It is nice to have some hardware interface to control a music Programm like Ableton without the mouse.
I found a Midi-controller project that use a serial to midi converter on the pc side to transform the incomming message.
It is also possible to change the bootloader of the arduino to get a hid device, so the serial to midi converter could be removed.
The test programm was designed to send controller messages, i just rewrote it for a piezo drumpad incomming signal.
Digital buttons are also available just uncomment the sending note line.
On pin 13 must be the oposit logic with a pull down, its because of the arduino board design.
here is the midified code:
so just have fun.