AnsweredAssumed Answered

Problem with USB lib

Question asked by cemer on Jul 29, 2013
Latest reply on Aug 1, 2013 by carpenter.adrian

I am testing the usb lib 4.0.0 for the VCP functionality on STM32L15xVB targets with 1.3.1 drvier on Win7 hosts. I tried two tests with both usart bridge and loop back examples and unfortunately seeing the same issue:

Under normal conditions, both examples seem to be working fairly stable, however, with one exception: Hiberbnating or resetting the host while the usb cable is connected. After the resume of the host the mcu seems to be receiving messages but cannot send any. Cable unplug/plug sequence did not help either, although I made sure the USB peripheral is properly powered down following the cable unplug. Besides, there seems to be a buffer size limitation (truncation) on the incoming messages from the hosts as well.

Only solution seems to be hard resetting the mcu. After the reset the vcp starts to work normally.

The problem happens with both 32bit and 64bits win7 hosts.

I am looking forward to hear any experiences and any tips that might be of help.

Thanks a lot.