From 18268280dc6c0bd44035b53655ae43e9c88245bd Mon Sep 17 00:00:00 2001
From: Akshay Nair <phenax5@gmail.com>
Date: Sat, 28 Feb 2026 17:37:19 +0530
Subject: Add set time mode + test for button

---
 justfile                 |  8 ++----
 src/button.c             | 53 ++++++++++++++++------------------
 src/button.h             | 17 ++++++-----
 src/display.c            | 34 ++++++++++++++++++----
 src/display.h            | 14 ---------
 src/main.c               |  2 +-
 src/mode.c               | 74 ++++++++++++++++++++++++++++++++++++++++++++++++
 src/mode.h               | 22 ++++++++++++++
 src/rtc.c                | 23 +++++++++------
 src/rtc.h                |  4 +++
 test/button_test.c       | 67 +++++++++++++++++++++++++++++++++++++++++++
 test/justfile            | 13 +++++++++
 test/stubbed/avr/io.h    | 46 +++++++++++++++---------------
 test/stubbed/testindex.c | 26 +++++++++++++++++
 14 files changed, 310 insertions(+), 93 deletions(-)
 create mode 100644 src/mode.c
 create mode 100644 src/mode.h
 create mode 100644 test/button_test.c
 create mode 100644 test/justfile
 create mode 100644 test/stubbed/testindex.c

diff --git a/justfile b/justfile
index e08c5fb..67ac3f0 100644
--- a/justfile
+++ b/justfile
@@ -1,6 +1,8 @@
 set export
 set unstable
 
+mod test
+
 default:
   just --choose || true
 
@@ -8,7 +10,7 @@ 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 src/button.c"
+SRCS := "src/main.c src/display.c src/rtc.c src/button.c src/mode.c"
 OUTDIR := "./out"
 PROGRAMMER := "arduino"
 UPLOAD_SPEED := "19200"
@@ -40,10 +42,6 @@ write-fuses: check-hexfile-exists
 read-fuses:
   {{AVRDUDE}} -U lfuse:r:-:h -U hfuse:r:-:h -U efuse:r:-:h
 
-test:
-  gcc -g -std=gnu99 -DSTUBBED=1 -I./src -I./test/stubbed/ -Wall -Wno-unused-variable {{SRCS}} -o {{OUTDIR}}/test
-  {{OUTDIR}}/test
-
 clean:
   rm -rf {{OUTDIR}}
 
diff --git a/src/button.c b/src/button.c
index dc52265..f7c2a07 100644
--- a/src/button.c
+++ b/src/button.c
@@ -2,42 +2,27 @@
 #include <stdint.h>
 
 #include "button.h"
-#include "rtc.h"
-
-enum ButtonState check_button_state();
-
-void button_tick() {
-  enum ButtonState button_state = check_button_state();
-  switch (button_state) {
-  case BUTTON_PRESSED:
-    if (seconds <= 10)
-      seconds = 0;
-    else
-      seconds -= 10;
-    break;
-  case BUTTON_LONG_PRESSED:
-    seconds += 10;
-    break;
-  default:
-    break;
-  }
-}
+#include "mode.h"
+
+void button_tick() { apply_button_state(check_button_state()); }
 
 bool is_button_active = false;
 uint16_t button_tick_count = 0;
+uint16_t button_inactive_for_ticks = 0;
 
 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;
+  // Disable button for some time
+  if (button_inactive_for_ticks > 0) {
+    button_inactive_for_ticks--;
+    return ButtonIdle;
   }
 
-  bool in_debounce_period = is_button_active && button_tick_count > 0 &&
-                            button_tick_count < DEBOUNCE_TICK_COUNT;
+  bool was_active = is_button_active;
+  bool in_debounce_period =
+      button_tick_count > 0 && button_tick_count < DEBOUNCE_TICK_COUNT;
 
