TWIMC:
This is a minimal working solution for me:
platformio.ini:
[env:bluepill_f103c8]
platform = ststm32
board = bluepill_f103c8
framework = arduino
upload_protocol = hid
build_flags =
-D PIO_FRAMEWORK_ARDUINO_ENABLE_CDC
Getting HID bootloader (stm32_binaries.zip)
Installing via stlink
cd stm32_binaries/F103/low_and_medium_density
st-flash write hid_generic_pc13.bin 0x8000000
Make sure that the tool is there
pio pkg install -g -t "platformio/tool-stm32duino"
Make sure that hid-flash is there, then upload as usual
pio run -t upload
PS The Docs somehow doesn’t mention the HID bootloader, which cost me my pound of flesh. Or, at least, an ounce.