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Problems with USB CDC implementation on STM32F401CB

Question asked by Thomas P. on Sep 23, 2014
Latest reply on Oct 15, 2014 by Montassar BEN ROMDHANE

I'm using the USB driver that is provided by STM32CubeMX 4.3.0. I want to use the CDC implemantation for virtual COM port communication between STM32F401CB and a PC.
But I'm facing mainly two problems:
1.) It is not possible to send less than 64 bytes via the CDC driver. In this case only one transmission is successfull. Why is this not possible? How to adopt the code to enable one byte transmissions as well?
2.) How to know if the transmission has been completed? I'm calling CDC_Transmit_FS(...) for sending data, but can't find any callback / interrupt that will be called when the PC has received the data. So in this case I don't know when I can start the next transmission cycle.

Thanks for any help!