#include <avr/io.h>
#include <stdint.h>

void wacht1sec() {
    uint8_t i;

    TCNT0 = 160;
    TCCR0 &= ~(1<<WGM01 | 1<<WGM00 | 1<<CS01);
    TCCR0 |= 1<<CS02 | 1<<CS00;

    for (i = 0; i < 10; i++) {
        TIFR = 1<<TOV0;
        while (!(TIFR & 1<<TOV0));
    }

    TCCR0 &= ~(1<<CS02 | 1<<CS01 | 1<<CS00);
}

int main(void) {
    void wacht1sec();

    DDRB = 0xFF;
    PORTB = 0xFF; /* alle LEDs uit */
    while (1) {	
        wacht1sec();
        PORTB ^= 1<<7; /* flip LED7 */
    }
    return 0;
}