#include <avr/io.h>
#include <util/delay.h>
#define SEGMENT_PORT PORTB
#define SEGMENT_DDR  DDRB
#define SEGMENT_A 0
#define SEGMENT_B 1
#define SEGMENT_C 2
#define SEGMENT_D 3
#define SEGMENT_E 4
#define SEGMENT_F 5
#define SEGMENT_G 6
#define COMMON_CATHODE 7
void displayDigit(uint8_t digit) 
{
    
    const uint8_t segmentCodes[] =
     {
        0b0111111, 
        0b0000110, 
        0b1011011, 
        0b1001111, 
        0b1100110, 
        0b1101101, 
        0b1111101, 
        0b0000111, 
        0b1111111, 
        0b1101111  
    };
    SEGMENT_PORT &= ~(1 << COMMON_CATHODE);
    SEGMENT_PORT = (SEGMENT_PORT & 0xF8) | (segmentCodes[digit] & 0x07);
    _delay_ms(5);
    SEGMENT_PORT |= (1 << COMMON_CATHODE);
    SEGMENT_PORT |= 0x07;
}

int main() 
{
    SEGMENT_DDR |= 0x87;
    while (1) {
        for (uint8_t i = 0; i <= 9; ++i) 
        {
            displayDigit(i);
            _delay_ms(1000); 
        }
    }

    return 0;
}