Big Piano Hack

Big Piano Hack.pde

/* Music Hackday 2010
 * Big Piano Hack
 */

const int LED_PIN = 13;
const byte CHANNEL = 0;

/* The pin numbers in chromatic order
 */
const int INPUT_PINS[] = {32, 30, 28, 26, 24, 22};
const int BASE_PITCH = 60;

int **states;

int current = 0, previous = 1;

int NUMBER_OF_PINS;

void setup() {
  // Obtain memory
  NUMBER_OF_PINS = (sizeof(INPUT_PINS)/sizeof(int));

  states = (int **) malloc(2 * sizeof(int *));
  states[0] = (int *) malloc(NUMBER_OF_PINS * sizeof(int));
  states[1] = (int *) malloc(NUMBER_OF_PINS * sizeof(int));

  // Set pin modes
  for (int i = 0; i < NUMBER_OF_PINS; i++) {
    pinMode(INPUT_PINS[i], INPUT);
  }

  // go GO G0!
  Serial.begin(115000);
}

void loop() {
  for (int i = 0; i < NUMBER_OF_PINS; i++) {
      int currentPin = INPUT_PINS[i];
      states[current][i] = digitalRead(currentPin);
     
       if (states[current][i] == HIGH && states[previous][i] == LOW)
         sendNoteOn(BASE_PITCH + i, 0x7F);
       else if (states[current][i] == LOW && states[previous][i] == HIGH)
         sendNoteOff(BASE_PITCH + i);
  }
 
  int tmp = current;
  current = previous;
  previous = tmp;
 
  delay(50);
}

void sendNoteOn(byte pitch, byte velocity) {
  sendMidiMessage(0x90 | CHANNEL, pitch, velocity); 
}

void sendNoteOff(byte pitch) {
  sendMidiMessage(0x80 | CHANNEL, pitch, 0x00); 
}

void sendMidiMessage(byte cmd, byte data1, byte data2) {  
  Serial.print(cmd, BYTE);
  Serial.print(data1, BYTE);
  Serial.print(data2, BYTE);
}