The Yocto-Temperature is a USB temperature sensor : it lets you measure the temperature via a USB connection, as well as record the ambient temperature on its internal flash for later retrieval when connected again by USB. This tiny USB thermometer is ideal for monitoring the temperature of a computer or server room and raising an alert.

This circuit has been designed so that the sensor itself can be moved further away from the USB connector by a few meters: simply split the board into two parts and solder a 4-wire cable on the designated pads.

This device can be connected directly to an Ethernet network using a YoctoHub-Ethernet, to a WiFi network using a YoctoHub-Wireless-n and to a GSM network using a YoctoHub-GSM.

Yocto-Temperature Yocto-Temperature Yocto-Temperature

USB cables and enclosures to be ordered separately.

CHF 29.94

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Product name:Yocto-Temperature
USB connector:micro-B
Sensor:MCP9804 (Microchip)
Refresh rate:10Hz
Measuring range:-40 ... +125C
Protection class, according to IEC 61140:class III
Normal operating temperature:5...40C
Extended operating temperature1:-30...85C
Supported Operating Systems:Windows (PC + IoT), Linux (Intel + ARM), macOS, Android
Drivers:Driverless, no driver needed
API / SDK / Libraries:C++ Obj-C C# VB.NET UWP Delphi Python Java Android LabVIEW
API / SDK / Libraries (TCP only):Javascript Node.js PHP
RoHS compliance:RoHS III (2011/65/UE+2015/863)
Suggested enclosure:YoctoBox-Long-Thin-Black-Vents
Harmonized tariff code:9032.9000
Cables and enclosures:available separately
Made in:Switzerland

1 The extended temperature range is defined based on components specifications and has been tested during a limited duration (1h). When using the device in harsh environments for a long period of time, we strongly advise to run extensive tests before going to production.

Accessories and related products

YoctoBox-Long-Thin-Black-Vents, Enclosure for Yoctopuce device (long, thin, black, vents)Micro-USB-Hub-V2, Micro USB hub (multi-TT) with solder pads, for DIY useFix-2.5mm, screws and spacersUSB-A-MicroB-50, USB 2.0 type A to Micro-B data cable, 50 cmPicoflex-U25, Picoflex Cable, U shape, 25cm

Related articles and application examples


User manual (HTML)
User manual (PDF)
Product brief
3D file (STEP)
RoHS certificate
Most recent firmware51180 (09/30/2022)
Programming libraries61305 (06/11/2024)
Command line API61199 (05/30/2024)
VirtualHub application61199 (05/30/2024)

Add a comment 26 comments

1 - anser Wednesday,august 01,2012 9H06


I have an android phone running gingerbread. I need an alert system for my server room.

Here's what I have in mind.

1) Connect a cheap android phone to the yocto-temperature.
2) Program the phone to send an sms in case of dangerous temperatures.
3) Leave phone + yocto-temperature in the server room.

My question:

Is there an android app that would do this?



2 - seb (Yocto-Team)Wednesday,august 01,2012 9H27


Today it is not possible, but we are planning to add USB direct access for android platform to our JAVA library.

You will have two solutions:

- 1 : The Android phone will support Host mode and you will able to connect directly the Yocto-Temperature to the phone

- 2 : The phone will only support USB accessory mode and in this case you will need a device that will provide power for both device (Yocto-Temperature + phone) and allow the phone to interact with the device.

We plan to support both solutions for end of this year, but if may be advanced or delayed according to the customers demand.

Yoctopuce Dev Team

3 - anser Friday,august 03,2012 13H10

Thanks, Sebastien.


4 - ok-alex Monday,november 26,2012 23H37

I read your comment (August 01, 2012) about android usb host and accessory modes. Are they implemented now?

5 - martinm (Yocto-Team)Tuesday,november 27,2012 5H29

@ok-alex: yes, the android library is available now, but you need a phone able to work in host mode.

6 - ok-alex Tuesday,november 27,2012 20H59

martinm, thanks for the answer.
One more question: can I connect 2 sensors to 1 board?
My idea is to connect your device to the android car audio system and display temperatures inside and outside the car. I'm sure that car system support host mode.

7 - martinm (Yocto-Team)Wednesday,november 28,2012 4H47

@ok-alex : actually no, you cannot plug 2 sensors on one single Yocto-Temperature board. You will have to use two Yocto-Temperature and an USB hub. You can also use a Yocto-thermocouple, which have 2 inputs.

8 - edward_valarm Friday,december 28,2012 22H20


Now it is possible with Valarm to connect a cheap Android phone to the Yocto-Temperature and get SMS and/or email alerts when the temperature goes out of a specified range. Valarm ( the Versatile Asset Locator And Remote Monitor ) has also implemented other functionalities ( such as asset & fleet tracking ) and is adding more and more features as well as support for various sensors. See http://www.valarm.net for full details.

The Valarm app is available directly at https://play.google.com/store/apps/details?id=net.valarm.android.pro

If you have any other comments or questions please don't hesitate to ask!


9 - sbence Monday,january 07,2013 9H25


is it possible with android&Valarm to query(across wifi) the temerature data periodically?

thanks in advance

Bence Soponyai

10 - edward_valarm Thursday,january 10,2013 9H17

@sbence :

Excellent question!

Yes, you can use Valarm's interval timer to periodically sync your data to the web via WiFi, then query and view it on a map (or download your data and use it anywhere!) at http://tools.valarm.net . You can also use Valarm SMS and remote control features: http://www.valarm.net/valarm-sms-text-message-alerts-and-remote-control/ .

