In this tutorial we will take a look at how you can use RFID readers with your Arduino to control things like keyless entry door locks and relays to control lights…

click on video below for full tutorial…

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Parts list:

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ARDUINO board:

RFID-RC522:

Logic LVL Converter:

RGB LED:

Breadboard:

Jumper Wires:

Schematic:

ARDUINO CODE:

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

#define RST_PIN 9 // Configurable, see typical pin layout above
#define SS_PIN 10 // Configurable, see typical pin layout above

MFRC522 mfrc522(SS_PIN, RST_PIN); // Create MFRC522 instance.

String read_rfid;
String ok_rfid_1 = “66f4608e”;
String ok_rfid_2 = “c08e3f52”; //add as many as you need.

#define red 3 // RGB led pins
#define green 4
#define relay 7 // Relay pin#

void setup() {
Serial.begin(9600); // Initialize serial communications with the PC
SPI.begin(); // Init SPI bus
mfrc522.PCD_Init(); // Init MFRC522 card
pinMode(red, OUTPUT);
pinMode(green, OUTPUT);
pinMode(relay, OUTPUT);
}
void dump_byte_array(byte *buffer, byte bufferSize) {
read_rfid = “”;
for (byte i = 0; i < bufferSize; i++) {
read_rfid = read_rfid + String(buffer[i], HEX);
}
}

void open_lock() {
// if rfid is good this is what will happen

digitalWrite(green, HIGH);
digitalWrite(relay, HIGH);
delay(5000); // how long the relay will be on
digitalWrite(green, LOW);
digitalWrite(relay, LOW);
}

void loop() {

// Look for new cards
if ( ! mfrc522.PICC_IsNewCardPresent())
return;

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

dump_byte_array(mfrc522.uid.uidByte, mfrc522.uid.size);
Serial.println(read_rfid);
if (read_rfid == ok_rfid_1) { // RFID #1
//ok, open the door.
open_lock();
}

if (read_rfid == ok_rfid_2) { // RFID #2
//also ok, open the door
open_lock();
}

if (read_rfid != ok_rfid_1 && read_rfid != ok_rfid_2)
{
digitalWrite(red,HIGH);
delay(2000);
digitalWrite(red,LOW);
}
}