger any USB or TCP transaction and can therefore be used in a debugger.

Returns :

a string that describes the servo (ex: Relay(MyCustomName.relay1)=RELAYLO1-123456.relay1)

servo→get_advertisedValue()
servo→advertisedValue()
servo.get_advertisedValue()servo.get_advertisedValue()servo→get_advertisedValue()servo→get_advertisedValue()[servo advertisedValue]servo.get_advertisedValue()servo.get_advertisedValue()servo.get_advertisedValue()servo.get_advertisedValue()servo.get_advertisedValue()YServo get_advertisedValue

Returns the current value of the servo (no more than 6 characters).

js
function get_advertisedValue()
nodejs
function get_advertisedValue()
php
function get_advertisedValue()
cpp
string get_advertisedValue()
m
-(NSString*) advertisedValue
pas
function get_advertisedValue(): string
vb
function get_advertisedValue() As String
cs
string get_advertisedValue()
java
String get_advertisedValue()
py
def get_advertisedValue()
cmd
YServo target get_advertisedValue

Returns :

a string corresponding to the current value of the servo (no more than 6 characters). On failure, throws an exception or returns Y_ADVERTISEDVALUE_INVALID.

servo→get_errorMessage()
servo→errorMessage()
servo.get_errorMessage()servo.get_errorMessage()servo→get_errorMessage()servo→get_errorMessage()[servo errorMessage]servo.get_errorMessage()servo.get_errorMessage()servo.get_errorMessage()servo.get_errorMessage()servo.get_errorMessage()

Returns the error message of the latest error with the servo.

js
function get_errorMessage()
nodejs
function get_errorMessage()
php
function get_errorMessage()
cpp
string get_errorMessage()
m
-(NSString*) errorMessage
pas
function get_errorMessage(): string
vb
function get_errorMessage() As String
cs
string get_errorMessage()
java
String get_errorMessage()
py
def get_errorMessage()

This method is mostly useful when using the Yoctopuce library with exceptions disabled.

Returns :

a string corresponding to the latest error message that occured while using the servo object

servo→get_errorType()
servo→errorType()
servo.get_errorType()servo.get_errorType()servo→get_errorType()servo→get_errorType()servo.get_errorType()servo.get_errorType()servo.get_errorType()servo.get_errorType()servo.get_errorType()

Returns the numerical error code of the latest error with the servo.

js
function get_errorType()
nodejs
function get_errorType()
php
function get_errorType()
cpp
YRETCODE get_errorType()
pas
function get_errorType(): YRETCODE
vb
function get_errorType() As YRETCODE
cs
YRETCODE get_errorType()
java
int get_errorType()
py
def get_errorType()

This method is mostly useful when using the Yoctopuce library with exceptions disabled.

Returns :

a number corresponding to the code of the latest error that occured while using the servo object

servo→get_friendlyName()
servo→friendlyName()
servo.get_friendlyName()servo.get_friendlyName()servo→get_friendlyName()servo→get_friendlyName()[servo friendlyName]servo.get_friendlyName()servo.get_friendlyName()servo.get_friendlyName()

Returns a global identifier of the servo in the format MODULE_NAME.FUNCTION_NAME.

js
function get_friendlyName()
nodejs
function get_friendlyName()
php
function get_friendlyName()
cpp
string get_friendlyName()
m
-(NSString*) friendlyName
cs
string get_friendlyName()
java
String get_friendlyName()
py
def get_friendlyName()

The returned string uses the logical names of the module and of the servo if they are defined, otherwise the serial number of the module and the hardware identifier of the servo (for exemple: MyCustomName.relay1)

Returns :

a string that uniquely identifies the servo using logical names (ex: MyCustomName.relay1) On failure, throws an exception or returns Y_FRIENDLYNAME_INVALID.

servo→get_functionDescriptor()
servo→functionDescriptor()
servo.get_functionDescriptor()servo.get_functionDescriptor()servo→get_functionDescriptor()servo→get_functionDescriptor()[servo functionDescriptor]servo.get_functionDescriptor()servo.get_functionDescriptor()servo.get_functionDescriptor()servo.get_functionDescriptor()servo.get_functionDescriptor()

Returns a unique identifier of type YFUN_DESCR corresponding to the function.

js
function get_functionDescriptor()
nodejs
function get_functionDescriptor()
php
function get_functionDescriptor()
cpp
YFUN_DESCR get_functionDescriptor()
m
-(YFUN_DESCR) functionDescriptor
pas
function get_functionDescriptor(): YFUN_DESCR
vb
function get_functionDescriptor() As YFUN_DESCR
cs
YFUN_DESCR get_functionDescriptor()
java
String get_functionDescriptor()
py
def get_functionDescriptor()

This identifier can be used to test if two instances of YFunction reference the same physical function on the same physical device.

Returns :

an identifier of type YFUN_DESCR. If the function has never been contacted, the returned value is Y_FUNCTIONDESCRIPTOR_INVALID.

servo→get_functionId()
servo→functionId()
servo.get_functionId()servo.get_functionId()servo→get_functionId()servo→get_functionId()[servo functionId]servo.get_functionId()servo.get_functionId()servo.get_functionId()servo.get_functionId()

Returns the hardware identifier of the servo, without reference to the module.

js
function get_functionId()
nodejs
function get_functionId()
php
function get_functionId()
cpp
string get_functionId()
m
-(NSString*) functionId
vb
function get_functionId() As String
cs
string get_functionId()
java
String get_functionId()
py
def get_functionId()

For example relay1

Returns :

a string that identifies the servo (ex: relay1) On failure, throws an exception or returns Y_FUNCTIONID_INVALID.

servo→get_hardwareId()
servo→hardwareId()
servo.get_hardwareId()servo.get_hardwareId()servo→get_hardwareId()servo→get_hardwareId()[servo hardwareId]servo.get_hardwareId()servo.get_hardwareId()servo.get_hardwareId()servo.get_hardwareId()

Returns the unique hardware identifier of the servo in the form SERIAL.FUNCTIONID.

js
function get_hardwareId()
nodejs
function get_hardwareId()
php
function get_hardwareId()
cpp
string get_hardwareId()
m
-(NSString*) hardwareId
vb
function get_hardwareId() As String
cs
string get_hardwareId()
java
String get_hardwareId()
py
def get_hardwareId()

The unique hardware identifier is composed of the device serial number and of the hardware identifier of the servo. (for example RELAYLO1-123456.relay1)

Returns :

a string that uniquely identifies the servo (ex: RELAYLO1-123456.relay1) On failure, throws an exception or returns Y_HARDWAREID_INVALID.

servo→get_logicalName()
servo→logicalName()
servo.get_logicalName()servo.get_logicalName()servo→get_logicalName()servo→get_logicalName()[servo logicalName]servo.get_logicalName()servo.get_logicalName()servo.get_logicalName()servo.get_logicalName()servo.get_logicalName()YServo get_logicalName

Returns the logical name of the servo.

js
function get_logicalName()
nodejs
function get_logicalName()
php
function get_logicalName()
cpp
string get_logicalName()
m
-(NSString*) logicalName
pas
function get_logicalName(): string
vb
function get_logicalName() As String
cs
string get_logicalName()
java
String get_logicalName()
py
def get_logicalName()
cmd
YServo target get_logicalName

Returns :

a string corresponding to the logical name of the servo. On failure, throws an exception or returns Y_LOGICALNAME_INVALID.

servo→get_module()
servo→module()
servo.get_module()servo.get_module()servo→get_module()servo→get_module()[servo module]servo.get_module()servo.get_module()servo.get_module()servo.get_module()servo.get_module()

Gets the YModule object for the device on which the function is located.

js
function get_module()
nodejs
function get_module()
php
function get_module()
cpp
YModule * get_module()
m
-(YModule*) module
pas
function get_module(): TYModule
vb
function get_module() As YModule
cs
YModule get_module()
java
YModule get_module()
py
def get_module()

If the function cannot be located on any module, the returned instance of YModule is not shown as on-line.

