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RFID based Secured access system using 8051 microcontroller (AT89C51)

Summary

Developed By: 
Himanshu Choudhary

This is a very useful application of RFID (Radio-frequency identification) and is very commonly used in institutes, offices, homes and so on. An RFID system consists of a reader device and a transponder. A transponder or tag has a unique serial number which is identified by the reader. Here RFID has been interfaced with AT89C51 to provide secured access. The relevant messages are also displayed on a 16x2 LCD. The free source code for the program is available in C.

 

RFID based Secured access system using 8051 microcontroller (AT89C51)

Description


Low frequency RFID works on the principle of radio waves and at the frequency of 125 KHz. There is a coil inside the RFID tag and when it is influenced by magnetic field, it sends an identity code to a device for further processing. (For more details, refer interfacing RFID with AT89C51).

 

The RFID tag is used as an identity for a particular user. If the identity (serial number of the tag) of the user is matched with the one already stored in this system, he gets immediate access through it. This RFID based secured access system also has many additional features. For example, a new user can register himself with the system. A registered user can also withdraw his entry from the system. These features can be accessed by pressing a tactile switch connected to the microcontroller.

 

In beginning, the user is prompted to scan his tag or ID. The serial code of the tag is identified by the reader module and is sent to AT89C51 for checking. If the ID is matched by the microcontroller, the user gets the access. On the contrary, if the tag is not identified, a message (‘Wrong ID’) is displayed on LCD screen.

 

A new user needs to press the switch to register after which his identity is verified twice with RFID tag. The new record is stored by the microcontroller to grant future access. The system also shows ‘Error’ if the tags do not match during verification. An existing user can delete his record by pressing the same switch. Again the verification is carried out and the user is deleted if the IDs match. If a different tag is scanned through the reader, LCD displays ‘you have shown different ID’.

 

When an RFID tag comes in this range, the reader detects it and sends a unique code of the tag serially. This serial code, consisting of 12 bytes, is received by the microcontroller. This code is treated as an ID for the user and is stored as an array in the microcontroller. If the ID is matched with this code, the user is granted access though the system. For more details on working and connections of the circuit, refer RFID interfacing through serial interrupt.

 

 

 

 

Circuit Diagram


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Components

MAX232 | IC MAX232
MAX232
 
The MAX232 IC is used to convert the TTL/CMOS logic levels to RS232 logic levels during serial communication of microcontrollers with PC. The controller operates at TTL logic level (0-5V) whereas the serial communication in PC works...
AT89C51 Microcontroller, Atmel 89C51 Controller Image
AT89C51 Microcontroller

AT89C51 is an 8-bit microcontroller and belongs to Atmel's 8051 family. ATMEL 89C51 has 4KB of Flash programmable and erasable read only memory (...

16 x 2 LCD | 16x2 Character LCD Module
LCD

 

LCD (Liquid Crystal Display) screen is an electronic display module and find a wide range of applications. A 16x2 LCD display is very basic module and is very commonly used in various devices and circuits. These modules are preferred over seven segments...

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