USB serial don't work for STM32F7

[doublemm (Markus Marks)]

Hello, i tried ot start the USB serial connection on a STM32F7 to get some debug messages, but it doesn’t work. When the program is started, it stops on this function: sem.try_acquire_for(rel_time).
Does anyone have the same problem or can help?

callstack:

[JohnnyK (Jan Kamidra)]

Hello,
I not tested it so deep but the example USBSerial seems be ok - 2x usb cable (St-link and USB-OTG), Nucleo-F767ZI, MbedOS 6.5, MbedStudio and serial terminal with DTR signal ON.

USB Serial not working in mbed-os 6

Hi there, I do not have LPC1768 but I’m working on the Nucleo-F429ZI with USB OTG and it is working. The USBSerial is set to blocking in the default. That mean it waits for a connection from opposite side, that is the reason why your code not reach the main. So until you not connect a terminal application on your pc to a correct port nothing will happen. The PC application also need manage the DTR signal. Also you can not call _printc for call a string without a for loop, the _printc(int c) …

BR, Jan