Automatic Room light controller with sensors

Automatic room light controller with sensors

ELECTRONICS & COMMUNICATION ENGG.(KGRCET)

A Mini Project Report Entitled

On

“AUTOMATIC ROOM LIGHT CONTROLLER WITH

SENSORS”

A report Submitted in partial fulfillment of the

Academic requirements for the award of the degree of BACHELOR OF TECHNOLOGY

in

ELECTRONICS AND COMMUNICATION ENGINEERING

by

P.BHASKAR (11QM1A0469)

T.SURESH (11QM1A0479)

S.PRAVEEN KUMAR (11QM1A0475)

Under the esteemed guidance of

P.ANUSHA,M.Tech.

Asst. Professor

DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING



KG REDDY COLLEGE OF ENGINEERING &

TECHNOLOGY

CHILKUR (V), MOINABAD (M), RANGA REDDY DISTRICT (A.P)

DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING

CERTIFICATE

This is to certify that the Dissertation entitled “AUTOMATIC ROOM

LIGHT CONTROLLER WITH SENSORS” is a bonafide work done by

P.BHASKAR(11QM1A0469), T.SURESH(11QM1A0479), S.PRAVEEN

KUMAR (11QM1A0475). in partial fulfillment of the academic

requirements for the award of the degree of Bachelor of Technology in

ELECTRONICS AND COMMUNICATION ENGINEERING, submitted to the

Department of ECE, KG REDDY College of Engineering & Technology,

Hyderabad.

INTERNAL GUIDE HOD OF ECE

P.ANUSHA,M.Tech. Mr.M.N.NARSAIAH, M.Tech(Ph.D)

Asst. Professor Associate Professor

EXTERNAL EXAMINER



ACKNOWLEDGMENT

With great pleasure we want to take this opportunity to express my heart felt

gratitude to all the people who helped in making this project work a grand success.

We are very much thankful to Mr. Krishna Reddy. Honourable chairman for his help in

providing good facilities in our college

We are highly indebted to Dr.Madhusudan Nair, Principal KGRCET for giving

permission to carry out this project in KGRCET.

We would like to thank M.N.Narsaiah, Assoc. Professor Head of the Department of

Electronics & Communication Engineering, for his moral support throughout the

period of our study in KGRCET.

We are grateful to P.ANUSHA for her valuable suggestions and guidance during the

execution of this project work.

We are very much thankful to KGRCET for giving us this opportunity to do this project

in embedded systems. We express our deep sense of gratitude to P.ANUSHA for her

constant guidance throughout the course of project work.

Finally we would like to thank the Teaching & Non- teaching staff of Department of

Electronics & Communication Engineering, for their co-operation.

P.BHASKAR (11QM1A0469)

T.SURESH (11QM1A0479)

S.PRAVEEN KUMAR (11QM1A0475)



CONTENTS Abstract i List of figures ii

List of table’s iii

List of screens iv

CHAPTER NO. CHAPTER NAME PAGE NO.

1. INTRODUCTION 1.1 Abbreviation of Embedded systems 1 1.2 Examples and Embedded systems 2

1.3 Embedded ‘C’ 2 1.4 Firmware 4

1.5 Operating systems 5

2. BLOCK DIAGRAM 2.1 Block diagram Explanation 6

3. HARDWARE REQUIREMENTS 3.1 Description of Microcontroller 9 3.2 Liquid Crystal Display 13

3.3 Relay switch 18 3.4 I R sensors 23

4. SOFTWARE DESCRIPTION 4.1 Keil Compiler 30 4.2 Pro Load 30

4.3 Procedural steps for Compilation Simulation and Dumping 31

4.3.1 Compilation and simulation steps 31

4.3.2 Dumping steps 36 4.4 Program Code 37

5. RESULT Result Analysis 40



CONCLUSION 41

FUTURE SCOPE 42

REFERENCES 43



ABSTRACT

In the undertaken project we have designed a circuit that switches on and switches

off automatically whenever a person enters and leave the room respectively. The benefit

of this circuit is that after entering the room person will not have to search for the light

switch the light will automatically be turned on and need not to switch it off as the person

leave the room, the room light will be turned off automatically.

When an object moves into a room it will be detected by the IR sensor ‘1’ this

makes the microcontroller to switch on the light using relay switch by understanding that

something has moved in to the room. if the last object moves out of the room it has

passes through IR sensor ‘2’ and microcontroller will switch OFF the light using relay.

Low cost, Easy to use. can be implemented in single door, Can be used to automatic

room light control.

Main advantage of this project is that it helps in energy conservation. Because

when there is nobody inside the room then lights are turned off.

It is used only when one person cuts the rays of the sensor hence cannot be used when

two or more persons cross the door simultaneously.

When anybody is inside the room and we need to switch OFF the power then we

have to do it manually. So, in this case we fail to automatically control the light.



LIST OF FIGURES

FIGURE NO. FIGURE NAME PAGE NO.

1.1 Embedded system 1

2.1 Block diagram of project 6

2.2 Circuit diagram of power supply 7

3.1 Pin diagram of 8051 9

3.2 Block diagram of 8051 10

3.3 Lcd display 15

3.4 Lcd interfacing 18

3.5 Relay switch 19

3.6 Internal structure of relay 20

3.7 4 Pin relay 21

3.8 Energized relay 21

3.9 De-Energized relay 22

3.10 Circuit diagram of relay 22

3.11 Circuit diagram of transmitter 25

3.12 Receiver 26

3.13 TSOP 1738 27

3.14 Block diagram of TSOP 28



LIST OF TABLES

TABLE NO. TABLE NAME PAGE NO.

