Materials Used

Wiring Instructions

RFID (RC522): SS = 53, RST = 31 (SPI interface)
LCD (16x2): RS,E,D4–D7 = pins 2–7 (Parallel wiring, no I2C)
Servo Motor: Pin 9
Green LED: Pin 41
Red LED: Pin 40
Keypad Rows: 24,26,28,30 | Cols: 32,34,36,38

Project Photos & Demo

Arduino Code

// RFID Lock System
#include <SPI.h>
#include <MFRC522.h>
#include <Servo.h>

#define RST_PIN 9
#define SS_PIN 10
#define SERVO_PIN 3
#define GREEN_LED 4
#define RED_LED 5
#define BUZZER 6

MFRC522 rfid(SS_PIN, RST_PIN);
Servo doorServo;

// Authorized card UID
byte authorizedUID[] = {0xDE, 0xAD, 0xBE, 0xEF};

void setup() {
  Serial.begin(9600);
  SPI.begin();
  rfid.PCD_Init();

  doorServo.attach(SERVO_PIN);
  doorServo.write(0); // Locked position

  pinMode(GREEN_LED, OUTPUT);
  pinMode(RED_LED, OUTPUT);
  pinMode(BUZZER, OUTPUT);

  digitalWrite(RED_LED, HIGH); // Initially locked
  Serial.println("RFID Lock System Ready");
}

void loop() {
  if (!rfid.PICC_IsNewCardPresent() || !rfid.PICC_ReadCardSerial()) {
    return;
  }

  if (checkAccess(rfid.uid.uidByte, rfid.uid.size)) {
    grantAccess();
  } else {
    denyAccess();
  }

  rfid.PICC_HaltA();
}

bool checkAccess(byte *uid, byte uidSize) {
  if (uidSize != sizeof(authorizedUID)) return false;

  for (byte i = 0; i < uidSize; i++) {
    if (uid[i] != authorizedUID[i]) return false;
  }
  return true;
}

void grantAccess() {
  Serial.println("Access Granted!");
  digitalWrite(RED_LED, LOW);
  digitalWrite(GREEN_LED, HIGH);
  tone(BUZZER, 1000, 200);

  doorServo.write(90); // Unlock
  delay(3000);
  doorServo.write(0);  // Lock

  digitalWrite(GREEN_LED, LOW);
  digitalWrite(RED_LED, HIGH);
}

void denyAccess() {
  Serial.println("Access Denied!");
  tone(BUZZER, 300, 500);
  for (int i = 0; i < 3; i++) {
    digitalWrite(RED_LED, LOW);
    delay(200);
    digitalWrite(RED_LED, HIGH);
    delay(200);
  }
}

🔧 Troubleshooting

RFID not reading cards? Check these common solutions:

What You Learned