6 files changed, 97 insertions, 21 deletions

diff --git a/justfile b/justfile
index 224a293..e08c5fb 100644
--- a/justfile
+++ b/justfile
@@ -8,7 +8,7 @@ AVR_LIBC := env("AVR_LIBC", "/usr/lib/avr")
 F_CPU := "32768"
 MCU := "attiny84a"
 MCU_PART := "attiny84"
-SRCS := "src/main.c src/display.c src/rtc.c"
+SRCS := "src/main.c src/display.c src/rtc.c src/button.c"
 OUTDIR := "./out"
 PROGRAMMER := "arduino"
 UPLOAD_SPEED := "19200"
diff --git a/src/button.c b/src/button.c
new file mode 100644
index 0000000..34d799c
--- /dev/null
+++ b/src/button.c
@@ -0,0 +1,57 @@
+#include <avr/io.h>
+#include <stdint.h>
+
+#include "avr/interrupt.h"
+#include "button.h"
+#include "rtc.h"
+
+bool is_button_active = false;
+
+uint16_t button_tick_count = 0;
+
+ISR(PCINT0_vect, ISR_FLATTEN) { button_tick(); }
+
+void button_tick() {
+  switch (check_button_state()) {
+  case BUTTON_PRESSED:
+    if (seconds <= 10)
+      seconds = 0;
+    else
+      seconds -= 10;
+    break;
+  case BUTTON_LONG_PRESSED:
+    seconds += 10;
+    break;
+  default:
+    break;
+  }
+}
+
+enum ButtonState check_button_state() {
+  if (is_button_active && button_tick_count >= LONG_PRESS_TICK_COUNT) {
+    button_tick_count = 0;
+    is_button_active = false;
+    return BUTTON_LONG_PRESSED;
+  }
+
+  bool in_debounce_period = is_button_active && button_tick_count > 0 &&
+                            button_tick_count < DEBOUNCE_TICK_COUNT;
+
+  // Ignore readings from debounce period
+  if (!in_debounce_period) {
+    DDRA &= ~(1 << PA0);
+    PORTA &= ~(1 << PA0);
+    is_button_active = (PINA & (1 << PA0)) == 0;
+  }
+
+  if (is_button_active) {
+    button_tick_count++;
+  } else {
+    if (button_tick_count >= DEBOUNCE_TICK_COUNT) {
+      button_tick_count = 0;
+      return BUTTON_PRESSED;
+    }
+  }
+
+  return BUTTON_IDLE;
+}
diff --git a/src/button.h b/src/button.h
new file mode 100644
index 0000000..bb41eb6
--- /dev/null
+++ b/src/button.h
@@ -0,0 +1,20 @@
+#ifndef _LOADED_BUTTON
+#define _LOADED_BUTTON
+#include <stdbool.h>
+#include <stdint.h>
+
+#define DEBOUNCE_TICK_COUNT 10
+#define LONG_PRESS_TICK_COUNT 60
+#define MAX_TICK_COUNT 80
+
+enum ButtonState {
+  BUTTON_IDLE = 0,
+  BUTTON_PRESSED = 1,
+  BUTTON_LONG_PRESSED = 2,
+};
+
+uint16_t extern button_tick_count;
+
+void button_tick();
+enum ButtonState check_button_state();
+#endif
diff --git a/src/display.c b/src/display.c
index 8de5043..7781b7e 100644
--- a/src/display.c
+++ b/src/display.c
@@ -3,6 +3,7 @@
 #include <stdint.h>
 #include <util/delay.h>
 
+#include "button.h"
 #include "display.h"
 #include "rtc.h"
 
@@ -38,8 +39,12 @@ volatile uint8_t current_digit = 0;
 
 // Render current digit
 void display_render(void) {
+  button_tick(); // Check button click
+
   DDRA |= 0b11111111;
   DDRB |= 0b11111111;
+  PORTA = 0b01111111;
+  PORTB = 0b00000000;
 
   write_time(minutes, seconds, current_digit);
 
diff --git a/src/main.c b/src/main.c
index cf6f7a8..6f621af 100644
--- a/src/main.c
+++ b/src/main.c
@@ -3,6 +3,7 @@
 #include <stdbool.h>
 #include <util/delay.h>
 
+#include "button.h"
 #include "display.h"
 #include "rtc.h"
 
@@ -15,17 +16,14 @@ FUSES = {
     .extended = 0xff,
 };
 
-// Display
-// timer 0 has lower priority than timer 1, so some ticks could get skipped due
-// to interrupt starvation
+// Display interrupt
+// Timer 0 has lower priority than timer 1, so some ticks could get skipped on
+// interrupt starvation
 ISR(TIM0_COMPA_vect, ISR_FLATTEN) { display_render(); }
 
 // RTC interrupt
 ISR(TIM1_COMPA_vect, ISR_FLATTEN) { rtc_increment(); }
 
-#define IS_BUTTON_ON() ((PINA & (1 << PA0)) == 0)
-#define ENABLE_BUTTON() (DDRA &= ~(1 << PA0))
-
 int main(void) {
   PRR = 0b0011; // Power reduction register. Shut down USI and ADC
 
@@ -35,20 +33,16 @@ int main(void) {
   sei();
 
   while (1) {
-    // ENABLE_BUTTON();
-    // if (IS_BUTTON_ON()) {
-    //   cli();
-    //   ENABLE_BUTTON();
-    //   _delay_ms(25); // Debounced
-    //   if (IS_BUTTON_ON()) {
-    //     seconds += 1;
-    //     sei();
-    //     _delay_ms(50);
-    //     continue;
-    //   }
+    // switch (button_tick()) {
+    // case BUTTON_PRESSED:
+    //   seconds += 5;
+    //   break;
+    // case BUTTON_LONG_PRESSED:
+    //   seconds += 10;
+    //   break;
+    // default:
+    //   break;
     // }
-    // sei();
-
 #ifdef STUBBED
     stub_run_timers();
     _delay_ms(100);
diff --git a/src/rtc.c b/src/rtc.c
index 1ac50c3..053e651 100644
--- a/src/rtc.c
+++ b/src/rtc.c
@@ -19,7 +19,7 @@ void rtc_setup(void) {
   TIMSK1 = (1 << OCIE1A); // Enable timer overflow interrupt
 }
 
-volatile uint8_t seconds = 10;
+volatile uint8_t seconds = 0;
 volatile uint8_t minutes = 0;
 volatile uint8_t hours = 0;