3.1 Description of Port 3 10

3.2 Pin Description of Lcd 14

3.3 Lcd Command codes 15



LIST OF SCREENS

SCREEN NO. SCREEN NAME PAGE NO.

4.3 Open keil and start a new project 31

4.4 Opening a new project 32

4.4 ATMEL (source code) 32

4.5 Creating a new project 33

4.6 Save it with “.c” 33

4.6 Adding files to group 34

4.7 Rebuilding all targets 35

4.8 Debugging the program 36



CHAPTER 1

INTRODUCTION

1.1 EMBEDDED SYSTEM:

An embedded system is a special-purpose system in which the computer is

completely encapsulated by or dedicated to the device or system it controls. Unlike a

general-purpose computer, such as a personal computer, an embedded system performs

one or a few predefined tasks, usually with very specific requirements. Since the system

is dedicated to specific tasks, design engineers can optimize it, reducing the size and cost

of the product. Embedded systems are often mass-produced, benefiting from economies

of scale.

Personal digital assistants (PDAs) or handheld computers are generally considered

embedded devices because of the nature of their hardware design, even though they are

more expandable in software terms. This line of definition continues to blur as devices

expand. With the introduction of the OQO Model 2 with the Windows XP operating

system and ports such as a USB port — both features usually belong to "general purpose

computers", — the line of nomenclature blurs even more.

Physically, embedded systems ranges from portable devices such as digital

watches and MP3 players, to large stationary installations like traffic lights, factory

controllers, or the systems controlling nuclear power plants.

In terms of complexity embedded systems can range from very simple with a

single microcontroller chip, to very complex with multiple units, peripherals and

networks mounted inside a large chassis or enclosure.

Fig 1.1. Embedded system



1.2 Examples of Embedded Systems:

Avionics, such as inertial guidance systems, flight control hardware/software

and other integrated systems in aircraft and missiles

● Cellular telephones and telephone switches

● Engine controllers and antilock brake controllers for automobiles

● Home automation products, such as thermostats,air conditioners, sprinklers, and

security monitoring systems.

● Handheld calculators

● Handheld computers

● Household appliances, including microwave ovens, washing machines, television

sets, DVD players and recorders

● Medical equipment

● Personal digital assistant

● Videogame consoles

● Computer peripherals such as routers and printers.

● Industrial controllers for remote machine operation.

1.3 What is an Embedded System?

An embedded system is an application that contains at least one programmable

computer and which is used by individuals who are, in the main, unaware that the system

is computer based.

Which Programming Language should you use?

Having decided to use an 8051 processor as the basis of your embedded system, the

next key decision that needs to be made is the choice of programming language. In order

to identify a suitable language for embedded systems, we might begin by making the

following observations.

● Computers (such as microcontroller, microprocessor or DSP chips) only accept

instructions in ‘machine code’ (‘object codes’). Machine code is, by definition, in

the language of the computer, rather than that of the programmer. Interpretation of

the code by the programmer is difficult and error prone.



● All software, whether in assembly, C, C++, Java or Ada must ultimately be

translated into machine code in order to be executed by the computer.

● Embedded processors – like the 8051 – have limited processor power and very

limited memory available: the language used must be efficient.

● The language chosen should be in common use.

Summary of C language Features:

It is ‘mid-level’, with ‘high- level’ features (such as support for functions and

modules), and ‘low- level’ features (such as good access to hardware via pointers).

● It is very efficient.

● It is popular and well understood.

● Even desktop developers who have used only Java or C++ can soon understand C

syntax.

● Good, well-proven compilers are available for every embedded processor (8-bit to

32-bit or more).

Basic C program structure:

//- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

//Basic blank C program that does nothing

// Includes

//- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

#include <reg51.h> // SFR declarations

Void main (void)

{

While (1);

{

Body of the loop // Infinite loop

}

} // match the braces



1.4 FIRMWARE:

Firmware is a software program permanently etched into a hardware device such as a

keyboards, hard drive, BIOS, or video cards. It is programmed to give permanent

instructions to communicate with other devices and perform functions like basic

input/output tasks. Firmware is typically stored in the flash ROM (read only memory) of

a hardware device. It can be erased and rewritten.

Firmware was originally designed for high level software and could be changed

without having to exchange the hardware for a newer device. Firmware also retains the

basic instructions for hardware devices that make them operative. Without firmware, a

hardware device would be non-functional.

Originally, firmware had read-only memory (ROM) and programmable read-only

memory (PROM). It was designed to be permanent. Eventually PROM chips could be

updated and were called erasable programmable read-only memory (EPROM). But

EPROM was expensive, time consuming to update and challenging to use. Firmware

eventually evolved from ROM to flash memory firmware; thus, it became easier to

update and user friendly.

levels of firmware:

1. Low Level Firmware: This is found in ROM, OTP/PROM and PLA structures.

Low level firmware is often read-only memory and cannot be changed or updated.

It is sometimes referred to as hardware.

2. High Level Firmware: This is used in flash memory for updates that is often

considered as software.

3. Subsystems: These have their own fixed microcode embedded in flash chips,

CPUs and LCD units. A subsystem is usually considered part of the hardware

device as well as high level firmware.

BIOS, modems and video cards are usually easy to update. But firmware in storage

devices usually gets overlooked; there are no standardized systems for updating

firmware. Fortunately, storage devices do not need to be updated often.



1.5 OPERATING SYSTEM:

What is an operating system? An operating system (sometimes abbreviated as "OS")

is the program that, after being initially loaded into the computer by a boot program,

manages all the other programs in a computer. The other programs are called applications

or application programs. The application programs make use of the operating system by

making requests for services through a defined application program interface (API). In

addition, users can interact directly with the operating system through a user interface

such as a command language or a graphical user interface (GUI).

