Introduction

A Digital Clock is an electronic device that displays time in a numerical format (HH:MM:SS) using LEDs, LCDs, or 7-segment displays. It is more precise and easier to read compared to analog clocks.

This project demonstrates how to build a real-time digital clock using Arduino and a Real-Time Clock (RTC) module.

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Objective of the Project

• To display time digitally using Arduino.
• To learn interfacing of RTC modules with microcontrollers.
• To implement a reliable and accurate clock system.
• To display hours, minutes, and seconds on an LCD or 7-segment display.

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Working Principle

The Digital Clock works using a Real-Time Clock (RTC) module.

How It Works

1. RTC module (DS1307 / DS3231) keeps track of the current time.
2. Arduino reads time from the RTC module.
3. Time is displayed on an LCD or 7-segment display.
4. Clock updates every second automatically.

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Components Required

• Arduino Uno
• RTC Module (DS1307 / DS3231)
• 16×2 LCD Display (or 7-segment display)
• Potentiometer (for LCD contrast, if using LCD)
• Jumper Wires
• Breadboard / PCB
• 5V Power Supply

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Circuit Diagram

Connections for RTC and LCD

RTC Module (DS3231 / DS1307):
SCL -> A5 (Arduino)
SDA -> A4 (Arduino)
VCC -> 5V
GND -> GND

16x2 LCD:
RS  -> D7
EN  -> D6
D4  -> D5
D5  -> D4
D6  -> D3
D7  -> D2
VCC -> 5V
GND -> GND
VO  -> Potentiometer middle pin

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Arduino Code for Digital Clock

#include <Wire.h>
#include <RTClib.h>
#include <LiquidCrystal.h>

RTC_DS3231 rtc;
LiquidCrystal lcd(7, 6, 5, 4, 3, 2);

void setup() {
  lcd.begin(16, 2);
  Wire.begin();
  rtc.begin();

  if (!rtc.begin()) {
    lcd.print("RTC Not Found!");
    while (1);
  }
}

void loop() {
  DateTime now = rtc.now();

  lcd.setCursor(0, 0);
  lcd.print("Time: ");
  if (now.hour() < 10) lcd.print("0");
  lcd.print(now.hour());
  lcd.print(":");
  if (now.minute() < 10) lcd.print("0");
  lcd.print(now.minute());
  lcd.print(":");
  if (now.second() < 10) lcd.print("0");
  lcd.print(now.second());

  lcd.setCursor(0, 1);
  lcd.print("Date: ");
  lcd.print(now.day());
  lcd.print("/");
  lcd.print(now.month());
  lcd.print("/");
  lcd.print(now.year());

  delay(1000);
}

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Code Explanation

• RTClib library is used to interface the RTC module.
• Arduino reads hours, minutes, and seconds from the RTC.
• LiquidCrystal library displays time and date on the LCD.
• Time updates every second automatically.

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Advantages

• Accurate timekeeping using RTC module
• Easy to read digital format
• Can display date along with time
• Expandable with alarms or timers

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Applications

• Digital alarm clocks
• Time display in schools/offices
• Embedded systems and microcontroller projects
• IoT-based smart clocks

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Future Enhancements

• Add alarm function
• Bluetooth or Wi-Fi synchronization
• 7-segment display for a compact clock
• Voice-controlled time display

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Conclusion

The Digital Clock using Arduino is a simple yet practical electronics project that demonstrates real-time tracking of hours, minutes, and seconds. It is highly useful for learning RTC interfacing, LCD programming, and embedded system design.