qmk_firmware/keyboards/planck/keymaps/grahampheath
..
config.h
keymap.c
readme.md
rules.mk

Graham's Planck

Sounds

I've added a 8ohm 0.5W speaker, its a bit large, but it fits in approximately the same space as the ProMicro. I soldered to the pcb hole labeled PC6 on my Rev 3 Planck PCB, and GND on the near by chip. Pic of an identical mod (not mine).