Midi notes to Digital outputs

Sorry don't know where it has gone. Copy it from here.

/* Midi Shield - Mike Cook May 2009
 * ----------------- 
 * listen for MIDI serial data, 
 * sends MIDI note on with push button on Pin 2
 
#####################################################################################################################################################

HARDWARE NOTE:
The MIDI Socket is connected to arduino RX through an opto-isolator to invert the MIDI signal 
and separate the circuits of individual instruments.

####################################################################################################################################################
*/

//variables setup

  byte incomingByte;
  byte note;
  byte button;
  int noteDown = LOW;
  int state=0;        // state machine variable 0 = command waiting : 1 = note waitin : 2 = velocity waiting
  byte channel = 1;  // MIDI channel to respond to (in this case channel 2) change this to change the channel number
                    // MIDI channel = the value in 'channel' + 1

//setup: declaring inputs and outputs and begin serial 
void setup() { 

  pinMode(13,OUTPUT);       // LED to light up
  pinMode(2,INPUT);         // push button to read
  digitalWrite(2,HIGH);     // enable internal pull up resistors
  button = digitalRead(2);  // initialise push button state
  state = 0;  // initialise state machine variable
  //start serial with MIDI baud rate 31250 or another standard speed for debugging
  Serial.begin(31250);        
  digitalWrite(13,LOW);     // Turn LED off
}

//loop: wait for serial data, and interpret the message 
void loop () {
  checkIn(); // see if anything has arrived at the input
  checkButton();
  }
  
void checkButton(){
  if(button != digitalRead(2)) {  // only do stuff on a change
    button = digitalRead(2);     // get new state of button
    if(button == HIGH) noteSend(0x80, 65, 0); else noteSend(0x90, 65, 127);
  }
}  

//  plays a MIDI note
void noteSend(byte cmd, byte data1, byte data2) {
  cmd = cmd | channel;        // merge channel number
  Serial.print((byte)cmd);    // command
  Serial.print((byte)data1);  // note number
  Serial.print((byte)data2);  // velocity
}
  
void checkIn(){
  if (Serial.available() > 0) {
    // read the incoming byte:
    incomingByte = Serial.read();

   switch (state){
      case 0:
    // look for as status-byte, our channel, note on
    // if (incomingByte== (144 | channel)){  // un comment and comment the line below - to read only one channel
      if ((incomingByte & 0xf0) == 0x90){    // this reads all channels
         noteDown = HIGH;
         state=1;
        }
    // look for as status-byte, our channel, note off
   // if (incomingByte== (128 | channel)){   // un comment and comment the line below - to read only one channel 
        if ((incomingByte & 0xf0) == 0x80){  // this reads all channels
         noteDown = LOW;
         state=1;
        }
        
       case 1:
       // get the note to play or stop
       if(incomingByte < 128) {
          note=incomingByte;
          state=2;
       }
       else{
       state = 0;  // reset state machine as this should be a note number
       }
       break;
       
       case 2:
       // get the velocity
       if(incomingByte < 128) {
         doNote(note, incomingByte, noteDown); // do something withh the note on message
       }
         state = 0;  // reset state machine to start            
     }
  }
}

void doNote(byte note, byte velocity, int down){
  // if velocity = 0 on a 'Note ON' command, treat it as a note off
  if ((down == HIGH) && (velocity == 0)){
      down = LOW; 
  }
  // do something with the note message 
  // this just toggles Pin 13 and ignores the note value and velocity
 if(down == LOW) digitalWrite(13, LOW); else  digitalWrite(13, HIGH);

}