2.1 Double power supply
2.2 Activity Led
2.3 USB power distribution
2.4 Electromagnetic compatibility (EMI)
3.1 Connecting Yoctopuce modules
3.2 Direct soldering of ribbon cable
3.3 Direct soldering on the up port
3.4 Minimal size
The Micro-USB-Hub-V2 is a very small USB hub (42x28mm)
allowing do-it-yourself enthusiasts to connect up to four USB 2.0 peripherals
to a single USB cable. It was conceived to be placed inside devices, while taking
up a minimum of space. This hub was designed mainly to connect Yoctopuce
modules, but it can very well be used with other USB 2.0 Hi-Speed, Full-Speed,
or Low-Speed peripherals. The Micro-USB-Hub-V2 is a multi-TT hub, this
allows better performance than a regular single TT hubs when several
USB 1.1 devices, such a Yoctopcue products, are connected.
Yoctopuce thanks you for buying this Micro-USB-Hub-V2 and sincerely hopes that
you will be fully satisfied with it. The Yoctopuce engineers have put a large amount of effort
to ensure your Micro-USB-Hub-V2 is easy to install anywhere.If you are nevertheless
disappointed with this product, do not hesitate to contact Yoctopuce support.
|USB Micro B connector (up port)
|Down port 1
|Down port 2
|External power supply connector
|Down port 4
|External power led
|Down port 3
2.1. Double power supply
Your Micro-USB-Hub-V2 is able to manage a double power supply.
You can simply connect the Micro-USB-Hub-V2 as is to your computer, and your computer
is then responsible to provide the power necessary to supply the whole.
In this case, be aware that a USB port does not supply more than 500mA,
theoretically. To follow the rules, you can provide a 5V power supply on the contacts
designed for this on the Micro-USB-Hub-V2. Peripherals connected to the hub are then
supplied by this external power supply. Warning: Make sure to get the correct
polarity when you connect your power supply, otherwise you risk to destroy
your hub and the USB peripherals connected to it.
Commutating from the USB bus power supply and the external power supply
is performed automatically, depending on the presence of voltage on the external
power supply. In the opposite to traditional USB hubs, commutating power supply is
not based on a mechanical contact in the power socket. Thus,
commutating power supplies does not depend only on the presence of a connector.
The led sitting right next to the
external power port will shine if then the hub is running on external power.
2.2. Activity Led
The activity led will shine when devices are detected on any down port.
If no device is present, then the activity led will stay off and the hub
will go to sleep mode to spare power.
2.3. 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 you controlling and planning overall power consumption
for your project, all Yoctopuce modules include a built-in current
sensor that indicates (with 5mA precision) the consumption of the module
on the USB bus.
Note also that the USB cable itself may also cause power supply issues,
in particular when the wires are too thin or when the cable is too long
Good cables are usually made using AWG 26 or AWG 28 wires for data lines
and AWG 24 wires for power.
2.4. Electromagnetic compatibility (EMI)
Connection methods to integrate the Micro-USB-Hub-V2 obviously have an impact
on the system overall electromagnetic emissions, and therefore also impact
the conformity with international standards.
When we perform reference measurements to validate the conformity of our
products with IEC CISPR 11, we do not use any enclosure but connect the
devices using a shielded USB cable, compliant with USB 2.0 specifications:
the cable shield is connected to both connector shells, and the total
resistance from shell to shell is under 0.6Ω. The USB cable length
is 3m, in order to expose one meter horizontally, one meter vertically
and keep the last meter close to the host computer within a ferrite bead.
If you use a non-shielded USB cable, or an improperly shielded cable,
your system will work perfectly well but you may not remain in conformity
with the emission standard. If you are building a system made of multiple
devices connected using 1.27mm pitch connectors, or with a sensor moved
away from the device CPU, you can generally recover the conformity by using
a metallic enclosure acting as an external shield.
Still on the topic of electromagnetic compatibility, the maximum supported
length of the USB cable is 3m. In addition to the voltage drop issue mentionned
above, using longer wires would require to run extra tests to assert compatibility
with the electromagnetic immunity standards.
Like all hubs on the market, the Micro-USB-Hub-V2 declares to the computer that it is
self-supplied, whether there is an active external power supply or not.
Doing so prevents the computer to which the hub is connected from deciding to limit
the power of the peripherals that are connected to it to 100mA for each port, which
would generally render them unusable.
Moreover, as on most USB hubs on the market, this hub does not contain
electronics to limit the power consumption on down ports.
The Micro-USB-Hub-V2 is not equipped with connectors on the down ports: you
must directly solder wires or connectors on the transversal contacts designed
for this. This considerably reduces the space needed compared to a USB socket
and the plug that fits in it. With the Micro-USB-Hub-V2, there are numerous connection
3.1. Connecting Yoctopuce modules
The Micro-USB-Hub-V2 is designed to allow you to connect up to
four Yoctopuce modules, fixing them with screws and spacers.
You will obtain a small compact block which will likely fit into your
project. Use M2.5 screws with a head diameter of no more than 4.5mm.
You can find such spacers and screw on Yoctopuce shop under the reference
Fix-2.5mm. For the USB connection between the modules and the hub, you can
solder electric wires, but the most practical solution is to solder
headers with 1.27 pitch, available on Yoctopuce shop under the reference
Board2Board-127. Alternatively, you can use small cables and connectors
available under the reference 1.27-1.27-11.
Assembly of Yoctopuce modules with screws and spacers.
Using headers for board to board connection
Warning: the connector is symmetrical and thus does not have
a polarizator: do not connect the modules the other way around,
or you will damage them forever. To help you, the connecting
contacts of the USB modules have all a square pad at one end,
corresponding to the ground of the USB bus. The square pads must
coincide when connecting.
Beware of the direction of the connection!
3.2. Direct soldering of ribbon cable
You can decide to connect your peripherals with 1.27mm ribbon cable.
Choose solid copper cable, this cable is less supple than a threaded one,
but much easier to solder. Get the direction right: square pads
You can solder ribbon cables.
3.3. Direct soldering on the up port
If you believe that the Micro-USB-Hub-V2 takes too much room in your project,
you can eliminate the
up port connector, and solder a USB cable instead: cut the printed circuit
with the help of a good pincer and, if needed, sandpaper the protruding parts.
You only need then to solder the cable on the contacts designed for this.
Caution: Get the direction right: orientation of the pad on the up port
is the other way around compared to the neighboring down ports.
You can solder the shield of the USB cable on the pad designed for it,
right next to the contacts for the wire.
Eliminate the up port connector...
... and solder a USB cable instead.
|[ + ]
|[ - ]
3.4. Minimal size
It is possible to lower the size of the Micro-USB-Hub-V2 down to 20x36mmmm
by cutting one of its ends. This allows you to slip it into the
most tiny locations, but you will loose the the possibility
to screw four Yoctopuce modules on it.
How to render the Micro-USB-Hub-V2 as small as possible.
You can find below a summary of the main technical characteristics
of your Micro-USB-Hub-V2 module.
|Microchip USB2514BI (USB 2.0)
|Normal operating temperature
|Extended operating temperature‡
|RoHS III (2011/65/UE+2015/863)