source: avrstuff/blinkled/main.c@ 4fbae10

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

#include <string.h>
#include <stdbool.h>

#ifdef __AVR_ATmega48P__
#define TIFR TIFR0
#endif

int main() {
        wdt_enable(WDTO_2S);
    // configure timer 0 for a rate of 16M/(256 * 256) = ~244Hz
    TCCR0A = 0;          // timer 0 prescaler: 256
        TCCR0B = 4;

        //debug LED - output
        DDRD |= 255;

        PORTD = 0xAA;

        while(1) {
                wdt_reset();


                // check timer if we need periodic reports
                if (TIFR & (1 << TOV0)) {
                        TIFR = (1 << TOV0); // reset flag
                        PORTD++;
                }
        }

        return 0;
}