AUTOMATIC ROOM LIGHT CONTROLLER

A Mini project Report

Submitted to the FACULTY of ENGINEERING of
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY, KAKINADA
in partial fulfillment of the requirements
for award of the Degree of
Bachelor of Technology
in
Electronics and Communication Engineering
by
B.HEMANTH KUMAR G.HYNDAVI
(07481A0433) (07481A0427)
Under the Guidance of
B.K.N.Srinivasa Rao
Associate professor

Department of Electronics and Communication Engineering

GUDLAVALLERU ENGINEERING COLLEGE
SESHADRIRAO KNOWLEDGE VILLAGE
GUDLAVALLERU-521356
ANDHRA PRADESH
2010
 CERTIFICATE

This is to certify that the mini project report entitled “AUTOMATIC ROOM
LIGHT CONTROLLER” is a bonafide record of work carried out by B.Hemanth kumar
(07481A0433) and G.Hyndavi(07481A0427) under my guidance and supervision in partial
fulfillment of the requirements for award of the degree of Bachelor of Technology in
Electronics and Communication Engineering of Jawaharlal Nehru Technological
University, Kakinada.

(B.K.N SRINIVASA RAO) (Ch.V.RAMA RAO)

PROJECT GUIDE HEAD OF THE DEPARTMENT
 ACKNOWLEDGEMENT

We are glad to express our deep sense of gratitude to Sri B.K.N.Srinivasa Rao,
Associate Professor, Electronics and Communication Engineering for his guidance and
cooperation in completing this project. Through this we want to convey our sincere thanks to
him for inspiring assistance during our project.
We express our heartful gratitude and deep indebtedness to our beloved Head of the
Department Sri Ch.V.Rama Rao, Associate Professor, Electronics and Communication
Engineering for his great help and encouragement in doing our project successfully.
We also express our gratitude to our principal Dr.P.Nageswara Reddy, for his
encouragement and facilities provided during the course of project.
We thank one and all who have rendered help to us directly or indirectly in the
completion of this work.

B.Hemanth Kumar

G.Hyndavi
 CONTENTS
Page No.

List of figure i
List of tables ii
Nomenclature iii
Abstract iv
Chapter 1: Introduction 1
1.1 Project definition 1
1.2 Project overview 1
Chapter 2: Circuit Description 2
2.1 Basic Block diagram 2
2.2 Block Diagram Description 3
Chapter 3: AT89C51 Microcontroller 6
3.1 Features 6
3.2 Architecture of 89c51 7
3.3 Pin Diagram 8
3.3.1 Pin Description 9
3.3.2 Oscillator Characteristic 11
3.4 Modes of AT89C51 12
3.4.1 Idle Mode 12
3.4.2 Power down Mode 12
Chapter 4: Description of Hardware Components 13
4.1 LCD Description 13
4.1.1 Introduction 13
4.1.2 Hardware Diagram 14
4.1.3 Pin Assignment 15
4.1.4 Pin Description 16
4.1.5 LCD Commands Description 17
 4.2 ULN2003 19
4.3 Power Supply 21
4.3.1 Introduction 21
4.3.2 Schematic Diagram 22
4.3.3 IC Voltage Regulators 22
4.3.4 Three Terminal Voltage Regulators 23
4.4 Infrared sensor (tsop 1738) 24
4.5 Infra Red LED 25
4.5.1 Features and Specifications 26
4.6 Relay 26
4.7 555 Timer 28
Chapter 5: Hardware Implementation 30
5.1Transmitter Section 30
5.1.1 Transmitter circuit 30
5.1.2 Description 30
5.2 Receiver Section 31
5.2.1 Receiver circuit 31
5.2.2 Description 32
Chapter 6: Software Implementation 33
6.1 Flow Chart 33
6.2 Software Code 34
Chapter 7: Results and Conclusion 38
Appendix A: Data Sheets of LM7805&7812 39
Appendix B: Data Sheets of Micro Controller AT89C51 41
Appendix C: Data Sheets of TSOP 1738 44
Appendix D: Data Sheets of ULN 2003 45
References 46
 LIST OF FIGURES

Fig No. Figure Name Page No.

2.1 Block diagram of Automatic room light controller 2
2.2 ULN2003 3
2.3 Infrared Led 4
2.4 Types of relays 5
3.1 Architecture of Micro controller AT89C51 7
3.2 Pin diagram of Micro controller AT89C51 8
3.3 Oscillator Connections 12
4.1 LCD Display 13
4.2 Hardware Diagram of LCD Display 14
4.3 Pin Assignment for LCD 15
4.4 Schematic Diagram of Driver 20
4.5 Pin Diagram of ULN2003 20
4.6 Block Diagram of Power Supply 21
4.7 Circuit Diagram of Power Supply 22
4.8 7805 IC Voltage Regulator 23
4.9 7812 IC Voltage Regulator 23
4.10 Infrared Sensor 24
4.11 Block Diagram of TSOP 1738 25
4.12 Application circuit 25
4.13 Circuit symbols of relays 27
4.14 Timer IC (555) 28
5.1 Transmitter circuit 30
5.2 Receiver circuit 31
6.1 Flowchart for software implementation 33
 LIST OF TABLES

Table No Table Title Page No

3.1 Alternative function of Port 3 Pins 10
4.1 Pin Description of LCD 16
4.2 LCD commands description 17
 NOMENCLATURE:

IR sensor infrared sensor.

LED light emitting diode.
LCD liquid crystal display.
 ABSTRACT:
(Key words: IR sensor, relay)

This Project “Automatic Room Light Controller with Visitor Counter using
Microcontroller” is a reliable circuit that takes over the task of controlling the room lights as
well as counting number of persons/visitors in the room very accurately.

When somebody enters into the room then the counter is incremented by one and the
light in the room will be switched ON and when any one leaves the room then the counter is
decremented by one. The light will be switched OFF only when all the persons in the room
go out. The total number of persons inside the room is also displayed on the LCD display.

The microcontroller does the above job. It receives the signals from the sensors, and
this signal is operated under the control of software which is stored in ROM. Microcontroller
AT89C51 continuously monitors the IR sensors 1&2, when any object pass through the IR
sensor’s then the IR rays falling on the IR sensor’s are obstructed and this obstruction is
sensed by the Microcontroller.