   // Ignore readings from debounce period
-  if (!in_debounce_period) {
+  if (!is_button_active || !in_debounce_period) {
     DDRA &= ~(1 << PA0);
     PORTA &= ~(1 << PA0);
     is_button_active = (PINA & (1 << PA0)) == 0;
@@ -45,12 +30,22 @@ enum ButtonState check_button_state() {
 
   if (is_button_active) {
     button_tick_count++;
+    if (button_tick_count >= LONG_PRESS_TICK_COUNT) {
+      button_tick_count = 0;
+      is_button_active = false;
+      button_inactive_for_ticks = BUTTON_INACTIVE_TICK_COUNT;
+      return ButtonLongPressed;
+    }
+    return ButtonActive;
   } else {
     if (button_tick_count >= DEBOUNCE_TICK_COUNT) {
       button_tick_count = 0;
-      return BUTTON_PRESSED;
+      button_inactive_for_ticks = BUTTON_INACTIVE_TICK_COUNT;
+      return ButtonPressed;
     }
+    if (!was_active)
+      button_tick_count = 0;
   }
 
-  return BUTTON_IDLE;
+  return ButtonIdle;
 }
diff --git a/src/button.h b/src/button.h
index 8aa7442..5152336 100644
--- a/src/button.h
+++ b/src/button.h
@@ -1,19 +1,22 @@
 #ifndef _LOADED_BUTTON
 #define _LOADED_BUTTON
 #include <stdbool.h>
-#include <stdint.h>
+
+#include "mode.h"
 
 #define DEBOUNCE_TICK_COUNT 10
 #define LONG_PRESS_TICK_COUNT 60
 #define MAX_TICK_COUNT 80
+#define BUTTON_INACTIVE_TICK_COUNT 10
+
+bool extern is_button_active;
 
-enum ButtonState {
-  BUTTON_IDLE = 0,
-  BUTTON_PRESSED = 1,
-  BUTTON_LONG_PRESSED = 2,
-};
+void button_tick();
 
+enum ButtonState check_button_state();
+
+// Exposed for test
 uint16_t extern button_tick_count;
+uint16_t extern button_inactive_for_ticks;
 
-void button_tick();
 #endif
diff --git a/src/display.c b/src/display.c
index 8380b81..3d83337 100644
--- a/src/display.c
+++ b/src/display.c
@@ -4,8 +4,17 @@
 #include <util/delay.h>
 
 #include "display.h"
+#include "mode.h"
 #include "rtc.h"
 
+// "_gfedcba"
+// Reversed because a-g is mapped to pa0-6. (pa7 is decimal)
+// Complemented because display is common anode
+static const uint32_t digit_masks[] = {
+    0b1000000, 0b1111001, 0b0100100, 0b0110000, 0b0011001,
+    0b0010010, 0b0000010, 0b1111000, 0b0000000, 0b0010000,
+};
+
 void display_setup() {
   // Set prescaler CS01 + CS00 (F_CPU / 64) + CTC
   // For 32768Hz -> 32768/64 = 512Hz
@@ -26,11 +35,27 @@ void display_setup() {
   PORTB = (1 << PB2);
 }
 
+void write_time(uint8_t digit_index, const uint8_t digits[4]);
+
+// Current digit position
 volatile uint8_t current_digit = 0;
 
 // Render current digit
 void display_render(void) {
-  write_time(current_digit);
+  switch (current_mode) {
+  case ModeDisplayTime: {
+    uint8_t digits[] = {minutes_digit1, minutes_digit2, seconds_digit1,
+                        seconds_digit2};
+    write_time(current_digit, digits);
+    break;
+  }
+  case ModeSetTime: {
+    uint8_t digits[] = {new_hours / 10, new_hours % 10, new_minutes / 10,
+                        new_minutes % 10};
+    write_time(current_digit, digits);
+    break;
+  }
+  }
 
   // Cycle through the 4 digits
   current_digit = (current_digit + 1) % 4;
@@ -53,14 +78,11 @@ static uint8_t special_segment_pins[] = {5, 10, 6, 7};
 // Digit position -> special segment anti-pin (pair of pin)
 static uint8_t special_segment_antipins[] = {10, 5, 7, 6};
 
-void write_time(uint8_t digit_index) {
+void write_time(uint8_t digit_index, const uint8_t digits[4]) {
   // reset pins
   uint16_t ddr = ~SPECIAL_SEGMENT_PINS;
   uint16_t port = 0;
 
-  uint8_t digits[] = {seconds_digit1, seconds_digit2, minutes_digit1,
-                      minutes_digit2};
-
   uint8_t digit = digits[digit_index];
   uint16_t segments = digit_masks[digit];
   uint8_t pin = special_segment_pins[digit_index];
@@ -92,7 +114,7 @@ void write_time(uint8_t digit_index) {
   }
 
