Teensy MIDI controller

teensy_midi.ino

const int channel = 1;
const int led = 13;

void setup() {
  pinMode(led, OUTPUT);
}

int programs[] = {
  1,   // acoustic grand piano
  9,   // celesta
  20,  // church organ
  43,  // cello
  53,  // choir aahs
  74,  // flute
  105, // sitar
  115  // steel drums
};

#define P    (sizeof(programs) / sizeof(int))

int notes[] = {
  48, 50, 52, 53, 55, 57, 59,
  60, 62, 64, 65, 67, 69, 71,
  72
};

#define N    (sizeof(notes) / sizeof(int))

void loop() {
  unsigned i, j, note;
  while (1) {
    for (j = 0; j < P; j++) {
      usbMIDI.sendProgramChange(programs[j] - 1, channel);
      for (i = 0; i < N; i++) {
        note = notes[i];
        usbMIDI.sendNoteOn(note, 100, channel);
        digitalWrite(led, HIGH);
        delay(500);
        usbMIDI.sendNoteOff(note, 100, channel);
        digitalWrite(led, LOW);
        delay(200);
      }
    }
  }
}