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 <avr/interrupt.h>
#include "lib/util.h"
#include "lib/7segment.h"
#include "lib/7segment_4digits.h"

int timer_start =  0xffff - (F_CPU / 1024 / 1000);
volatile uint32_t ticks = 0;
volatile bool counting = false;
volatile bool beeping = false;

void start_timer() {
    // Sets the Clock Select. See table on page 157 the Atmel datasheet.
    TCCR1B |= _BV(CS10) | _BV(CS12); // clk/1024

    // Set the TOIE (Timer Overflow Interrupt Enable) bit
    // on TIMSK1 (Timer 1 Interrupt Mask Register).
    TIMSK1 |= _BV(TOIE1);

    // Sets the current timer value
    TCNT1 = timer_start;

    // Enable interrupts
    sei();
}

void main() {
    start_timer();
    prog_7segment_4digit();
}

// ISR is used to handle interrupts. TIMER1_OVF_vect
// is triggered whenever timer 1 (16 bit) overflows.
ISR(TIMER1_OVF_vect) {
    TCNT1 = timer_start; // TODO figure out how to get the correct number
    if (counting) ticks += 1;

    if (bit_is_set(PIND, PIND0)) {
        PORTD &= 0b11111110;
    } else if (beeping) {
        PORTD |= 0b00000001;
    }
}

void prog_7segment() {
    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);
    }
}

void beep() {
    beeping = true;
    _delay_ms(50);
    beeping = false;
}

void prog_7segment_4digit() {
    DDRF  = 0b11111111;
    DDRK  = 0b00001111;
    DDRD  = 0b00000001;
    PORTK = 0b11000000; // set pull-up

    float num = 0.0f;
    bool pressed_pause = false;
    bool pressed_clear = false;

    while(1) {
        show_float(ticks / 1000.0f);
        float sleep_time = update_display();

        if (!pressed_pause && bit_is_clear(PINK, PINK7)) {
            beep();
            counting = !counting;
            pressed_pause = true;
        } else if (pressed_pause && bit_is_set(PINK, PINK7)) {
            pressed_pause = false;
        }

        if (bit_is_clear(PINK, PINK6)) {
            if (!pressed_clear) beep(50);
            ticks = 0;
            counting = false;
            pressed_clear = true;
        } else pressed_clear = false;
    }
}