#include <SPI.h> 
  #include <MFRC522.h> 
  #include <EEPROM.h> 
   
  #define RST_PIN 9 
  #define SS_PIN 10 
  #define RelayPin 8 
   
  MFRC522 mfrc522(SS_PIN, RST_PIN); 
   
  String lastRfid = ""; 
  String kart1 = ""; 
  String kart2 = ""; 
  String kart3 = ""; 
  String kart4 = ""; 
   
  MFRC522::MIFARE_Key key; 
   
   
  void setup() 
  { 
    Serial.begin(9600); 
    SPI.begin(); 
    mfrc522.PCD_Init(); 
    pinMode(RelayPin, OUTPUT); 
    digitalWrite(RelayPin, LOW); 
    Serial.println("RFID KART OKUMA UYGULAMASI"); 
    Serial.println("--------------------------"); 
    Serial.println(); 
    //EEPROM'dan kart bilgisini oku 
    readEEPROM(); 
  } 
   
  void loop() 
  { 
    //yeni kart okununmadıkça devam etme 
    if ( ! mfrc522.PICC_IsNewCardPresent()) 
    { 
      return; 
    } 
    if ( ! mfrc522.PICC_ReadCardSerial()) 
    { 
      return; 
    } 
    //kartın UID'sini oku, rfid isimli string'e kaydet 
    String rfid = ""; 
    for (byte i = 0; i < mfrc522.uid.size; i++) 
    { 
      rfid += mfrc522.uid.uidByte[i] < 0x10 ? " 0" : " "; 
      rfid += String(mfrc522.uid.uidByte[i], HEX); 
    } 
    //string'in boyutunu ayarla ve tamamını büyük harfe çevir 
    rfid.trim(); 
    rfid.toUpperCase(); 
     
    if (rfid == lastRfid) 
      return; 
    lastRfid = rfid; 
   
    Serial.print("Kart 1: "); 
    Serial.println(kart1); 
    Serial.print("Kart 2: "); 
    Serial.println(kart2); 
    Serial.print("Kart 3: "); 
    Serial.println(kart3); 
    Serial.print("Kart 4: "); 
    Serial.println(kart4); 
    Serial.print("Okunan: "); 
    Serial.println(rfid); 
    Serial.println(); 
    //1 nolu kart okunduysa LED'i yak, 2 nolu kart okunduysa LED'i söndür 
    if (rfid == kart1) 
    { 
      digitalWrite(RelayPin, HIGH); 
      Serial.println("LED yandi."); 
      delay(1000); 
      digitalWrite(RelayPin, LOW); 
    } 
    if (rfid == kart2) 
    { 
      digitalWrite(RelayPin, HIGH); 
      Serial.println("LED yandi."); 
      delay(1000); 
      digitalWrite(RelayPin, LOW); 
    } 
    if (rfid == kart3) 
    { 
      digitalWrite(RelayPin, HIGH); 
      Serial.println("LED yandi."); 
      delay(1000); 
      digitalWrite(RelayPin, LOW); 
    } 
    if (rfid == kart4) 
    { 
      digitalWrite(RelayPin, HIGH); 
      Serial.println("LED yandi."); 
      delay(1000); 
      digitalWrite(RelayPin, LOW); 
    } 
   
    Serial.println(); 
    delay(200); 
   
  } 
   
  void readEEPROM() 
  { 
    //EEPROM'dan ilk kartın UID'sini oku (ilk 4 byte) 
    for (int i = 0 ; i < 4 ; i++) 
    { 
      kart1 += EEPROM.read(i) < 0x10 ? " 0" : " "; 
      kart1 += String(EEPROM.read(i), HEX); 
    } 
    //EEPROM'dan ikinci kartın UID'sini oku 
    for (int i = 4 ; i < 8 ; i++) 
    { 
      kart2 += EEPROM.read(i) < 0x10 ? " 0" : " "; 
      kart2 += String(EEPROM.read(i), HEX); 
    } 
    //EEPROM'dan 3 kartın UID'sini oku 
    for (int i = 8 ; i < 12 ; i++) 
    { 
      kart3 += EEPROM.read(i) < 0x10 ? " 0" : " "; 
      kart3 += String(EEPROM.read(i), HEX); 
    } 
     //EEPROM'dan 4 kartın UID'sini oku 
    for (int i = 12 ; i < 16 ; i++) 
    { 
      kart4 += EEPROM.read(i) < 0x10 ? " 0" : " "; 
      kart4 += String(EEPROM.read(i), HEX); 
    } 
    //Okunan stringleri düzenle 
    kart1.trim(); 
    kart1.toUpperCase(); 
    kart2.trim(); 
    kart2.toUpperCase(); 
    kart3.trim(); 
    kart3.toUpperCase(); 
    kart4.trim(); 
    kart4.toUpperCase(); 
  }