An operating system performs these services for applications:

In a multitasking operating system where multiple programs can be running at the same

time, the operating system determines which applications should run in what order and

how much time should be allowed for each application before giving another application

a turn.

It manages the sharing of internal memory among multiple applications.

It handles input and output to and from attached hardware devices, such as hard disks,

printers, and dial-up ports.

It sends messages to each application or interactive user (or to a system operator)

about the status of operation and any errors that may have occurred.

It can offload the management of what are called batch jobs (for example,

printing) so that the initiating application is freed from this work.

On computers that can provide parallel processing, an operating system can

manage how to divide the program so that it runs on more than one processor at a time.

All major computer platforms (hardware and software) require and sometimes

include an operating system. Linux, Windows, VMS, OS/400, AIX, and z/OS are all

examples of operating systems.

http://searchwinit.techtarget.com/definition/boot

http://searchsoftwarequality.techtarget.com/definition/application-program

http://searchexchange.techtarget.com/definition/application-program-interface

http://searchwindevelopment.techtarget.com/definition/GUI

http://searchcio-midmarket.techtarget.com/definition/multitasking

http://searchenterpriselinux.techtarget.com/definition/Linux

http://searchwindowsserver.techtarget.com/definition/Windows

http://search400.techtarget.com/definition/OS-400

http://search400.techtarget.com/definition/AIX

http://searchdatacenter.techtarget.com/definition/z-OS



CHAPTER 2

BLOCK DIAGRAM

In this “Automatic room light controller with sensors” project we have mainly

used hardware components like Relay switch, I R sensors, Lcd display and Tsop 1738.

And the automatic room light controller with sensors are explained with neat block

diagram as shown below.

Fig2.1. block diagram

2.1 Block Diagram Explanation:

In this section we will be discussing about the complete block diagram and

functional description of our project. And also brief description of each block in the block

diagram.

Micro controller:

In this project work the microcontroller is plays major role. Microcontroller were

originally used as components in complicated process-control systems. However, because

of their small size and low price, microcontrollers are now also being used in regulators

IR sensor

2

Receiver

2

Power Supply

IR sensor

1

Receiver

1

Micro

Controller

LCD Display

Relay



for individual control loops. In several areas microcontroller are now outperforming their

analog counterparts and are cheaper as well.

Power Supply

This section is meant for supplying Power to all the sections mentioned above. It

basically consists of a Transformer to step down the 230V ac to 12V ac followed by

diodes. Here diodes are used to rectify the ac to dc. After rectification the obtained

rippled dc is filtered using a capacitor Filter. A positive voltage regulator is used to

regulate the obtained dc voltage(5V).

Fig.2.2. circuit diagram of power supply

But here in this project two power supplies are used one is meant to supply

operating voltage for Microcontroller and the other is to supply control voltage for

Relays.

LCD Display Section:

This section is basically meant to show up the status of the project. This project

makes use of Liquid Crystal Display to display / prompt for necessary information.

Relay Switch:

Relay is a electrical to magnetic converting switch when input is high magnetic field is

produced switch is on otherwise switch is off.



CHAPTER 3

HARDWARE REQUIREMENTS

3.1 AT89C51 MICROCONTROLLER

3.1.1 Features

➢ AT89C51 based architecture

➢ 8-Kbytes of on-chip Reprogrammable Flash Memory

➢ 128 x 8 RAM

➢ Two 16-bit Timer/Counters

➢ Full duplex serial channel

➢ Boolean processor

➢ Four 8-bit I/O ports, 32 I/O lines

➢ Memory addressing capability

– 64K ROM and 64K RAM

➢ Power save modes:

– Idle and power-down

➢ Six interrupt sources

➢ Most instructions execute in 0.3 us

➢ CMOS and TTL compatible

➢ Maximum speed: 40 MHz @ Vcc = 5V

➢ Industrial temperature available

➢ Packages available:

– 40-pin DIP

– 44-pin PLCC

– 44-pin PQFP

3.1.2 The Microcontroller:

A microcontroller is a general purpose device, but that is meant to read data,

perform limited calculations on that data and control its environment based on those

calculations. The prime use of a microcontroller is to control the operation of a machine

using a fixed program that is stored in ROM and that does not change over the lifetime of



the system. The microcontroller design uses a much more limited set of single and double

byte instructions that are used to move data and code from internal memory to the ALU.

The microcontroller is concerned with getting data from and to its own pins; the

architecture and instruction set are optimized to handle data in bit and byte size.

The AT89S52 is a low-power, high-performance CMOS 8-bit microcontroller

with 8Kbytes of Flash Programmable and erasable read only memory (EROM). The

device is manufactured using Atmel’s high-density nonvolatile memory technology and

is functionally compatible with the industry-standard 80C51 microcontroller instruction

set and pin out. By combining versatile 8-bit CPU with Flash on a monolithic chip, the

Atmel’s AT89c51 is a powerful microcomputer, which provides a high flexible and cost-

effective solution to many embedded control applications.

AT89C51 Block Diagram

Fig3.1. block diagram of 8051



3.1.4 Pin configuration of AT89c51 Microcontroller

Fig3.1.2. 8051 micro controller



3.1.5 Pin Description:

VCC

Supply voltage

GND

Ground

Port 0

Port 0 is an 8-bit open drain bi-directional I/O port. As an output port, each pin

can sink eight TTL inputs. When 1s are written to port 0 pins, the pins can be used as

high impedance inputs.

