#include <SPI.h>
#include <MFRC522.h>

#define RST_PIN  22
#define SS_PIN   21

MFRC522 mfrc522(SS_PIN, RST_PIN);

void setup() {
  Serial.begin(115200);
  SPI.begin();
  mfrc522.PCD_Init();
  delay(4);
  Serial.println("RFID Reader Ready");
}

void loop() {
  if (!mfrc522.PICC_IsNewCardPresent()) return;
  
  if (!mfrc522.PICC_ReadCardSerial()) return;
  
  Serial.print("Tag ID: ");
  for (byte i = 0; i < mfrc522.uid.size; i++) {
    Serial.print(mfrc522.uid.uidByte[i] < 0x10 ? " 0" : " ");
    Serial.print(mfrc522.uid.uidByte[i], HEX);
  }
  Serial.println();
  
  delay(1000);
}