How to Use RFID Sensor with Arduino (Card + Tag)

In this tutorial, you will build a device that uses RFID detection to turn on an LED light. This application can be used, for example, to open a door with RFID control.

This is a tutorial suitable for learning in video format, if you prefer a more complete tutorial you can find it at this link!

Parts Required

• Arduino
• RC522 RFID Reader
• Jumper wires
• LED
• Breadboard

Circuit

Connect the LED light and resistor to the digital output pin 4 (as you can see in the following code).

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

#define LED_BUILTIN 4 // Configurable, set LED pin

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

void setup() {
  // initialize digital pin LED_BUILTIN as an output.
  pinMode(LED_BUILTIN, OUTPUT);

  Serial.begin(9600);   // Initialize serial communications with the PC
  while (!Serial);    // Do nothing if no serial port is opened (added for Arduinos based on ATMEGA32U4)
  SPI.begin();      // Init SPI bus
  mfrc522.PCD_Init();   // Init MFRC522
  delay(4);       // Optional delay. Some board do need more time after init to be ready, see Readme
  mfrc522.PCD_DumpVersionToSerial();  // Show details of PCD - MFRC522 Card Reader details
  Serial.println(F("Scan PICC to see UID, SAK, type, and data blocks..."));
}

void loop() {
  // Reset the loop if no new card present on the sensor/reader. This saves the entire process when idle.
  if ( ! mfrc522.PICC_IsNewCardPresent()) {
    return;
  }

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

  digitalWrite(LED_BUILTIN, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(1000);                       // wait for a second
  digitalWrite(LED_BUILTIN, LOW);    // turn the LED off by making the voltage LOW
  delay(1000);                       // wait for a second

  // Dump debug info about the card; PICC_HaltA() is automatically called
  mfrc522.PICC_DumpToSerial(&(mfrc522.uid));
}

The code shown will turn the light on and off at 2-second intervals, if you want to put a button to control it just add a digital input.

References

[1] https://www.sensingthecity.com/using-an-rfid-sensor-to-blink-an-led-light/