https://www.youtube.com/watch?v=4QYlIZP8Dl4
https://oshwlab.com/scherbakov.al/controller2
https://oshwlab.com/scherbakov.al/1-a0-c3-on
https://oshwlab.com/scherbakov.al/2-c_3-g_4-on
https://oshwlab.com/scherbakov.al/3-a4-f6-on
https://oshwlab.com/scherbakov.al/4-f_6-c8-on
https://oshwlab.com/scherbakov.al/1-a0-c3-off
https://oshwlab.com/scherbakov.al/2-c_3-g_4-off
https://oshwlab.com/scherbakov.al/2-c_3-g_4-off
Moved here: https://github.com/ScherbakovAl/midi_keyboard_h723