/* RFID Door Lock System Uses MFRC522 & Servo Motor Author: Study For Next */ #include <SPI.h> #include <MFRC522.h> #include <Servo.h> #define SS_PIN 10 #define RST_PIN 9 MFRC522 mfrc522(SS_PIN, RST_PIN); Servo myServo; String validTag = "A1 B2 C3 D4"; // Change to your UID void setup() { Serial.begin(9600); SPI.begin(); mfrc522.PCD_Init(); myServo.attach(3); myServo.write(0); // Locked Position pinMode(LED_BUILTIN, OUTPUT); } void loop() { if (!mfrc522.PICC_IsNewCardPresent()) return; if (!mfrc522.PICC_ReadCardSerial()) return; String content= ""; for (byte i = 0; i < mfrc522.uid.size; i++) { content.concat(String(mfrc522.uid.uidByte[i] < 0x10 ? " 0" : " ")); content.concat(String(mfrc522.uid.uidByte[i], HEX)); } content.toUpperCase(); if (content.substring(1) == validTag) { Serial.println("Access Granted"); myServo.write(90); // Unlock delay(3000); myServo.write(0); // Lock } else { Serial.println("Access Denied"); // Beep Buzzer } }