This 41-button Arduino keyboard PCB is a stepping stone to his ... The keypad uses an onboard ATMega328P to scan the matrix for button presses, decode them, and send them via UART or I²C to ...

This allowed [JenShen] to scan the keyboard matrix with an Arduino and generate MIDI notes and send them to other synths. In the video after the break, you can check out [JenShen]’s circuit and ...