This project implements the USB I/O board protocol for the Tormach / PathPilot controller. It supports both the input and output directions, mapping them to pins on the Teensy. By default, the input pins use the Teensy touch reading functions. You can easily change this with a #define at the top.
Pick up a Teensy 3.2 board from pjrc, or from Amazon: https://amzn.to/2M3B8oV
Upload this firmware, using the Teensyduino installer on the Arduino IDE: https://www.pjrc.com/teensy/td_download.html
By default, this shows up as board 0 but you can change the ID to 1/2/3 if you want to support the multiple-boards support of PathPilot.
You also need to install the udev rule (as root, with sudo) in /etc/udev/rules.d on the PathPilot, found here in file 40-teensy.rules
You can change the project to work on an Arduino (with different I/O pins) by changing the #define ON_ARDUINO to 1
Copyright 2019 Jon Watte; released under MIT license; no warranty given or liability accepted.