Returns :

an instance of YModule

servo→get_module_async()
servo→module_async()
servo.get_module_async()servo.get_module_async()

Gets the YModule object for the device on which the function is located (asynchronous version).

js
function get_module_async(callback, context)
nodejs
function get_module_async(callback, context)

If the function cannot be located on any module, the returned YModule object does not show as on-line. This asynchronous version exists only in Javascript. It uses a callback instead of a return value in order to avoid blocking Firefox javascript VM that does not implement context switching during blocking I/O calls. See the documentation section on asynchronous Javascript calls for more details.

Parameters :

callbackcallback function that is invoked when the result is known. The callback function receives three arguments: the caller-specific context object, the receiving function object and the requested YModule object
contextcaller-specific object that is passed as-is to the callback function

Returns :

nothing : the result is provided to the callback.

servo→get_neutral()
servo→neutral()
servo.get_neutral()servo.get_neutral()servo→get_neutral()servo→get_neutral()[servo neutral]servo.get_neutral()servo.get_neutral()servo.get_neutral()servo.get_neutral()servo.get_neutral()YServo get_neutral

Returns the duration in microseconds of a neutral pulse for the servo.

js
function get_neutral()
nodejs
function get_neutral()
php
function get_neutral()
cpp
int get_neutral()
m
-(int) neutral
pas
function get_neutral(): LongInt
vb
function get_neutral() As Integer
cs
int get_neutral()
java
int get_neutral()
py
def get_neutral()
cmd
YServo target get_neutral

Returns :

an integer corresponding to the duration in microseconds of a neutral pulse for the servo

On failure, throws an exception or returns Y_NEUTRAL_INVALID.

servo→get_position()
servo→position()
servo.get_position()servo.get_position()servo→get_position()servo→get_position()[servo position]servo.get_position()servo.get_position()servo.get_position()servo.get_position()servo.get_position()YServo get_position

Returns the current servo position.

js
function get_position()
nodejs
function get_position()
php
function get_position()
cpp
int get_position()
m
-(int) position
pas
function get_position(): LongInt
vb
function get_position() As Integer
cs
int get_position()
java
int get_position()
py
def get_position()
cmd
YServo target get_position

Returns :

an integer corresponding to the current servo position

On failure, throws an exception or returns Y_POSITION_INVALID.

servo→get_range()
servo→range()
servo.get_range()servo.get_range()servo→get_range()servo→get_range()[servo range]servo.get_range()servo.get_range()servo.get_range()servo.get_range()servo.get_range()YServo get_range

Returns the current range of use of the servo.

js
function get_range()
nodejs
function get_range()
php
function get_range()
cpp
int get_range()
m
-(int) range
pas
function get_range(): LongInt
vb
function get_range() As Integer
cs
int get_range()
java
int get_range()
py
def get_range()
cmd
YServo target get_range

Returns :

an integer corresponding to the current range of use of the servo

On failure, throws an exception or returns Y_RANGE_INVALID.

servo→get_userData()
servo→userData()
servo.get_userData()servo.get_userData()servo→get_userData()servo→get_userData()[servo userData]servo.get_userData()servo.get_userData()servo.get_userData()servo.get_userData()servo.get_userData()

Returns the value of the userData attribute, as previously stored using method set_userData.

js
function get_userData()
nodejs
function get_userData()
php
function get_userData()
cpp
void * get_userData()
m
-(void*) userData
pas
function get_userData(): Tobject
vb
function get_userData() As Object
cs
object get_userData()
java
Object get_userData()
py
def get_userData()

This attribute is never touched directly by the API, and is at disposal of the caller to store a context.

Returns :

the object stored previously by the caller.

servo→isOnline()servo.isOnline()servo.isOnline()servo→isOnline()servo→isOnline()[servo isOnline]servo.isOnline()servo.isOnline()servo.isOnline()servo.isOnline()servo.isOnline()

Checks if the servo is currently reachable, without raising any error.

js
function isOnline()
nodejs
function isOnline()
php
function isOnline()
cpp
bool isOnline()
m
-(BOOL) isOnline
pas
function isOnline(): boolean
vb
function isOnline() As Boolean
cs
bool isOnline()
java
boolean isOnline()
py
def isOnline()

If there is a cached value for the servo in cache, that has not yet expired, the device is considered reachable. No exception is raised if there is an error while trying to contact the device hosting the servo.

Returns :

true if the servo can be reached, and false otherwise

servo→isOnline_async()servo.isOnline_async()servo.isOnline_async()

Checks if the servo is currently reachable, without raising any error (asynchronous version).

js
function isOnline_async(callback, context)
nodejs
function isOnline_async(callback, context)

If there is a cached value for the servo in cache, that has not yet expired, the device is considered reachable. No exception is raised if there is an error while trying to contact the device hosting the requested function.

This asynchronous version exists only in Javascript. It uses a callback instead of a return value in order to avoid blocking the Javascript virtual machine.

Parameters :

callbackcallback function that is invoked when the result is known. The callback function receives three arguments: the caller-specific context object, the receiving function object and the boolean result
contextcaller-specific object that is passed as-is to the callback function

Returns :

nothing : the result is provided to the callback.

servo→load()servo.load()servo.load()servo→load()servo→load()[servo load: ]servo.load()servo.load()servo.load()servo.load()servo.load()

Preloads the servo cache with a specified validity duration.

js
function load(msValidity)
nodejs
function load(msValidity)
php
function load($msValidity)
cpp
YRETCODE load(int msValidity)
m
-(YRETCODE) load: (int) msValidity
pas
function load(msValidity: integer): YRETCODE
vb
function load(ByVal msValidity As Integer) As YRETCODE
cs
YRETCODE load(int msValidity)
java
int load(long msValidity)
py
def load(msValidity)

By default, whenever accessing a device, all function attributes are kept in cache for the standard duration (5 ms). This method can be used to temporarily mark the cache as valid for a longer period, in order to reduce network trafic for instance.

Parameters :

msValidityan integer corresponding to the validity attributed to the loaded function parameters, in milliseconds

Returns :

YAPI_SUCCESS when the call succeeds. On failure, throws an exception or returns a negative error code.

servo→load_async()servo.load_async()servo.load_async()

Preloads the servo cache with a specified validity duration (asynchronous version).

js
function load_async(msValidity, callback, context)
nodejs
function load_async(msValidity, callback, context)

By default, whenever accessing a device, all function attributes are kept in cache for the standard duration (5 ms). This method can be used to temporarily mark the cache as valid for a longer period, in order to reduce network trafic for instance. This asynchronous version exists only in Javascript. It uses a callback instead of a return value in order to avoid blocking the Javascript virtual machine.

Parameters :

msValidityan integer corresponding to the validity of the loaded function parameters, in milliseconds
callbackcallback function that is invoked when the result is known. The callback function receives three arguments: the caller-specific context object, the receiving function object and the error code (or YAPI_SUCCESS)
contextcaller-specific object that is passed as-is to the callback function

Returns :

nothing : the result is provided to the callback.

servo→move()servo.move()servo.move()servo→move()servo→move()[servo move: ]servo.move()servo.move()servo.move()servo.move()servo.move()YServo move

Performs a smooth move at constant speed toward a given position.

js
function move(target, ms_duration)
nodejs
function move(target, ms_duration)
php
function move($target, $ms_duration)
cpp
int move(int target, int ms_duration)
m
-(int) move: (int) target : (int) ms_duration
pas
function move(target: LongInt, ms_duration: LongInt): integer
vb
function move(ByVal target As Integer,
  ByVal ms_duration As Integer) As Integer
cs
int move(int target, int ms_duration)
java
int move(int target, int ms_duration)
py
def move(target, ms_duration)
cmd
YServo target move target ms_duration

Parameters :

targetnew position at the end of the move
ms_durationtotal duration of the move, in milliseconds

Returns :

YAPI_SUCCESS if the call succeeds.

