1Hz - 1MHz Frequency Generator Using Arduino

square_wave_generator.ino

// Taken from https://forum.arduino.cc/index.php?topic=116094.15
// "Here's my code to set up timer 1 "
// dynamic frequency generator
// for timer2
#include <avr/io.h>
#include <avr/interrupt.h>

unsigned long frequency = 1000000 ; // in hertz
void setup(){
  pinMode(9,1);
  pinMode(10,1);
  DFG(frequency);
  Serial.begin(57600);
}

void loop(){
}

void DFG(unsigned long tempfreq){
  cli();//disable interupts
  TCCR1A = 0;//registers for timer 1
  TCCR1B = 0;
  TCNT1=0;
  TCCR1A |= _BV(COM1A0) + _BV(COM1B0);
  TCCR1B |=_BV(WGM12); 
  TCCR1C = _BV(FOC1A);
   if(tempfreq > 122 && tempfreq < 1000001){
  OCR1A = (8000000/tempfreq)-1;//#TIMER COUNTS
  TCCR1B |= _BV(CS10);
  }
  else if(tempfreq <= 122 && tempfreq > 15){
    OCR1A = (1000000/tempfreq)-1;
    TCCR1B |= _BV(CS11);
  }
  else if(tempfreq <= 15 && tempfreq > 4){
    OCR1A = (125000/tempfreq)-1;
    TCCR1B |= _BV(CS10) + _BV(CS11);
  }
  
  //TIMSK1 = _BV(OCIE1A);//TIMER1 COMPARE INTERUPT
  sei();//enable interupts
}