   DDRA = ddr;
-  DDRB = ddr >> 8;
   PORTA = port;
+  DDRB = ddr >> 8;
   PORTB = port >> 8;
 }
diff --git a/src/display.h b/src/display.h
index 44c0c0e..0353705 100644
--- a/src/display.h
+++ b/src/display.h
@@ -1,22 +1,8 @@
 #ifndef _LOADED_DISPLAY
 #define _LOADED_DISPLAY
-#include <stdint.h>
-
-// "_gfedcba"
-// Reversed because a-g is mapped to pa0-6. (pa7 is decimal)
-// Complemented because display is common anode
-static const uint32_t digit_masks[] = {
-    0b1000000, 0b1111001, 0b0100100, 0b0110000, 0b0011001,
-    0b0010010, 0b0000010, 0b1111000, 0b0000000, 0b0010000,
-};
-
-// Current digit position
-volatile extern uint8_t current_digit;
 
 void display_setup(void);
 
-void write_time(uint8_t digit_index);
-
 void display_render(void);
 
 #endif
diff --git a/src/main.c b/src/main.c
index 98b63a2..2e20b7b 100644
--- a/src/main.c
+++ b/src/main.c
@@ -28,7 +28,7 @@ ISR(TIM0_COMPA_vect, ISR_FLATTEN) {
 ISR(TIM1_COMPA_vect, ISR_FLATTEN) { rtc_increment(); }
 
 // Button interrupt
-ISR(PCINT0_vect, ISR_FLATTEN) { button_tick(); }
+// ISR(PCINT0_vect, ISR_FLATTEN) { button_tick(); }
 
 int main(void) {
   PRR = 0b0011; // Power reduction register. Shut down USI and ADC
diff --git a/src/mode.c b/src/mode.c
new file mode 100644
index 0000000..b6fad97
--- /dev/null
+++ b/src/mode.c
@@ -0,0 +1,74 @@
+#include <stdint.h>
+
+#include "mode.h"
+#include "rtc.h"
+
+enum Mode current_mode = ModeDisplayTime;
+volatile uint8_t new_minutes = 0;
+volatile uint8_t new_hours = 0;
+volatile uint8_t current_digit_index = 0;
+volatile uint16_t time_set_timeout_ticks = 0;
+
+void increment_digit() {
+  switch (current_digit_index) {
+  case 0:
+    new_hours = (new_hours + 10) % 24;
+    break;
+  case 1:
+    new_hours = (new_hours + 1) % 24;
+    break;
+  case 2:
+    new_minutes = (new_minutes + 10) % 60;
+    break;
+  case 3:
+    new_minutes = (new_minutes + 1) % 60;
+    break;
+  }
+}
+
+void apply_button_state(enum ButtonState button_state) {
+  switch (current_mode) {
+  case ModeDisplayTime:
+    switch (button_state) {
+    case ButtonLongPressed:
+      new_minutes = minutes;
+      new_hours = hours;
+      current_digit_index = 0;
+      current_mode = ModeSetTime;
+      break;
+    default:
+      break;
+    }
+    break;
+  case ModeSetTime:
+    if (button_state == ButtonIdle) {
+      time_set_timeout_ticks =
+          time_set_timeout_ticks == 0 ? 0 : time_set_timeout_ticks - 1;
+      if (time_set_timeout_ticks == 0) {
+        current_mode = ModeDisplayTime;
+        return;
+      }
+    } else {
+      time_set_timeout_ticks = 10 * 1024;
+    }
+
+    switch (button_state) {
+    case ButtonPressed:
+      increment_digit();
+      break;
+    case ButtonLongPressed:
+      if (current_digit_index == 3) {
+        rtc_set_minutes(new_minutes);
+        rtc_set_hours(new_hours);
+        current_mode = ModeDisplayTime;
+        current_digit_index = 0;
+      } else {
+        current_digit_index++;
+      }
+      break;
+    default:
+      break;
+    }
+    break;
+  }
+}
diff --git a/src/mode.h b/src/mode.h
new file mode 100644
index 0000000..db65fc8
--- /dev/null
+++ b/src/mode.h
@@ -0,0 +1,22 @@
+#ifndef _LOADED_MODE
+#define _LOADED_MODE
+#include <stdint.h>
+enum Mode {
+  ModeDisplayTime,
+  ModeSetTime,
+};
+
+enum ButtonState {
+  ButtonIdle = 0,
+  ButtonActive = 1,
+  ButtonPressed = 2,
+  ButtonLongPressed = 3,
+};
+
+extern enum Mode current_mode;
+extern volatile uint8_t new_minutes;
+extern volatile uint8_t new_hours;
+
+void apply_button_state(enum ButtonState button_state);
+
+#endif
diff --git a/src/rtc.c b/src/rtc.c
index 53a5983..bbf79e1 100644
--- a/src/rtc.c
+++ b/src/rtc.c
@@ -38,13 +38,20 @@ void rtc_increment(void) {
   seconds_digit2 = (seconds / 10) % 10;
   if (s >= 60) {
     uint8_t m = minutes + 1;
-    minutes = m % 60;
-    minutes_digit1 = minutes % 10;
-    minutes_digit2 = (minutes / 10) % 10;
-    if (m >= 60) {
-      hours = (hours + 1) % 24;
-      hours_digit1 = hours % 10;
-      hours_digit2 = (hours / 10) % 10;
-    }
+    rtc_set_minutes(m);
+    if (m >= 60)
+      rtc_set_hours(hours + 1);
   }
 }
+
+void rtc_set_minutes(uint8_t m) {
+  minutes = m % 60;
+  minutes_digit1 = minutes % 10;
+  minutes_digit2 = (minutes / 10) % 10;
+}
+
+void rtc_set_hours(uint8_t h) {
+  hours = h % 24;
+  hours_digit1 = hours % 10;
+  hours_digit2 = (hours / 10) % 10;
+}
diff --git a/src/rtc.h b/src/rtc.h
index c1c1730..991c188 100644
--- a/src/rtc.h
+++ b/src/rtc.h
@@ -17,4 +17,8 @@ void rtc_setup(void);
 
