// Author:  Nien Lam
// Date:    09-28-2009
// Title:   Photo Sensor Tone Generator 
// Descr:   Using a photocell, play tones within 2 octaves of the C major scale.


// Periods in microseconds for 2 octaves starting with Middle C
int  scale[]     = {3830, 3400, 3038, 2864, 2550, 2272, 2028, 1912, 1704, 1517, 1433, 1276, 1136, 1012, 955};
char scaleNote[] = {'c',  'd',  'e',  'f',  'g',  'a',  'b',  'C',  'D',  'E',  'F',  'G',  'A',  'B',  'S'};
int noteNum      = sizeof(scale) / sizeof(int);

// Note duration
long duration = 200000;

// Sensor ranges
int sValMin, sValMax;

// Temp variables
int note     = 0;
int lastNote = 0;
int ii;


void setup() {
  Serial.begin(9600); 
  pinMode(9, OUTPUT); 
  sValMin = analogRead(0);
  sValMax = analogRead(0);
}


void loop() {
  Serial.println(analogRead(0));   

  // Set ranges
  sValMin = min(sValMin, analogRead(0));
  sValMax = max(sValMax, analogRead(0));

  lastNote = note;

  ii   = map(analogRead(0), sValMin, sValMax, 0, noteNum - 1);
  note = scale[ii];

  if (lastNote != note) {
    Serial.print("Note: ");
    Serial.println(scaleNote[ii]);
    playTone(scale[ii]);  
  }
}


void playTone(int n) {
  long elapsed_time = 0;

  while(elapsed_time < duration) {
    digitalWrite(9, HIGH);
    delayMicroseconds(n / 2);
    digitalWrite(9, LOW);
    delayMicroseconds(n / 2 );
    elapsed_time += (n);
  }
}