On failure, throws an exception or returns a negative error code.

servo→nextServo()servo.nextServo()servo.nextServo()servo→nextServo()servo→nextServo()[servo nextServo]servo.nextServo()servo.nextServo()servo.nextServo()servo.nextServo()servo.nextServo()

Continues the enumeration of servos started using yFirstServo().

js
function nextServo()
nodejs
function nextServo()
php
function nextServo()
cpp
YServo * nextServo()
m
-(YServo*) nextServo
pas
function nextServo(): TYServo
vb
function nextServo() As YServo
cs
YServo nextServo()
java
YServo nextServo()
py
def nextServo()

Returns :

a pointer to a YServo object, corresponding to a servo currently online, or a null pointer if there are no more servos to enumerate.

servo→registerValueCallback()servo.registerValueCallback()servo.registerValueCallback()servo→registerValueCallback()servo→registerValueCallback()[servo registerValueCallback: ]servo.registerValueCallback()servo.registerValueCallback()servo.registerValueCallback()servo.registerValueCallback()servo.registerValueCallback()

Registers the callback function that is invoked on every change of advertised value.

js
function registerValueCallback(callback)
nodejs
function registerValueCallback(callback)
php
function registerValueCallback($callback)
cpp
int registerValueCallback(YServoValueCallback callback)
m
-(int) registerValueCallback: (YServoValueCallback) callback
pas
function registerValueCallback(callback: TYServoValueCallback): LongInt
vb
function registerValueCallback() As Integer
cs
int registerValueCallback(ValueCallback callback)
java
int registerValueCallback(UpdateCallback callback)
py
def registerValueCallback(callback)

The callback is invoked only during the execution of ySleep or yHandleEvents. This provides control over the time when the callback is triggered. For good responsiveness, remember to call one of these two functions periodically. To unregister a callback, pass a null pointer as argument.

Parameters :

callbackthe callback function to call, or a null pointer. The callback function should take two arguments: the function object of which the value has changed, and the character string describing the new advertised value.

servo→set_logicalName()
servo→setLogicalName()
servo.set_logicalName()servo.set_logicalName()servo→set_logicalName()servo→set_logicalName()[servo setLogicalName: ]servo.set_logicalName()servo.set_logicalName()servo.set_logicalName()servo.set_logicalName()servo.set_logicalName()YServo set_logicalName

Changes the logical name of the servo.

js
function set_logicalName(newval)
nodejs
function set_logicalName(newval)
php
function set_logicalName($newval)
cpp
int set_logicalName(const string& newval)
m
-(int) setLogicalName: (NSString*) newval
pas
function set_logicalName(newval: string): integer
vb
function set_logicalName(ByVal newval As String) As Integer
cs
int set_logicalName(string newval)
java
int set_logicalName(String newval)
py
def set_logicalName(newval)
cmd
YServo target set_logicalName newval

You can use yCheckLogicalName() prior to this call to make sure that your parameter is valid. Remember to call the saveToFlash() method of the module if the modification must be kept.

Parameters :

newvala string corresponding to the logical name of the servo.

Returns :

YAPI_SUCCESS if the call succeeds. On failure, throws an exception or returns a negative error code.

servo→set_neutral()
servo→setNeutral()
servo.set_neutral()servo.set_neutral()servo→set_neutral()servo→set_neutral()[servo setNeutral: ]servo.set_neutral()servo.set_neutral()servo.set_neutral()servo.set_neutral()servo.set_neutral()YServo set_neutral

Changes the duration of the pulse corresponding to the neutral position of the servo.

js
function set_neutral(newval)
nodejs
function set_neutral(newval)
php
function set_neutral($newval)
cpp
int set_neutral(int newval)
m
-(int) setNeutral: (int) newval
pas
function set_neutral(newval: LongInt): integer
vb
function set_neutral(ByVal newval As Integer) As Integer
cs
int set_neutral(int newval)
java
int set_neutral(int newval)
py
def set_neutral(newval)
cmd
YServo target set_neutral newval

The duration is specified in microseconds, and the standard value is 1500 [us]. This setting makes it possible to shift the range of use of the servo. Be aware that using a range higher than what is supported by the servo is likely to damage the servo.

Parameters :

newvalan integer corresponding to the duration of the pulse corresponding to the neutral position of the servo

Returns :

YAPI_SUCCESS if the call succeeds.

On failure, throws an exception or returns a negative error code.

servo→set_position()
servo→setPosition()
servo.set_position()servo.set_position()servo→set_position()servo→set_position()[servo setPosition: ]servo.set_position()servo.set_position()servo.set_position()servo.set_position()servo.set_position()YServo set_position

Changes immediately the servo driving position.

js
function set_position(newval)
nodejs
function set_position(newval)
php
function set_position($newval)
cpp
int set_position(int newval)
m
-(int) setPosition: (int) newval
pas
function set_position(newval: LongInt): integer
vb
function set_position(ByVal newval As Integer) As Integer
cs
int set_position(int newval)
java
int set_position(int newval)
py
def set_position(newval)
cmd
YServo target set_position newval

Parameters :

newvalan integer corresponding to immediately the servo driving position

Returns :

YAPI_SUCCESS if the call succeeds.

On failure, throws an exception or returns a negative error code.

servo→set_range()
servo→setRange()
servo.set_range()servo.set_range()servo→set_range()servo→set_range()[servo setRange: ]servo.set_range()servo.set_range()servo.set_range()servo.set_range()servo.set_range()YServo set_range

Changes the range of use of the servo, specified in per cents.

js
function set_range(newval)
nodejs
function set_range(newval)
php
function set_range($newval)
cpp
int set_range(int newval)
m
-(int) setRange: (int) newval
pas
function set_range(newval: LongInt): integer
vb
function set_range(ByVal newval As Integer) As Integer
cs
int set_range(int newval)
java
int set_range(int newval)
py
def set_range(newval)
cmd
YServo target set_range newval

A range of 100% corresponds to a standard control signal, that varies from 1 [ms] to 2 [ms], When using a servo that supports a double range, from 0.5 [ms] to 2.5 [ms], you can select a range of 200%. Be aware that using a range higher than what is supported by the servo is likely to damage the servo.

Parameters :

newvalan integer corresponding to the range of use of the servo, specified in per cents

Returns :

YAPI_SUCCESS if the call succeeds.

On failure, throws an exception or returns a negative error code.

servo→set_userData()
servo→setUserData()
servo.set_userData()servo.set_userData()servo→set_userData()servo→set_userData()[servo setUserData: ]servo.set_userData()servo.set_userData()servo.set_userData()servo.set_userData()servo.set_userData()

Stores a user context provided as argument in the userData attribute of the function.

js
function set_userData(data)
nodejs
function set_userData(data)
php
function set_userData($data)
cpp
void set_userData(void* data)
m
-(void) setUserData: (void*) data
pas
procedure set_userData(data: Tobject)
vb
procedure set_userData(ByVal data As Object)
cs
void set_userData(object data)
java
void set_userData(Object data)
py
def set_userData(data)

This attribute is never touched by the API, and is at disposal of the caller to store a context.

Parameters :

dataany kind of object to be stored

servo→wait_async()servo.wait_async()servo.wait_async()

Waits for all pending asynchronous commands on the module to complete, and invoke the user-provided callback function.

js
function wait_async(callback, context)
nodejs
function wait_async(callback, context)

The callback function can therefore freely issue synchronous or asynchronous commands, without risking to block the Javascript VM.

Parameters :

callbackcallback function that is invoked when all pending commands on the module are completed. The callback function receives two arguments: the caller-specific context object and the receiving function object.
contextcaller-specific object that is passed as-is to the callback function

Returns :

nothing.

19.4. External power supply control interface

Yoctopuce application programming interface allows you to control the power source to use for module functions that require high current. The module can also automatically disconnect the external power when a voltage drop is observed on the external power source (external battery running out of power).

In order to use the functions described here, you should include:

js
<script type='text/javascript' src='yocto_dualpower.js'></script>
nodejs
var yoctolib = require('yoctolib');
var YDualPower = yoctolib.YDualPower;
php
require_once('yocto_dualpower.php');
cpp
#include "yocto_dualpower.h"
m
#import "yocto_dualpower.h"
pas
uses yocto_dualpower;
vb
yocto_dualpower.vb
cs
yocto_dualpower.cs
java
import com.yoctopuce.YoctoAPI.YDualPower;
py
from yocto_dualpower import *
Global functions
yFindDualPower(func)

Retrieves a dual power control for a given identifier.

yFirstDualPower()

Starts the enumeration of dual power controls currently accessible.

