VCP in buffer not updated (from device to PC) about debugdonglefw HOT 8 CLOSED

Could you check if adding USART_vDeinit(vcp_uart); to line 141 of vcp_if.c has any effect on this problem?

from debugdonglefw.

Hi, I tried that and it did not help.
Furthermore, if I send 1 byte X, close the port, wait 1 second, open the port, wait 1 second -> all subsequent next transfer will fail with the 1st byte being X and the rest being 0 (I say the rest because it sends back the same number of bytes it received).

Edited: really only the first transfer following the re-opening of the port is wrong then if the port is not closed all transfers are good.

from debugdonglefw.

One more question, was the incorrect data received on the host before the port was closed (meaning that you receive it once before closing and once after reopening)?

from debugdonglefw.

Hi, thank you for taking time to look into it.

The incorrect data is received only after reopening, not before closing.

from debugdonglefw.

What I see as the most probable root cause is that the endpoint packet is prepared in the device peripheral, but isn't read by the host until after the reopening of the port. So the new setting of TX_COUNT register applies, but the previously loaded data isn't cleared. A possible solution could be to set TX_COUNT to 0 when the line config is set, but I can't promise any deadline for actually checking it (it's summertime after all :) ).

from debugdonglefw.

No problems.
In the meantime as I know that the first packet will be wrong I can initiate a dummy read on the COM port and discard the answer.

Enjoy the summertime :-)

from debugdonglefw.

I pushed updates to USBDevice and DebugDongle: CDC has a more sensible application interface for the majority use case (serial ports). The data interface is closed and reopened when the line coding parameters are set. This should resolve this issue, however I haven't tested it yet. If the set line coding message isn't sent by the host every time the port is opened then there is no way to fix this on the device side alone.

from debugdonglefw.

I'm closing this as it's either solved by the API change or the host doesn't resend line config when reconnecting, in which case the problem cannot be solved on the device side.

from debugdonglefw.