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

The RC522 RFID Module, manufactured by NXP Semiconductors (Part ID: MFRC522), 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. Its versatility and affordability make it a popular choice for applications such as:

• Access control systems
• Inventory and asset management
• Contactless payment systems
• Attendance tracking
• IoT projects requiring RFID integration

The module is widely used in hobbyist and professional projects due to its compatibility with microcontrollers like the Arduino UNO.

The RC522 RFID Module has an 8-pin interface for communication and power. Below is the pinout:

To use the RC522 RFID Module with an Arduino UNO, follow these steps:

1. Wiring the Module: Connect the module to the Arduino UNO as shown in the table below:

   RC522 Pin	Arduino UNO Pin
   VCC	3.3V
   GND	GND
   RST	Pin 9
   IRQ	Not connected
   MISO	Pin 12
   MOSI	Pin 11
   SCK	Pin 13
   SDA/SS	Pin 10

2. Install Required Libraries:

   • Download and install the MFRC522 library from the Arduino Library Manager.
   • Go to Sketch > Include Library > Manage Libraries, search for "MFRC522," and install it.

3. Upload Example Code: Use the following example code to read RFID tags:

   #include <SPI.h>
   #include <MFRC522.h>
   
   #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 a new card is present
     if (!rfid.PICC_IsNewCardPresent()) {
       return; // Exit if no card is detected
     }
   
     // Check if the card can be read
     if (!rfid.PICC_ReadCardSerial()) {
       return; // Exit if reading fails
     }
   
     // Print the UID of the 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();
   }
   

4. Test the Setup:

   • Open the Serial Monitor in the Arduino IDE (set the baud rate to 9600).
   • Place an RFID card or tag near the module. The card's UID (Unique Identifier) should appear in the Serial Monitor.

• Power Supply: Always use a 3.3V power source for the module. Connecting it to 5V can permanently damage the device.
• Reading Distance: Ensure the RFID card or tag is within 5 cm of the module for reliable communication.
• Interference: Avoid placing the module near metal objects or other electronic devices that may cause interference.
• Library Updates: Keep the MFRC522 library updated to ensure compatibility with the latest Arduino IDE versions.

1. The module is not detected by the Arduino:

   • Double-check the wiring connections, especially the SPI pins (MISO, MOSI, SCK, and SDA/SS).
   • Ensure the module is powered with 3.3V and not 5V.

2. No output in the Serial Monitor:

   • Verify that the Serial Monitor baud rate is set to 9600.
   • Ensure the MFRC522 library is correctly installed.

3. The module cannot read RFID cards:

   • Confirm that the card is compatible with the ISO/IEC 14443A standard.
   • Ensure the card is within the 5 cm reading range.

4. The module resets unexpectedly:

   • Check the power supply for stability. Use a capacitor (e.g., 10µF) across the VCC and GND pins to filter noise.

Q: Can the RC522 module write data to RFID cards?
A: Yes, the RC522 module supports both reading and writing data to compatible RFID cards and tags.

Q: Can I use the RC522 module with a 5V microcontroller?
A: Yes, but you must use a logic level shifter to convert the 5V signals to 3.3V to avoid damaging the module.

Q: What is the maximum number of RFID cards the module can handle simultaneously?
A: The RC522 module can only communicate with one RFID card or tag at a time.

Q: Can the module work with other microcontrollers besides Arduino?
A: Yes, the RC522 module can be used with other microcontrollers like ESP32, Raspberry Pi, and STM32, provided the appropriate libraries and connections are used.

This concludes the documentation for the RC522 RFID Module. For further assistance, refer to the official datasheet or community forums.