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

#define SS_PIN    10
#define RST_PIN   9
#define servo_PIN 8

String user1ID =  "14 4A 6D 2B";
String user2ID =  "39 4B C8 B8";

Servo myservo;
MFRC522 mfrc522(SS_PIN, RST_PIN);

void setup()
{

  Serial.begin(9600);   // Initiate a serial communication
  SPI.begin();      // Initiate  SPI bus
  mfrc522.PCD_Init();   // Initiate MFRC522
  Serial.println("Approximate your card to the reader...");
  Serial.println();
  myservo.attach(servo_PIN);
  myservo.write(0);
}

void loop() {
  // Look for new cards
  if ( ! mfrc522.PICC_IsNewCardPresent())
  {
    return;
  }

  // Select one of the cards
  if ( ! mfrc522.PICC_ReadCardSerial())
  {
    return;
  }

  //Show UID on serial monitor
  Serial.println ("");
  Serial.println("UID tag :");
  String content = "";
  byte letter;
  for (byte i = 0; i < mfrc522.uid.size; i++)
  {
    content.concat(String(mfrc522.uid.uidByte[i] < 0x10 ? " 0" : " "));
    content.concat(String(mfrc522.uid.uidByte[i], HEX));
    content.toUpperCase();
  }
  Serial.println(content.substring(1));
  if (content.substring(1) == user1ID || content.substring(1) == user2ID) {
    myservo.write(90);
    delay(2000);
    myservo.write(0);
    delay(1000);
  }
}