YDualPower methods
dualpower→describe()

Returns a short text that describes the power control in the form TYPE(NAME)=SERIAL.FUNCTIONID.

dualpower→get_advertisedValue()

Returns the current value of the power control (no more than 6 characters).

dualpower→get_errorMessage()

Returns the error message of the latest error with the power control.

dualpower→get_errorType()

Returns the numerical error code of the latest error with the power control.

dualpower→get_extVoltage()

Returns the measured voltage on the external power source, in millivolts.

dualpower→get_friendlyName()

Returns a global identifier of the power control in the format MODULE_NAME.FUNCTION_NAME.

dualpower→get_functionDescriptor()

Returns a unique identifier of type YFUN_DESCR corresponding to the function.

dualpower→get_functionId()

Returns the hardware identifier of the power control, without reference to the module.

dualpower→get_hardwareId()

Returns the unique hardware identifier of the power control in the form SERIAL.FUNCTIONID.

dualpower→get_logicalName()

Returns the logical name of the power control.

dualpower→get_module()

Gets the YModule object for the device on which the function is located.

dualpower→get_module_async(callback, context)

Gets the YModule object for the device on which the function is located (asynchronous version).

dualpower→get_powerControl()

Returns the selected power source for module functions that require lots of current.

dualpower→get_powerState()

Returns the current power source for module functions that require lots of current.

dualpower→get_userData()

Returns the value of the userData attribute, as previously stored using method set_userData.

dualpower→isOnline()

Checks if the power control is currently reachable, without raising any error.

dualpower→isOnline_async(callback, context)

Checks if the power control is currently reachable, without raising any error (asynchronous version).

dualpower→load(msValidity)

Preloads the power control cache with a specified validity duration.

dualpower→load_async(msValidity, callback, context)

Preloads the power control cache with a specified validity duration (asynchronous version).

dualpower→nextDualPower()

Continues the enumeration of dual power controls started using yFirstDualPower().

dualpower→registerValueCallback(callback)

Registers the callback function that is invoked on every change of advertised value.

dualpower→set_logicalName(newval)

Changes the logical name of the power control.

dualpower→set_powerControl(newval)

Changes the selected power source for module functions that require lots of current.

dualpower→set_userData(data)

Stores a user context provided as argument in the userData attribute of the function.

dualpower→wait_async(callback, context)

Waits for all pending asynchronous commands on the module to complete, and invoke the user-provided callback function.

YDualPower.FindDualPower()
yFindDualPower()
yFindDualPower()YDualPower.FindDualPower()yFindDualPower()yFindDualPower()yFindDualPower()yFindDualPower()yFindDualPower()YDualPower.FindDualPower()YDualPower.FindDualPower()YDualPower.FindDualPower()

Retrieves a dual power control for a given identifier.

js
function yFindDualPower(func)
nodejs
function FindDualPower(func)
php
function yFindDualPower($func)
cpp
YDualPower* yFindDualPower(const string& func)
m
YDualPower* yFindDualPower(NSString* func)
pas
function yFindDualPower(func: string): TYDualPower
vb
function yFindDualPower(ByVal func As String) As YDualPower
cs
YDualPower FindDualPower(string func)
java
YDualPower FindDualPower(String func)
py
def FindDualPower(func)

The identifier can be specified using several formats:

This function does not require that the power control is online at the time it is invoked. The returned object is nevertheless valid. Use the method YDualPower.isOnline() to test if the power control is indeed online at a given time. In case of ambiguity when looking for a dual power control by logical name, no error is notified: the first instance found is returned. The search is performed first by hardware name, then by logical name.

Parameters :

funca string that uniquely characterizes the power control

Returns :

a YDualPower object allowing you to drive the power control.

YDualPower.FirstDualPower()
yFirstDualPower()
yFirstDualPower()YDualPower.FirstDualPower()yFirstDualPower()yFirstDualPower()yFirstDualPower()yFirstDualPower()yFirstDualPower()YDualPower.FirstDualPower()YDualPower.FirstDualPower()YDualPower.FirstDualPower()

Starts the enumeration of dual power controls currently accessible.

js
function yFirstDualPower()
nodejs
function FirstDualPower()
php
function yFirstDualPower()
cpp
YDualPower* yFirstDualPower()
m
YDualPower* yFirstDualPower()
pas
function yFirstDualPower(): TYDualPower
vb
function yFirstDualPower() As YDualPower
cs
YDualPower FirstDualPower()
java
YDualPower FirstDualPower()
py
def FirstDualPower()

Use the method YDualPower.nextDualPower() to iterate on next dual power controls.

Returns :

a pointer to a YDualPower object, corresponding to the first dual power control currently online, or a null pointer if there are none.

dualpower→describe()dualpower.describe()dualpower.describe()dualpower→describe()dualpower→describe()[dualpower describe]dualpower.describe()dualpower.describe()dualpower.describe()dualpower.describe()dualpower.describe()

Returns a short text that describes the power control in the form TYPE(NAME)=SERIAL.FUNCTIONID.

js
function describe()
nodejs
function describe()
php
function describe()
cpp
string describe()
m
-(NSString*) describe
pas
function describe(): string
vb
function describe() As String
cs
string describe()
java
String describe()
py
def describe()

More precisely, TYPE is the type of the function, NAME it the name used for the first access to the function, SERIAL is the serial number of the module if the module is connected or "unresolved", and FUNCTIONID is the hardware identifier of the function if the module is connected. For example, this method returns Relay(MyCustomName.relay1)=RELAYLO1-123456.relay1 if the module is already connected or Relay(BadCustomeName.relay1)=unresolved if the module has not yet been connected. This method does not trigger any USB or TCP transaction and can therefore be used in a debugger.

Returns :

a string that describes the power control (ex: Relay(MyCustomName.relay1)=RELAYLO1-123456.relay1)

dualpower→get_advertisedValue()
dualpower→advertisedValue()
dualpower.get_advertisedValue()dualpower.get_advertisedValue()dualpower→get_advertisedValue()dualpower→get_advertisedValue()[dualpower advertisedValue]dualpower.get_advertisedValue()dualpower.get_advertisedValue()dualpower.get_advertisedValue()dualpower.get_advertisedValue()dualpower.get_advertisedValue()YDualPower get_advertisedValue

Returns the current value of the power control (no more than 6 characters).

js
function get_advertisedValue()
nodejs
function get_advertisedValue()
php
function get_advertisedValue()
cpp
string get_advertisedValue()
m
-(NSString*) advertisedValue
pas
function get_advertisedValue(): string
vb
function get_advertisedValue() As String
cs
string get_advertisedValue()
java
String get_advertisedValue()
py
def get_advertisedValue()
cmd
YDualPower target get_advertisedValue

Returns :

a string corresponding to the current value of the power control (no more than 6 characters). On failure, throws an exception or returns Y_ADVERTISEDVALUE_INVALID.

dualpower→get_errorMessage()
dualpower→errorMessage()
dualpower.get_errorMessage()dualpower.get_errorMessage()dualpower→get_errorMessage()dualpower→get_errorMessage()[dualpower errorMessage]dualpower.get_errorMessage()dualpower.get_errorMessage()dualpower.get_errorMessage()dualpower.get_errorMessage()dualpower.get_errorMessage()

Returns the error message of the latest error with the power control.

js
function get_errorMessage()
nodejs
function get_errorMessage()
php
function get_errorMessage()
cpp
string get_errorMessage()
m
-(NSString*) errorMessage
pas
function get_errorMessage(): string
vb
function get_errorMessage() As String
cs
string get_errorMessage()
java
String get_errorMessage()
py
def get_errorMessage()

This method is mostly useful when using the Yoctopuce library with exceptions disabled.

