rfid.ino

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

#define RST_PIN D4
#define SS_PIN D8

MFRC522 mfrc522(SS_PIN, RST_PIN);

void setupRfid() {
  SPI.begin();
  mfrc522.PCD_Init();
}

String processRfid() {
  String rfidData = "";

  if ( ! mfrc522.PICC_IsNewCardPresent())
    return "";

  if ( ! mfrc522.PICC_ReadCardSerial())
    return "";

  rfidData = rfidDataToString(mfrc522.uid.uidByte, mfrc522.uid.size);

  return rfidData;
}

String rfidDataToString(byte *buffer, byte bufferSize) {
  String temp = "";
  for (byte i = 0; i < bufferSize; i++) {
    temp += buffer[i] < 0x10 ? "0" : "";
    temp += String(buffer[i], HEX);
  }

  return temp;
}