Arduino RFID Attendance System

📖 1. Introduction

RFID attendance systems are widely used in schools, colleges, and offices. However, most basic systems require reprogramming the Arduino every time a new card is added.

In this project, we design a smart RFID attendance system with an Admin Card, which allows:

Adding new RFID cards without editing code
Switching between normal mode and registration mode
Displaying status on LCD
Providing buzzer confirmation

This makes the system professional, flexible, and user-friendly.

🔧 2. Components

Arduino UNO
RC522 RFID Module
RFID Cards / Tags
16x2 LCD Display with I2C Module
Buzzer
Connecting wires
Breadboard

🔌 3. Circuit and Connections

PINOUT RFID

PINOUT LCD WITH I2C

📍 RFID RC522:

SDA → Pin 10
SCK → Pin 13
MOSI → Pin 11
MISO → Pin 12
RST → Pin 9
GND → GND
3.3V → 3.3V ⚠️

📍 LCD (I2C):

VCC → 5V
GND → GND
SDA → A4
SCL → A5

📍 Buzzer:

Positive → Pin 8
Negative → GND

⚙️ 4. Step by Step Circuit Working

System starts in Normal Mode
RFID card is scanned
Arduino reads unique UID

🔐 If Admin Card scanned:

System enters Add Mode
LCD shows “Scan New Card”

➕ In Add Mode:

Next scanned card is stored
LCD shows “Card Added”
System returns to normal mode

✅ In Normal Mode:

If card is stored → Access Granted
If not → Unknown Card

💻 5. Code


#include <SPI.h>
#include <MFRC522.h>
#include <Wire.h>
#include <LiquidCrystal_I2C.h>

#define SS_PIN 10
#define RST_PIN 9
#define buzzer 8

MFRC522 mfrc522(SS_PIN, RST_PIN);
LiquidCrystal_I2C lcd(0x27, 16, 2);

// 🔴 Replace with your Admin Card UID
String adminUID = "a1b2c3d4";

// Store users
String users[10];
int userCount = 0;

bool addMode = false;

void setup() {
  SPI.begin();
  mfrc522.PCD_Init();

  pinMode(buzzer, OUTPUT);

  lcd.init();
  lcd.backlight();

  Serial.begin(9600);
  lcd.print("Scan Card...");
}

void loop() {

  if (!mfrc522.PICC_IsNewCardPresent()) return;
  if (!mfrc522.PICC_ReadCardSerial()) return;

  String uid = "";

  for (byte i = 0; i < mfrc522.uid.size; i++) {
    uid += String(mfrc522.uid.uidByte[i], HEX);
  }

  lcd.clear();

  // 🔐 ADMIN MODE
  if (uid == adminUID) {
    addMode = true;
    lcd.print("Admin Mode");
    lcd.setCursor(0,1);
    lcd.print("Scan New Card");
    delay(2000);
    return;
  }

  // ➕ ADD NEW CARD
  if (addMode) {
    users[userCount] = uid;
    userCount++;

    lcd.print("Card Added");
    digitalWrite(buzzer, HIGH);
    delay(1000);
    digitalWrite(buzzer, LOW);

    addMode = false;
    lcd.clear();
    lcd.print("Scan Card...");
    delay(1500);
    return;
  }

  // ✅ NORMAL MODE
  bool found = false;

  for (int i = 0; i < userCount; i++) {
    if (uid == users[i]) {
      found = true;
      break;
    }
  }

  if (found) {
    lcd.print("Access Granted");
    digitalWrite(buzzer, HIGH);
  } else {
    lcd.print("Unknown Card");
  }

  delay(2000);
  digitalWrite(buzzer, LOW);
}

🔍 6. Step by Step Code Working

RFID module reads UID using SPI
UID stored as string
If UID = Admin UID → enters Add Mode
In Add Mode:
- Next card is saved in array
- Confirmation displayed
In Normal Mode:
- UID compared with stored users
- Access granted or denied

💡 7. Tips

✔ Always use 3.3V for RC522 ⚠️
✔ First find Admin UID using Serial Monitor
✔ Increase array size for more users
✔ Keep RFID card close to reader
✔ Use good power supply

🚀 8. Uses

Student attendance system
Office entry system
Door access control
Smart ID systems

⚠️ 9. Common Issues and Solutions

❌ RFID not working

✔ Check 3.3V supply

❌ Card not detected

✔ Bring card closer

❌ LCD not working

✔ Check I2C address

❌ Users lost after restart

✔ Use EEPROM (upgrade)

🧠 10. Conclusion

This project provides a smart and flexible RFID system with admin control. It eliminates the need for reprogramming and makes the system highly practical for real-world use.

With this only a limited number of RFID can be stored say 20 numbers, we can use other storage methods to improve this

Basic Electronics for Beginners

Translate