Interfacing MFRC522 RFID Reader with Arduino

                         MFRC522 RFID

RFID means radio-frequency identification. RFID uses electromagnetic fields to transfer data over short distances, RFID is useful to identify people, to make transactions you can use the RFID system to open a door. for example, only the person with the right information on his card or tag is allowed to enter.
An RFID system uses :
tags attached to the object to be identified, we have an electromagnetic card. each tag has its own identification (UID)

the  reader, that sends a signal to the tag and read its response

Specifications :

1. input voltage is 3.3v

2. Frequency 13.56Mhz

Library :

RFID Library Here

PIN LAYOUT :

RES   - D9

SDA   - D10

MOSI - D11

MISO - D12

SCK   - D13

3.3V   - 3.3V

GND  - GND

CODE :  LED AND SERVO

 
#include "SPI.h"
#include "MFRC522.h" // LibrARY 

#define SS_PIN 10
#define RST_PIN 9
#define SP_PIN 8

MFRC522 rfid(SS_PIN, RST_PIN);

MFRC522::MIFARE_Key key;

void setup() {
  Serial.begin(9600);
  SPI.begin();
  rfid.PCD_Init();
}

void loop() {
  if (!rfid.PICC_IsNewCardPresent() || !rfid.PICC_ReadCardSerial())
    return;

  // Serial.print(F("PICC type: "));
  MFRC522::PICC_Type piccType = rfid.PICC_GetType(rfid.uid.sak);
  // Serial.println(rfid.PICC_GetTypeName(piccType));

  // Check is the PICC of Classic MIFARE type
  if (piccType != MFRC522::PICC_TYPE_MIFARE_MINI &&
    piccType != MFRC522::PICC_TYPE_MIFARE_1K &&
    piccType != MFRC522::PICC_TYPE_MIFARE_4K) {
    Serial.println(F("Your tag is not of type MIFARE Classic."));
    return;
  }

  String strID = "";
  for (byte i = 0; i < 4; i++) {
    strID +=
    (rfid.uid.uidByte[i] < 0x10 ? "0" : "") +
    String(rfid.uid.uidByte[i], HEX) +
    (i!=3 ? ":" : "");
  }
  strID.toUpperCase();

 
  Serial.print("Tap card key: ");
  Serial.println(strID);

  rfid.PICC_HaltA();
  rfid.PCD_StopCrypto1();
}