boolean myflag1 = true;
void setup() {
  DDRB = 0xFF; // Set PORTB as outputs
  TCCR1A = 0; // initialize timer1
  TCCR1B = 0; // clear all bit
  OCR1A = 10416; // target at 1 Hz
  TIMSK1 = 0; // disable all interrupts
  TCNT1 = 0x0; // Reset Counter
  TIFR1 = 0x6 ; // Clear all interrupt flags
  TCCR1B |= (1 << WGM12); // set to CTC mode (Have a look at Table 2-2)
  TCCR1B |= (1 << CS12); // prescaler 256 (Have a look at Table 2-1)
}
void loop() {
  if(TIFR1 & (1 <<OCF1A)){ // check match interrupt
    TIFR1 = (1 << OCF1A); // clear match interrupt
    if(myflag1){
      PORTB &= ~(1 <<PORTB7); // turn off PB7
    }
    else{
      PORTB = (1 <<PORTB7); // turn on PB7
    }
    myflag1 =! myflag1; // toggle flag
  }
}