Virtual COM Port Trouble

Scott Gravenhorst · ‎2017-08-10

Posted on August 11, 2017 at 00:03

Fedora 25 (64 bit)

STM32F746G Discovery board

I've been able to program the board using a simple Makefile project. The board flashes and runs the program, in this case, a LED flasher that has code to send messages to the Virtual COM Port.

I've been able to see the data with gtkterm -p /dev/ttyACM0 -s 115200

However, it won't work until I run st-util on the host and control C out of it.

I've been informed that all of the functionality I need for VCP is part of OpenOCD and that I need not even have installed the texane software.

I've read the whole OpenOCD manual and I see no solution there.

BTW, I can run openocd and get GDB to work. I just can't make the VCP work without the st-util 'hack'.

I really need the VCP for the end application which is a MIDI music synthesizer. I'd like to verify the the MIDI hardware interface is working properly by sending the hexadecimal values of the MIDI bytes received.

Is there something else I need to read to understand what is going on with this?

Scott Gravenhorst · ‎2017-08-18

Posted on August 18, 2017 at 22:16

Embarrassing... I am replying here for archive and in case this happens to anyone else...

I had written the init code for the USART myself and I must have done something wrong, though I can't seem to find what it is.

I fixed the problem by starting a new project. I began with STM32CubeMX and added all of the devices I needed, set up the clock muxes and then added my user code into main.c and elsewhere as needed. The project now works properly with LEDs flashing and text streaming out of the VCP and there is no longer any need to run st-util.

My lesson learned here - STM32CubeMX is an amazing tool which I will now use with regularity.