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

#define RST_PIN 9
#define SS_PIN  10

MFRC522 reader(SS_PIN, RST_PIN);

void setup() {
  Serial.begin(115200);
  SPI.begin();
  reader.PCD_Init();
  reader.PCD_DumpVersionToSerial();
  Serial.println("MFRC522 reader initialized");
}

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

  Serial.print("UID:");
  for (byte i = 0; i < reader.uid.size; i++) {
    Serial.print(' ');
    if (reader.uid.uidByte[i] < 0x10) Serial.print('0');
    Serial.print(reader.uid.uidByte[i], HEX);
  }
  Serial.println();

  reader.PICC_HaltA();
  reader.PCD_StopCrypto1();
}