#include <SPI.h>

#include <MFRC522.h>

MFRC522 mfrc522(10, 9);

void setup() {

    Serial.begin(9600);

    delay(500);      

}

void loop() {   

    SPI.begin();

    mfrc522.PCD_Init();

    if ( ! mfrc522.PICC_IsNewCardPresent()) return;

    if ( ! mfrc522.PICC_ReadCardSerial()) return;

    Serial.print("Codice Card: ");

    VectorPrint(mfrc522.uid.uidByte, 4);

    Serial.println(); 

    mfrc522.PICC_HaltA();

    mfrc522.PCD_StopCrypto1();    

}

void VectorPrint(byte *x, byte dv) {      

    char ch[2];

    for (byte i = 0; i < dv; i++) {

      DectoHex(x[i], ch);

      Serial.print(ch[0]);

      Serial.print(ch[1]);         

    }    

  }

  void DectoHex(byte z, char ch[2]) {

    byte nb;

    nb = z / 16;

    if (nb>9){nb = nb + 55;}

    else {nb = nb + 48;}

    ch[0] = char(nb);

    nb = z % 16;

    if (nb>9){nb = nb + 55;}

    else {nb = nb + 48;}

    ch[1] = char(nb);

  }