//storage variables
boolean toggle0 = 0;
boolean toggle1 = 0;
boolean toggle2 = 0;

void setup(){
  
  //set pins as outputs
  pinMode(8, OUTPUT);
  pinMode(9, OUTPUT);
  pinMode(13, OUTPUT);

cli();//stop interrupts

//set timer0 interrupt at 2kHz
  TCCR0A = 0;// set entire TCCR2A register to 0
  TCCR0B = 0;// same for TCCR2B
  TCNT0  = 0;//initialize counter value to 0
  // set compare match register for 2khz increments
  OCR0A = 124;// = (16*10^6) / (2000*64) - 1 (must be <256)
  // turn on CTC mode
  TCCR0A |= (1 << WGM01);
  // Set CS01 and CS00 bits for 64 prescaler
  TCCR0B |= (1 << CS01) | (1 << CS00);   
  // enable timer compare interrupt
  TIMSK0 |= (1 << OCIE0A);

//set timer1 interrupt at 1Hz
  TCCR1A = 0;// set entire TCCR1A register to 0
  TCCR1B = 0;// same for TCCR1B
  TCNT1  = 0;//initialize counter value to 0
  // set compare match register for 1hz increments
  OCR1A = 15624;// = (16*10^6) / (1*1024) - 1 (must be <65536)
  // turn on CTC mode
  TCCR1B |= (1 << WGM12);
  // Set CS12 and CS10 bits for 1024 prescaler
  TCCR1B |= (1 << CS12) | (1 << CS10);  
  // enable timer compare interrupt
  TIMSK1 |= (1 << OCIE1A);

//set timer2 interrupt at 8kHz
  TCCR2A = 0;// set entire TCCR2A register to 0
  TCCR2B = 0;// same for TCCR2B
  TCNT2  = 0;//initialize counter value to 0
  // set compare match register for 8khz increments
  OCR2A = 249;// = (16*10^6) / (8000*8) - 1 (must be <256)
  // turn on CTC mode
  TCCR2A |= (1 << WGM21);
  // Set CS21 bit for 8 prescaler
  TCCR2B |= (1 << CS21);   
  // enable timer compare interrupt
  TIMSK2 |= (1 << OCIE2A);


sei();//allow interrupts

}//end setup

ISR(TIMER0_COMPA_vect){//timer0 interrupt 2kHz toggles pin 8
//generates pulse wave of frequency 2kHz/2 = 1kHz (takes two cycles for full wave- toggle high then toggle low)
  if (toggle0){
    digitalWrite(8,HIGH);
    toggle0 = 0;
  }
  else{
    digitalWrite(8,LOW);
    toggle0 = 1;
  }
}

ISR(TIMER1_COMPA_vect){//timer1 interrupt 1Hz toggles pin 13
//generates pulse wave of frequency 1Hz/2 = 0.5kHz (takes two cycles for full wave- toggle high then toggle low)
  if (toggle1){
    digitalWrite(13,HIGH);
    toggle1 = 0;
  }
  else{
    digitalWrite(13,LOW);
    toggle1 = 1;
  }
}
  
ISR(TIMER2_COMPA_vect){//timer1 interrupt 8kHz toggles pin 9
//generates pulse wave of frequency 8kHz/2 = 4kHz (takes two cycles for full wave- toggle high then toggle low)
  if (toggle2){
    digitalWrite(9,HIGH);
    toggle2 = 0;
  }
  else{
    digitalWrite(9,LOW);
    toggle2 = 1;
  }
}

void loop(){
}