#define F_CPU 7372800UL

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

uint16_t time = 0;
uint8_t data[4];
uint8_t dotOn = 0;

void time2data(uint16_t time, uint8_t data[]) {

	uint8_t i;

	for (i = 0; i < 4; ++i) {
		data[3 - i] = time % 10;
		time /= 10;
	}
}

ISR (TIMER1_COMPA_vect) {
	time = (time >= 10000) ? 0: time + 1;

	if (!(time % 50)) {
		dotOn = ~dotOn;
	}

	else {
		dotOn = dotOn;
	}

	time2data(time, data);
}

int main () {

	DDRA = 0xff;
	DDRB = 0xf0;

	uint8_t values[] = {0x3f, 0x06, 0x5b, 0x4f, 0x66, 0x6d, 0x7d, 0x07, 0x7f, 0x6f};
	uint8_t i;

	TCCR1A = 0;
	TCCR1B = _BV(WGM12) | _BV(CS11);
	OCR1A = 9216;
	TIMSK = _BV(OCIE1A);
	sei();

	//time2data(8888, data);
	//dotOn = 1;

	while (1) {

		for (i = 0; i < 4; ++i) {
			PORTA = values[data[i]];

			if (i == 1 && dotOn) {
				PORTA |= _BV(7);
			}

			PORTB = _BV(4 + i);
			_delay_ms(1);
		}
	}
}