Step 1: Requirements

Step 2: Building and Wiring

Step 3: Programming

//electronicsvoorjou.nl
// Download the MFRC522 library here: https://github.com/ljos/MFRC522 or https://www.arduinolibraries.info/libraries/mfrc522

#include
#include

// Indicates the pins
#define SS_PIN 10
#define RST_PIN 9

// Indicates to which pin the LED is connected
const int ledpin1 = 7;
const int ledpin2 = 6;
const int buzzer = 8;

// Creates own veriable for card reader
MFRC522 myReader (SS_PIN, RST_PIN);

void setup ()
{

// set buzzer to pin 8 as output
pinMode (buzzer, OUTPUT);

// Start communication with the monitor
Serial.begin (9600);

// Library SPI
SPI.begin ();

// Up to version 1.4.5 this call
myReader.PCD_Init ();

// Print on monitor: “..”
Serial.println (“Present your key-tag”);
Serial.println ();

// initialize pin 7 and 6 as output
pinMode (ledpin1, OUTPUT);
pinMode (ledpin2, OUTPUT);
}

void loop ()
{

// see if no new maps are detected
digitalWrite (ledpin1, HIGH);
if (! myReader.PICC_IsNewCardPresent ())
{

// not found, stops searching
return;
}

// Checks whether the key tag can be read
if (! myReader.PICC_ReadCardSerial ())
{
// failed to read
return;
}

// Show UID on serial monitor
String key = "";
for (byte i = 0; i <myReader.uid.size; i ++)
{
key.concat (String (myReader.uid.uidByte [i] <0x10? ”0 ″:” “));
key.concat (String (myReader.uid.uidByte [i], HEX));
}

// Uppercase code of found key for better comparison
key.toUpperCase ();

// Print to monitor so you know which key is being read
Serial.println ();
Serial.print (“key tag is:“);
Serial.print (key);

// Grants access if key “..” is the same
// Each key tag has its own code, read your code via monitor
Serial.println ();
Serial.print ("Access:");
if (key == ”93 F9 BE A9 ″)
{

// Red LED off, green turns on
digitalWrite (ledpin1, LOW);
digitalWrite (ledpin2, HIGH);

// Determines the frequency of the buzzer
tone (buzzer, 1000);
// wait 1 second
delay (1000);
// stops sound
noTone(buzzer);

// Print on monitor
Serial.print (“Issued”);
delay (3000);
digitalWrite (ledpin1, HIGH);
digitalWrite (ledpin2, LOW);
}

else {

// Red LED on, green off
digitalWrite (ledpin1, HIGH);
digitalWrite (ledpin2, LOW);

// Determines the frequency of the buzzer
tone (buzzer, 500);
// wait 1 second
delay (1000);
// stops sound
noTone(buzzer);

// Print on monitor
Serial.print (“Not issued”);
delay (3000);
}
Serial.println ();
}