This is firmware to run on this cute one key keyboard from Techkeys.
Forum post on compiling the Techkeys firmware
Download AVR GCC from http://andybrown.me.uk/2012/04/28/avr-gcc-4-7-0-and-avr-libc-1-8-0-compiled-for-windows/
Add to path
set PATH=C:\tools\avr-gcc\bin;c:\tools\dfu-programmer\;%PATH%
Run make
Install dfu-programmer
Short the 2 pads next to the USB connector. In the Device Manager, you'll see at the top Atmel USB Devices -> ATmega16U2
Run make flash
Original code from komar007 on Geekhack, changes Copyright (C) 2017 Julien Vanier.
Released under the MIT license.