qmk-firmware/keyboards/handwired/onekey/blackpill_f401
..
blackpill_f401.c
chconf.h
config.h
halconf.h
mcuconf.h
readme.md
rules.mk

f401 blackpill onekey

Supported Hardware: STM32F401CCU6 WeAct v1.3.

To trigger keypress, short together pins B0 and A7.