USB1.1 & 2 conflict with hub


I work on a school project using a USB-to-RS232 adapter and a USB Wifi key (zd1211) with the beagleboard.

Both devices are connected to the beagleboard via a USB2 hub adapter.

The problem I have is that Wifi doesn’t work when the USB-to-RS232 adapter is connected to the Hub.
I think it is a conflict between USB1.1 & USB2, but does it come from the Hub or from Linux USB support?



Bonjour Maxime,

Are you using the BeagleBoard USB OTG port in host mode? If so, it
can only source 100 mA to power any attached devices. This is enough
for one low power device and maybe a hub, but usually not two
devices. If this is the problem, you'll need an external +5V supply
for the USB hub.

There is helpful USB OTG information at the BeagleBoard wiki and BeagleBoard FAQ


Hi Maxime,

with USB2.0 Hubs the connection between Host and Hub is always High-Speed if the Hub can do so. It is the Hubs responsibility to convert 1.0, 1.1 Nodes to the high speed protocol of it’s connection to the Host. Any standard high speed Hub should be capable to do so.

So I think John is right when pointing out the problem to the power supply.
Try to use external powered Hub and see what happens. With the Hub I’m using I can even supply the Beagle Board from the Hub, so I only need one supply.


COQUELIN Maxime schrieb:

Hi all,
Thanks for your help!

Actually I use an external powered Hub. The power supply powers the BeagleBoard too. The problem might come from my power supply which perhaps isn’t strong enough.
I will try with 2 power supplies.

For the software, we use poky linux with the lastest kernel from the Omap Git(2.6.28). So I don’t think it comes from that if Jason says he has ever seen both speeds running on the same bus.