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Virtual COM Port: UART over USB for STM32F072

Question asked by Aggarwal.Gaurav.004 on Jun 4, 2016
Latest reply on Jun 6, 2016 by ForumSTM32.ForumSTM3
Dear all,

I am trying to get UART (USART?) working over USB for a STM32F072C8 part. The idea is to get basic getc/putc working via the USB for a custom board that we have designed. I intend to make the device  look like CDC class to the Windows Host PC so that I can use a Putty or Hyper-term to just get the output (UART Tx from STM32) on a console terminal.

I looked at the sample code in STM32CubeF0 for USB_Device/CDC_Standalone for the STM32F072B_Eval project. Obviously this is for the Discovery or similar boards while our board is custom and different set of peripherals are used.

In any case, I had hoped to pull out the essential components but the USB device is not recognized by the host PC.  The Win Device Manager has an error/warning triangle mark.

Question - what are the things that I should look at and how do I proceed with the debug? The example seems to use 48MHz clock called USE_USB_CLKSOURCE_CRSHSI48 in the main.h file. However, we have a 12 MHz crystal on our board.

Can somebody tell me where all and what all do I have to change from the STM32CubeF0 Project for _Eval to get it going with 12MHz?

Many thanks!