The MFRC522 RFID Module is a low-cost RFID reader/writer module commonly used with Arduino, ESP8266, and ESP32 projects for access control, attendance systems, smart parking, inventory management, and automation.
Features
Frequency: 13.56 MHz
Communication: SPI
Works with:
Arduino UNO
ESP8266 NodeMCU
ESP32
Reads RFID cards/tags such as:
MIFARE 1K
RFID keychains
NFC cards (limited support)
MFRC522 Pinout
MFRC522 Pin
Arduino UNO
ESP32
NodeMCU ESP8266
SDA (SS)
D10
GPIO5
D2
SCK
D13
GPIO18
D5
MOSI
D11
GPIO23
D7
MISO
D12
GPIO19
D6
RST
D9
GPIO4
D1
GND
GND
GND
GND
3.3V
3.3V
3.3V
3.3V
⚠️ Important:
Use 3.3V only
Do NOT connect to 5V directly
 
Arduino Example Code
#include <SPI.h>
#include <MFRC522.h>
#define SS_PIN 10
#define RST_PIN 9
MFRC522 rfid(SS_PIN, RST_PIN);
void setup() {
  Serial.begin(9600);
  SPI.begin();
  rfid.PCD_Init();
  Serial.println("Scan RFID Card");
}
void loop() {
  // Check if card present
  if (!rfid.PICC_IsNewCardPresent())
    return;
  // Read card
  if (!rfid.PICC_ReadCardSerial())
    return;
  Serial.print("Card UID: ");
  for (byte i = 0; i < rfid.uid.size; i++) {
    Serial.print(rfid.uid.uidByte[i], HEX);
    Serial.print(" ");
  }
  Serial.println();
  rfid.PICC_HaltA();
}
 
Common Projects
Smart door lock
Attendance system
Smart parking
Cashless payment
Student ID verification
IoT access control
Common Problems
1. “Communication failure”
Check SPI wiring
Ensure module uses 3.3V
2. Card not detected
Bring tag closer
Verify supported card type
3. ESP32 reset issue
Use stable 3.3V supply