Dual regulated water supply








  • Introduction
  • Block diagram
  • Circuit Diagram
  • Hardware description
  • Component List
  • Software’s Used
  • Applications
  • Bibliography


In Electronics Access control system, we will control the door using password protection. In this project we will control it using

microcontroller 89s52. we will use key matrix to enter data, if entered data will match with stored data in micro controller, then only it will allow the door to open, otherwise it will remain locked.

The main key in this project is coding of password. we will use stepper motor to open the door, so that door will open step by step.

We will use LCD display to show the entered password.

It will also show the entered password match with stored password, if the password will match then it will show access successful, otherwise it will show denied. LCD display will also show clock. if entered password three times denied, then it will move the programmer in continuous loop & will not allow to entered password.

When signal match with the stored password then microcontroller will give its output to stepper motor circuit through port3. it will give supply to stepper motor & Rx pulses from microcontroller.

Then door will open.

Block Diagram of Electronic Access Control system:

Key Board

For password


Driving Circuit


DC motor drive circuit

DC motor


LCD display


What is Open SYSTEM?

An open system is the normal desktop computer where you can use it for any tasks. If you want to process text documents you can install Ms-word if you want to send mail you can use outlook express and counts on.

What is Embedded System ?

An embedded system is the system where you can use it for a specific task.


A microcontroller (often abbreviated MCU) is a single computer chip that executes a user program, normally for the purpose of controlling some device hence the name microcontroller.

A microcontroller is differed from microprocessor in many ways. Basically microprocessors are the devices which can process huge amount of data. A microprocessor can’t do anything on it own. Even to light a led a microprocessor needs minimum of a ROM, RAM, Latch, Address decoders, PORT controllers. But for the same application if you take a microcontroller you barely need a crystal and some capacitors.

So from this you can understand how versatile the microcontroller is.

Different micro controllers in market

  • PIC: One of the famous micro controllers used in the industries. It is based on RISC Architecture which makes the microcontroller process faster than other microcontroller.
  • INTEL: These are the first to manufacture micro controllers. These are not as sophisticated other micro controllers but still the easiest one to learn.
  • Atmel: Atmel’s AVR micro controllers are one of the most powerful in the embedded industry. This is the only microcontroller having 1kb of ram even the entry stage. But it is unfortunate that in India we are unable to find this kind of microcontroller.

Intel 8051:

Intel 8051 is CISC architecture which is easy to program in assembly language and also has a good support for High level languages.

The memory of the microcontroller can be extended up to 64k.

This microcontroller is one of the easiest micro controllers to learn.

The 8051 microcontroller is in the field for more than 20 years. There are lots of books and study materials are readily available for 8051.

ATMEL 89s51:


  • Compatible with MCS®-51 Products
  • 4K Bytes of In-System Programmable (ISP) Flash Memory – Endurance: 1000 Write/Erase Cycles
  • 4.0V to 5.5V Operating Range
  • Fully Static Operation: 0 Hz to 33 MHz
  • Three-level Program Memory Lock
  • 128×8-bit Internal RAM
  • 32 Programmable I/O Lines
  • Two 16-bit Timer/Counters
  • Six Interrupt Sources
  • Full Duplex UART Serial Channel
  • Low-power Idle and Power-down Modes
  • Interrupt Recovery from Power-down Mode
  • n Dual Data Pointer
  • Power-off Flag
  • Flexible ISP Programming (Byte and Page Mode)

Description :

The AT89S51 is a low-power, high-performance CMOS 8-bit microcontroller with 4K bytes of In-System Programmable Flash memory. The device is manufactured using Atmel’s high-density nonvolatile memory technology and is compatible with the Indus-try-standard 80C51 instruction set and pin out. The on-chip Flash allows the program memory to be reprogrammed in-system or by a conventional nonvolatile memory pro-gramme. By combining a versatile 8-bit CPU with In-System Programmable Flash on a monolithic chip, the Atmel AT89S51 is a powerful

microcontroller which provides a highly-flexible and cost-effective solution to many embedded control applications.

Component List:

Microcontroller 89s52

LCD display 16*2 matrix

Keys matrix

DC Motor

Wood or ply

Crystal 11.0592Mhz

Resistance 220 ohm

Capacitor 0.01 micro farad

Keyboard general or push to on Button

DIP switches

Connecting wires

Microcontroller programming kit

12v supply

Copper clad board

Ferric chloride




8051 programmer universal kit

CRO 20 MHz

Digital multimeter


Keil for Programming

Or CAD for PCB designing

Proteus 7.6 Simulation

Features :

LCD display- entered password show on LCD

Programmable- flexible- programming can be change , so this project is flexible

Component easily available

Low cost

General use for security system


  1. Security System of offices, lockers , rooms.
  2. For cranes – we can make cranes with same logic.
  3. For lift control- with change in programming we can change in to lift control circuit.






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