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

ISR(TIMER1_COMPA_vect) {
	PORTB^=0x01;
}

int main() {
	DDRB=0xFF; PORTB=0xFF;
	OCR1A=1799; TCCR1B=0x0D;
	TIMSK|=(1<<OCIE1A); sei();
	set_sleep_mode(SLEEP_MODE_IDLE);
	while(1) {
		sleep_mode();
	}
	return 0;
}