I have recently a weird problem using the USB connection. I use the ASF USB CDC and everything works fine receiving data and printing them using printf.
Whenever the computer is booted at the same time as the controller device, the connection is somehow out of sync, and only data which is sent using printf without any placeholders (like %i and the like) is then appears, while for the printf commands which contain placeholders appear only as a newline command (0x0A).
Even after extensive searching and reading a lot about USB communication events, I still have no idea where this comes from. Any ideas or suggestions?