Arduino for STM32

I've tried input/output with a TTL module attached to hardware pins 10 and 11 and that works.

It would be great to hear any ideas into what might be happening with the USB port but at least I can proceed with my project for now.

Thank you for replying.

I am using the core from this URL:

https://github.com/stm32duino/BoardManagerFiles/raw/main/package_stmicroelectronics_index.json

The settings in the Arduino IDE are as follows:

Board: Generic STM32F1 series
Board part number: BluePill F103C6 (32k)
U(S)ART support ...

Hello,

I am trying to understand a very basic USB communication problem I am having with a STM32F103C6 (bluepill) device.

I am successfully programming it with a ST-Link v2. However, USB communication is not working as expected.

Writing data to the Serial device works and I can see the data ...