RFID Based Attendance System – Circuit, Working, Source Code

In this article, we’ve developed two distinct RFID-based Attendance system projects utilizing an 8051 microcontroller and an AVR (ATmega 8) microcontroller.

Traditionally, college attendance has been documented on paper, which can lead to errors and consumes a significant amount of time when done manually. Consequently, the proposed attendance system employs RFID technology to streamline the attendance-taking process.

In this approach, each student is provided with an RFID tag, and the institution utilizes a central control unit. Whenever a student places their RFID card near the reader, the system records their attendance, a process that is elaborated upon in this article.

However, it’s advisable to have a basic understanding of how to connect an LCD to an AVR microcontroller before delving into this post, as this aspect is also covered in the circuit design.


  • Construction and Output Video
  • RFID Based Attendance System Circuit Principle
  • Circuit 1 RFID Based Attendance System Circuit Diagram using AVR
    • Circuit Components
    • Circuit Design of RFID Based Attendance System
    • RFID based Attendance System Circuit Simulation Video
    • How to Operate RFID Based Attendance System Circuit?
    • Output Video (RFID Attendance System using AVR)
  • Circuit 2 RFID based Attendance System using 8051
    • Circuit Diagram
    • Components Required
    • Circuit Design
    • Working
  • Applications of RFID Based Attendance System
  • Limitations of RFID Based Attendance System

Construction and Output Video

RFID Based Attendance System Circuit Principle

The RFID-based attendance system comprises RFID readers, RFID tags, LCD displays, and microcontroller units. RFID connectivity to the microcontroller is established through USART, where RFID cards transmit data to a reader, which subsequently relays it to the microcontroller.

Various applications leverage radio frequency technology, and RFID tags are categorized into two types: passive tags and active tags. Passive tags incorporate a 13-digit number tag, while active tags are equipped with read/write functionality, enabling both reading from and writing to them. This project utilizes passive tags.

Active tags can be assigned to students in real-time, with their roll numbers serving as tags. The RFID reader incorporates a copper winding.

When the tag is brought close to the reader, data is transmitted to the reader through induced mutual inductance energy. The reader then transfers this data to the microcontroller, which continually checks for incoming data. Upon receiving data, the microcontroller compares it with the database.

If the tag is authenticated, the microcontroller records the attendance. Additionally, you can view the output video of the RFID-based attendance system for further reference.

Circuit 1 RFID Based Attendance System Circuit Diagram using AVR


  • ATMEGA8 Microcontroller.
  • RFID Reader
  • RFID Tags.
  • LCD display

Circuit Design of RFID Based Attendance System

The circuit structure of an RFID-based attendance system follows a straightforward configuration. The RFID Reader features transmit and receive pins, which are linked to the microcontroller’s corresponding transmit and receive pins, specifically PD0 and PD1. Ground (GND) is connected to the ground, while VCC is linked to a 5-volt source.

In cases where the module’s pins are not readily accessible, a DB9 connection can be utilized for the connection. In this setup, the receiver pin corresponds to PD0, and the transmitter pin corresponds to PD1.

The RFID module employs USART as its communication protocol for interacting with the controller. USART stands for Universal Synchronous and Asynchronous Receive and Transmit. UART, or Universal Asynchronous Receiver/Transmitter, facilitates the transmission of serial data from the RFID module to the microcontroller. Within the ATmega8 microprocessor, USART registers are internally present. To enable serial data transmission or reception, these registers must be appropriately configured.

Port B of the microcontroller is linked to the LCD display. The LCD operates in 4-bit mode, as specified in the circuit diagram. Data ports D4 through D7 are interconnected with the microcontroller’s PB0 through PB3 pins.

Specifically, the RS pin is connected to PB4, the RW pin is attached to PB5, and the enable pin is joined with PB6 of the microcontroller. To display data on the LCD, the initial steps involve configuring the LCD in 4-bit mode. Subsequently, the RW pin is set to low, the RS pin is set to high, and the enable pin is set to high. Data is then transmitted via the data pins, followed by lowering the enable pin to complete the data transfer.

RFID based Attendance System Circuit Simulation Video

How to Operate RFID Based Attendance System Circuit?

  1. Switch on the circuit after making all of the above connections.
  2. “PLEASE SWIPE THE CARD” is displayed on the LCD.
  3. Place the RFID tag in close proximity to the reader.
  4. The data in the tag is then read by the reader and transmitted to the controller.
  5. The tag is compared to the database by the microcontroller. If the tags match, the LCD will display “authenticated” and your attendance will be taken.
  6. Now insert a card that isn’t in the database and verify that it is authenticated.
  7. The LCD now reads “Unauthorized,” and the attendance will never be taken.
  8. In this way, we can use implement this circuit.

Output Video (RFID Attendance System using AVR)

Circuit 2 RFID based Attendance System using 8051

The above circuit shows RFID based attendance system using AVR. Here is the same project but using 8051 microcontrollers. Let us see the circuit and working of this circuit.Circuit working principle is same as the above circuit.

Circuit Diagram

Components Required

  • AT89C51 Microcontroller
  • AT89C51 Programming Board
  • 11.0592 MHz Quartz Crystal
  • 2 x 33pF Ceramic Capacitors
  • 2 x 10KΩ Resistor
  • 10µF Electrolytic Capacitor
  • 2 x Push Button
  • 16 x 2 LCD Display
  • 3 x 1KΩ Resistor
  • 10KΩ POT
  • EM-18 RFID Reader Module
  • RFID Tags or Cards
  • Connecting Wires

Circuit Design

The project’s major components are an 8051-based microcontroller, a 162 LCD, and an RFID reader module.
We’ll start by looking at the microcontroller’s fundamental connections. A crystal, a reset circuit, and external access will all be required here.

An 11.0592 MHz quartz crystal is attached to pins 18 (XTAL2) and 19 (XTAL1) of the microcontroller to use the on-chip oscillator. From the crystal to ground, two 33pF ceramic capacitors are connected.

The reset on the 8051 microcontroller is active high, which means it will reset when a high pulse is applied to the RST pin. From the microcontroller’s RST (Pin 9) to ground, a 10K resistor is connected.

Between the positive supply and the RST pin is a 10F electrolytic capacitor. The capacitor is attached to a push button.

A 10K resistor is used to link the External Access pin (Pin 31) to positive supply. The basic connections to the microcontroller are now complete.

The LCD will now be connected to the microcontroller. A pot is attached to the LCD’s contrast adjust pin, Pin 3, to modify the display’s contrast.

To begin, connect the LCD’s three control pins, RS, RW, and E, to P3.6, GND, and P3.7, respectively. Then connect the LCD display’s 8 data pins to the microcontroller’s PORT1 pins.

After connecting the display, now we are going to connect the RFID reader module. Connect the TX pin of RFID Reader to RXD pin i.e. P3.0 of the microcontroller. Similarly, connect the RX pin of RFID Reader to TXD pin i.e. P3.1 of the microcontroller.

Finally, a button is connected to P3.3 (IN) to view the attendance details. 


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