Sumer_is_Icummen_In_6.ino

/*
  Summer is Icummen In - Part 6
  By Chris Chungbin
  Plays the second accompanying part of a piece of 13th-century polyphony
*/

unsigned long temp=360;  //set note rate in bpm of the GCF of note duration
unsigned int t=0;  //time var in periods of the variable "temp"

float pitch[]=        {523.25, 466.16, 523.25, 000.00, 349.23, 392.00, 349.32, 392.00, 466.16,
                       523.25, 466.16, 523.25, 000.00, 349.23, 392.00, 349.32, 392.00, 466.16,
                       523.25, 466.16, 523.25, 000.00, 349.23, 392.00, 349.32, 392.00, 466.16,
                       523.25, 466.16, 523.25, 000.00, 349.23, 392.00, 349.32, 392.00, 466.16,
                       523.25, 466.16, 523.25, 000.00, 349.23, 392.00, 349.32, 392.00, 466.16,
                       523.25, 466.16, 523.25, 000.00, 349.23, 392.00, 349.32, 392.00, 466.16,
                       523.25, 466.16, 523.25, 000.00, 349.23, 392.00, 349.32, 392.00, 466.16,
                       523.25, 466.16, 523.25, 000.00, 349.23, 392.00, 349.32, 392.00, 466.16,
                       523.25, 466.16, 523.25, 000.00, 349.23, 392.00, 349.32, 0};  //frequency of each note in Hz
unsigned int time[]=  {3,      3,      3,      3,      3,      3,      3,      2,      1,
                       3,      3,      3,      3,      3,      3,      3,      2,      1,
                       3,      3,      3,      3,      3,      3,      3,      2,      1,
                       3,      3,      3,      3,      3,      3,      3,      2,      1,
                       3,      3,      3,      3,      3,      3,      3,      2,      1,
                       3,      3,      3,      3,      3,      3,      3,      2,      1,
                       3,      3,      3,      3,      3,      3,      3,      2,      1,
                       3,      3,      3,      3,      3,      3,      3,      2,      1,
                       3,      3,      3,      3,      3,      3,      3,      1,1,1};  //duration of note in time rate periods - multiple of shortest note value - add 2 other elements after the last duration to allow index shifting later

void setup() {
  pinMode(8, OUTPUT);  //audio out
  pinMode(7, INPUT);  //sync pulse from syncing board
  pinMode(6, OUTPUT);  //ready signal out to syncing board
  digitalWrite(6, LOW);


  temp=60000000/temp;  //convert tempo to period in microseconds

  for(int i=0; i<sizeof(pitch)/4; i++) {
    pitch[i]=pitch[i]/2;
  }

  for(int i=sizeof(time)/2-1; i>0; i--) {  //this and the next for() convert time[] to start time of note
    time[i]=time[i-1];
  }
  time[0]=0;
  for(int i=1; i<sizeof(time)/2-1; i++) {
   time[i]=time[i-1]+time[i];
  }
  digitalWrite(6, HIGH);
}

void loop() {
  t=0;
  unsigned long s=micros();  //period start time
  unsigned long p=0;  //period
  boolean in=0;  //input
  boolean waiting=0;  //ready to wait for next pulse?
  while(!in) {
    in=digitalRead(7);
  }
  digitalWrite(6,LOW);
  in=0;
  while(in) {
    in=digitalRead(7);
  }
  while(!in) {
    in=digitalRead(7);
  }
  unsigned long start=micros();  //start time recorded

  for (int i=0; i<sizeof(pitch)/4; i++) {
    while(time[i+1]>t) {
      s=micros();
      in=digitalRead(7);
      if(waiting&&in) {
        t=t+1;
        waiting=0;
      }
      if(!(waiting||in)) {
        waiting=1;
      }
      if(pitch[i]==0) {
      }
      else {
        p=1000000/pitch[i];
        digitalWrite(8, HIGH);
        delayMicroseconds(p/3);
        digitalWrite(8, LOW);
        while(micros()-s<p) {
          //waits in this incredibly exciting loop until the current period is done
        }
      }
    }
  }

  while(1) {
  }
}