RFID Sensor

An RFID Sensor (Radio Frequency Identification Reader) is a device used to gather information from an RFID tag, which is used to track individual objects.

It is a wireless identification technology that uses radio waves to transfer data from the card tag to an RFID reader and identify the object presence.

Just like the bar code technology, RFID is used to identify objects, persons, by reading the card tag. This is better than the bar code because the bar code can sometimes be damaged or unreadable.

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rfid sensor

This RFID module is a 125KHz card reader mini-module which is design to read ing code from the 125KHz card tag.

It is mainly used in companies to access authorized employees, attendance systems, personal identification.

RC522 RFID Pinout

rfid pinout
  • VCC (3.3v):- VCC pin is connected to the Arduino 3.3V pin to supply power to the module. Connecting it to the 5v Arduino pin can destroy the RFID module.
  • RST:- This pin is used to reset the module.
  • GND:- This pin connects to the GND pin of Arduino.
  • IRQ:- This is blocking or interrupt pin that can alert the microcontroller when it comes around the RFID tag.
  • MISO/SCL/TX:- This pin is  Master-In-Slave-Out. It acts as serial data output and connects to the Arduino RX pin.
  • MOSI:- Master-Out-Slave-In pin is SPI input to the RC522 module.
  • SCK:– Serial Clock is accepting clock pulses provided by Arduino.
  • SS / SDA / Rx:- When the SPI interface is enabled it acts like Signal input when the I2C interface is enabled it acts like Serial data and acts as Serial data input when the UART interface is enabled. This pin usually connects to the Arduino TX pin.


Dimensions60mm × 39mm
Working voltage5V DC
Read RangeUp to 3 cm
Max Data Transfer Rate10 Mbit/s

Uses of RFID

  • In attendance system.
  • Door Looking System.
  • Provide access to employees in the company.
  • Home/office security systems.

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