Considering all modern MIDI controllers have ability to communicate via USB you might think it will be quite nice to connect MIDI keyboard we built directly to USB port on your PC? That’s exactly what we are going to do. Below are the end-to-end steps I took to make it work. It might help someone? May be you?
This instructions were tested on Arduino UNO and should work with Arduino MEGA (not tested, please let me know if you managed to make it work?)
To achieve this we are going to use HIDUINO firmware that makes Arduino UNO board to appear as USB HID (MIDI) device.