Returns :

a string corresponding to the latest error message that occured while using the power control object

dualpower→get_errorType()
dualpower→errorType()
dualpower.get_errorType()dualpower.get_errorType()dualpower→get_errorType()dualpower→get_errorType()dualpower.get_errorType()dualpower.get_errorType()dualpower.get_errorType()dualpower.get_errorType()dualpower.get_errorType()

Returns the numerical error code of the latest error with the power control.

js
function get_errorType()
nodejs
function get_errorType()
php
function get_errorType()
cpp
YRETCODE get_errorType()
pas
function get_errorType(): YRETCODE
vb
function get_errorType() As YRETCODE
cs
YRETCODE get_errorType()
java
int get_errorType()
py
def get_errorType()

This method is mostly useful when using the Yoctopuce library with exceptions disabled.

Returns :

a number corresponding to the code of the latest error that occured while using the power control object

dualpower→get_extVoltage()
dualpower→extVoltage()
dualpower.get_extVoltage()dualpower.get_extVoltage()dualpower→get_extVoltage()dualpower→get_extVoltage()[dualpower extVoltage]dualpower.get_extVoltage()dualpower.get_extVoltage()dualpower.get_extVoltage()dualpower.get_extVoltage()dualpower.get_extVoltage()YDualPower get_extVoltage

Returns the measured voltage on the external power source, in millivolts.

js
function get_extVoltage()
nodejs
function get_extVoltage()
php
function get_extVoltage()
cpp
int get_extVoltage()
m
-(int) extVoltage
pas
function get_extVoltage(): LongInt
vb
function get_extVoltage() As Integer
cs
int get_extVoltage()
java
int get_extVoltage()
py
def get_extVoltage()
cmd
YDualPower target get_extVoltage

Returns :

an integer corresponding to the measured voltage on the external power source, in millivolts

On failure, throws an exception or returns Y_EXTVOLTAGE_INVALID.

dualpower→get_friendlyName()
dualpower→friendlyName()
dualpower.get_friendlyName()dualpower.get_friendlyName()dualpower→get_friendlyName()dualpower→get_friendlyName()[dualpower friendlyName]dualpower.get_friendlyName()dualpower.get_friendlyName()dualpower.get_friendlyName()

Returns a global identifier of the power control in the format MODULE_NAME.FUNCTION_NAME.

js
function get_friendlyName()
nodejs
function get_friendlyName()
php
function get_friendlyName()
cpp
string get_friendlyName()
m
-(NSString*) friendlyName
cs
string get_friendlyName()
java
String get_friendlyName()
py
def get_friendlyName()

The returned string uses the logical names of the module and of the power control if they are defined, otherwise the serial number of the module and the hardware identifier of the power control (for exemple: MyCustomName.relay1)

Returns :

a string that uniquely identifies the power control using logical names (ex: MyCustomName.relay1) On failure, throws an exception or returns Y_FRIENDLYNAME_INVALID.

dualpower→get_functionDescriptor()
dualpower→functionDescriptor()
dualpower.get_functionDescriptor()dualpower.get_functionDescriptor()dualpower→get_functionDescriptor()dualpower→get_functionDescriptor()[dualpower functionDescriptor]dualpower.get_functionDescriptor()dualpower.get_functionDescriptor()dualpower.get_functionDescriptor()dualpower.get_functionDescriptor()dualpower.get_functionDescriptor()

Returns a unique identifier of type YFUN_DESCR corresponding to the function.

js
function get_functionDescriptor()
nodejs
function get_functionDescriptor()
php
function get_functionDescriptor()
cpp
YFUN_DESCR get_functionDescriptor()
m
-(YFUN_DESCR) functionDescriptor
pas
function get_functionDescriptor(): YFUN_DESCR
vb
function get_functionDescriptor() As YFUN_DESCR
cs
YFUN_DESCR get_functionDescriptor()
java
String get_functionDescriptor()
py
def get_functionDescriptor()

This identifier can be used to test if two instances of YFunction reference the same physical function on the same physical device.

Returns :

an identifier of type YFUN_DESCR. If the function has never been contacted, the returned value is Y_FUNCTIONDESCRIPTOR_INVALID.

dualpower→get_functionId()
dualpower→functionId()
dualpower.get_functionId()dualpower.get_functionId()dualpower→get_functionId()dualpower→get_functionId()[dualpower functionId]dualpower.get_functionId()dualpower.get_functionId()dualpower.get_functionId()dualpower.get_functionId()

Returns the hardware identifier of the power control, without reference to the module.

js
function get_functionId()
nodejs
function get_functionId()
php
function get_functionId()
cpp
string get_functionId()
m
-(NSString*) functionId
vb
function get_functionId() As String
cs
string get_functionId()
java
String get_functionId()
py
def get_functionId()

For example relay1

Returns :

a string that identifies the power control (ex: relay1) On failure, throws an exception or returns Y_FUNCTIONID_INVALID.

dualpower→get_hardwareId()
dualpower→hardwareId()
dualpower.get_hardwareId()dualpower.get_hardwareId()dualpower→get_hardwareId()dualpower→get_hardwareId()[dualpower hardwareId]dualpower.get_hardwareId()dualpower.get_hardwareId()dualpower.get_hardwareId()dualpower.get_hardwareId()

Returns the unique hardware identifier of the power control in the form SERIAL.FUNCTIONID.

js
function get_hardwareId()
nodejs
function get_hardwareId()
php
function get_hardwareId()
cpp
string get_hardwareId()
m
-(NSString*) hardwareId
vb
function get_hardwareId() As String
cs
string get_hardwareId()
java
String get_hardwareId()
py
def get_hardwareId()

The unique hardware identifier is composed of the device serial number and of the hardware identifier of the power control. (for example RELAYLO1-123456.relay1)

Returns :

a string that uniquely identifies the power control (ex: RELAYLO1-123456.relay1) On failure, throws an exception or returns Y_HARDWAREID_INVALID.

dualpower→get_logicalName()
dualpower→logicalName()
dualpower.get_logicalName()dualpower.get_logicalName()dualpower→get_logicalName()dualpower→get_logicalName()[dualpower logicalName]dualpower.get_logicalName()dualpower.get_logicalName()dualpower.get_logicalName()dualpower.get_logicalName()dualpower.get_logicalName()YDualPower get_logicalName

Returns the logical name of the power control.

js
function get_logicalName()
nodejs
function get_logicalName()
php
function get_logicalName()
cpp
string get_logicalName()
m
-(NSString*) logicalName
pas
function get_logicalName(): string
vb
function get_logicalName() As String
cs
string get_logicalName()
java
String get_logicalName()
py
def get_logicalName()
cmd
YDualPower target get_logicalName

Returns :

a string corresponding to the logical name of the power control. On failure, throws an exception or returns Y_LOGICALNAME_INVALID.

dualpower→get_module()
dualpower→module()
dualpower.get_module()dualpower.get_module()dualpower→get_module()dualpower→get_module()[dualpower module]dualpower.get_module()dualpower.get_module()dualpower.get_module()dualpower.get_module()dualpower.get_module()

Gets the YModule object for the device on which the function is located.

js
function get_module()
nodejs
function get_module()
php
function get_module()
cpp
YModule * get_module()
m
-(YModule*) module
pas
function get_module(): TYModule
vb
function get_module() As YModule
cs
YModule get_module()
java
YModule get_module()
py
def get_module()

If the function cannot be located on any module, the returned instance of YModule is not shown as on-line.

Returns :

an instance of YModule

dualpower→get_module_async()
dualpower→module_async()
dualpower.get_module_async()dualpower.get_module_async()

Gets the YModule object for the device on which the function is located (asynchronous version).

js
function get_module_async(callback, context)
nodejs
function get_module_async(callback, context)

If the function cannot be located on any module, the returned YModule object does not show as on-line. This asynchronous version exists only in Javascript. It uses a callback instead of a return value in order to avoid blocking Firefox javascript VM that does not implement context switching during blocking I/O calls. See the documentation section on asynchronous Javascript calls for more details.

