Automatic Door Lock Using RFID

Step 1: Gather the Supplies

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Step 2: Circuit Diagram

Make all the connections as shown in the diagram above.

If you want to see how I modified the DVD Writer to make it work with the Arduino then Click Here .

The IR sensor gives the status of the door's open or closed state.

As we bring the correct RFID card in the readers proximity the door opens. It will stay open for a short time and then close again. But let's assume that a person entered by using the correct tag and now he wants to come out. This could be achieved using another RFID module at the inside but I went on with a easy method.

I gave a switch in the inside to open the door. This will help the person to get outside.

Step 3: Coding

The code for this project is given below. But before uploading the code you will have to find the Tag number of your RFID Tag. And to do that check out this instructable >> Click Here .

Now change the UID in the code below and upload it to your Arduino Board.

#include <SPI.h>
#include <MFRC522.h>
#define SS_PIN 10
#define RST_PIN 9
const int Relay = 4;
const int sen1 = 2;
const int SW = 5;
int buttonState = 0;
int val1;
MFRC522 mfrc522(SS_PIN, RST_PIN);
void setup() 
{
  digitalWrite(Relay, HIGH);  Serial.begin(9600);   // Initiate a serial communication
  SPI.begin();      // Initiate  SPI bus
  mfrc522.PCD_Init();   // Initiate MFRC522
  pinMode(Relay, OUTPUT);
  pinMode(sen1, INPUT);
  pinMode(SW, INPUT);
  digitalWrite(Relay, HIGH);
  delay(250);
  digitalWrite(Relay,LOW); 
  delay(250);
  digitalWrite(Relay,HIGH);
  delay(250);
  digitalWrite(Relay,LOW);
  digitalWrite(Relay,HIGH);
  delay(250);
  digitalWrite(Relay,LOW);
}
void loop() 
{
  val1 = digitalRead(sen1); 
  Serial.println("SEN1");
  Serial.println(val1);
  buttonState = digitalRead(SW);
  Serial.println("Button");
  Serial.println(buttonState);
  {
  if (val1 == HIGH && buttonState == HIGH) 
  {
    digitalWrite(Relay, HIGH);
    delay(250);
    digitalWrite(Relay,LOW);
    delay(4000);
    digitalWrite(Relay,HIGH);
    delay(250);
    digitalWrite(Relay,LOW);
  }
  else 
  {
    digitalWrite(Relay, LOW);
  }
  rfid();
  }
}
void rfid()
{
    if ( ! mfrc522.PICC_IsNewCardPresent()) 
  {
    return;
  }
  if ( ! mfrc522.PICC_ReadCardSerial()) 
  {
    return;
  }
  String content= "";
  byte letter;
  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();
  int val1 = digitalRead(sen1);
  if (val1 == HIGH && content.substring(1) == "F4 90 E0 1F") //change here the UID of the card/cards that you want to give access
  {
    Serial.println("Authorized access");
    digitalWrite(Relay,HIGH);
    delay(250);
    digitalWrite(Relay,LOW);
    delay(4000);
    digitalWrite(Relay,HIGH);
    delay(250);
    digitalWrite(Relay,LOW);
  }
  else
  {
    Serial.println("Unauthorized access");
  }
}

The.ino file for this code is given below. You can directly download it.

If you have any trouble with the code then please drop a comment below. I will try my best to answer your queries.