// pattern  34, 567, 012
#include <stdint.h>

#define DDRA  (*(volatile uint8_t*)0x21)
#define PORTA (*(volatile uint8_t*)0x22)

uint8_t pattern[3] = {
    0x18,   // 34
    0xE0,   // 567
    0x07    // 012
};

void delay1sec(void){
    TCNT1  = 0;
    TCCR1A = 0x00;
    TCCR1B = 0x05;
    while (TCNT1 < 15625);
    TCCR1B = 0x00;
}

void setup() {
    DDRA = 0xFF;
}

void loop() {
    for (uint8_t i = 0; i < 3; i++) {
        PORTA = pattern[i];
        delay1sec();
        PORTA = 0x00;
        delay1sec();
    }
}