Arduino Project

Arduino Birthday Countdown Timer with LCD Display

Course Introduction

In this lesson, you will learn how to use Arduino along with I2C LCD, Active Buzzer, LEDs, and resistors to create a birthday show.

Note

If this is your first time working with an Arduino project, we recommend downloading and reviewing the basic materials first.

1.1 Install Arduino IDE(Important)
1.2 Introduction of Arduino IDE

Required Components

In this project, we need the following components:

SN

COMPONENT INTRODUCTION

QUANTITY

PURCHASE LINK

1

Arduino UNO R4 Minima/Arduino UNO R4 WIFI

1

BUY

2

USB Type-C cable

1

×

3

Breadboard

1

BUY

4

Wires

Several

BUY

5

220Ω resistor

Several

BUY

6

LED

Several

BUY

7

I2C LCD 1602

1

BUY

8

Active Buzzer

1

×

Wiring

1.webp__PID:7e4ec6e1-c57c-4351-ada3-5d87f76e3ea9

Common Connections:

Active Buzzer
＋: Connect to 8 on the Arduino.
－: Connect to breadboard’s negative power bus.

LED
Connect the LEDs cathode to the negative power bus on the breadboard, and the LEDs anode to a 22Ω resistor then to 3 to 7 on the Arduino.

I2C LCD 1602
SDA: Connect to SDA on the Arduino.
SCL: Connect to SCL on the Arduino.
GND: Connect to breadboard’s negative power bus.
VCC: Connect to breadboard’s red power bus

Writing the Code

Note
You can copy this code into Arduino IDE.
To install the library, use the Arduino Library Manager and search for LiquidCrystal I2C and install it. Don’t forget to select the board(Ar
Don’t forget to select the board(Arduino UNO R4 Minima) and the correct port before clicking the Upload button.


#include 
#include 

// LCD
LiquidCrystal_I2C lcd(0x27, 16, 2);

// LED pins
const int ledPins[] = {3, 4, 5, 6, 7};
const int ledCount = 5;

// Passive buzzer pin
const int BUZZER_PIN = 8;

// Start time
int year = 2026;
int month = 5;
int day = 31;
int hour = 23;
int minute = 59;
int second = 50;

unsigned long lastSecondUpdate = 0;
unsigned long lastLedUpdate = 0;

bool birthdayStarted = false;

int ledIndex = 0;

// Notes
#define NOTE_C4  262
#define NOTE_D4  294
#define NOTE_E4  330
#define NOTE_F4  349
#define NOTE_G4  392
#define NOTE_A4  440
#define NOTE_AS4 466
#define NOTE_B4  494
#define NOTE_C5  523

// Happy Birthday melody
int melody[] = {
  NOTE_C4, NOTE_C4, NOTE_D4, NOTE_C4, NOTE_F4, NOTE_E4,
  NOTE_C4, NOTE_C4, NOTE_D4, NOTE_C4, NOTE_G4, NOTE_F4,
  NOTE_C4, NOTE_C4, NOTE_C5, NOTE_A4, NOTE_F4, NOTE_E4, NOTE_D4,
  NOTE_AS4, NOTE_AS4, NOTE_A4, NOTE_F4, NOTE_G4, NOTE_F4
};

int noteDurations[] = {
  4, 4, 2, 2, 2, 1,
  4, 4, 2, 2, 2, 1,
  4, 4, 2, 2, 2, 2, 1,
  4, 4, 2, 2, 2, 1
};

const int melodyLength = sizeof(melody) / sizeof(melody[0]);

int currentNote = 0;
unsigned long noteStartTime = 0;
bool notePlaying = false;

void setup() {
  lcd.init();
  lcd.backlight();

  for (int i = 0; i < ledCount; i++) {
    pinMode(ledPins[i], OUTPUT);
    digitalWrite(ledPins[i], LOW);
  }

  pinMode(BUZZER_PIN, OUTPUT);

  updateLCD();
}

void loop() {
  updateClock();

  if (year == 2026 && month == 6 && day == 1 && hour == 0 && minute == 0) {
    birthdayStarted = true;
  }

  if (birthdayStarted) {
    lcd.setCursor(0, 1);
    lcd.print("Happy Birthday ");

    runLedEffect();
    playBirthdaySong();
  }
}

void updateClock() {
  if (millis() - lastSecondUpdate >= 1000) {
    lastSecondUpdate = millis();

    second++;

    if (second >= 60) {
      second = 0;
      minute++;
    }

    if (minute >= 60) {
      minute = 0;
      hour++;
    }

    if (hour >= 24) {
      hour = 0;
      day++;
    }

    if (month == 5 && day > 31) {
      month = 6;
      day = 1;
    }

    updateLCD();
  }
}

void updateLCD() {
  lcd.setCursor(0, 0);

  lcd.print(year);
  lcd.print("-");

  printTwoDigits(month);
  lcd.print("-");

  printTwoDigits(day);
  lcd.print(" ");

  printTwoDigits(hour);
  lcd.print(":");

  printTwoDigits(minute);
  lcd.print(" ");

  lcd.setCursor(0, 1);

  if (birthdayStarted) {
    lcd.print("Happy Birthday ");
  } else {
    lcd.print("Time ");

    printTwoDigits(hour);
    lcd.print(":");

    printTwoDigits(minute);
    lcd.print(":");

    printTwoDigits(second);
    lcd.print(" ");
  }
}

void printTwoDigits(int value) {
  if (value < 10) {
    lcd.print("0");
  }
  lcd.print(value);
}

void runLedEffect() {
  if (millis() - lastLedUpdate >= 120) {
    lastLedUpdate = millis();

    for (int i = 0; i < ledCount; i++) {
      digitalWrite(ledPins[i], LOW);
    }

    digitalWrite(ledPins[ledIndex], HIGH);

    ledIndex++;

    if (ledIndex >= ledCount) {
      ledIndex = 0;
    }
  }
}

void playBirthdaySong() {
  if (!notePlaying) {
    int noteDuration = 1000 / noteDurations[currentNote];

    tone(BUZZER_PIN, melody[currentNote], noteDuration);

    noteStartTime = millis();
    notePlaying = true;
  } else {
    int noteDuration = 1000 / noteDurations[currentNote];

    if (millis() - noteStartTime >= noteDuration * 1.3) {
      noTone(BUZZER_PIN);

      currentNote++;

      if (currentNote >= melodyLength) {
        currentNote = 0;
      }

      notePlaying = false;
    }
  }
}