Circuit Documentation

Summary of the Circuit

This circuit is designed to control a door lock system using RFID technology. It features an Arduino UNO microcontroller interfaced with an RFID-RC522 module to read RFID tags. The system unlocks a magnetic lock if an authorized RFID tag is presented. Visual feedback is provided through a green LED for access granted and a red LED for access denied. An audible alert is given by a buzzer, with different tones indicating accepted or rejected tags. The circuit is powered by a 5V adapter, and a 12V power supply is used to control the magnetic lock through a 12V relay.

Component List

Arduino UNO

• Microcontroller board based on the ATmega328P
• Used as the main controller for the RFID door lock system

RFID-RC522

• RFID reader/writer module
• Operates at 13.56 MHz for reading RFID tags

LED: Two Pin (green)

• Visual indicator for access granted
• Lights up when an authorized RFID tag is detected

LED: Two Pin (red)

• Visual indicator for access denied
• Lights up when an unauthorized RFID tag is detected

Buzzer

• Audible indicator for access granted or denied
• Sounds with different tones based on the RFID tag status

5V Adapter

• Power supply for the Arduino UNO and RFID-RC522
• Converts AC to 5V DC

Magnetic Lock

• Electromagnetic locking mechanism
• Secures the door and is controlled by the relay

12V Relay

• Electromechanical switch
• Used to control the high-power circuit of the magnetic lock with the Arduino's low-power signal

12V Power Supply

• Provides power to the magnetic lock through the relay
• Supplies 12V DC

Wiring Details

Arduino UNO

• 3.3V connected to RFID-RC522 VCC (3.3V)
• GND connected to common ground net
• Vin connected to 5V Adapter 5V output
• D13 connected to RFID-RC522 SCK
• D12 connected to RFID-RC522 MISO
• D11 connected to RFID-RC522 MOSI
• D10 connected to RFID-RC522 SDA
• D5 connected to red LED cathode
• D4 connected to green LED cathode
• D3 connected to 12V Relay IN
• D2 connected to buzzer PIN

RFID-RC522

• VCC (3.3V) connected to Arduino UNO 3.3V
• GND connected to common ground net
• SCK connected to Arduino UNO D13
• MISO connected to Arduino UNO D12
• MOSI connected to Arduino UNO D11
• SDA connected to Arduino UNO D10

LED: Two Pin (green)

• anode connected to common ground net
• cathode connected to Arduino UNO D4

LED: Two Pin (red)

• anode connected to common ground net
• cathode connected to Arduino UNO D5

Buzzer

• PIN connected to Arduino UNO D2
• GND connected to common ground net

5V Adapter

• 5V connected to Arduino UNO Vin
• GND connected to common ground net

Magnetic Lock

• S connected to 12V Relay DC+
• GND connected to 12V Relay NO

12V Relay

• IN connected to Arduino UNO D3
• DC+ connected to Magnetic Lock S and 12V Power Supply +
• DC- connected to 12V Power Supply -
• NO connected to Magnetic Lock GND

12V Power Supply

• + connected to 12V Relay DC+
• - connected to 12V Relay DC-

Documented Code

/*
 * This Arduino Sketch controls a door lock system using RFID.
 * The system reads RFID tags and unlocks the door if the tag is authorized.
 * A buzzer sounds differently for accepted and rejected tags.
 * Two example RFID tags are used for access control.
 */

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

#define RST_PIN 9
#define SS_PIN 10
#define RED_LED_PIN 5
#define GREEN_LED_PIN 4
#define RELAY_PIN 3
#define BUZZER_PIN 2

MFRC522 mfrc522(SS_PIN, RST_PIN);

// Example authorized RFID tag UIDs
byte authorizedUID1[] = {0xDE, 0xAD, 0xBE, 0xEF};
byte authorizedUID2[] = {0xCA, 0xFE, 0xBA, 0xBE};

void setup() {
  Serial.begin(9600);
  SPI.begin();
  mfrc522.PCD_Init();
  pinMode(RED_LED_PIN, OUTPUT);
  pinMode(GREEN_LED_PIN, OUTPUT);
  pinMode(RELAY_PIN, OUTPUT);
  pinMode(BUZZER_PIN, OUTPUT);
  digitalWrite(RELAY_PIN, LOW); // Ensure the relay is off initially
}

void loop() {
  if (!mfrc522.PICC_IsNewCardPresent() || !mfrc522.PICC_ReadCardSerial()) {
    return;
  }

  if (isAuthorized(mfrc522.uid.uidByte, mfrc522.uid.size)) {
    grantAccess();
  } else {
    denyAccess();
  }

  mfrc522.PICC_HaltA();
}

bool isAuthorized(byte *uid, byte uidSize) {
  if (uidSize != 4) return false;
  if (memcmp(uid, authorizedUID1, 4) == 0) return true;
  if (memcmp(uid, authorizedUID2, 4) == 0) return true;
  return false;
}

void grantAccess() {
  digitalWrite(GREEN_LED_PIN, HIGH);
  digitalWrite(RED_LED_PIN, LOW);
  digitalWrite(RELAY_PIN, HIGH);
  tone(BUZZER_PIN, 1000, 200); // Short beep for accepted tag
  delay(5000); // Keep the door unlocked for 5 seconds
  digitalWrite(RELAY_PIN, LOW);
  digitalWrite(GREEN_LED_PIN, LOW);
}

void denyAccess() {
  digitalWrite(RED_LED_PIN, HIGH);
  digitalWrite(GREEN_LED_PIN, LOW);
  tone(BUZZER_PIN, 500, 1000); // Long beep for rejected tag
  delay(1000);
  digitalWrite(RED_LED_PIN, LOW);
}

This code is responsible for initializing the RFID reader and setting up the pins for the LEDs, relay, and buzzer. It continuously checks for new RFID cards, compares the UID of the card with authorized UIDs, and then either grants or denies access accordingly. The relay is activated to unlock the door for authorized access, and the LEDs and buzzer provide the corresponding visual and audible feedback.