This document is a project report submitted to Rajasthan Technical University for a Bachelor of Technology degree. It outlines the design of an auto dialer home security system using a microcontroller, GSM modem, and sensors. The system is designed to detect intruders or fires using infrared and fire sensors, and then send an SMS alert to a user's phone number through the GSM modem. The report describes the basic design criteria, components used including the AT89C2051 microcontroller and GSM modem interface, and sensor modules for infrared and fire detection.

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A
Project report on
“Auto Dialer Home Security”
Submitted to
Rajasthan Technical University, Kota
In Partial Fulfillment of the requirement for the award of the degree of
Bachelor of Technology
In
“Electronics & Communication Engineering”
2010-2011
Submitted by Supervised by
Vaibhav Jindal “Mr. Gaurav Vijay”
Sushil kumar (Dept. of Electronics & Communication Engg.)
Shray Gautam
Modi Institute of Technology
Nayagaon, Rawatbhata Road, Kota

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Modi Institute of Technology, Kota
Session 2010-11
CERTIFICATE
This is to certify that the Project entitled “Auto Dialer Home Security” has been
submitted to the Rajasthan Technical University, Kota in partial fulfillment of the
requirements for the award of the degree of Bachelor of Technology in
“Electronics& Communication Engg.” by following students of Final year
B.Tech.(Electronics & Communication Engineering).
Vaibhav jindal (07E1MIECM45P085)
Sushil Kumar (07E1MIECM45P082)
Shray gautam (07E1MIECM45P078)
(Gaurav Vijay) ( R.N.Piplia)
HOD
(Electronics & Communication Engg ) (Electronics & Communication Engg )
Date: May /2011

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ACKNOWLEDGEMENT
With deep esteem and profound respect, We wish to acknowledge my
supervisor, Gaurav Vijay for the valuable guidance We received from his through
formal information, discussion and timely inspiration. He had not only encouraged
me throughout this venture but also took great pains in going through the
manuscript carefully and suggested correction, which greatly improve the quality
of the text as well as seminar.
We would like to take this opportunity to thank Mr. R.N.Piplia Head of
Electronics and Communication Engineering, for the encourage and inspiration;
he has provided us during the preparation of this seminar.
At last but not least, We would like to thank all of them who helped me
directly in my endeavor.
Submitted By:
Vaibhav Jindal (07E1MIECM45P085)
Sushil Kumar (07E1MIECM45P082)
Shray Gautam (07E1MIECM45P078)
Electronic and Communication
VIII Semester & Final year

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CHAPTER 1
BASIC DESIGN CRITERIA
The basic design criterion involves outlining the actions or
functions which we want to be implemented and performed by the device. We are also concerned
with expected behavior of the device. These have been out lined as follows
i. The circuit should turn ON immediately as soon as it gets an input signal from the sensor
unit.
ii. Choice of sensors for the sensors unit should be based on our requirements, availability,
compatibility and complexity of implementation of them. As for this prototype model we
have used only two sensor for detecting intruder and fire using fire sensors and infrared
LEDs
iii. A suitable microprocessor should be chosen depending on the security requirements and
ease of interfacing of various other circuits which are going to be used. Again as for this
prototype we have chosen AT89C2051 microcontroller which is a very versatile
microprocessor for such proposes
iv. Since we want to inform the person on is mobile through gsm modem.
v. The circuit should have the provision for the Sending a SMS on the number which is
feeded in the programming.
vi. The circuit should have a provision of automatically switching OFF the line after the
message has been transferred.
vii. The circuit should be nose resistant error free with minimum delay
viii. The manufacturing cost should be kept in mind while designing because since we are
working on a home based application hence should not be to much costlier.
ix. The components availability factor should also be kept in, mind while designing meaning
the components required should be easily available , easy to build and easy to test.

