qmk_firmware/keyboards/handwired/onekey/stm32f405_feather
..
config.h
readme.md
rules.mk

readme.md

Adafruit Feather STM32F405 Express onekey

To trigger keypress, short together pins GPIO 12 / PC2 and GPIO 11 / PC3.

https://learn.adafruit.com/adafruit-stm32f405-feather-express/dfu-bootloader-details#enabling-dfu-bootloader-mode-3045622-2