/* Name: main.c
 * Author: <insert your name here>
 * Copyright: <insert your copyright message here>
 * License: <insert your license reference here>
 */

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

#define LED_ON  PORTB |= _BV(PB0);
#define LED_OFF PORTB &= ~(_BV(PB0));
#define TOGGLE_LED PORTB ^= _BV(PB0);

ISR(WDT_OVERFLOW_vect)
{
    TOGGLE_LED;    
}

void sleep()
{
    WDTCSR |= (1<<WDP2) | (1<<WDP1) | (1<<WDP0);
    WDTCSR |= (1<<WDIE);
    set_sleep_mode(SLEEP_MODE_PWR_DOWN);
    sleep_enable();
    sleep_cpu();
    
    //wake up
    sleep_disable();
    MCUSR = 0;
}

int main(void)
{
    DDRB |= (1<<PB0);
    sei();
    for(;;){
        sleep();
    }
    return 0;   /* never reached */
}