int main() 
{
DDRB = 0b00101100;

timer_init();
while (true)
    {
      PORTB = 0b00101100;
      timer_delay_1s();
      PORTB = 0b00000000;
      timer_delay_1s();
    }
}

void timer_delay_1s(void)
{
    TCNT1 = 49911;
    TIFR1 |= (1 << TOV1);

    while (!(TIFR1 & (1 << TOV1)))
    {
        ;
    }
}

void timer_init(void)
{
    TCCR1A = 0x00;  
    TCCR1B = (1 << CS12) | (1 << CS10);
}