miditroube.c

#include "MIDI.h"

void HandleNoteOn(byte channel, byte pitch, byte velocity) {
  if (velocity == 0) { digitalWrite(13, LOW); }
  else { digitalWrite(13, HIGH); }
}

void setup() {
  pinMode(13, OUTPUT);
  digitalWrite(13, HIGH);
  delay(10);
  digitalWrite(13, LOW);
  
  MIDI.begin();    
  MIDI.setHandleNoteOn(HandleNoteOn);
}

void loop() {
  MIDI.read();
}