How to Use RC522 RFID Module: Examples, Pinouts, and Specs

The RC522 RFID Module, manufactured by NXP Semiconductors (Part ID: MFRC522-based RC522 Module), is a compact and cost-effective device designed for reading and writing RFID tags. Operating at a frequency of 13.56 MHz, it supports communication with a variety of RFID cards and tags, including MIFARE cards. This module is widely used in applications such as:

• Access control systems (e.g., door locks, attendance systems)
• Inventory management (e.g., tracking assets or goods)
• Contactless payment systems
• IoT projects requiring RFID-based identification

Its small size, low power consumption, and SPI communication interface make it an excellent choice for integration into microcontroller-based systems, including Arduino projects.

The RC522 RFID Module has 8 pins for interfacing. Below is the pinout and description:

1. Power the Module: Connect the VCC pin to a 3.3V power source and the GND pin to ground.
2. Connect to a Microcontroller: Use the SPI interface to connect the module to a microcontroller (e.g., Arduino UNO). The typical connections are:
   • MISO → Arduino Pin 12
   • MOSI → Arduino Pin 11
   • SCK → Arduino Pin 13
   • SDA/SS → Arduino Pin 10
   • RST → Arduino Pin 9
3. Install Required Libraries: For Arduino, install the "MFRC522" library from the Arduino IDE Library Manager.
4. Write Code: Use the library functions to initialize the module, read RFID tags, and process data.

Below is an example Arduino sketch to read RFID tags using the RC522 module:

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

// Define RC522 module pins
#define RST_PIN 9  // Reset pin connected to Arduino pin 9
#define SS_PIN 10  // Slave Select pin connected to Arduino pin 10

MFRC522 rfid(SS_PIN, RST_PIN); // Create an instance of the MFRC522 class

void setup() {
  Serial.begin(9600); // Initialize serial communication
  SPI.begin();        // Initialize SPI bus
  rfid.PCD_Init();    // Initialize the RC522 module
  Serial.println("Place your RFID card near the reader...");
}

void loop() {
  // Check if an RFID card is present
  if (!rfid.PICC_IsNewCardPresent() || !rfid.PICC_ReadCardSerial()) {
    return; // Exit if no card is detected
  }

  // Print the UID of the detected card
  Serial.print("Card UID: ");
  for (byte i = 0; i < rfid.uid.size; i++) {
    Serial.print(rfid.uid.uidByte[i], HEX); // Print each byte in hexadecimal
    Serial.print(" ");
  }
  Serial.println();

  // Halt the card to stop further communication
  rfid.PICC_HaltA();
}

• Power Supply: Ensure the module is powered with 3.3V. Using 5V may damage the module.
• Reading Distance: The effective reading distance depends on the tag type and orientation. Keep the tag within 5 cm of the antenna for reliable operation.
• Interference: Avoid placing the module near metal objects or other electronic devices that may cause interference.
• Reset Pin: Use the RST pin to reset the module if it becomes unresponsive.

1. Can the RC522 module write data to RFID tags?

   • Yes, the module supports both reading and writing to compatible RFID tags.

2. What is the maximum range of the RC522 module?

   • The maximum range is approximately 5 cm, depending on the tag type and environmental conditions.

3. Can I use the RC522 module with a 5V microcontroller?

   • Yes, but you must use a logic level shifter to convert the 5V signals to 3.3V to avoid damaging the module.

4. Does the module support NFC?

   • The RC522 module supports ISO/IEC 14443 A, which is a subset of NFC standards. However, it is not a full NFC module.

By following this documentation, you can effectively integrate the RC522 RFID Module into your projects and troubleshoot common issues.