microcontrolling/main.c

#define __AVR_ATmega2560__
#define F_CPU 16000000UL
#define DISPLAY PORTF

#include <avr/io.h>
#include <util/delay.h>
#include <stdbool.h>
#include "lib/7segment.h"

void main() {
    DDRF  = 0b11111111;
    DDRK  = 0b00000000;
    PORTK = 0b00000001; // enable pull-up resistor

    uint8_t val = 0;

    set_display(&PORTF, val, false);

    while(1) {
        loop_until_bit_is_clear(PINK, PINK0);

        if (val >= 9) {
            val = 0xff; // will overflow to 0 when incremented
        }

        set_display(&PORTF, ++val, true);

        // debounce
        _delay_ms(200);

        loop_until_bit_is_set(PINK, PINK0);
        set_display(&PORTF, val, false);
    }
}