Port 0 can also be configured to be the multiplexed low order address/data bus

during access to external program and data memory. In this mode, P 0 has internal pull-

ups. Port 0 also receives the code bytes during Flash programming and outputs the code

bytes during program verification. External pull-ups are required during program

verification.

Port 1

Port 1 is an 8-bit bi-directional I/O port with internal pull-ups. The port 1output

buffers can sink/source four TTL inputs. When 1s are written to port 1 pins, they are

pulled high by the internal pull-ups can be used as inputs. As inputs, Port 1 pins that are

externally being pulled low will source current (1) because of the internal pull-ups.

Port 2

Port 2 is an 8-bit bi-directional I/O port with internal pull-ups. The port 2 output



externally being pulled low will source current because of the internal pull-ups.

Port 2 emits the high-order address byte during fetches from external program

memory and during access to DPTR. In this application Port 2 uses strong internal pull-

ups when emitting 1s. During accesses to external data memory that use 8-bit data

address (MOVX@R1), Port 2 emits the contents of the P2 Special Function Register.

Port 2 also receives the high-order address bits and some control signals during Flash

programming and verification.



Port 3

Port 3 is an 8-bit bi-directional I/O port with internal pull-ups. The port 3 output



externally being pulled low will source current because of the internal pull-ups.

Port 3 also receives some control signals for Flash Programming and verification.

TABLE 3.1 port 3 description.

Port pin Alternate Functions

P3.0 RXD(serial input port)

P3.1 TXD(serial input port)

P3.2 INT0(external interrupt 0)

P3.3 INT1(external interrupt 1)

P3.4 T0(timer 0 external input)

P3.5 T1(timer 1 external input)

P3.6 WR(external data memory write strobe)

P3.7 RD(external data memory read strobe)

RST

Rest input A on this pin for two machine cycles while the oscillator is running

resets the device.

ALE/PROG:

Address Latch Enable is an output pulse for latching the low byte of the address

during access to external memory. This pin is also the program pulse input (PROG)

during Flash programming.

In normal operation ALE is emitted at a constant rate of 1/16 the oscillator

frequency and may be used for external timing or clocking purpose. Note, however, that

one ALE pulse is skipped during each access to external Data memory.



PSEN

Program Store Enable is the read strobe to external program memory when the

AT89c51 is executing code from external program memory PSEN is activated twice each

machine cycle, except that two PSEN activations are skipped during each access to

external data memory.

__

EA /VPP

External Access Enable (EA) must be strapped to GND in order to enable the

device to fetch code from external program memory locations starting at 0000h up to

FFFFH. Note, however, that if lock bit 1 is programmed EA will be internally latched on

reset. EA should be strapped to Vcc for internal program executions. This pin also

receives the 12-volt programming enable voltage (Vpp) during Flash programming when

12-volt programming is selected.

XTAL1

Input to the inverting oscillator amplifier and input to the internal clock operating

circuit.

XTAL 2

Output from the inverting oscillator amplifier.

3.2 LIQUID CRYSTAL DISPLAY

Liquid crystal displays (LCD s) have materials which combine the properties of

both liquids and crystals. Rather than having a melting point, they have a temperature

range within which the molecules are almost as mobile as they would be in a liquid, but

are grouped together in an ordered form similar to a crystal.

An LCD consists of two glass panels, with the liquid crystal material sand

witched in between them. The inner surface of the glass plates are coated with transparent

electrodes which define the character, symbols or patterns to be displayed polymeric

layers are present in between the electrodes and the liquid crystal, which makes the liquid

crystal molecules to maintain a defined orientation angle.



One each polarisers are pasted outside the two glass panels. These polarisers

would rotate the light rays passing through them to a definite angle, in a particular

direction

When the LCD is in the off state, light rays are rotated by the two polarisers and

the liquid crystal, such that the light rays come out of the LCD without any orientation,

and hence the LCD appears transparent.

When sufficient voltage is applied to the electrodes, the liquid crystal molecules

would be aligned in a specific direction. The light rays passing through the LCD would

be rotated by the polarisers, which would result in activating / highlighting the desired

characters.

The LCD’s are lightweight with only a few millimeters thickness. Since the

LCD’s consume less power, they are compa tible with low power electronic circuits, and

can be powered for long durations.

The LCD s won’t generate light and so light is needed to read the display. By

using backlighting, reading is possible in the dark. The LCD’s have long life and a wide

operating temperature range.

Changing the display size or the layout size is relatively simple which makes the

LCD’s more customer friendly.

The LCD s used exclusively in watches, calculators and measuring instruments is

the simple seven-segment displays, having a limited amount of numeric data. The recent

advances in technology have resulted in better legibility, more information displaying

capability and a wider temperature range. These have resulted in the LCD s being

extensively used in telecommunications and entertainment electronics. The LCD s has

even started replacing the cathode ray tubes (CRTs) used for the display of text and

graphics, and also in small TV applications.



Fig3.3 Lcd display

LCD operation

In recent years the LCD is finding widespread use replacing LED s (seven-segment

LED or other multi segment LED s). This is due to the following reasons:

1. The declining prices of LCD s.

2. The ability to display numbers, characters and graphics. This is in

contract to LED s, which are limited to numbers and a few characters.

3. Incorporation of a refreshing controller into the LCD, there by relieving the CPU

of the task of refreshing the LCD. In the contrast, the LED must be refreshed by

the CPU to keep displaying the data.

4. Ease of programming for characters and graphics.

LCD pin description

The LCD discussed in this section has 14 pins. The function of each pin is given

in table.



