Andrew Lunn andrew@lunn.ch
Fri Jun 2 08:09:00 GMT 2006

On Fri, Jun 02, 2006 at 07:54:57AM +0000, John Eigelaar wrote:
> I have been using the recent at91 usb driver to implement a USB-CDC
> (USBSerial emulation ) device on an at91sam7s256 board.
> My CDC device enumarates properly and is seens as a serial port on both
> Linux and Windows. If I however try to connect to the serial port with
> either minicom or hyperterminal the serial application hangs.
> I could get hyperterminal to connect once and that work fine while the
> session was connect but when I hanged up and tried again hyperterminal
> hung.
> I previously ported the FraaRTOS CDC code to eCos, before there was any
> at91 driver available, and that code works fine as a serial port.
> Any ideas on how to go about debugging this ? 
> Any experiences with USB-CDC would be appreciated.
> I have SnoopyPro and the diag serial port here at my disposal ...
> Thankx
> John Eigelaar

Hi John

I did find what i think is one silicon bug in the AT91SAM7S. Maybe it
is related?

I found that the first Bulk OUT message on an endpoint did not always
trigger an interrupt. It was only when the second Bulk OUT message
arrived was the interrupt triggered and i could process both messages.
After that it seemed to work O.K.

This bug causes the eCos USB tester software a problem. It sends a
single Bulk OUT message and then uses the control pipe to poll to see
if the message has been received. After 10 polls it gives up and gives
a warning. It then sends the next Bulk OUT message and another warning
is then generated by the target because it received an unexpected

When do you see the problem? Do you receive the first Bulk OUT


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