USB Woes

Beagleblog

Jul 25, 2009 GMT
Oliver Frommel

[edit: this blog post is about the Beagleboard Rev B. As Jason Kridner points out in the comments, Rev C features two USB ports, so you can use one for host mode and the other as a USB slave]

I have been using the Beagleboard with a terminal connection over the serial line for quite a while. But now I want to attach keyboard and mouse to use it as a standalone computer. For this I need a USB hub because the board only features a mini USB port. If you are going to just connect the hub to it you won't have much fun because the Beagleboard doesn't find the peripherals.

The reason for this is that the USB controller chip on the board can operate as a master as well as a slave. Usually, when you connect it to a PC, it's running as slave. To have mouse and keyboard working you need to make the Beaglboard run in host (master) mode, however. As far as I know there is no way to do this with software (you need to have the voltage level of individual pins). To make this work you need a special cable that has a mini A and a mini B plug. I went to several local dealers with no success and finally ordered one online.

Additionally I had to get two power supplies, one for the Beagleboard (in this setup you can no longer power it over USB) and one for the USB hub. So my collection of additional hardware is constantly getting bigger.

When I boot the Beagleboard everything works great, it finds mouse and keyboard, and I am able to use it like a real computer. Now the only problem is that I can't use networking over USB because that requires the Beagleboard operating in slave mode. Looks like there's only one way out: going to the shop again and getting a USB ethernet device that I can plug into the hub, too ..

Comments

  • Yeah, right

    Thanks for the clarification. I had wanted to add this but forgot about it as I only have the Rev B board ..
    I guess it's much less hassle with Rev C happy

    Best
    Oliver
  • Rev C has full-size A USB port

    You mention only one of the USB ports. Rev C has 2 ports, eliminating the need for the mini-A connector cable.
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