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

void display_digit(uint8_t digit) {
 
    uint8_t segment_codes[10] = {0x3F, 0x06, 0x5B, 0x4F, 0x66, 0x6D, 0x7D, 0x07, 0x7F, 0x6F};
    PORTD = segment_codes[digit]; 
}

int main(void) {
    DDRD = 0xFF; 
    while (1) {
        for (uint8_t i = 0; i < 10; i++) { 
            display_digit(i);
            _delay_ms(500); 
        }
    }
}