Arduino MFRC522 Tutorial – Is RFID Tag Present or Removed?

This tutorial is originally posted on High Voltages.

Most of the RFID tutorials on the internet will teach you how to read RFID cards. But that will not tell you when the tag is absent. For example, in an RFID based attendance system, we do not need to know for how long the card was there. Still, for some cases, we need to know that the card is present or removed. For instance, in 6 candles games, it is necessary to put all candles at a specified location for triggering the output. For that card under candles must stay at that position. Otherwise, it will disturb the sequence. We will use Arduino and mfrc522 to learn this concept.

In this tutorial, we are going to write a code that on detecting the card will turn on the Green LED. And when we remove the tag, it will turn off the Green LED. Also, the results will appear on the serial monitor. You can modify the code and use it for various purposes. Sounds good? Let’s start.

We will not need a list of items for this tutorial. If you are following my videos and trying my tutorials, you will already have Arduino Uno, MFRC522 RFID reader, Jumper wires, Solderless Breadboard, and LEDs. Are you not following my words? Don’t worry; I have a picture for you.

After connecting MFRC522, connect LED to pin D7 and GND.

find code at High Voltages

By following this tutorial, you will be able to know how RFID works, how to interface the RFID module with Arduino, and how to detect the removal of RFID tags.