You issue may be there (or not).
To really really know, you can use some wide bandwidth digital oscilloscopes
to see how the USB signals are behaving.
Or try to use a good shielded USB cable.
Guess what is the cheapest option, try it, and after that please tell us what
did you find.
Best regards
Paulo Ferreira
On 28/10/2013, at 14:22, Bai Shi <[email protected]> wrote:
> Erm.. very good question. It indeed is the same external power supply
> connected to the Beagle Board. Or I would say all the power come from the
> same ATX power supply though it might (tiny little chance) be in different
> rails.
>
> Frankly speaking the line was rather short (less than 5cm) so I didn't bother
> to do shielding at all. The D+ and D- is using Cat5 ethernet cable.
>
> Does it make any significance?
>
> Regards,
> Bai Shi
>
>
> On Mon, Oct 28, 2013 at 9:56 PM, Paulo Ferreira <[email protected]> wrote:
>
> On 28/10/2013, at 13:27, Bai Shi <[email protected]> wrote:
>
> > My usb device draws power from external power supply, only D+ and D- is
> > connected to BBB. It works 90% of time but when I mess around too much
> > (on/off too frequently maybe, not confirmed), it will reset the USB of BBB
> > and then it will behave very strangely. Every access to /sys/bus/usb take
> > more than 15 seconds and timeout eventually.
> >
> > Hope my experience gives some hint...
>
> Is the same external power supply connected to the Beagle Board?
>
> So, the ground shield of the USB cable is connect only on one side (the
> device) or is it completely "floating"?
>
> Best regards
>
> Paulo Ferreira
>
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