 void rtc_increment(void);
 
+void rtc_set_minutes(uint8_t m);
+
+void rtc_set_hours(uint8_t h);
+
 #endif
diff --git a/test/button_test.c b/test/button_test.c
new file mode 100644
index 0000000..3c48e43
--- /dev/null
+++ b/test/button_test.c
@@ -0,0 +1,67 @@
+#include "button.h"
+#include "mode.h"
+#include <assert.h>
+#include <avr/io.h>
+
+void test_button_press() {
+  assert(check_button_state() == ButtonIdle);
+
+  PINA &= ~(1 << PA0); // Button is pressed
+  assert(check_button_state() == ButtonActive);
+  for (int i = 0; i < DEBOUNCE_TICK_COUNT; i++)
+    assert(check_button_state() == ButtonActive);
+
+  PINA |= (1 << PA0); // Button is released
+
+  assert(check_button_state() == ButtonPressed); // Detects button press
+  assert(check_button_state() == ButtonIdle);    // Resets to idle
+}
+
+void test_button_long_press() {
+  assert(check_button_state() == ButtonIdle);
+
+  // Button is pressed for a while
+  PINA &= ~(1 << PA0);
+  for (int i = 0; i < LONG_PRESS_TICK_COUNT - 1; i++)
+    assert(check_button_state() == ButtonActive);
+
+  assert(check_button_state() == ButtonLongPressed); // Detects button press
+
+  assert(check_button_state() == ButtonIdle); // Resets to idle
+}
+
+void test_button_inactive_after_press() {
+  assert(check_button_state() == ButtonIdle);
+
+  // Button is pressed
+  PINA &= ~(1 << PA0);
+  for (int i = 0; i < DEBOUNCE_TICK_COUNT; i++)
+    assert(check_button_state() == ButtonActive);
+  PINA |= (1 << PA0); // Button is released
+  assert(check_button_state() == ButtonPressed);
+  assert(check_button_state() == ButtonIdle); // Resets to idle
+
+  // Button is pressed again
+  PINA &= ~(1 << PA0);
+
+  // Button stays inactive for some time
+  for (int i = 0; i < BUTTON_INACTIVE_TICK_COUNT - 1; i++)
+    assert(check_button_state() == ButtonIdle);
+  // Button becomes active again after delay
+  assert(check_button_state() == ButtonActive);
+}
+
+void before_each() {
+  PINA = (1 << PA0); // Active on low
+  button_tick_count = 0;
+  button_inactive_for_ticks = 0;
+}
+#define TEST before_each();
+
+int main() {
+  TEST test_button_press();
+  TEST test_button_long_press();
+  TEST test_button_inactive_after_press();
+  return 0;
+}
+
diff --git a/test/justfile b/test/justfile
new file mode 100644
index 0000000..626e094
--- /dev/null
+++ b/test/justfile
@@ -0,0 +1,13 @@
+OUTDIR := "../out"
+TSRCS := "../src/display.c ../src/rtc.c ../src/button.c ../src/mode.c ./stubbed/testindex.c"
+
+TCFLAGS := f"-g -std=gnu99 -DSTUBBED=1 -I../src -I./stubbed/ -Wall -Wno-unused-variable {{TSRCS}}"
+
+main:
+  gcc {{TCFLAGS}} ../src/main.c -o {{OUTDIR}}/test_main
+  {{OUTDIR}}/test_main
+
+button:
+  gcc {{TCFLAGS}} ./button_test.c -o {{OUTDIR}}/test_button
+  {{OUTDIR}}/test_button
+
diff --git a/test/stubbed/avr/io.h b/test/stubbed/avr/io.h
index 40cc460..c056ef1 100644
--- a/test/stubbed/avr/io.h
+++ b/test/stubbed/avr/io.h
@@ -2,13 +2,13 @@
 #define STUB_AVR_IO
 #include <stdio.h>
 
