Arduino Pot to Frequency

//dynamic frequency generator
//50% Duty cycle square wave 1Hz to 1MHz
//for timer2

#include <avr/io.h>
#include <avr/interrupt.h>

#define TOLERANCE 10

unsigned long frequency = 1000000;
int potPin = A0;

void setup(){
  pinMode(9,1); // Pins 9 & 10
  pinMode(10,1); // are output.
//Serial.begin(57600);
}

int oldVal = 0;

void loop(){
  int val = analogRead(potPin);

  int diff = abs(val - oldVal); // absolute value

  if (diff > TOLERANCE)
  {
    oldVal = val; // only save if the val has changed enough to avoid slowly drifting
    DFG(map(val, 0, 1023, 1, 1000000)); // map 10-bit analog read to freq
  }
}

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
}