See full app features here: http://www.valarm.net/about/device-features-list/ and web features here: http://www.valarm.net/about/web-features-list/

If you have any more questions or comments feel free to post here and/or email us at info@valarm.net .


11 - sbence Thursday,january 24,2013 9H36


now I have the device, working perfectly with my PC!

I've read the user manual so I can separate the sensor with wiring again. How long can be the wire eg.: can I use cat5e cable around 30-40 meters?

thanks in advance

Kind regards
Bence Soponyai

12 - mvuilleu (Yocto-Team)Thursday,january 24,2013 9H42


The longest we have tested is 25m using dummy flat cable. So I believe 30-40m of Cat5 cable has a good chance to work, although we cannot guarantee since we have not tested it. When doing your tests, open the "log" view of the device in the VirtualHub and look for any I2C error. This will tell you if it works perfectly well, works a bit or does not work at all.

You can post a comment with the result of your tests, that will be interesting !


13 - nodepond Monday,january 19,2015 14H11

I have bought this sensor about one year ago and have never tested it before. Today I connected the temperature-sensor and the sensor returns a much to high value.

Its value is about 2-4 celsius about the normal temperature - so a significant difference. Currently The sensor returns 25 celsius, although we have a temperature of 21 - 22. Did I had the luck of a getting defect device? Is there anything I can do about it, like calibrating or mapping minimum and maximum temperatures? I flashed the latest firmware today as well...

14 - mvuilleu (Yocto-Team)Monday,january 19,2015 14H18

@nodepond: I doubt the sensor chip itself is faulty, the Microchip sensor used in the Yocto-Temperature is a digital sensor based on an internal PT100 and is factory calibrated. Most likely what you are observing is the side-effect of some local warming source.
- is the sensor in free air or in an enclosure ?
- check how is the sensor positionned: the sensitive part at the end of the device should be free from any warming source, including the CPU of the sensor itself. The position with the USB wire at the bottom is not a good one, as the heat from the USB CPU will go up to the sensor. It is best to have it placed for instance vertically on its long edge.
- for the most precise measurements, you can evenmove the sensor part further away from the CPU, as described in the manual.

15 - nodepond Monday,january 19,2015 16H20

Thanks for your reply. Some little testing later it seems, that you were right with your advices. It seems, that I had the sensor (without any enclosure btw) too near (above) my computer - resulting in more heat in this area than in the room. The next thing was what you described, I operated the device with the USB-port to the bottom, resulting in even more heat-disturbance.

I took the meter and put it more far away from the computer and into a horizontal position and the meter-data is similar to other sensors.

16 - sketch34 Sunday,june 26,2016 23H53

Any tips on how to set up yocto-temperature inside a thermowell for measuring water temperature? Want to measure in the range approximately -5C to 110C.

17 - martinm (Yocto-Team)Monday,june 27,2016 8H16

@sketch34: The sensor part of the Yocto-temperature can be cut away and might fit in your thermowell, some soldering work will be required though. You may want to consider the Yocto-Thermocouple and the Yocto-PT100 as well.

18 - matthieu161 Monday,december 19,2016 15H31


I'm trying to use Yocto Temperature with my MacBook Pro 2015 IOS Sierra.
Once connected, I launch Virtual Hub and the got to But I can't see the device, I have only one line : VIRTHUB0-3e927ded7e VirtualHub configure view log file

Can you help me solving this issue?


19 - martinm (Yocto-Team)Monday,december 19,2016 15H54

@matthieu161: make sure that you are using a regular USB cable, not a charging cable. Then contact Yoctopuce support by email.

20 - matthieu161 Monday,december 19,2016 17H07

Thanks it works now with a regular cable

21 - badmathbrweing Friday,august 17,2018 13H43

Is it possible to connect a pt100 or other style probe to this board? I need to measure temperature inside a thermowell and the broken apart board won't fit.

22 - martinm (Yocto-Team)Friday,august 17,2018 13H49

@badmathbrweing : nope, but you can use a Yocto-PT100 (www.yoctopuce.com/EN/products/yocto-pt100) if your probe is a PT100, A Yocto-Thermocouple (www.yoctopuce.com/EN/products/yocto-thermocouple) if your probe is a thermocouple or a Yocto-maxiThermistor (www.yoctopuce.com/EN/products/yocto-maxithermistor)if your probe is a thermistor (NTC or PTC).

23 - lortscla Tuesday,september 04,2018 14H30

Could you please explain what the 'min and max temperatures' indicate within the sensors area, when I click on the serial number for the sensor (through the Window's virtual hub). Thank you.

24 - martinm (Yocto-Team)Tuesday,september 04,2018 14H41

@lortscla: these are the minimum and the maximum temperature measured since the device was powered up (or since last Min/max reset).

25 - caveman Monday,december 18,2023 9H10


I'm thinking about purchasing a Yocto-temperature or Yocto-meteo-V2 to first play around with, then, if successful, assemble a complete PWS (wind/dir, temp, pressure, humidity) for use here in the interior of Alaska, using the Yocto-PT100 because our temps can go below -50F. And we do get lightning, so ultimately it needs to be wireless, using your wireless hub.

Question: Your data says the Yocto-temp sensors only go down -30C, but your reseller https://gerelectronics.com/product/yocto-temperature/ says it has a measuring range -40C to +125C. Which is correct?

Also, if the temp gets below its range, what kind of values does it output? I.e., does it flat-line or output undefined data?

26 - martinm (Yocto-Team)Monday,december 18,2023 10H31

The Microchip MCP9804 sensor used in the Yocto-temperature can measure down to -40C, but the limiting factor is the USB connector which is formally rated for -30C only.

Yoctopuce, get your stuff connected.