Hello, I am trying to implement USB CDC on the ST32F4 discovery board, and I am running into issues. I generate the project using the STM32CUBEMX software, which theoretically includes all the usbd middlewares. I had an initial problem where when connecting the usb, windows would give me error 10, but I fixed that by changing all the maxpacketsize variables to 64 per another post. My current problem is that the board can only successfully receive 1 character over the serial terminal, every other one sent from the pc results in a "cancelled" according to the usb sniffer I have installed. I have tried a lot of different things and searched the forum, but I can't seem to find anyone who has my exact problem. There also seems to be a mixing of ST usb code and Keil usb code, which doesn't help the situation. A screenshot of the sniffer is available at: http://imgur.com/47m2SXc . I would post code but I'm not quite sure what part(s) to post. Any help would be appreciated.