TABLE 3.2: Pin description for LCD:

Pin symbol I/O Description

1 Vss -- Ground

2 Vcc -- +5V power supply

3 VEE -- Power supply to

control contrast

4 RS I RS=0 to select

command register

RS=1 to select

data register

5 R/W I R/W=0 for write

R/W=1 for read

6 E I/O Enable

7 DB0 I/O The 8-bit data bus










TABLE 3.3: LCD Command Codes

Code

(hex)

Command to LCD Instruction

Register

1 Clear display screen

2 Return home

4 Decrement cursor

6 Increment cursor

5 Shift display right

7 Shift display left

8 Display off, cursor off

A Display off, cursor on

C Display on, cursor off

E Display on, cursor on

F Display on, cursor blinking

10 Shift cursor position to left

14 Shift cursor position to right

18 Shift the entire display to the left

1C Shift the entire display to the right

80 Force cursor to beginning of 1st line

C0 Force cursor to beginning of 2nd line

38 2 lines and 5x7 matrix

Uses:

The LCDs used exclusively in watches, calculators and measuring instruments are

the simple seven-segment displays, having a limited amount of numeric data. The recent

advances in technology have resulted in better legibility, more information displaying

capability and a wider temperature range. These have resulted in the LCDs being

extensively used in telecommunications and entertainment electronics. The LCDs have



even started replacing the cathode ray tubes (CRTs) used for the display of text and

graphics, and also in small TV applications.

Lcd Interfacing

Sending commands and data to LCDs with a time delay:

Fig 3.4. lcd interfacing

To send any command from table 2 to the LCD, make pin RS=0. For data, make

RS=1.Then place a high to low pulse on the E pin to enable the internal latch of the LCD.

3.3 RELAY SWITCH

A relay is an electrically operated switch. Many relays use an electromagnet to

mechanically operate a switch, but other operating principles are also used, such as solid

state relays - . Relays are used where it is necessary to control a circuit by a low-power

http://en.wikipedia.org/wiki/Electric

http://en.wikipedia.org/wiki/Switch

http://en.wikipedia.org/wiki/Electromagnet

http://en.wikipedia.org/wiki/Solid-state_relay





signal (with complete electrical isolation between control and controlled circuits), or

where several circuits must be controlled by one signal. The first relays were used in long

distance telegraph circuits as amplifiers . they repeated the signal coming in from one

circuit and re-transmitted it on another circuit.Relays were used extensively in telephone

exchanges and early computers to perform logical operations.

Ex: A relay is used to control the air conditioner in your home. The AC unit

probably runs off of 220VAC at around 30A. That's 6600 Watts! The coil that controls

the relay may only need a few watts to pull the contacts together.

Fig 3.5. relay switch

The internal structure of the relay is shown in the image above which is embedded

inside the plastic covering.

Relay switch shown in the image above consists of five terminals. Two terminals are

used to give the input DC voltage also known as the operating voltage of the

relay. Relays are available in different operating voltages like 6V, 12V, 24V etc. The rest

of the three terminals are used to connect the high voltage AC circuit. The terminals are

called Common, Normally Open (NO) and Normally Closed (NC). Relays are available

in various types & categories and in order to identify the correct configuration of the

http://en.wikipedia.org/wiki/Electrical_telegraph

http://www.engineersgarage.com/electronic-components/relays



output terminals, it is best to see the data sheet or manual. You can also identify the

terminals using a multimeter and at times it is printed on the relay itself.

Working

The working of a relay can be better understood by explaining the following

diagram given below.

Fig 3.6. internal structure

The diagram shows an inner section diagram of a relay. An iron core is

surrounded by a control coil. As shown, the power source is given to the electromagnet

through a control switch and through contacts to the load. When current starts flowing

through the control coil, the electromagnet starts energizing and thus intensifies the

magnetic field. Thus the upper contact arm starts to be attracted to the lower fixed arm

and thus closes the contacts causing a short circuit for the power to the load. On the other

hand, if the relay was already de-energized when the contacts were closed, then the

contact move oppositely and make an open circuit.

As soon as the coil current is off, the movable armature will be returned by a

force back to its initial position. This force will be almost equal to half the strength of the

magnetic force. This force is mainly provided by two factors. They are the spring and

also gravity.

Relays are mainly made for two basic operations. One is low voltage application

and the other is high voltage. For low voltage applications, more preference will be given



to reduce the noise of the whole circuit. For high voltage applications, they are mainly

designed to reduce a phenomenon called arcing.

Relay Basics

The basics for all the relays are the same. Take a look at a 4 – pin relay shown

below. There are two colours shown. The green colour represents the control circuit and

the red colour represents the load circuit. A small control coil is connected onto the

control circuit. A switch is connected to the load. This switch is controlled by the coil in

the control circuit. Now let us take the different steps that occour in a relay.

Fig 3.7. 4 pin relay

Energized Relay (ON)

As shown in the circuit, the current flowing through the coils represented by pins

1 and 3 causes a magnetic field to be aroused. This magnetic field causes the closing of

the pins 2 and 4. Thus the switch plays an important role in the relay working. As it is

apart of the load circuit, it is used to control an electrical circuit that is connected to it.

Thus, when the relay in energized the current flow will be through the pins 2 and 4.

Fig 3.8. Energized relay



De – Energized Relay (OFF)

As soon as the current flow stops through pins 1 and 3, the switch opens and thus

the open circuit prevents the current flow through pins 2 and 4. Thus the relay becomes

de-energized and thus in off position.

Fig 3.9. De-Energized relay

In simple, when a voltage is applied to pin 1, the electromagnet activates, causing

a magnetic field to be developed, which goes on to close the pins 2 and 4 causing a

closed circuit. When there is no voltage on pin 1, there will be no electromagnetic force

and thus no magnetic field. Thus the switches remain open.

