inoProjects/Theremin/Theremin.ino

/*
 *@author James McKenzie
 *@lang C89 Based
 *@contact lunarised@outlook.com
 */
int mode;
void setup() {
  pinMode(6, INPUT_PULLUP);		//Mode Select Pin
  pinMode (13, OUTPUT);			//LED Indicator Pin
  pinMode(8, OUTPUT);			//Speaker Pin
  pinMode (7, INPUT_PULLUP);		//Play Pin
  pinMode(5, INPUT_PULLUP);		//+Octave Play Pin
  Serial.begin (9600);			//Set up a Serial Connection
  pinMode(11, OUTPUT);   		//Trigger pin 
  pinMode(12, INPUT);    		//Echo pin

}

void loop() {
  if (digitalRead(6) ==HIGH){
    mode = 0;
  }else{
    mode = 1;
  }
  float note = 0;
  if (digitalRead(7) == LOW || digitalRead(5) == LOW){
    if (mode == 0){
      note = tune(getNote());
    }
    else{
      note = getNote();
    }
    if (digitalRead(5)==LOW){ 		//if the octave button is pressed
      note *= 2;
    }
    digitalWrite(13, HIGH);
    Serial.print(note);      		//print frequency
    Serial.println(" hz");		//print units after frequency
    tone(8, note); 
  }
  else{
    noTone(8);
  }
}
/*
 * Method that uses an UltraSonic sensor to calculate a frequency
 * @return A Frequency generated by a sensor
 */
float getNote(){

  float echoTime;
  float calculatedDistance;
  digitalWrite(11, HIGH);
  delayMicroseconds(20); 
  digitalWrite(11, LOW);
  echoTime = pulseIn(12, HIGH);                                       
  calculatedDistance = echoTime / 8; 	//Change this value to decrease
  					//the playing physical range
  calculatedDistance += 110;		//Minimum value
  if (calculatedDistance > 1760){ 	//Prevent high pitched sounds 
    calculatedDistance = 1760;		//Maximum Value
  }
  return calculatedDistance;
}

/*
 * Method which takes a note, and brings the note down to a correct pitch
 * @param toTune	The Note in which you are autotuning
 * @return		The Note that has now been autotuned
 */
float tune(float toTune){
  if (toTune> 523.75){ 			//C5
    return 523.75;
  }
  if (toTune> 493.88){ 			//B4
    return 493.88;
  }
  if (toTune> 440){ 			//A4
    return 440;
  }
    if (toTune> 392){ 			//G4
    return 392;
  }
    if (toTune> 349.23){ 		//F4
    return 349.23;
  }
    if (toTune> 329.63){ 		//E5
    return 329.63;
  }
    if (toTune> 293.66){ 		//D4
    return 293.66;
  }
    if (toTune> 261.63){ 		//C4
    return 261.63;
  }
    if (toTune> 246.94){ 		//B3
    return 246.94;
  }
    if (toTune> 220){ 			//A3
    return 220;
  }
    if (toTune> 196){ 			//G3
    return 196;
  }
    if (toTune> 174.61){ 		//F3
    return 174.61;
  }
}