MPE-DIY-Device using a Teensy LC, 4 finger-joysticks and a Led&Key-panel (GNU General Public License 3) Power and Midi over USB, connection of external keyboard or "button-matrix" required.
If you want to build your Teensy firmware from source, please copy the ZIP to a dedicated folder on your computer. You will need Teensyduino to build the software, software and documentation for this IDE are to be found here: https://www.pjrc.com/teensy/teensyduino.html
The *.hex-file is the prebuild firmware. No building from source or IDE needed, here. This binary can be loaded directly to the Teensy using the Teensy loader, which you will find at the link as below: https://www.pjrc.com/teensy/loader.html
Please note: Currently it is recommended to build from source, because the joysticks and their cabeling can be adjusted to your needs here, which may be different to the binary right now which still was done with a prototype of the hardware.