The Cortex Guitar Board
This project has been cooking for some time. The idea is to design a board with a small ARM microcontroller (Cortex-M4) that can be used to implement audio effects for things like guitar effects. It is small enough to be implanted in an electric guitar or in a small stomp box.
This is what the first revision of the board looks like in a wah-wah pedal context (click for magnification):
The board is based on a STM32F405RG microcontroller (192KiB RAM, Cortex-M4 with DSP and floating point instructions) and a WM8731 audio codec.
GitHub project (firmware and KiCAD PCB design): github.com/JonasNorling/guitarboard
Hackaday project page: https://hackaday.io/project/7936-cortex-guitar-board