How to Use ESP8266 with RFID RC522 13.56MHz Module

This tutorial covers wiring NodeMCU ESP8266 with the RFID RC522 13.56MHz module to read card UID values. Suitable for door lock systems or attendance tracking projects.

Required Components

• NodeMCU ESP8266 V2 (CP2102)
• RFID RC522 13.56MHz module
• Micro USB cable for computer connection
• Breadboard 830 points
• Jumper wires (M-M, M-F, F-F)
• RFID card or key tag supporting 13.56MHz

Circuit Wiring ESP8266 to RC522

Connect wires according to the table below

ESP8266	RC522
3V3	3V3
GND	GND
D0	RST
D8	SDA
D7	MOSI
D6	MISO
D5	SCK

Note: RC522 uses SPI communication, so connect ESP8266 SPI pins correctly.

Install MFRC522 Library

1. Open Arduino IDE
2. Go to Sketch > Include Library > Manage Libraries
3. Search for “MFRC522”
4. Click Install on MFRC522 by GithubCommunity

Code to Read RFID Card UID

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

// Define pins connected to RC522
#define SDA_PIN  D8    // GPIO15
#define RST_PIN  D0    // GPIO16

MFRC522 rfid(SDA_PIN, RST_PIN);

void setup() {
  Serial.begin(115200);
  SPI.begin();           // Start SPI communication
  rfid.PCD_Init();       // Initialize RC522
  Serial.println("ESP8266 + RFID RC522 Ready");
  Serial.println("Tap card or key tag to read UID");
}

void loop() {
  // Check for new card presence
  if (!rfid.PICC_IsNewCardPresent()) {
    return;
  }
  
  // Read card data
  if (!rfid.PICC_ReadCardSerial()) {
    return;
  }
  
  // Print UID value
  Serial.print("UID: ");
  for (byte i = 0; i < rfid.uid.size; i++) {
    Serial.print(rfid.uid.uidByte[i], HEX);
    Serial.print(" ");
  }
  Serial.println();
  
  // Stop reading card
  rfid.PICC_HaltA();
}

Upload and Test Steps

1. Open Serial Monitor in Arduino IDE
2. Change baud rate to 115200
3. Place RFID card or key tag near the RC522 module
4. Observe the UID value displayed on Serial Monitor

Reference Video

• https://www.youtube.com/embed/zbpJ2UbMsrA

Summary

Using ESP8266 with RC522 is straightforward. Just connect SPI pins correctly, install the library, and upload the code. Each card has a unique UID that you can use to build authorized card checking logic for your projects.