-static int DDRA = 0;
-static int DDRB = 0;
+extern int DDRA;
+extern int DDRB;
 
-static int PORTA = 0;
-static int PORTB = 0;
-static int PINA = 0;
-static int PINB = 0;
+extern int PORTA;
+extern int PORTB;
+extern int PINA;
+extern int PINB;
 
 #define PA0 0
 #define PA1 1
@@ -24,23 +24,23 @@ static int PINB = 0;
 #define PB3 3
 #define PB4 4
 
-static int PRR = 0;
-static int TCCR0B = 0;
-static int TCCR0A = 0;
-static int TIMSK0 = 0;
-static int TIFR0 = 0;
-static int OCR0A = 0;
-static int OCR0B = 0;
-static int TCNT0 = 0;
-static int TCCR1B = 0;
-static int TCCR1A = 0;
-static int TIMSK1 = 0;
-static int TIFR1 = 0;
-static int OCR1A = 0;
-static int OCR1B = 0;
-static int TCNT1 = 0;
-static int TCNT1H = 0;
-static int TCNT1L = 0;
+extern int PRR;
+extern int TCCR0B;
+extern int TCCR0A;
+extern int TIMSK0;
+extern int TIFR0;
+extern int OCR0A;
+extern int OCR0B;
+extern int TCNT0;
+extern int TCCR1B;
+extern int TCCR1A;
+extern int TIMSK1;
+extern int TIFR1;
+extern int OCR1A;
+extern int OCR1B;
+extern int TCNT1;
+extern int TCNT1H;
+extern int TCNT1L;
 
 #define CS00 1
 #define CS01 1
diff --git a/test/stubbed/testindex.c b/test/stubbed/testindex.c
new file mode 100644
index 0000000..e3c8866
--- /dev/null
+++ b/test/stubbed/testindex.c
@@ -0,0 +1,26 @@
+
+int DDRA = 0;
+int DDRB = 0;
+
+int PORTA = 0;
+int PORTB = 0;
+int PINA = 0;
+int PINB = 0;
+
+int PRR = 0;
+int TCCR0B = 0;
+int TCCR0A = 0;
+int TIMSK0 = 0;
+int TIFR0 = 0;
+int OCR0A = 0;
+int OCR0B = 0;
+int TCNT0 = 0;
+int TCCR1B = 0;
+int TCCR1A = 0;
+int TIMSK1 = 0;
+int TIFR1 = 0;
+int OCR1A = 0;
+int OCR1B = 0;
+int TCNT1 = 0;
+int TCNT1H = 0;
+int TCNT1L = 0;
-- 
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