ELECTRONIC CODE LOCK DEVICE

CIRCUIT DESIGN OF ELECTRONIC CODE LOCK

INTRODUCTION

o Access control system that allows only authorized persons to access a

restricted area

o Allows the user to unlock the device with a password.

o The major components include a keypad, LCD and the controller P89V51

which belongs to the 8051 series of microcontrollers.

o User can also set his password to ensure better protection.

Can be adapted to any electronic gadget which needs to be protected

from unauthorised persons/access.

Responds only to the right sequence of four digits that are keyed in

remotely.

If a wrong key is touched, it resets the lock.

Block Diagram

COMPONENTS USED IN THE DEVICE

LCD 16*2

Resistors 10k*12, 1k*10, 1.5k

Crystal 11.0592Hz

Capacitors 33pF*2, 10µF, 0.1µF*3

IC7805

Battery power 9V

Switches

LED’s

Connecting wires

Microcontroller P89V51

MICROCONTROLLER P89V51

16/32/64 kB flash and 1024 B of data RAM

A key feature of the P89V51 is its X2 mode option.

The flash program memory supports both parallel programming and

in serial ISP

Supports 12-clock (default) or 6-clock mode selection via software

or ISP

Features

80C51 CPU

5 V operating voltage from 0 MHz to 40 MHz

16/32/64 kB of on-chip flash user code memory

PCA (programmable counter array) with capture/compare functions

Four 8-bit I/O ports with three high-current port 1 pins

Three 16-bit timers/counters

BLOCK DIAGRAM OF MICROCONTROLLER

PIN DIAGRAM

Vcc-Pin 40 provides supply voltage to the chip. The voltage source

is +5 V.

GND- Pin 20 is the ground.

RST-Pin 9 is the reset pin. It is an input and is active high (normally

low).

EA pin is connected to the Vcc and connected to pin no. 31.

PSEN is “program store enable.” It is the read strobe to external

program memory.

ALE is output pin and is active high. When connecting a

microcontroller to external memory, port 0 provides both address

and data.

I/O PORT PINS AND THEIR FUNCTIONS

PORT 0:an 8-bit open drain bidirectional I/O port. It is the

multiplexed low-order address and data bus

PORT 1:an 8-bit bidirectional I/O port. P1.5, P1.6, P1.7 have high

current drive of 16mA

PORT 2:8-bit bidirectional I/O port, it receives control signals and a

partial of high-order address bits during the programming

LIQUID CRYSTAL DISPLAY

o Flat panel display, electronic visual display, video display that uses the light modulating properties of liquid crystals .

APPLICATIONS

Used in computer monitors, television, instrument panels,

aircraft cockpit displays, signage, etc

an electronically modulated optical device made up of any number

of segments filled with liquid crystals and arrayed in front of a

light source or reflector to produce images in monochrome

Also used in video players, gaming devices, clocks, watches,

calculators, and telephones and have wide range of screen sizes

Vcc

1615141312111098

654321

7

1615141312111098

654321

7

D7

E

Vcc

D4

ContrastRS

Gnd

R/W

Gnd

D0

D3

D6D5

13

2

D2D1

LCD Pin Description

POWER SUPPLY

COMPONENTS USED

The transformer steps down the 220 V a/c. into 12 V a/c

A rectifier transforms ac into dc by limiting. The output resulting from a rectifier is a pulsating D.C. voltage

The ripple of the D.C. voltage is smoothened using a filter capacitor

The voltage regulator regulates the supply if the supply if the line voltage increases or decreases

WORKING OF PROJECT

As the program starts, string ‘Enter Password’ is displayed on LCD

After the four digits are entered, the user is prompted to ‘Confirm Password’

If the passwords do not match, a message is displayed to indicate ‘Wrong Password’

Again the keypad is scanned for pressed keys and corresponding digits are identified

If all the four digits match with set password, the lock output pin goes high

The system gets locked if more than three attempts are made with wrong password to open the electronic lock

The high output of the logic circuit enables the AND gate

APPLICATIONS:

used to automate the door locking process, so the user need not to carry the door lock keys

used in Mobile phones for security purposes

Used in Banks lockers

used in applications like Lift, Telephone Locking, Refrigerators etc

RESULT AND CONCLUSION

Result:-all electronics devices plays very important role in Programming and in Electronics Department

Conclusion:-All electronics devices can perform many functions using interfacing and programming with Embedded C language

Future scope:-In future, the improved version of Microcontrollers will be more useful.In serial communication and Robotics, everywhere we need Microcontrollers to store program in it

REFERENCES

www.electronicsforyou.com

www.encyclopedia.com

www.wikipedia.com

Thank you