BLOCK DIAGRAM:

Fig 3.10. circuit diagram of relay



Relay Applications

Relays are used to realize logic functions. They play a very important role in

providing safety critical logic.

Relays are used to provide time delay functions. They are used to time the delay

open and delay close of contacts.

Relays are used to control high voltage circuits with the help of low voltage

signals. Similarly they are used to control high current circuits with the help of low

current signals.

They are also used as protective relays. By this function all the faults during

transmission and reception can be detected and isolated.

3.4 I R SENSORS

An infrared sensor is an electronic instrument that is used to sense certain

characteristics of its surroundings by either emitting and/or detecting infrared radiation. It

is also capable of measuring heat of an object and detecting motion. Infrared waves are

not visible to the human eye.

In the electromagnetic spectrum, infrared radiation is the region having

wavelengths longer than visible light wavelengths, but shorter than microwaves. The

infrared region is approximately demarcated from 0.75 to 1000µm. The wavelength

region from 0.75 to 3µm is termed as near infrared, the region from 3 to 6µm is termed

mid- infrared, and the region higher than 6µm is termed as far infrared.

Infrared technology is found in many of our everyday products. For example, TV

has an IR detector for interpreting the signal from the remote control. Key benefits of

infrared sensors include low power requirements, simple circuitry, and their portable

feature.

Types of Infra-Red Sensors

Infra-red sensors are broadly classified into two types:

Thermal infrared sensors – These use infrared energy as heat. Their photo

sensitivity is independent of wavelength. Thermal detectors do not require cooling;

however, they have slow response times and low detection capab ility.



Quantum infrared sensors – These provide higher detection performance and

faster response speed. Their photo sensitivity is dependent on wavelength. Quantum

detectors have to be cooled so as to obtain accurate measurements. The only exception is

for detectors that are used in the near infrared region.

Working Principle

A typical system for detecting infrared radiation using infrared sensors includes

the infrared source such as blackbody radiators, tungsten lamps, and silicon carbide. In

case of active IR sensors, the sources are infrared lasers and LEDs of specific IR

wavelengths. Next is the transmission medium used for infrared transmission, which

includes vacuum, the atmosphere, and optical fibers.

Thirdly, optical components such as optical lenses made from quartz, CaF2, Ge

and Si, polyethylene Fresnel lenses, and Al or Au mirrors, are used to converge or focus

infrared radiation. Likewise, to limit spectral response, band-pass filters are ideal.

Finally, the infrared detector completes the system for detecting infrared radiation. The

output from the detector is usually very small, and hence pre-amplifiers coupled with

circuitry are added to further process the received signals.

Applications

* The following are the key application areas of infrared sensors:

* Tracking and art history

* Climatology, meteorology, and astronomy

* Thermography, communications, and alcohol testing

* Heating, hyperspectral imaging, and night vision

* Biological systems, photobiomodulation, and plant health

* Gas detectors/gas leak detection

* Water and steel analysis, flame detection

* Anesthesiology testing and spectroscopy

* Petroleum exploration and underground solution

* Rail safety.



A ) TRANSMITTER

IR Transmitter and Receiver pair can be easily made using 555 Timer, IR LED

and TSOP1738 IR Receiver. This can be used for remote controls, burglar alarms etc.

TSOP1738 is a very commonly used IR receiver for PCM remote control systems. It has

only 3 pins, Vcc, GND and Output. It can be powered using a 5V power supply and its

active low output can be directly connected to a microcontroller or microprocessor. It has

high immunity against ambient light and other electrical disturbances. It is able to transfer

data up to 2400 bits per second. The PCM carrier frequency of TSOP1738 is 38KHz, so

we want to design a astable multivibrator of 38KHz. This can be done by using 555

Timer. and TSOP1738 IR Receiver. This can be used for remote controls, burglar alarms

etc. TSOP1738 is a very commonly used IR receiver for PCM remote control systems. It

has only 3 pins, Vcc, GND and Output. It can be powered using a 5V power supply and

its active low output can be directly connected to a microcontroller or microprocessor. It

has high immunity against ambient light and other electrical disturbances. It is able to

transfer data up to 2400 bits per second. The PCM carrier frequency of TSOP1738 is

38KHz, so we want to design a astable multivibrator of 38KHz. This can be done by

using 555 Timer.

Circuit Diagram of Transmitter

Fig 3.11. circuit diagram of transmitter

In the above circuit, 555 Timer is wired as an Astable Multivibrator. The 100μF

capacitor (C1) is used to reduce ripples in the power supply. 1st

and 8th

pins of 555 are

used to give power Vcc and GND respectively. 4th

pin is the reset pin which is active low

http://www.electrosome.com/555-timer-ic/

http://www.electrosome.com/tsop1738-receiver-ir-remote-control/

http://www.electrosome.com/tsop1738-receiver-ir-remote-control/

http://electrosome.com/astable-multivibrator-555-timer/



input, hence it is connected to Vcc. 5th

pin is the Control Voltage pin which is not used in

this application, hence it is grounded via a capacitor to avoid high frequency noises

through that pin. Capacitor C2, Resistors R1, R2 determines the time period of

oscillation. Capacitor C2 charges to Vcc via resistors R1 and R2. It discharges through

Resistor R2 and 7th

pin of 555. The voltage across capacitor C2 is connected to the

internal comparators via 2n d

and 6th

pins of 555. Output is taken from the 3ed

pin of the

IC. Please read the article Astable Multivibrator using 555 Timer for more detailed

working. Charging time constant of the capacitor (output HIGH period) is determined by

the expression 0.693(R1+R2)C2 and discharging time constant (output LOW period) is

determined by 0.693R2C2. They are approximately equal.

