Arduino for STM32

No. USB bootloader does not enable Serial USB in your sketches. It's just a bootloader - a program that loads on boot and allows you to flash your program. If you haven't enabled USB Serial in your sketch, there won't be USB Serial.

Using USB bootloader you cannot overwrite bootloader.
There is ...

Thanks for that input.


I don't know how to deal with PIO, but with Arduino IDE, once you flashed "generic_boot20_pc13.bin" via serial or st-link, you'll get COM port (and it will be named "COM10 Maple Mini"). Port number may be different in your case.
At this point use you must use USB to upload ...

I have flashed the `generic_boot20_pc13.bin` with an st-link - which wrote a bootloader and a sketch (printing to the serial).

Now this provided a USB serial on the host that:

- provides the serial from the sketch over USB
- a way to flash a new sketches via USB

The 2nd flash wasn't via st-link ...

I have flashed the bootloader to a bluepill.

$ st-info --probe
Found 1 stlink programmers
version: V2J17S4
serial: 54FF67064882565217411887
flash: 65536 (pagesize: 1024)
sram: 20480
chipid: 0x0410
descr: F1xx Medium-density
$ st-flash write generic_boot20_pc13.bin 0x8000000
...
2023-02-25T17 ...