Radio RF Wifi Circuit Diagrams

RFID Based Attendance System – Circuit, Working, Source Code

In this article, we have developed two distinct RFID-based attendance system projects using two different microcontrollers, namely the 8051 microcontroller and the AVR (ATmega 8) microcontroller.

Typically, college attendance procedures rely on manual paper-based methods, which can result in errors and consume considerable time. To address these issues, we have implemented an automated attendance system leveraging technology.

In this system, each student is provided with an RFID tag, and the educational institution is equipped with a control unit. Whenever a student places their RFID card near the reader, the attendance is automatically recorded. The details of this process are elaborated in the article.

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


  • Construction and Output Video
  • Based Attendance System Circuit Principle
  • Circuit 1 Based Attendance System Circuit Diagram using AVR
    • Circuit Components
    • Circuit Design of 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. The connection between RFID and the microcontroller is established through USART. RFID cards transmit data to a reader, which in turn forwards it to the microcontroller.

Radio frequency technology finds application in various scenarios, and RFID tags fall into two categories: passive and active. Passive tags come equipped with a 13-digit number tag, while active tags possess read/write capabilities, allowing data to be both read from and written to them. For this project, passive tags are employed.

In the case of active tags, they can be instantly assigned to students, with their roll numbers serving as tags. An RFID reader includes a copper winding.

When the tag is placed in proximity to the reader, data is transferred to the reader through induced mutual inductance energy. The reader then relays this data to the microcontroller. The microcontroller continuously monitors incoming data and, upon receipt, cross-references 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 structural layout of an RFID-based attendance system’s circuit is relatively uncomplicated. The RFID Reader features transmit and receive pins, which are linked to the microcontroller’s corresponding transmit and receive pins, typically PD0 and PD1. Ground (GND) is connected to the ground, while VCC is connected to the 5-volt supply.

In instances where the module’s pins are unavailable, a DB9 connection can be employed for connection. The receiver pin corresponds to PD0, while the transmitter pin corresponds to PD1.

The RFID module utilizes the USART communication protocol to interact with the controller. USART stands for Universal Synchronous and Asynchronous Receive and Transmit, and it facilitates the transmission of serial data from the RFID module to the microcontroller. Internally, the ATmega8 microprocessor incorporates USART registers, which must be declared to enable serial data transmission or reception.

The microcontroller’s Port B interfaces with the LCD display. The LCD is configured to connect to the microcontroller in 4-bit mode, as indicated in the circuit diagram. Data ports D4–D7 are linked to the microcontroller’s PB0–PB3 pins.

Furthermore, the RS pin is connected to PB4, the RW pin is connected to PB5, and the enable pin is linked to PB6 of the microcontroller. To display data on the LCD, the initial step is to set the LCD in 4-bit mode. Subsequently, the RW pin is set low, the RS pin is set high, and the enable pin is raised to a high state. Data is then transmitted through the data pins, followed by lowering the enable pin. This process allows data to be displayed on the LCD.

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 primary components of the project include an 8051-based microcontroller, a 16×2 LCD, and an RFID reader module. Let’s begin by examining the essential connections for the microcontroller.

For the microcontroller’s fundamental connections, we need a crystal, a reset circuit, and provisions for external access. We’ll use an 11.0592 MHz quartz crystal connected to pins 18 (XTAL2) and 19 (XTAL1) of the microcontroller to utilize its on-chip oscillator. To ground, we connect two 33pF ceramic capacitors, one on each side of the crystal.

The reset function on the 8051 microcontroller is active high, which implies that it resets when a high pulse is applied to the RST pin. A 10K resistor is connected from the microcontroller’s RST (Pin 9) to the ground. Between the positive supply and the RST pin, there’s a 10uF electrolytic capacitor, which is linked to a push button.

We use a 10K resistor to connect the External Access pin (Pin 31) to the positive supply, completing the basic connections to the microcontroller.

Next, we’ll establish the connections between the microcontroller and the LCD. To adjust the contrast of the display, we connect a potentiometer to the LCD’s contrast adjust pin, Pin 3.

For the LCD connections, start by linking the three control pins (RS, RW, and E) to the microcontroller: P3.6, GND, and P3.7, respectively. Subsequently, connect the eight data pins of the LCD display to the microcontroller’s PORT1 pins.

With the LCD display successfully connected, it’s time to establish the connections for the RFID reader module. Connect the TX pin of the RFID Reader to the RXD pin (P3.0) of the microcontroller. Similarly, link the RX pin of the RFID Reader to the TXD pin (P3.1) of the microcontroller.

Lastly, we connect a button to P3.3 (IN) to access and view the attendance details.

RFID Based Attendance System


The objective of this project is to develop an RFID-based Attendance System utilizing an 8051 microcontroller, where the attendance of students or employees is automatically logged by simply swiping a card. This page provides an explanation of the project’s operation.

Upon activating this circuit, the microcontroller initially displays the message “Swipe the card” on the LCD screen. When the RFID reader detects an ID card, it transmits the card’s unique identifier to the microcontroller via a serial connection.

Subsequently, we need to compare the acquired card number with the numbers stored in the microcontroller’s memory or in a database, using the appropriate code.

If a match is found between any of these numbers and the received card number, the corresponding name associated with that number is displayed on the LCD screen. Simultaneously, the attendance for the individual linked to the corresponding number is recorded.

Pressing a button concludes the attendance recording process, and the details are repetitively displayed on the LCD until the microcontroller is reset.

Applications of RFID Based Attendance System

  • RFID based attendance system can be used in educational institutions, industries, anywhere.
  • RFID is emerging technology and is used in applications where authentication is needed.

Limitations of RFID Based Attendance System

  • RFID attendance system is secured, but there is a chance of misusing the cards. One person can give another person’s attendance if he/she had RFID card.
  • If the card was swiped for more than once, there is a chance of giving attendance for next days also if code is not written properly.

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