Arduino

Midi

http://arduino.cc/en/Tutorial/Midi

/*
 MIDI note player
 
 This sketch shows how to use the serial transmit pin (pin 1) to send MIDI note data.
 If this circuit is connected to a MIDI synth, it will play 
 the notes F#-0 (0x1E) to F#-5 (0x5A) in sequence.

 
 The circuit:
 * digital in 1 connected to MIDI jack pin 5
 * MIDI jack pin 2 connected to ground
 * MIDI jack pin 4 connected to +5V through 220-ohm resistor
 Attach a MIDI cable to the jack, then to a MIDI synth, and play music.

 created 13 Jun 2006
 modified 30 Aug 2011
 by Tom Igoe 

 This example code is in the public domain.
 
 http://www.arduino.cc/en/Tutorial/MIDI
 
 */

void setup() {
  //  Set MIDI baud rate:
  Serial.begin(31250);
}

void loop() {
  // play notes from F#-0 (0x1E) to F#-5 (0x5A):
  for (int note = 0x1E; note < 0x5A; note ++) {
    //Note on channel 1 (0x90), some note value (note), middle velocity (0x45):
    noteOn(0x90, note, 0x45);
    delay(100);
    //Note on channel 1 (0x90), some note value (note), silent velocity (0x00):
    noteOn(0x90, note, 0x00);   
    delay(100);
  }
}

//  plays a MIDI note.  Doesn't check to see that
//  cmd is greater than 127, or that data values are  less than 127:
void noteOn(int cmd, int pitch, int velocity) {
  Serial.write(cmd);
  Serial.write(pitch);
  Serial.write(velocity);
}