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1.1 IMPLEMENTATION OF DESIGN REQUIREMENTS
A basic functional block diagram of the circuit is shown in fig. This gives an over view of
possible implementation of previously stated design requirements.
HOME SECURITY WITH GSM MODEM
Major Circuit

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1.2 Basic components used are:
Microcontroller AT89S52
GSM Modem
Op-Amplifier LM324N
Voltage Regulator
Sensor unit- Fire & IR Sensor Modules
1.3 Basic steps of Action:
1. Activation signal from Sensor unit
2. Microcontroller interface
3. Send a Message by GSM modem.
4. Switching OFF the line after the message has been transferred.
1.4 SENSOR UNIT
In this sensor unit it is our choice, how many sensors’ we use. , In this project we use two
separate identical circuits for implementing two different sensors the two electronics circuit are
used with infra red sensors and fire alarm sensor.

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CHAPTER 2
2.1 MICROCONTROLLER 2051 CONTROL UNIT
Pin Diagram of 2051 Controller
The 2051 is a low voltage (2.7V - 6V), high performance CMOS 8-bit microcontroller
with 2 Kbytes of Flash programmable and erasable read only memory (PEROM). This device is
compatible with the industry standard 8051 instruction set and pin out. The 2051 is a powerful
microcomputer which provides a highly flexible and cost effective solution to many embedded
control applications. The 2051 provides the following features:
 2 Kbytes of Flash
 128 bytes of RAM
 15 I/O lines
 Two16-bit timer/counters
 Five vector, two-level interrupt architecture
 Full duplex serial port
 Precision analog comparator
 On chip oscillator and clock circuitry

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In addition, the 2051 is designed with static logic for operation down to zero frequency
and supports two software selectable power saving modes. The Idle Mode stops the CPU while
allowing the RAM, timer/counters, serial port and interrupt system to continue functioning. The
Power Down Mode saves the RAM contents but freezes the oscillator disabling all other chip
functions until the next hardware reset.
Microcontroller 2051 is characterized with negative triggering. The input in the form of
negative pulses from the two sensor circuits are used to trigger the microcontroller .The input
from the Fire sensor is send to the Pin no 6 and input for the Infrared sensor is send to the Pin no
3 .One buzzer is connected to the pin no 17 (Port p1.5) This buzzer is turned “ON” when circuit
senses an input from the input sensors. After the Microcontroller senses the input it performs
three functions with a definite time delay in between each functions.
Pin Description
VCC
Supply voltage.
GND
Ground.
Port 1 is an 8-bit bidirectional I/O port. Port pins P1.2 to P1.7 provide internal pullups. P1.0 and
P1.1 require external pullups. P1.0 and P1.1 also serve as the positive input (AIN0) and the
negative input (AIN1), respectively, of the on-chip precision analog comparator. The Port 1
output buffers can sink 20 Ma and can drive LED displays directly. When 1s are written to Port 1
pins, they can be used as inputs. When pins P1.2 to P1.7 are used as inputs and are externally
pulled low, they will source current (IIL) because of the internal pullups.
Port 1 also receives code data during Flash programming and program verification.
Port 3 pins P3.0 to P3.5, P3.7 are seven bidirectional I/O pins with internal pullups. P3.6 is hard-
wired as an input to the output of the on-chip comparator and is not accessible as a general
purpose I/O pin. The Port 3 output buffers can sink 20 mA. When 1s are written to Port 3 pins
they are pulled high by the internal pullups and can be used as inputs. As inputs, Port 3 pins that
are externally being pulled low will source current (IIL) because of the pullups. Port 3 also
serves the functions of various special features of the AT89C2051 as listed below:

