INTRODUCTION

Here is a project called ‘Digital Code Lock using AT89C2051′.

LCD is used for display and a keyboard is used to input  the keys. This

project source code is written in C.

This a simple project with efficient hacking prevention

from Brute Force etc. The basic user lock is of 5 Digits and Master Lock

is of 10 digits so its not easy for an intruder to break the lock unless

you keep the code simple.

The input is taken from a 4×3 Keypad (please see the schematic

for more information) and Display the user input on a 2×16 LCD. A pin

is assigned as output for activating and deactivating the lock. For

demonstration an LED is connected to that pin.

The user has two options either he/she can use its own 5 digit

code or use the default 5 digit code. If user has to do setup his own

code, then he has to enter “12345″ and press ‘#’. After this.. controller

will ask for 10 Digit master password which is preprogrammed in the

controller. Entering master lock, user can enter the new 5 digit code

for the lock and press ‘#’ to save it.

Keypad has 12 keys (4×3) starting from 1,2,3,4,5,6,7,8,9,*,0,#

(please see the schematic for layout). Numeric keys are used for

entering numbers. ‘*’ is used as the Cancel key and ‘#’ is used as the

Enter key.

CIRCUIT DIAGRAM

PROJECT DESCRIPTIONIn my project Wireless Digital Code Lock with a Status Display is used to protect the efficient hacking prevent from brute force etc.The basic user lock is of 4 Digits and Master lock is of 1 digit so itâ„¢s not easy for an intruder to break the lock unless you keep the code simple. The input is taken from a 4x3 Keypad The user input is displayed on a 2x16 LCD A pin is assigned as output for activating and deactivating the lock. For demonstration i have connected an LED to that pin.

HARDWARE REQUIREMENTSMICROCONTROLLER(AT89S51) UNITPOWER SUPPLYKEYPAD UNITBUZZER UNITSOFTWARE REQUIREMENTSEMBEDDED CKEIL COMPILER

SOFTWARE IMPLEMENTATIONThe software used for this project is KEIL, FLASH Programmer, OrCAD and Visual Basic6.0. Keil is used to develop the program for AT89S51 microcontroller. Flash programmer is used to download the program into the AT89S51 microcontroller.OrCAD software is used to design the PCB layout.

BLOCK DIAGRAM:TRANSMITTER SECTIONBLOCK DIAGRAM:RECIEVER SECTIONCIRCUIT DIAGRAM

MICROCONTROLLERThe AT89S52 is a low-power, high-performance CMOS 8-bit microcontroller with 8K bytes of in-system programmable Flash memory.

POWER SUPPLYPower supply is a reference to a source of electrical power. A device or system that supplies electrical or other types of energy to an output load or group of loads is called a power supply unit or PSU.

STEP DOWN TRANSFORMERThe transformer is transferring the electrical voltage or current from one circuit into another circuit without changing the frequency. When (0-220V) AC is applied at the primary winding, it will step down the power supply voltage and given as(0-6V) AC in the secondary winding as an output.

ENCODER (HT12E)The 212 encoders are a series of CMOS LSIs for remote control system applications. They are capable of encoding information which consists of N address bits and 12_N data bits.

DECODER (HT12D) The 212 decoders are a series of CMOS LSIs for remote control system applications. They are paired with Holtek_s 212 series of encoders.The decoders receive serial addresses and data from a programmed 212 series of encoders that are transmitted by a carrier using an RF or an IR transmission medium.

TRANSMITTER MODULE (STT433)The transmitter operates from a 1.5-12V supply, making it ideal for battery-powered applications. The transmitter employs a SAW-stabilized oscillator, ensuring accurate frequency control for best range performance.

RECEIVER MODULE (STR433)The STR-433 is ideal for short-range remote control applications where cost is a primary concern. The receiver module requires no external RF components except for the antenna.

LCD DISPLAY (16x2)LCD module have 8-bit data interface and control pins. One can send data as 8-bit or in pair of two 4-bit nibbles.To display any character on LCD micro controller has to send its ASCII value to the data bus of LCD. LCD display used here is having 16x2 size. It means 2 lines each with 16 character.

KEYPAD SWITCHESThe key board here we are interfacing is a matrix keyboard. This key board is designed with a particular rows and columns. These rows and columns are connected to the microcontroller through its ports of the micro controller 8051. We normally use 8*8 matrix key board.

BUZZER

Buzzer is an electromagnet that automatically connects and disconnects many times per minute. This will cause the vibration of the armature and creation of a buzzing sound.

APPLICATIONSItâ„¢s used to prevent from hacking.It can be used in any device.It protects any device and is very secured.