// by Les Hall 2013
// public domain code - use freely


// global variables
int outPins[] = {3, 4, 0, 1, 2};
unsigned int counter = 0;
byte sum = 0;
unsigned int numWaves = 16;
unsigned int indexMax = 128;
byte sineTable[128];
unsigned long nextTime = 0;
unsigned long prevTime = 0;
unsigned long deltaTime = 0;
unsigned long noteDuration = 200000;


// the setup routine runs once when you press reset:
void setup() {
  for (int i = 0; i < 5; ++i) {
    pinMode( outPins[i], OUTPUT);
  }
  
  for (int i = 0; i < indexMax; ++i) {
    sineTable[i] = byte( 255.0 * ( sin(TWO_PI * float(i) / float(indexMax) ) + 1.0 ) / 2.0 );
  }
  
  prevTime = micros();
}


// the loop routine runs over and over again forever:
void loop() {
  nextTime = micros();
  deltaTime = nextTime - prevTime;
  
  if ( deltaTime >= noteDuration ) {
    prevTime = nextTime;
    sum = 0;
    for( int i = 0; i < 32; ++i ) {
      sum += bitRead(counter, i);
    }
  }

  unsigned int sineWave = sineTable[counter & 0x007F] * sum;

  for( int i = 0; i <= 4; ++i ) {
    if( bitRead(sineWave, i+6) == 0 ) {
      digitalWrite( outPins[i], LOW);
    } else { 
      digitalWrite( outPins[i], HIGH);
    }
  }
  
  ++counter;
  
  delayMicroseconds(16 * int( sum ) );
}