B) RECEIVER

Fig 3.12. receiver

For receiving signals send by the transmitter you need only TSOP1738. Connect 5V to

Vs and Ground to GND pin of TSOP1738. The output will be active low. Output of

TSOP1738 will be HIGH when no signals fall on it and the output will be LOW when

38KHz infrared rays fall on it.

http://electrosome.com/astable-multivibrator-555-timer/



3.4.1 TSOP1738

The TSOP 1738 is a member of IR remote control receiver series. This IR sensor

module consists of a PIN diode and a pre amplifier which are embedded into a single

package. The output of TSOP is active low and it gives +5V in off state. When IR waves,

from a source, with a centre frequency of 38 kHz incident on it, its output goes low.

Lights coming from sunlight, fluorescent lamps etc. may cause disturbance to it and

result in undesirable output even when the source is not transmitting IR signals. A

bandpass filter, an integrator stage and an automatic gain control are used to suppress

such disturbances.

Fig 3.13. tsop

TSOP module has an inbuilt control circuit for amplifying the coded pulses from

the IR transmitter. A signal is generated when PIN photodiode receives the signals. This

input signal is received control (AGC). For a range of inputs, the output is fed back to

AGC in order to adjust the gain to a suitable level. The signal from AGC is passed to a

band pass filter to filter undesired frequencies. After this, the signal goes to a

demodulator and this demodulated output drives an npn transistor. The collector output of

the transistor is obtained at pin 3 of TSOP module.

Members of TSOP17xx series are sensitive to different centre frequencies of the

IR spectrum. For example TSOP1738 is sensitive to 38 kHz whereasTSOP1740 to 40

kHz centre frequency.y an automatic gain



AVAILABLE TYPES FOR DIFFERENT CARRIER FREQUENCIES

TSOP1730 30 KHZ

TSOP1733 33 KHZ

TSOP1736 36 KHZ

TSOP1737 36.7 KHZ

TSOP1738 38 KHZ

TSOP1740 40 KHZ

TSOP1756 56 KHZ

BLOCK DIAGRAM OF TSOP1738

Fig 3.14.block diagram of tsop

3.4.2 FEATURES OF TSOP1738

* Photo detector and preamplifier in one package

* Internal filter for PCM frequency

* Improved shielding against electrical

* field disturbance

* TTL and CMOS compatibility

* Output active low

* Low power consumption

* High immunity against ambient light

* Continuous data transmission possible



(1200 bit/s)

*Suitable burst length ≥10 cycles/burst

ADVANTAGES AND FUTURE SCOPES

* It can be used in our homes because we often forget to switch off our room lights

* It helps in energy conservation

* In future , we can send this data to remote areas using mobile or internet

* Voice alarm system can be used to indicate that room is full & person can’t enter inside

* It can be used in various rooms like seminar halls , where the capacity of the room is

limited and should not be exceeded.



CHAPTER 4

SOFTWARE DESCRIPTION

This project is implemented using following software’s:

● KEIL Compiler- for compilation part

● Proload-for simulation part

4.1 KEIL Compiler:

Keil compiler is software used where the machine language code is written and

compiled. After compilation, the machine source code is converted into hex code which

is to be dumped into the microcontroller for further processing. Keil compiler also

supports C language code.

It’s important that you know C language for microcontroller which is

commonly known as Embedded C. As we are going to use Keil C51 Compiler, hence we

also call it Keil C.

Keil C is not much different from a normal C program. If you know assembly,

writing a C program is not a crisis. In keil, we will have a main function, in which all

your application specific work will be defined. In case of embedded C, you do not have

any operating system running in there. So you have to make sure that your program or

main file should never exit. This can be done with the help of simple while (1) or for (;;)

loop as they are going to run infinitely.

We have to add header file for controller you are using, otherwise you will not

be able to access registers related to peripherals.

#include <REG51.h> //header file for 89C51

4.2 Proload:

Proload is software which accepts only hex files. Once the machine code is

converted into hex code, that hex code has to be dumped into the microcontroller and this

is done by the Proload. Proload is a programmer which itself contains a microcontroller

in it other than the one which is to be programmed.



This microcontroller has a program in it written in such a way that it accepts

the hex file from the Kiel compiler and dumps this hex file into the microcontroller which

is to be programmed. As the proload programmer kit requires power supply to be

operated, this power supply is given from the power supply circuit designed above. It

should be noted that this programmer kit contains a power supply section in the board

itself but in order to switch on that power supply, a source is required. Thus this is

accomplished from the power supply board with an output of 12volts or from an adapter

connected to 230V AC.

4.3 Procedural steps for compilation, simulation and dumping:

4.3.1 Compilation and simulation steps:

To create a project, write and test the previous example source code, follow

the following steps:

1. Open Keil and start a new project.

Fig 4.3: Step-1



2. You will be prompted to choose a name for your new project, Create a separate folder

where all the files of your project will be stored, choose a name and click save. The

following window will appear where you will be asked to select a device for Target

'Target 1'

3. From the list at the left, seek for the brand name ATMEL, then under ATMEL, select

AT89S52. You will notice that a brief description of the device appears on the right.

Leave the two upper check boxes unchecked and click OK. The AT89S52 will be called

your 'Target device', which is the final destination of your source code. You will be asked

whether to 'copy standard 8051 startup code' click No.

Fig 4.4: Step-2, 3



4. Click File, New, and something similar to the following window should appear. The

box named 'Text1' is where your code should be written later.

Fig 4.5: Step-4

5. Now you have to click 'File, Save as' and choose a file name for your source code

ending with the letter '.c'. You can name as 'code.c' for example and click save. Then

you have to add this file to your project work space at the left as shown in the

following.



