URS_K02G01Z02

#define F_CPU 7372800UL

#include <avr/io.h>
#include <util/delay.h>

void blink(uint8_t cnt) {
    if (cnt <= 3) {
        PORTA = PORTA & ~_BV(4+cnt) & ~_BV(3-cnt);
    } else {
        cnt = cnt % 4;
        PORTA = PORTA | _BV(4+cnt) | _BV(3-cnt);
    }
}

int main() {
    DDRA = 0xff;
    PORTA = 0xff;

    uint8_t cnt = 0;
    while (1) {
        blink(cnt);
        cnt = (cnt+1) % 8;
        _delay_ms(200);
    }
}