RFID Card Scan Arduino Code

#include <LiquidCrystal_I2C.h>

#include <SPI.h>

#include <MFRC522.h>

#define RST_PIN 9

#define SS_PIN  10

byte readCard[4];

byte a = 0;

LiquidCrystal_I2C lcd(0x27, 16, 2);

MFRC522 mfrc522(SS_PIN, RST_PIN);

void setup() {

  Serial.begin(9600);

  lcd.init();

  lcd.backlight();

  while (!Serial);

  SPI.begin();

  mfrc522.PCD_Init();

  delay(4);

  mfrc522.PCD_DumpVersionToSerial();

  lcd.setCursor(2, 0);

  lcd.print("Put your card");

}

void loop() {

  if ( ! mfrc522.PICC_IsNewCardPresent()) {

    return 0;

  }

  if ( ! mfrc522.PICC_ReadCardSerial()) {

    return 0;

  }

  lcd.clear();

  lcd.setCursor(0, 0);

  lcd.print("Scanned UID");

  a = 0;

  Serial.println(F("Scanned PICC's UID:"));

  for ( uint8_t i = 0; i < 4; i++) {  //

    readCard[i] = mfrc522.uid.uidByte[i];

    Serial.print(readCard[i], HEX);

    Serial.print(" ");

    lcd.setCursor(a, 1);

    lcd.print(readCard[i], HEX);

    lcd.print(" ");

    delay(500);

    a += 3;

  }

  Serial.println("");

  mfrc522.PICC_HaltA();

  return 1;

}