pwm sound revisited, pitch and volume control

Forum 2005-2010 (read only) Software Development
1

I needed something to send tones to a piezo on pin 10, with out bit banging (desperately need the cpu cycles for other things). Borrowing from the servo threads, this is what I came up with. I believe this is a different approach that what is currently in the playground.

//pin 10 pwm sound with pitch and volume control
#define piezoPin 10 //pin 9 works too
#define minVol 0
#define maxVol 13  //rough guess, any more uses more power but not much louder
#define minPitch 0x0FFF 
#define maxPitch 0x01FF
//add some defines for specific notes and play a song without bitbanging

void setup(){
  pinMode(piezoPin,OUTPUT);
  TCCR1A = 0x00; // sets timer control bits to PWM Phase and Frequency Correct mode 
  TCCR1B = 0x12; // sets timer control bits to Prescaler N = 8 
  analogWrite(piezoPin, 3); //something less than full volume
}

void loop(){
  //control the pitch
  for(int j=0;j<3;j++){ //control pitch
    for(int x = minPitch; x > maxPitch;x-=10){ //
      ICR1 = x; 
      delay(10);
    }
  }
  
  //control the volume
  ICR1 = (minPitch +  maxPitch)/2;
  for(int j=0;j<3;j++){
    for(int x = minVol; x < maxVol;x++){ //
      analogWrite(piezoPin, x);
      delay(500);
    }
  }
}