#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/sleep.h>

ISR(TIMER2_OVF_vect) {
	PORTB^=0x01;
}

int main() {
	DDRB=0xFF; PORTB=0xFF;
	ASSR|=(1<<AS2);
	TCCR2=0x04;
	TIMSK|=(1<<TOIE2); sei();
	set_sleep_mode(SLEEP_MODE_PWR_SAVE);
	while(1) {
		sleep_mode();
	}
	return 0;
}