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Port Pin Alternate Functions
P3.0 RXD (serial input port)
P3.1 TXD (serial output 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)
Port 3 also receives some control signals for Flash programming and programming verification.
RST Reset input. All I/O pins are reset to 1s as soon as RST goes high. Holding the RST pin
high for two machine cycles while the oscillator is running resets the device. Each machine cycle
takes 12 oscillator or clock cycles.
XTAL1 Input to the inverting oscillator amplifier and input to the internal clock operating
circuit.
XTAL2 Output from the inverting oscillator amplifier.
Oscillator Characteristics
XTAL1 and XTAL2 are the input and output, respectively, of an inverting amplifier
which can be configured for use as an on-chip oscillator, as shown in Figure 1. Either a quartz
crystal or ceramic resonator may be used. To drive the device from an external clock source,
XTAL2 should be left unconnected while XTAL1 is driven as shown in Figure 2. There are no
requirements on the duty cycle of the external clock signal, since the input to the internal
clocking circuitry is through a divide by- two flip-flop, but minimum and maximum voltage high
and Low time specifications must be observed.
2.2 GSM MODEM
The GSM net used by cell phones provides a low cost, long range, wireless
communication channel for applications that need connectivity rather than high data rates.
Machinery such as industrial refrigerators and freezers, HVAC, vending machines, vehicle
service etc. could benefit from being connected to a GSM system.

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Take a given example. A garage offers a very special package to their customers. Based on the
mechanics knowledge and the given vehicle, tailored service intervals can be specified. A part of
the service agreement is installation of a GSM modem in the vehicle. An onboard service
application can then notify the garage when the vehicle approaches its service interval. The
garage will schedule an appointment and inform the customer.
The customer will benefit from a reliable and well-serviced vehicle at a minimum cost. The
garage on the other hand can provide excellent customer support, vehicle statistics, efficient
work scheduling, and minimum stocks. This application note describes how to use an AVR to
control a GSM modem in a cellular phone. The interface between modem and host is a textual
protocol called Hayes AT-Commands. These commands enable phone setup, dialing, text
messaging etc.
GSM Modem
Theory of Operation
The protocol used by GSM modems for setup and control is based on the Hayes AT
Command set. The GSM modem specific commands are adapted to the services offered by a
GSM modem such as: text messaging, calling a given Phone number, deleting memory locations
etc. Since the main objective for this application note is to show how to send and receive text

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messages, only a subset of the AT-Command set needs to be implemented. The European
Telecommunication Standard Institute (ETSI) GSM 07.05 defines the AT-Command interface
for GSM compatible modems. From this document some selected commands are chosen, and
presented briefly in this section. This command subset will enable the modem to send and
receive SMS messages. For further details, please consult GSM 07.05.
Connection Diagram
Block Diagram
AT-Command set
The following section describes the AT-Command set. The commands can be tried out by
connecting a GSM modem to one of the PC’s COM ports. Type in the test command, adding CR
+ LF (Carriage return + Line feed = rn) before executing. The following AT commands are
used

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Command Description
AT Check if serial interface and GSM modem is working.
ATE0 Turn echo off, less traffic on serial line.
AT+CNMI Display of new incoming SMS.
AT+CPMS Selection of SMS memory.
AT+CMGF SMS string format, how they are compressed.
AT+CMGR Read new message from a given memory location.
AT+CMGS Send message to a given recipient.
AT+CMGD Delete message.
Interfacing the GSM modem from a PC
All the commands are in the above table
Hardware setup and communication settings
To test the available modem and how it responds to AT-Commands, connect it to a PCs
COM port. This application note assumes that the phone will be connected using a RS232 data
cable, though IrDA® could be used if available.
With the phone connected, open a terminal application. Communication settings should
be found in the modem datasheet. If no such information can be obtained.
Now the connected system should enable sending AT-Commands from the terminal window.
Test with “AT” to verify this.
Connecting the same RS232 data cable to the AVR Butterfly, a suitable adapter has to be made.
Outputs from the level-shifter on the AVR Butterfly are routed to a 3x1 header, and not directly
compatible with the RS232 cable.
An adapter is easily made out of a male DSUB9 connector and two 2-wire cables
(Supplied with the STK500). Pin-out and wiring for such an adapter.

