STM32 Virtual COM Example - Send over USB Problem

[harira2]

Posted on May 05, 2010 at 10:56

STM32 Virtual COM Example - Send over USB Problem

[rudolf]

Posted on May 17, 2011 at 13:49

You are not alone. I too have the same issue.

It seems that the CDC host driver is not transmitting IN tokens. When exactly are these tokens tranmitted by the driver? Does it poll the device?

[rudolf]

Posted on May 17, 2011 at 13:49

Hi,

I've found my problem, maybe it'll work for you aswell. I've added the line:

SetEPTxValid(ENDP1);

After the USB_SIL_Write call. Seems to be in accordance to the ref manual:

...and finally sets STAT_TX to ‘11 (VALID) to re-enable transmissions. While the STAT_TX bits are equal to ‘10 (NAK), any IN request addressed to that endpoint is NAKed, indicating a flow control condition: the USB host will retry the transaction until it succeeds.

Worked for me.

Cheers.