Re: [beagleboard] questions about adding USB ports and motor drivers

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Gerald Coley

Apr 30, 2013, 8:48:03 AM4/30/13
Putting power on these pins is the way the board was designed and it is intended to allow as indicated in the System Reference Manual.


On Mon, Apr 29, 2013 at 11:19 PM, M@ Dunlap <> wrote:
Hello all, I work in a robotics lab and both of our Videre Erratics burned out, replacement parts are out of the question (company didn't open source anything before they bit the dust), so it falls to me to design replacement computers for them.  I have a degree in electronics from the school of hard knocks (and I spend a little time studying abroad in wikipedistan), and one in software engineering from a real school, so if I say something stupid please forgive me, I'm just a software guy.

The goal is to design a cape that will allow a BeagleBone to replace the proprietary (and dead) motherboards that the robots had been using.  Essentially the cape needs two VNH2SP30s, a 4-port USB hub, and whatever circuitry is required to step down the voltage from the (12V+) battery to a manageable 5V for the USB hub.  My current questions are:

1) Given that the Bone has some fancy high speed busses like GPMC and MMC, is the best way to add USB ports really via hubs (a la TUSB8040As or the like), or is there a chip that may save me from having to connect the cape via a tiny USB cable?

2) If I push 5V down from a cape on P9_5 and P9_6 will the bone come on?  Is that a safe thing to do?  The chart at seems to suggest that 5V via the expansion header should work, but I haven't found any other mention that it's safe or reasonable.

3) Are there any precautions I should take having high current H bridges on the same PCB as high speed USB circuitry?

4) Do any of you know what the two MOSFETs and the darlington are for in this schematic?

Thanks for your help!


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