Parameters :

callbackcallback function that is invoked when the result is known. The callback function receives three arguments: the caller-specific context object, the receiving function object and the requested YModule object
contextcaller-specific object that is passed as-is to the callback function

Returns :

nothing : the result is provided to the callback.

dualpower→get_powerControl()
dualpower→powerControl()
dualpower.get_powerControl()dualpower.get_powerControl()dualpower→get_powerControl()dualpower→get_powerControl()[dualpower powerControl]dualpower.get_powerControl()dualpower.get_powerControl()dualpower.get_powerControl()dualpower.get_powerControl()dualpower.get_powerControl()YDualPower get_powerControl

Returns the selected power source for module functions that require lots of current.

js
function get_powerControl()
nodejs
function get_powerControl()
php
function get_powerControl()
cpp
Y_POWERCONTROL_enum get_powerControl()
m
-(Y_POWERCONTROL_enum) powerControl
pas
function get_powerControl(): Integer
vb
function get_powerControl() As Integer
cs
int get_powerControl()
java
int get_powerControl()
py
def get_powerControl()
cmd
YDualPower target get_powerControl

Returns :

a value among Y_POWERCONTROL_AUTO, Y_POWERCONTROL_FROM_USB, Y_POWERCONTROL_FROM_EXT and Y_POWERCONTROL_OFF corresponding to the selected power source for module functions that require lots of current

On failure, throws an exception or returns Y_POWERCONTROL_INVALID.

dualpower→get_powerState()
dualpower→powerState()
dualpower.get_powerState()dualpower.get_powerState()dualpower→get_powerState()dualpower→get_powerState()[dualpower powerState]dualpower.get_powerState()dualpower.get_powerState()dualpower.get_powerState()dualpower.get_powerState()dualpower.get_powerState()YDualPower get_powerState

Returns the current power source for module functions that require lots of current.

js
function get_powerState()
nodejs
function get_powerState()
php
function get_powerState()
cpp
Y_POWERSTATE_enum get_powerState()
m
-(Y_POWERSTATE_enum) powerState
pas
function get_powerState(): Integer
vb
function get_powerState() As Integer
cs
int get_powerState()
java
int get_powerState()
py
def get_powerState()
cmd
YDualPower target get_powerState

Returns :

a value among Y_POWERSTATE_OFF, Y_POWERSTATE_FROM_USB and Y_POWERSTATE_FROM_EXT corresponding to the current power source for module functions that require lots of current

On failure, throws an exception or returns Y_POWERSTATE_INVALID.

dualpower→get_userData()
dualpower→userData()
dualpower.get_userData()dualpower.get_userData()dualpower→get_userData()dualpower→get_userData()[dualpower userData]dualpower.get_userData()dualpower.get_userData()dualpower.get_userData()dualpower.get_userData()dualpower.get_userData()

Returns the value of the userData attribute, as previously stored using method set_userData.

js
function get_userData()
nodejs
function get_userData()
php
function get_userData()
cpp
void * get_userData()
m
-(void*) userData
pas
function get_userData(): Tobject
vb
function get_userData() As Object
cs
object get_userData()
java
Object get_userData()
py
def get_userData()

This attribute is never touched directly by the API, and is at disposal of the caller to store a context.

Returns :

the object stored previously by the caller.

dualpower→isOnline()dualpower.isOnline()dualpower.isOnline()dualpower→isOnline()dualpower→isOnline()[dualpower isOnline]dualpower.isOnline()dualpower.isOnline()dualpower.isOnline()dualpower.isOnline()dualpower.isOnline()

Checks if the power control is currently reachable, without raising any error.

js
function isOnline()
nodejs
function isOnline()
php
function isOnline()
cpp
bool isOnline()
m
-(BOOL) isOnline
pas
function isOnline(): boolean
vb
function isOnline() As Boolean
cs
bool isOnline()
java
boolean isOnline()
py
def isOnline()

If there is a cached value for the power control in cache, that has not yet expired, the device is considered reachable. No exception is raised if there is an error while trying to contact the device hosting the power control.

Returns :

true if the power control can be reached, and false otherwise

dualpower→isOnline_async()dualpower.isOnline_async()dualpower.isOnline_async()

Checks if the power control is currently reachable, without raising any error (asynchronous version).

js
function isOnline_async(callback, context)
nodejs
function isOnline_async(callback, context)

If there is a cached value for the power control in cache, that has not yet expired, the device is considered reachable. No exception is raised if there is an error while trying to contact the device hosting the requested function.

This asynchronous version exists only in Javascript. It uses a callback instead of a return value in order to avoid blocking the Javascript virtual machine.

Parameters :

callbackcallback function that is invoked when the result is known. The callback function receives three arguments: the caller-specific context object, the receiving function object and the boolean result
contextcaller-specific object that is passed as-is to the callback function

Returns :

nothing : the result is provided to the callback.

dualpower→load()dualpower.load()dualpower.load()dualpower→load()dualpower→load()[dualpower load: ]dualpower.load()dualpower.load()dualpower.load()dualpower.load()dualpower.load()

Preloads the power control cache with a specified validity duration.

js
function load(msValidity)
nodejs
function load(msValidity)
php
function load($msValidity)
cpp
YRETCODE load(int msValidity)
m
-(YRETCODE) load: (int) msValidity
pas
function load(msValidity: integer): YRETCODE
vb
function load(ByVal msValidity As Integer) As YRETCODE
cs
YRETCODE load(int msValidity)
java
int load(long msValidity)
py
def load(msValidity)

By default, whenever accessing a device, all function attributes are kept in cache for the standard duration (5 ms). This method can be used to temporarily mark the cache as valid for a longer period, in order to reduce network trafic for instance.

Parameters :

msValidityan integer corresponding to the validity attributed to the loaded function parameters, in milliseconds

Returns :

YAPI_SUCCESS when the call succeeds. On failure, throws an exception or returns a negative error code.

dualpower→load_async()dualpower.load_async()dualpower.load_async()

Preloads the power control cache with a specified validity duration (asynchronous version).

js
function load_async(msValidity, callback, context)
nodejs
function load_async(msValidity, callback, context)

By default, whenever accessing a device, all function attributes are kept in cache for the standard duration (5 ms). This method can be used to temporarily mark the cache as valid for a longer period, in order to reduce network trafic for instance. This asynchronous version exists only in Javascript. It uses a callback instead of a return value in order to avoid blocking the Javascript virtual machine.

Parameters :

msValidityan integer corresponding to the validity of the loaded function parameters, in milliseconds
callbackcallback function that is invoked when the result is known. The callback function receives three arguments: the caller-specific context object, the receiving function object and the error code (or YAPI_SUCCESS)
contextcaller-specific object that is passed as-is to the callback function

Returns :

nothing : the result is provided to the callback.

dualpower→nextDualPower()dualpower.nextDualPower()dualpower.nextDualPower()dualpower→nextDualPower()dualpower→nextDualPower()[dualpower nextDualPower]dualpower.nextDualPower()dualpower.nextDualPower()dualpower.nextDualPower()dualpower.nextDualPower()dualpower.nextDualPower()

Continues the enumeration of dual power controls started using yFirstDualPower().

js
function nextDualPower()
nodejs
function nextDualPower()
php
function nextDualPower()
cpp
YDualPower * nextDualPower()
m
-(YDualPower*) nextDualPower
pas
function nextDualPower(): TYDualPower
vb
function nextDualPower() As YDualPower
cs
YDualPower nextDualPower()
java
YDualPower nextDualPower()
py
def nextDualPower()

Returns :

a pointer to a YDualPower object, corresponding to a dual power control currently online, or a null pointer if there are no more dual power controls to enumerate.

dualpower→registerValueCallback()dualpower.registerValueCallback()dualpower.registerValueCallback()dualpower→registerValueCallback()dualpower→registerValueCallback()[dualpower registerValueCallback: ]dualpower.registerValueCallback()dualpower.registerValueCallback()dualpower.registerValueCallback()dualpower.registerValueCallback()dualpower.registerValueCallback()

Registers the callback function that is invoked on every change of advertised value.

js
function registerValueCallback(callback)
nodejs
function registerValueCallback(callback)
php
function registerValueCallback($callback)
cpp
int registerValueCallback(YDualPowerValueCallback callback)
m
-(int) registerValueCallback: (YDualPowerValueCallback) callback
pas
function registerValueCallback(callback: TYDualPowerValueCallback): LongInt
vb
function registerValueCallback() As Integer
cs
int registerValueCallback(ValueCallback callback)
java
int registerValueCallback(UpdateCallback callback)
py
def registerValueCallback(callback)

The callback is invoked only during the execution of ySleep or yHandleEvents. This provides control over the time when the callback is triggered. For good responsiveness, remember to call one of these two functions periodically. To unregister a callback, pass a null pointer as argument.

