Interface MFRC522 RFID with Arduino

Introduction

The MFRC522 RFID module is a popular RFID reader module used with Arduino to read RFID tags. It communicates via SPI, enabling quick data exchange and making it suitable for security and access control projects. Here’s a guide on setting up the MFRC522 RFID module with Arduino and reading RFID tag data.

Required Components

• Arduino Board (e.g., Arduino Uno)
• MFRC522 RFID module, RFID tags
• Jumper Wires
• Breadboard (optional)

Pinout

Circuit Diagram / Wiring

• RFID SENSOR VCC → 5V (Arduino)
• RFID SENSOR GND → GND (Arduino)
• RFID SENSOR SDA  → Pin D10 (Arduino)
• RFID SENSOR SCK  → Pin D13 (Arduino)
• RFID SENSOR MOSI → Pin D11 (Arduino)
• RFID SENSOR MISO  → Pin D12 (Arduino)
• RFID SENSOR IRQ  → Pin D9 (Arduino)
• RFID SENSOR RST  → Pin D8 (Arduino)

Programming With Arduino

• Go to the “Libraries” tab on the left-hand side of the screen.
• Click on the “Library Manager” button (book icon) at the top of the Libraries tab.
• In the Library Manager window, type “MFRC522” in the search bar, locate the MFRC522 library, and click on the “Install” button next to it.

• Copy and paste the provided code into a new sketch in the Arduino IDE:

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

#define RST_PIN 8
#define SS_PIN 10

MFRC522 mfrc522(SS_PIN, RST_PIN); // Create MFRC522 instance

// Define UIDs for object 1 and object 2
byte object1UID[] = {0x83, 0x4D, 0x4C, 0xC5}; // UID of object 1
byte object2UID[] = {0xE5, 0xF6, 0x07, 0x08}; // UID of object 2 (change as needed)

void setup() {
  Serial.begin(9600); // Initialize serial communications with the PC
  while (!Serial); // Do nothing if no serial port is opened
  SPI.begin(); // Init SPI bus
  mfrc522.PCD_Init(); // Init MFRC522
  delay(4); // Optional delay
  Serial.println(F("Scan PICC to see UID..."));
}

void loop() {
  // Reset the loop if no new card present on the sensor/reader.
  if (!mfrc522.PICC_IsNewCardPresent()) {
    return;
  }

  // Select one of the cards
  if (!mfrc522.PICC_ReadCardSerial()) {
    return;
  }

  // Print the detected UID in a readable format
  Serial.print("Card UID: ");
  for (byte i = 0; i < mfrc522.uid.size; i++) {
      Serial.print(mfrc522.uid.uidByte[i], HEX);
      if (i < mfrc522.uid.size - 1) {
          Serial.print(" ");
      }
  }
  Serial.println(); // New line after printing UID

  // Check the UID of the scanned card
  if (compareUID(mfrc522.uid.uidByte, object1UID)) {
    Serial.println("Object 1 detected!");
  } 
  else if (compareUID(mfrc522.uid.uidByte, object2UID)) {
    Serial.println("Object 2 detected!");
  } 
  else {
    Serial.println("Unknown object detected!");
  }

  // Halt the PICC
  mfrc522.PICC_HaltA();
}

// Function to compare two UIDs
bool compareUID(byte *uid1, byte *uid2) {
  for (byte i = 0; i < 4; i++) { // Adjust the number of bytes based on your UID length
    if (uid1[i] != uid2[i]) {
      return false;
    }
  }
  return true;
}

Explanation

• The code uses the MFRC522 library to interface with an RFID reader.
• It defines two unique UIDs for two different RFID cards to detect them.
• In the setup() function, it initializes the Serial Monitor and the RFID reader.
• The loop() function checks for new cards, reads their UIDs, and compares them with predefined UIDs.
• Depending on the detected UID, it prints messages indicating which object is detected or if an unknown object is scanned.

Testing and Troubleshooting

• Ensure the connections (SDA, SCK, MOSI, MISO, RST, and GND) between the MFRC522 module and Arduino are secure and correctly configured.
• Verify that the power supply is adequate; the MFRC522 should be powered with 3.3V, not 5V, to avoid damage.
• If the module does not respond, check the SPI library installation in your Arduino IDE and ensure the correct board is selected.
• Use the Serial Monitor to check for any error messages or debugging information that can help identify issues during the scanning process.