6.After right-clicking on 'source group 1', click on 'Add files to group...', then you will

be prompted to browse the file to add to 'source group 1', choose the file that you just

saved, eventually 'code.c' and add it to the source group.

You will notice that the file is added to the project tree at the left.

Fig4.6: Step-5, 6

7. In some versions of this software you have to turn ON manually the option to generate

HEX files. make sure it is turned ON, by right-clicking on target 1, Options for target

'target 1', then under the 'output' tab, by checking the box 'generate HEX file '. This step

is very important as the HEX file is the compiled output of your project that is going to

be transferred to the microcontroller.



8. You can then start to write the source code in the window titled 'code.c' then before

testing your source code; you have to compile your source code, and correct eventual

syntax errors. In KEIL IDE, this step is called 'rebuild all targets' and has this icon: .

Fig 4.7: Step-7

9. If after rebuilding the targets, the 'output window' shows that there is 0 errors, then

you are ready to test the performance of your code. In keil, like in most development

environment, this step is called Debugging, and has this icon: . After clicking on the

debug icon, you will notice that some part of the user interface will change; some new

icons will appear, like the run icon circled in the following figure:



Fig 4.8: Step-8

10. Select the ports and click on the RUN Option. It will end up the compilation and

simulation processes.

4.3.2 Dumping steps:

After designing the project using Keil Compiler, to observe the output, the

program should be dumped in microcontroller of your project using a dumper and the

procedure for dumping is as follows:

1. Install the Proload Software in the PC.

2. Now connect the Programmer kit to the PC (CPU) through serial cable.

3. Power up the programmer kit from the ac supply through adapter.



4. Now place the microcontroller in the GIF socket provided in the Programmer k it.

5. Click on the proload icon in the PC. A window appears providing the information like

Hardware model, com port, device type, Flash size etc. Click on browse option to select

the hex file to be dumped into the microcontroller and then click on “Auto program” to

program the microcontroller with that particular hex file.

6. The status of the microcontroller can be seen in the small status window in the bottom

of the page.

7. After this process is completed, remove the microcontroller from the programmer kit

and place it in your system board. Now the system board behaves according to the

program written in the microcontroller.

4.4 PROGRAM CODE

#include<reg51.h>

#define LCD P2

sbit rs=P1^0;

sbit rw=P1^1;

sbit en=P1^2;

sbit Ir1=P1^3;

sbit Ir2=P1^4;

sbit relay=P1^5;

void delay();

void lcdcmnd(unsigned char);

void lcddata(unsigned char);

void main()

{

unsigned char E[]="bulb is on", M[]="bulb is off";

unsigned char lcmd[]={0x38,0x01,0x0E,0x06,0x80};

unsigned int i,z;

for(i=0;i<5;i++)

{

LCD=lcmd[i];



rs=0;

rw=0;

en=1;

delay();

en=0;

}

while(1)

{

lcdcmnd(0x01);

delay();

lcdcmnd(0x0C);

delay();

z=0;

for(i=0;i<1000;i++)

{

if(Ir1==1&&Ir2==0);

{

Relay=1;

for(i=0;i<10;i++)

{

lcddata(E[i]);

}

++z;

}

Else if(Ir1==0&&Ir2==1)

{

--z;

}

}

if(z==0)

{



lcdcmnd(0x01);

Relay=0;

for(i=0;i<11;i++)

{

lcddata(M[i]);

}

}

}

}

void delay()

{

int i;

for(i=0;i<1000;i++);

}



CHAPTER 5

RESULT

RESULT ANALYSIS:

When an object moves into a room it will be detected by the IR sensor ‘1’ this

makes the microcontroller to switch on the light using relay switch by

understanding that something has moved in to the room. if the last object moves

out of the room it has passes through IR sensor ‘2’ and microcontroller will

switch OFF the light using relay.

Low cost, Easy to use. can be implemented in single door, Can be used to

automatic room light control.

Main advantage of this project is that it helps in energy conservation. Because

when there is nobody inside the room then lights are turned off.



CONCLUSION

The goal of this project is to develop a system, which used to save power

automatically.

This project mainly consists of microcontroller (89C51) and LCD which helps the

project to be cost effective.

Even though the project was completed successfully but during the development

some obstructions were faced like for loose connection we have got some erroneous

output. Also due to some internal problem in the equipment we have not got desirable

output. So, for better output or for better display we have to be very careful while doing

the project.

During the project it has also been noticed that It is used only when one person

cuts the rays of the sensor hence cannot be used when two or more persons cross the door

simultaneously.



FUTURE SCOPE

Sensors can acts as alarm for security purpose. Mainly used for power

consumption.It can be used in our homes because we often forget to switch off our room

lights It helps in energy conservation In future, we can send this data to remote areas

using mobile or internet Voice alarm system can be used to indicate that room is full &

person can’t enter inside It can be used in various rooms like seminar halls, where the

capacity of the room is limited and should not be exceeded.



REFERENCES

Muhammad Ali Mazidi-“THE 8051 MICROCONTROLLER AND EMBEDDED

SYSTEMS”, Pearson.

Ayala-“INTRODUCTION TO 8051 MICROCONTROLLER”.

www.microcontroller8051.com

www.miniproject.com

www.howstuffworks.com

www.instructables.com/id/cellphone-operated-robot/

www.dnatechindia.com

www.answers.com

http://www.microcontroller8051.com/

http://www.miniproject.com/

http://www.howstuffworks.com/

http://www.instructables.com/id/cellphone-operated-robot/

http://www.dnatechindia.com/

http://www.answers.com/

Automatic Room light controller with sensors

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