Parameters :

callbackthe callback function to call, or a null pointer. The callback function should take two arguments: the function object of which the value has changed, and the character string describing the new advertised value.

dualpower→set_logicalName()
dualpower→setLogicalName()
dualpower.set_logicalName()dualpower.set_logicalName()dualpower→set_logicalName()dualpower→set_logicalName()[dualpower setLogicalName: ]dualpower.set_logicalName()dualpower.set_logicalName()dualpower.set_logicalName()dualpower.set_logicalName()dualpower.set_logicalName()YDualPower set_logicalName

Changes the logical name of the power control.

js
function set_logicalName(newval)
nodejs
function set_logicalName(newval)
php
function set_logicalName($newval)
cpp
int set_logicalName(const string& newval)
m
-(int) setLogicalName: (NSString*) newval
pas
function set_logicalName(newval: string): integer
vb
function set_logicalName(ByVal newval As String) As Integer
cs
int set_logicalName(string newval)
java
int set_logicalName(String newval)
py
def set_logicalName(newval)
cmd
YDualPower target set_logicalName newval

You can use yCheckLogicalName() prior to this call to make sure that your parameter is valid. Remember to call the saveToFlash() method of the module if the modification must be kept.

Parameters :

newvala string corresponding to the logical name of the power control.

Returns :

YAPI_SUCCESS if the call succeeds. On failure, throws an exception or returns a negative error code.

dualpower→set_powerControl()
dualpower→setPowerControl()
dualpower.set_powerControl()dualpower.set_powerControl()dualpower→set_powerControl()dualpower→set_powerControl()[dualpower setPowerControl: ]dualpower.set_powerControl()dualpower.set_powerControl()dualpower.set_powerControl()dualpower.set_powerControl()dualpower.set_powerControl()YDualPower set_powerControl

Changes the selected power source for module functions that require lots of current.

js
function set_powerControl(newval)
nodejs
function set_powerControl(newval)
php
function set_powerControl($newval)
cpp
int set_powerControl(Y_POWERCONTROL_enum newval)
m
-(int) setPowerControl: (Y_POWERCONTROL_enum) newval
pas
function set_powerControl(newval: Integer): integer
vb
function set_powerControl(ByVal newval As Integer) As Integer
cs
int set_powerControl(int newval)
java
int set_powerControl(int newval)
py
def set_powerControl(newval)
cmd
YDualPower target set_powerControl newval

Parameters :

newvala value among Y_POWERCONTROL_AUTO, Y_POWERCONTROL_FROM_USB, Y_POWERCONTROL_FROM_EXT and Y_POWERCONTROL_OFF corresponding to the selected power source for module functions that require lots of current

Returns :

YAPI_SUCCESS if the call succeeds.

On failure, throws an exception or returns a negative error code.

dualpower→set_userData()
dualpower→setUserData()
dualpower.set_userData()dualpower.set_userData()dualpower→set_userData()dualpower→set_userData()[dualpower setUserData: ]dualpower.set_userData()dualpower.set_userData()dualpower.set_userData()dualpower.set_userData()dualpower.set_userData()

Stores a user context provided as argument in the userData attribute of the function.

js
function set_userData(data)
nodejs
function set_userData(data)
php
function set_userData($data)
cpp
void set_userData(void* data)
m
-(void) setUserData: (void*) data
pas
procedure set_userData(data: Tobject)
vb
procedure set_userData(ByVal data As Object)
cs
void set_userData(object data)
java
void set_userData(Object data)
py
def set_userData(data)

This attribute is never touched by the API, and is at disposal of the caller to store a context.

Parameters :

dataany kind of object to be stored

dualpower→wait_async()dualpower.wait_async()dualpower.wait_async()

Waits for all pending asynchronous commands on the module to complete, and invoke the user-provided callback function.

js
function wait_async(callback, context)
nodejs
function wait_async(callback, context)

The callback function can therefore freely issue synchronous or asynchronous commands, without risking to block the Javascript VM.

Parameters :

callbackcallback function that is invoked when all pending commands on the module are completed. The callback function receives two arguments: the caller-specific context object and the receiving function object.
contextcaller-specific object that is passed as-is to the callback function

Returns :

nothing.

20. Troubleshooting

20.1. Linux and USB

To work correctly under Linux, the the library needs to have write access to all the Yoctopuce USB peripherals. However, by default under Linux, USB privileges of the non-root users are limited to read access. To avoid having to run the VirtualHub as root, you need to create a new udev rule to authorize one or several users to have write access to the Yoctopuce peripherals.

To add a new udev rule to your installation, you must add a file with a name following the "##-arbitraryName.rules" format, in the "/etc/udev/rules.d" directory. When the system is starting, udev reads all the files with a ".rules" extension in this directory, respecting the alphabetical order (for example, the "51-custom.rules" file is interpreted AFTER the "50-udev-default.rules" file).

The "50-udev-default" file contains the system default udev rules. To modify the default behavior, you therefore need to create a file with a name that starts with a number larger than 50, that will override the system default rules. Note that to add a rule, you need a root access on the system.

In the udev_conf directory of the VirtualHub for Linux47 archive, there are two rule examples which you can use as a basis.

Example 1: 51-yoctopuce.rules

This rule provides all the users with read and write access to the Yoctopuce USB peripherals. Access rights for all other peripherals are not modified. If this scenario suits you, you only need to copy the "51-yoctopuce_all.rules" file into the "/etc/udev/rules.d" directory and to restart your system.

# udev rules to allow write access to all users # for Yoctopuce USB devices SUBSYSTEM=="usb", ATTR{idVendor}=="24e0", MODE="0666"

Example 2: 51-yoctopuce_group.rules

This rule authorizes the "yoctogroup" group to have read and write access to Yoctopuce USB peripherals. Access rights for all other peripherals are not modified. If this scenario suits you, you only need to copy the "51-yoctopuce_group.rules" file into the "/etc/udev/rules.d" directory and restart your system.

# udev rules to allow write access to all users of "yoctogroup" # for Yoctopuce USB devices SUBSYSTEM=="usb", ATTR{idVendor}=="24e0", MODE="0664", GROUP="yoctogroup"

20.2. ARM Platforms: HF and EL

There are two main flavors of executable on ARM: HF (Hard Float) binaries, and EL (EABI Little Endian) binaries. These two families are not compatible at all. The compatibility of a given ARM platform with of one of these two families depends on the hardware and on the OS build. ArmHL and ArmEL compatibility problems are quite difficult to detect. Most of the time, the OS itself is unable to make a difference between an HF and an EL executable and will return meaningless messages when you try to use the wrong type of binary.

All pre-compiled Yoctopuce binaries are provided in both formats, as two separate ArmHF et ArmEL executables. If you do not know what family your ARM platform belongs to, just try one executable from each family.

21. Troubleshooting

21.1. Linux and USB

To work correctly under Linux, the the library needs to have write access to all the Yoctopuce USB peripherals. However, by default under Linux, USB privileges of the non-root users are limited to read access. To avoid having to run the VirtualHub as root, you need to create a new udev rule to authorize one or several users to have write access to the Yoctopuce peripherals.

To add a new udev rule to your installation, you must add a file with a name following the "##-arbitraryName.rules" format, in the "/etc/udev/rules.d" directory. When the system is starting, udev reads all the files with a ".rules" extension in this directory, respecting the alphabetical order (for example, the "51-custom.rules" file is interpreted AFTER the "50-udev-default.rules" file).

