Project Documentation

Arduino UNO RFID Attendance System with Real-Time Clock and LCD Display

Circuit Documentation

Summary

This document provides a detailed overview of a circuit designed to interface an Arduino UNO with an RFID reader, an LCD display, an RTC module, and a piezo buzzer. The circuit is intended to log and display login and logout times, and it includes a button to trigger the logout process. The Arduino UNO serves as the central microcontroller, coordinating the operations of the connected components.

Component List

Arduino UNO
- Description: A microcontroller board based on the ATmega328P.
- Pins: UNUSED, IOREF, Reset, 3.3V, 5V, GND, Vin, A0, A1, A2, A3, A4, A5, SCL, SDA, AREF, D13, D12, D11, D10, D9, D8, D7, D6, D5, D4, D3, D2, D1, D0
RFID-RC522
- Description: An RFID reader module.
- Pins: VCC (3.3V), RST, GND, IRQ, MISO, MOSI, SCK, SDA
LCD Display 16x4 I2C
- Description: A 16x4 character LCD display with I2C interface.
- Pins: SCL, SDA, VCC, GND
rtc MODULE
- Description: A Real-Time Clock (RTC) module.
- Pins: 32k, SQW, SCL, SDA, VCC, GND
Piezo Buzzer
- Description: A simple piezoelectric buzzer.
- Pins: pin 1, pin 2

Wiring Details

Arduino UNO

3.3V connected to RFID-RC522 VCC (3.3V)
D9 connected to RFID-RC522 RST
GND connected to RFID-RC522 GND
D12 connected to RFID-RC522 MISO
D11 connected to RFID-RC522 MOSI
D13 connected to RFID-RC522 SCK
D10 connected to RFID-RC522 SDA
SCL connected to LCD Display 16x4 I2C SCL and rtc MODULE SCL
SDA connected to LCD Display 16x4 I2C SDA and rtc MODULE SDA
5V connected to LCD Display 16x4 I2C VCC and rtc MODULE VCC
GND connected to LCD Display 16x4 I2C GND and rtc MODULE GND
D5 connected to Piezo Buzzer pin 1
GND connected to Piezo Buzzer pin 2

RFID-RC522

VCC (3.3V) connected to Arduino UNO 3.3V
RST connected to Arduino UNO D9
GND connected to Arduino UNO GND
MISO connected to Arduino UNO D12
MOSI connected to Arduino UNO D11
SCK connected to Arduino UNO D13
SDA connected to Arduino UNO D10

LCD Display 16x4 I2C

SCL connected to Arduino UNO SCL and rtc MODULE SCL
SDA connected to Arduino UNO SDA and rtc MODULE SDA
VCC connected to Arduino UNO 5V and rtc MODULE VCC
GND connected to Arduino UNO GND and rtc MODULE GND

rtc MODULE

SCL connected to Arduino UNO SCL and LCD Display 16x4 I2C SCL
SDA connected to Arduino UNO SDA and LCD Display 16x4 I2C SDA
VCC connected to Arduino UNO 5V and LCD Display 16x4 I2C VCC
GND connected to Arduino UNO GND and LCD Display 16x4 I2C GND

Piezo Buzzer

pin 1 connected to Arduino UNO D5
pin 2 connected to Arduino UNO GND

Code Documentation

Main Code

#include <Wire.h>
#include <RTClib.h>
#include <LiquidCrystal_I2C.h>

// Initialize the LCD display with I2C address 0x27 and size 16x2
LiquidCrystal_I2C lcd(0x27, 16, 2);

// Initialize the RTC module
RTC_DS3231 rtc;

// Variables to store login and logout times
DateTime loggedIn;
DateTime loggedOut;

// Variable to store the period (AM/PM)
String period = "AM";

// Pin definitions
const byte BUZZER_PIN = 5;  // You can use any available digital pin
const byte BUTTON_PIN = 3;   // Ensure this pin is available on the Uno

// Variables to track button state
byte lastState = LOW;  // Previous state of the button
int currentState;      // Current state of the button

void setup() {
  // Start the I2C communication
  Wire.begin();
  
  // Set pin modes
  pinMode(BUZZER_PIN, OUTPUT);
  pinMode(BUTTON_PIN, INPUT_PULLUP);
  
  // Initialize serial communication at 9600 bits per second
  Serial.begin(9600);
  
  // Initialize the LCD display
  lcd.init();
  lcd.backlight();
  
  // Initialize the RTC module
  if (!rtc.begin()) {
    Serial.print("Couldn't find RTC");
    Serial.flush();
    while (1);
  }
  
  // Check if the RTC lost power and set the time if necessary
  if (rtc.lostPower()) {
    Serial.println("RTC lost power, let's set the time!");
    rtc.adjust(DateTime(F(__DATE__), F(__TIME__)));
  }
  
  // Display the login time on the LCD
  lcd.clear();
  lcd.print("Logged In:");
  loggedIn = rtc.now();
  displayTime(loggedIn);
}

void loop() {
  // Read the state of the button
  currentState = digitalRead(BUTTON_PIN);
  
  // Check for button press (transition from HIGH to LOW)
  if (lastState == HIGH && currentState == LOW) {
    // Sound the buzzer
    tone(BUZZER_PIN, 2000); // Send a 2kHz sound signal
    delay(500);             // for 0.5 seconds
    noTone(BUZZER_PIN);     // Stop the tone
    
    // Display the logout time on the LCD
    lcd.clear();
    lcd.print("Logged Out:");
    loggedOut = rtc.now();
    displayTime(loggedOut);
    
    delay(3000);
    lcd.clear();
    
    // Calculate and display the elapsed time
    long elapsedSeconds = loggedOut.unixtime() - loggedIn.unixtime();
    int elapsedHours = elapsedSeconds / 3600;
    int elapsedMinutes = (elapsedSeconds % 3600) / 60;
    int elapsedSecondsRemaining = elapsedSeconds % 60;
    
    lcd.print("Elapsed time:");
    lcd.setCursor(0, 1);
    lcd.print(elapsedHours);
    lcd.print("h ");
    lcd.print(elapsedMinutes);
    lcd.print("m ");
    lcd.print(elapsedSecondsRemaining);
    lcd.print("s");
    
    delay(5000);
    lcd.clear();
  }
  
  // Update the last state of the button
  lastState = currentState;
}

// Function to display time on the LCD
void displayTime(DateTime time) {
  lcd.setCursor(0, 1);
  int hour = time.hour();
  if (hour >= 12) {
    period = "PM";
    if (hour > 12) {
      hour -= 12;
    }
  } else if (hour == 0) {
    hour = 12;
  }
  lcd.print(hour);
  lcd.print(':');
  if (time.minute() < 10) lcd.print('0'); // Leading zero for minutes
  lcd.print(time.minute());
  lcd.print(':');
  if (time.second() < 10) lcd.print('0'); // Leading zero for seconds
  lcd.print(time.second());
  lcd.print(' ');
  lcd.print(period);
}

Additional Code

#include <Wire.h>
#include <RTClib.h>
#include <LiquidCrystal_I2C.h>

// Initialize the LCD display with I2C address 0x27 and size 16x2
LiquidCrystal_I2C lcd(0x27, 16, 2);

// Initialize the RTC module
RTC_DS3231 rtc;

// Variables to store login and logout times
DateTime loggedIn;
DateTime loggedOut;

// Variable to store the period (AM/PM)
String period = "AM";

// Pin definitions
const byte BUZZER_PIN = 5;  // You can use any available digital pin
const byte BUTTON_PIN = 3;   // Ensure this pin