What is RFID ? How It Works?

Long days went by when people used to stand and wait in long checkout lines at the grocery store. Thanks to Radio Frequency IDentification (RFID) technology. With this RFID based automatic checkout solution through walking, you can fill your car and walk right out of the door. Now you will have to wait as someone rings each item in your cart one at a time. Instead, the RFID tag attached to the item will communicate with the RFID reader that will detect every item in the cart and each will ring almost immediately.


For most of our RFID based Arduino projects, RC522 RFID Reader/RFID Reader is the most rfid-based reader. It is easy to interface with low power, low cost, very rugged, and insanely popular among hobbyists.

What is RFID technology and how does it work?

The RFID or radio frequency identification system has two main components, the transponder/video associated with an object to be identified.

A reader has a radio frequency module and an antenna that generates high frequency electromagnetic fields. On the other hand, the tag is usually an inactive device, which means it doesn’t have a battery. Instead it is a microchip that stores and processes information, and receives an antenna and transmits a signal.

To read the encoded information on a tag, it is placed in close proximity to the reader (does not need to be within sight of the reader’s direct line). A reader generates an electromagnetic field that causes electrons to move through the antenna of the tag and later power the chip.

The chip operated inside the tag then reacts by sending your stored information back to the reader as another radio signal. This is called backscatter. Backscatter, or electromagnetic/magnetic. Changes in the RF waveform, detected and interpreted by the reader then sends the data out to a computer or microcontroller.

RFID Module

Hardware Overview – RC522 RFID Reader/Writer Module


Rc522 RFID module based on MFRC522 IC from NXP is one of the most affordable RFID options that you can get online for at least four dollars. It usually comes with an RFID card tag containing 1KB memory and key fob tags. And best of all, it can write a tag, so you can store some sort of secret message in it.

The RC522 RFID Reader module is designed to create a 13.56MHz electromagnetic field that it uses to communicate with the RFID tag (ISO 14443A standard tag). The reader can communicate with a microcontroller on a 4-pin serial peripheral interface (SPI) with a maximum data rate of 10Mbps. It also supports communication on I2C and UART protocols.

The module comes with a barrier pin. It’s easy because instead of constantly asking the RFID modules “Is there a card in view yet? “The module will alert us when a tag comes into its vicinity.

The operating voltage of the module is from 2.5 to 3.3V, but the good news is that the logic pins are 5-volt tolerant, so we can easily connect it to an Arduino or 5V Power source.


Frequency Range13.56 MHz ISM Band
Operating Supply Voltage2.5 V to 3.3 V
Host InterfaceSPI / I2C / UART
Max. Operating Current13-26mA
Min. Current(Power down)10µA
Logic Inputs5V Tolerant
Read Range5 cm

Related posts

Leave a Comment