simplify code

lib/7segment_4digits.c

@@ -30,14 +30,14 @@ void update_display_digit(int digit) {
     display_value(digit, display[digit]);
 }
 
-// Returns the amount of microseconds we blocked for
-float update_display_all_sync() {
-    int sleep_time = 2000;
+// Returns the amount of milliseconds we blocked for
+uint32_t update_display_all_sync() {
+    uint32_t sleep_time_ms = 1;
     for (int i = 0; i < 4; i++) {
-        display_value(i, display[i]);
-        _delay_us(sleep_time);
+        update_display_digit(i);
+        _delay_ms(sleep_time_ms);
     }
-    return sleep_time * 4;
+    return sleep_time_ms * 4;
 }
 
 void show_float(float value) {

lib/7segment_4digits.h

@@ -8,6 +8,6 @@ void update_next_digit();
 
 void update_display_digit(int digit);
 
-float update_display_all_sync();
+uint32_t update_display_all_sync();
 
 void show_float(float value);

lib/util.c

@@ -4,6 +4,7 @@ int num_digits(int num) {
     return 1;
 }
 
+// chatgpt generated
 int get_digit_at_position(int number, int index) {
     if (index < 0) {
         return -1;

main.c

@@ -5,86 +5,50 @@
 #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 tick_timer_start =  0xffff - (F_CPU / 1024 / 1000); // 1ms
-volatile uint32_t ticks = 0;
-volatile beep_time = 0;
-volatile bool counting = false;
-
-void start_timer() {
-    // Sets the Clock Select. See table on page 157 the Atmel datasheet.
-    TCCR1B |= _BV(CS10) | _BV(CS12); // clk/1024
-    TCCR2B |= _BV(CS22); // clk/64
-
-    // Set the TOIE (Timer Overflow Interrupt Enable) bit
-    // on TIMSK1 (Timer 1 Interrupt Mask Register).
-    TIMSK1 |= _BV(TOIE1);
-    TIMSK2 |= _BV(TOIE2);
-
-    // Sets the current timer value
-    TCNT1 = tick_timer_start;
-
-    // Enable interrupts
-    sei();
-}
-
-// ISR is used to handle interrupts. TIMER1_OVF_vect
-// is triggered whenever timer 1 (16 bit) overflows.
-ISR(TIMER1_OVF_vect) {
-    TCNT1 = tick_timer_start;
-    if (counting) {
-        ticks += 1;
-        if (TICK_BEEP && ticks % 1000 == 0 && !beep_time) beep_time = 10;
-    }
-
-    if (bit_is_set(PIND, PIND0)) {
-        PORTD &= 0b11111110;
-    } else if (beep_time > 0) {
-        PORTD |= 0b00000001;
-        beep_time--;
-    }
-}
-
-ISR(TIMER2_OVF_vect) {
-    update_next_digit();
-}
-
-void beep() {
-    beep_time = 50;
-}
-
 void main() {
     DDRF  = 0b11111111;
     DDRK  = 0b00001111;
     DDRD  = 0b00000001;
     PORTK = 0b11000000; // set pull-up
 
-    start_timer();
-
-    float num = 0.0f;
+    uint32_t millis = 0;
+    bool counting = false;
     bool pressed_pause = false;
     bool pressed_clear = false;
 
     while(1) {
-        show_float(ticks / 1000.0f);
+        // show_float() doesn't actually print to the display directly, it only updates
+        // a variable stored in memory. We call `update_display_all_sync()` periodically,
+        // which reads the stored variable and outputs it.
+        show_float(millis / 1000.0f);
 
+        // Cycles through all 4 displays, turns them on for a set amount of time
+        // while displaying the value set by `show_float()` earlier and returns
+        // the total amount waited.
+        uint32_t sleep_time = update_display_all_sync();
+
+        if (counting) {
+            // We can use the returned sleep_time to (inaccurately) count time.
+            millis += sleep_time;
+        }
+
+        // If the button connected to PIN7 is pressed, pause or unpause the counter.
         if (!pressed_pause && bit_is_clear(PINK, PINK7)) {
             counting = !counting;
             pressed_pause = true;
-            beep();
         } else if (pressed_pause && bit_is_set(PINK, PINK7)) {
             pressed_pause = false;
         }
 
+        // If the button connected  to PIN6 is pressed, reset and pause the counter.
         if (bit_is_clear(PINK, PINK6)) {
-            ticks = 0;
+            millis = 0;
             counting = false;
 
-            if (!pressed_clear) beep();
             pressed_clear = true;
         } else pressed_clear = false;
     }