#include <avr/io.h>
#include <avr/interrupt.h>
// global variable to count the number of overflows
volatile uint8_t tot_overflow;
// initialize timer, interrupt and variable
volatile bool is_interupt;

volatile uint8_t counter;
volatile uint8_t tab_size;
volatile uint32_t tab[26] = { 0x80, 0x00, 0x80, 0x00, 0x80, 0x00, 0x80, 0x80, 0x80, 0x00, 0x80, 0x80, 0x80, 0x00, 0x80, 0x80, 0x80, 0x00, 0x80, 0x00, 0x80, 0x00, 0x80, 0x00, 0x00, 0x00};

void timer1_init()
{
	sei();

	// set up timer with prescaler = 8
	TCCR1B |= (1 << CS10);
	// initialize counter
	TCNT1 = 0;
	// enable overflow interrupt
	TIMSK1 |= (1 << TOIE1);
	// enable global interrupts
	sei();
	// initialize overflow counter variable
	tot_overflow = 0;
	is_interupt = false;
}
// TIMER1 overflow interrupt service routine
// called whenever TCNT1 overflows
ISR(TIMER1_OVF_vect)
{
	// keep track of the number of overflows
	tot_overflow++;
	// check for number of overflows here itself
	// 61 overflows = 2 seconds delay (approx.)
	if(tot_overflow >= 61) // NOTE: '>=' used instead of '=='
	{
		is_interupt = true;
		tot_overflow = 0;
		// reset overflow counter
	}
}

volatile bool is_on;

int main(void)
{


	DDRB=0xFF;

	is_on = false;
	tab_size = 26;
	counter = 0;
	//PORTB = 0x80;

	// initialize timer
	timer1_init();
	    // loop forever
	while(1)
	{
		if(is_interupt){
			if(counter >= tab_size){
				counter = 0;
			}
			PORTB = tab[counter];
			counter++;
			is_interupt = false;
		}
	}
}