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Smart Cards (RFID MFRC522) | NexaLearn IoT Lab | NexaLearn

Security & Smart Home30 دقيقة

Smart Cards (RFID MFRC522)

Reading keyfobs and smart door cards.

Lesson Content

The MFRC522 module operates at 13.56MHz and reads passive tags (cards with no internal battery) using electromagnetic induction. It uses the SPI protocol for communication, which requires specific wires (MISO, MOSI, SCK, CS). Each card has a unique identification number (UID) programmed at the factory that cannot be easily changed.

Components Needed

Arduino UnoRC522 RFID Moduleبطاقة وميدالية

Wiring Notes

Operates at 3.3V, NOT 5V (5V will damage it). SCK to 13, MISO to 12, MOSI to 11, SDA(SS) to 10, RST to 9.

Code Example

#include <SPI.h>
#include <MFRC522.h>
MFRC522 mfrc522(10, 9);
void setup() {
  Serial.begin(9600); SPI.begin(); mfrc522.PCD_Init();
}
void loop() {
  if ( ! mfrc522.PICC_IsNewCardPresent() || ! mfrc522.PICC_ReadCardSerial() ) return;
  String uid = "";
  for (byte i = 0; i < mfrc522.uid.size; i++) {
    uid += String(mfrc522.uid.uidByte[i], HEX);
  }
  Serial.println(uid);
  mfrc522.PICC_HaltA();
}

Common Mistakes

Connecting the module's 3.3V power wire to the 5V pin on Arduino.

Next Lesson

Membrane Keypad (4×4)