Electronic Key Management System With I-Button And Avr Microcontroller

Abstract

Electronic Key Management System is the system in which keys are managed and secured in the electronic locker, every key is attached with a chip using fob which works on the mechanism of 1-Wire Communication and chip has unique 64 bit data stored in the chip which can be fetched using microcontroller, and build a login system to display the keys available in the locker and can only be accessed by authorized person.

Introduction

It is the requirement of hotels, offices, banks, colleges, universities, casinos, police stations, and all other places where keys are using on daily bases and all need to manage and secure them from unauthorized person, so we developed this system to make them secure and make a mechanism to find a key without any trouble to look for the right key. This system has two main parts. Hardware, in which AVR ATmega16 microcontroller is used to lock the keys using solenoid and get the data from the I-button (chip) which is attached with the fobs to identify the keys. Software, which will give the access to the authorized person to login to the display and get the key which is access to the particular person, however in this article we will just discuss the hardware of the system.

Literature Review

iButton – how does the iButton work? The silicon chip inside the stainless steel can is connected via two internal wires to the sides and front face of the iButton. All communication with iButtons is reduced to a single signal plus ground for a simple, self–aligning contact long and short pulses encode the binary 1’s and 0’s.

Because iButtons are digital circuits, they talk directly to other chips in a computer, resulting in minimal cost interface using one CMOS/TTL logic signal. A reader/writer for iButtons can be implemented with just one spare I/O line of a microcomputer, often a free resource in a system.

Methodology

The whole system cycle starts with the user verification, once it is done, the system will ask the mode of operation.

Mode 1: Request for key

Mode 2: Returning key

MODE 1: Once the mode is selected next step is the selection of required key, the controller will read all slots, before system unlocking. User have to enter the date and time of returning this key. This step will unlock the slot, LED will illuminate to tell the user here is the key you are looking for among several keys, so that user can easily identify it. If the requested key is not present then, the system will automatically indicate the respective person who has that key.

MODE 2: While returning any key, after user verification the key fob with i-button can be inserted in a particular slot where the LED is illuminate; the microcontroller read the address and update the system.

Implementation

Power supply

9V AC/DC input supply is required for the power supply. Bridge rectifier converts the input AC supply into DC or it can correct the polarity when we apply DC input. The input supply must be capable to provide up to 1A supply current. A filter capacitor and a voltage regulator LM7805 is used to provide the regulated +5V supply for microcontroller, also the unregulated DC supply of 12 V is taken from bridge rectifier for relays.

Communication port (comm port)

A comm. port is provided for serial communication with system. DB-9 female connector is used as the comm. port. The In-built UART can receive or transmit the serial data through a line drive MAX232. This line driver IC converts the incoming RS 232 signals into the TTL for microcontroller. Similarly it converts the TTL signals coming from micro controller to RS 232.

Realys

12 volt DC Relays are used to control the solenoid and Darlington transistor are used to increase the current to operate the relays. A digital output pin of the micro controller is connected to the base of a transistor which controls the current to a normally open, SPST (single pole single through) relay. When the relay coil is energized, it closes the contacts, which allows current from the 12V supply to flow through the solenoid. When the solenoid coil is energized, the lock opens & allows releasing the key.

Micro controller

ATmega16 is an 8-bit high performance microcontroller of Atmel’s Mega AVR family with low power consumption. Atmega16 is based on enhanced RISC (Reduced Instruction Set Computing) architecture with 131 powerful instructions. Most of the instructions execute in one machine cycle. Atmega16 can work on a maximum frequency of 16MHz.

LCD interface

Pin crimp shell connector is used to interface an LCD module with the microcontroller. Microcontroller is used at this connector for data bus of LCD module. The contrast pin of LCD module should be connected to ground. The backlight LCD module is connected to the supply to turn on backlight permanently. Here we used LCD for trouble shooting in case of any failure in the system.

Conclusion

Electronic Key Management System successfully implemented. The whole process is controlled by a controller. This project improving security and administrative effectiveness with lower operational cost. Distribution of keys significantly reduces the risk of compromise; only authorized users are able to access the system. This reduces the risk of the keys or asset falling into the wrong hands or stops entry into restricted areas.