/*using Timer 1 for delay in Normal mode(TIMER1 - 16bit)
ATMega2560 clock = 16MHz*/

void T1Delay(void);

void setup() {
  volatile uint8_t *DDR_F=(volatile uint8_t *)0x30;
  *DDR_F|=(1<<3);  //Settng portF 3rd pin as output pin
  T1Delay();
}

void T1Delay(){
  volatile char *TIMER1_TCCR1A =0x80;
  volatile char *TIMER1_TCCR1B =0x81;
  volatile uint16_t *TIMER1_TCNT1 =0x84;
  volatile uint16_t *TIMER1_OCR1A =0x88;
  volatile char *TIMER1_TIMSK1=0x6f;
  *TIMER1_TCCR1A =0;
  *TIMER1_TCCR1B=0;
  *TIMER1_TCNT1 =0;  //CTC mode
  *TIMER1_TCCR1B=0x0c;// CTC mode & 256 prescalar
  *TIMER1_OCR1A = 31250;
  *TIMER1_TIMSK1=0x02;// enable interrupt mode for Output compare match A
}

ISR(TIMER1_COMPA_vect)
{
  volatile uint8_t *PORT_F=(volatile uint8_t *)0x31;
  *PORT_F^=(1<<3);

}
void loop() {
  // put your main code here, to run repeatedly:

}