The "50-udev-default" file contains the system default udev rules. To modify the default behavior, you therefore need to create a file with a name that starts with a number larger than 50, that will override the system default rules. Note that to add a rule, you need a root access on the system.

In the udev_conf directory of the VirtualHub for Linux48 archive, there are two rule examples which you can use as a basis.

Example 1: 51-yoctopuce.rules

This rule provides all the users with read and write access to the Yoctopuce USB peripherals. Access rights for all other peripherals are not modified. If this scenario suits you, you only need to copy the "51-yoctopuce_all.rules" file into the "/etc/udev/rules.d" directory and to restart your system.

# udev rules to allow write access to all users # for Yoctopuce USB devices SUBSYSTEM=="usb", ATTR{idVendor}=="24e0", MODE="0666"

Example 2: 51-yoctopuce_group.rules

This rule authorizes the "yoctogroup" group to have read and write access to Yoctopuce USB peripherals. Access rights for all other peripherals are not modified. If this scenario suits you, you only need to copy the "51-yoctopuce_group.rules" file into the "/etc/udev/rules.d" directory and restart your system.

# udev rules to allow write access to all users of "yoctogroup" # for Yoctopuce USB devices SUBSYSTEM=="usb", ATTR{idVendor}=="24e0", MODE="0664", GROUP="yoctogroup"

21.2. ARM Platforms: HF and EL

There are two main flavors of executable on ARM: HF (Hard Float) binaries, and EL (EABI Little Endian) binaries. These two families are not compatible at all. The compatibility of a given ARM platform with of one of these two families depends on the hardware and on the OS build. ArmHL and ArmEL compatibility problems are quite difficult to detect. Most of the time, the OS itself is unable to make a difference between an HF and an EL executable and will return meaningless messages when you try to use the wrong type of binary.

All pre-compiled Yoctopuce binaries are provided in both formats, as two separate ArmHF et ArmEL executables. If you do not know what family your ARM platform belongs to, just try one executable from each family.

22. Characteristics

You can find below a summary of the main technical characteristics of your Yocto-Servo module.

Width20 mm
Length45 mm
Weight5 g
USB connectormicro-B
Channels5
Supported Operating SystemsWindows, Linux (Intel + ARM), Mac OS X, Android
Driversno driver needed
API / SDK / Libraries (USB+TCP)C++, Objective-C, C#, VB .NET, Delphi, Python, Java/Android
API / SDK / Libraries (TCP only)Javascript, Node.js, PHP, Java
RoHSyes
USB Vendor ID0x24E0
USB Device ID0x0012
Suggested enclosureYoctoBox-Short-Thick-Black

23. Index

A
advertisedValue
API
B
beacon
C
CheckLogicalName
D
describe
DisableExceptions
download
DualPower
E
EnableExceptions
EnableUSBHost
extVoltage
F
FindDualPower
FindModule
FindServo
firmwareRelease
FirstDualPower
FirstModule
FirstServo
FreeAPI
functionCount
functionId
functionName
functionValue
G
get_advertisedValue
get_beacon
get_errorMessage
get_errorType
get_extVoltage
get_firmwareRelease
get_friendlyName
get_functionDescriptor
get_functionId
get_hardwareId
get_icon2d
get_lastLogs
get_logicalName
get_luminosity
get_module
get_module_async
get_neutral
get_persistentSettings
get_position
get_powerControl
get_powerState
get_productId
get_productName
get_productRelease
get_range
get_rebootCountdown
get_serialNumber
get_upTime
get_usbBandwidth
get_usbCurrent
get_userData
GetAPIVersion
GetTickCount
H
HandleEvents
I
InitAPI
isOnline
isOnline_async
L
load
load_async
logicalName
luminosity
M
Module
move
N
neutral
nextDualPower
nextModule
nextServo
P
persistentSettings
position
powerControl
powermodes
powerState
PreregisterHub
productId
productName
productRelease
R
range
reboot
rebootCountdown
RegisterDeviceArrivalCallback
RegisterDeviceRemovalCallback
RegisterHub
RegisterHubDiscoveryCallback
RegisterLogFunction
registerValueCallback
revertFromFlash
S
saveToFlash
SelectArchitecture
serialNumber
Servo
set_beacon
set_logicalName
set_luminosity
set_neutral
set_position
set_powerControl
set_range
set_usbBandwidth
set_userData
SetDelegate
SetTimeout
Sleep
T
techspec
triggerFirmwareUpdate
U
UnregisterHub
UpdateDeviceList
UpdateDeviceList_async
upTime
usbBandwidth
usbCurrent
usbcurrent
W
wait_async
wiring
Y
YDualPower
YModule
YServo


  1. support@yoctopuce.com
  2. The HID driver is the one that takes care of the mouse, the keyboard, etc.
  3. Although they existed for some time, Mini A connectors are not available anymore http://www.usb.org/developers/Deprecation_Announcement_052507.pdf
  4. You can use the terminal Ref MPT 0.5/2-2,54 from Phoenix Contact
  5. http://www.yoctopuce.com/EN/products/category/enclosures
  6. short-short-short long-long-long short-short-short
  7. support@yoctopuce.com
  8. www.yoctopuce.com/EN/virtualhub.php
  9. The interface was tested on FireFox 3+, IE 6+, Safari, and Chrome. It does not work with Opera.
  10. www.yoctopuce.com/EN/virtualhub.php
  11. More information available in the virtual hub documentation
  12. www.yoctopuce.com/EN/virtualhub.php
  13. http://www.yoctopuce.com/EN/libraries.php
  14. If you want to recompile the command line API, you also need the C++ API.
  15. http://www.yoctopuce.com/EN/libraries.php
  16. http://www.yoctopuce.com/EN/virtualhub.php
  17. Actually, as soon as Opera implements support for the HTTP Access-Control-Allow-Origin header.
  18. www.yoctopuce.com/EN/libraries.php
  19. www.yoctopuce.com/EN/virtualhub.php
  20. If you do not have a text editor, use Notepad rather than Microsoft Word.
  21. A couple of free PHP servers: easyPHP for Windows, MAMP for Mac OS X.
  22. www.yoctopuce.com/EN/libraries.php
  23. www.yoctopuce.com/EN/virtualhub.php
  24. If you do not have a text editor, use Notepad rather than Microsoft Word.
  25. http://www.microsoft.com/visualstudio/en-us/products/2010-editions/visual-cpp-express
  26. www.yoctopuce.com/EN/libraries.php
  27. www.yoctopuce.com/EN/libraries.php
  28. www.yoctopuce.com/EN/article/new-objective-c-library-for-mac-os-x
  29. http://www.microsoft.com/visualstudio/en-us/products/2010-editions/visual-basic-express
  30. www.yoctopuce.com/EN/libraries.php
  31. The sources of this DLL are available in the C++ API
  32. Remember to change the filter of the selection window, otherwise the DLL will not show.
  33. http://www.microsoft.com/visualstudio/en-us/products/2010-editions/visual-csharp-express
  34. www.yoctopuce.com/EN/libraries.php
  35. The sources of this DLL are available in the C++ API
  36. Remember to change the filter of the selection window, otherwise the DLL will not show.
  37. Actually, Borland provided free versions (for personal use) of Delphi 2006 and 2007. Look for them on the Internet, you may still be able to download them.
  38. Delphi libraries are regularly tested with Delphi 5 and Delphi XE2.
  39. www.yoctopuce.com/EN/libraries.php
  40. Use the Tools / Environment options menu.
  41. http://www.python.org/download/
  42. www.yoctopuce.com/EN/libraries.php
  43. www.yoctopuce.com/EN/libraries.php
  44. www.yoctopuce.com/EN/virtualhub.php
  45. www.yoctopuce.com/EN/libraries.php
  46. Yoctohubs are a plug and play way to add network connectivity to your Yoctopuce devices. more info on http://www.yoctopuce.com/EN/products/category/extensions-and-networking
  47. http://www.yoctopuce.com/FR/virtualhub.php
  48. http://www.yoctopuce.com/FR/virtualhub.php
Yoctopuce, get your stuff connected.