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Communication Setting

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Schematics for serial adapter
Status (AT)
The “AT” command is a status request used for testing if a compatible modem is connected and
that the serial interface is working properly.
Command Response Comment
“AT” “OK” Connected and working.
“ERROR” Serial line OK, modem error.
2.3 SENSOR
In the case of fire sensor we use op amplifier as a main component. Pin no 6 connected to
the sensor. Pin no. 1, 4, 5&11 are connected to Micro-controller AT89C2051’s pin no. 3, 4, 5&10.
It should be noted that the input to the microcontroller should by op amplifier.
IR SENSOR
IR sensor consists of two sensors. The first sensor presented is infrared based, while the
second one uses a red LED and a Cds photocell. The infrared based sensor emits the infrared
rays and the second sensor detects the rays which are reflected from the obstacle. A line sensor in

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its simplest form is a sensor capable of detecting a contrast between adjacent surfaces, such as
difference in color, roughness, or magnetic properties, for example. The simplest would be
detecting a difference in color, for example black and white surfaces. Using simple
optoelectronics, such as infrared photo-transistors, color contrast can easily be detected. Infrared
emitter/detectors or photo-transistors are inexpensive and are easy to interface to a
microcontroller.
The theory of operation is simple and for brevity, only the basics will be considered. When light
shines on a white surface, most of the incoming light is reflected away from the surface. In
contrast, most of the incoming light is absorbed if the surface is black. Therefore, by shining
light on a surface and having a sensor to detect the amount of light that is reflected, a contrast
between black and white surfaces can be detected.
LIGHT REFLECTING ON A WHITE AND BLACK SURFACE
Using what we know about light and black and white surfaces, the objective of tracking a
line is simple can be achieved using the appropriate sensors. In this article, we will consider the
use of three pairs of emitter and detector. The drive configuration for the robot is assumed to be
differential, i.e., like the tracks of an army tank vehicle. From the figure, the three pairs of
sensors are used to keep the robot on the line as it moves. Each sensor output is monitored to
determine the location of the tape relative to the robot. The main objective of the robot is to

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position itself such that the tape line falls between the two extreme sensors. If the tape line ever
ventures past these two extreme sensors, then the robot corrects by turning in the appropriate
direction to maintain tracking. Two different types of light sensors set up in the configuration
shown below will be used for line tracking.
IR SENSOR
Features
1. High reliability
2. Light weight
3. Low cost
4. Long detection range
5. Small size
6. Wide spectral response
7. Low forward voltage
Applications
1. Prevention from un authorized access
2. Burglar alarm system
3. Obstacle detection

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4. Home and industrial automation
5. Infrared remote control units with high power requirements
6. Infrared source for optical counters and card readers
7. IR source for smoke detectors.
FIRE SENSOR
The word thermistor is an acronym for thermal resistor, i.e.., a temperature sensitive
resistor. It is used to detect very small changes in temperature. The variation in temperature is
reflected through appreciable variation of the resistance of the device. Thermistor with both
negative temperature co-efficient (NTC) and positive temperature coefficient (PTC) is available,
but NTC thermistors are more common. The negative-temperature coefficient means that the
resistance increases with the increase in temperature.
NTC THERMISTOR PTC THERMISTOR
FEATURES
1. 0.5°C accuracy guarantee able (at +25°C)
2. Rated for full −55° to +150°C range
3. Suitable for remote applications

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4. Operates from 4 to 30 volts
5. Calibrated directly in ° Celsius (Centigrade)
6. Linear + 10.0 mV/°C scale factor
7. Low cost due to wafer-level trimming
APPLICATIONS
1. Temperature measurement and control
2. Liquid level measurement
3. Home and industrial automation
4. Temperature compensation in electronic circuits
5. Time delay measurement
2.4 Three-terminal 1A Positive Voltage Regulator
The MC78XX/LM78XX/MC78XXA series of three terminal positive regulators are available
in the TO-220/D-PAK package and with several fixed output voltages, making them useful in a
wide range of applications. