Pedaliero is a simple program to send Raw HID packets via USB.
Developed for a teensy 2 (should work on other arduino board with minor tweakings)
Either compile it yourself using the make, or directly flash the pedaliero.hex to your teensy.
You can plug up to 23 switches and 1 potentiometer in the F0 pin (if you find out how to modify my code to allow more analog inputs, please tell me !)
Loosely based on Poly_PedalBoard