AT91RM9200: USB broken? No!

[Bernd Walter]

On Tue, Jul 20, 2010 at 11:37:19AM -0400, Greg Ansley wrote:
> It's a QFP so the errors are OK.
> 
> Turned out to be a bad solder joint on pin 1 of the USB connector 
> (power). Connector on this card is not very mechanically stable with the 
> mounting posts going into huge worthless holes. :-(

That makes sense.
A device pulls up one of the data line up to 3.3V with a 1.5k Ohm
resistor to show presense.
A bus powered device however can't do this without having power and
a self powered device isn't allowd to supply current into data wires
without sensing the 5V, although many self powered devices
violate this rule.
So in fact a few self powered devices might function without 5V
from USB, although they are not allowed to.

> Error messages were just a red herring, after not having seen them for 
> weeks while working on the SAM9G20.
> 
> Greg
> 
> On 7/20/10 9:58 AM, Bernd Walter wrote:
> >So it looks like your device isn't noticed as being connected at all,
> >which is a bit strange because your error messages clearly show that
> >it got the faulty device connected from the secondary port.
> >
> >   
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-- 
B.Walter <bernd at bwct.de> http://www.bwct.de
Modbus/TCP Ethernet I/O Baugruppen, ARM basierte FreeBSD Rechner uvm.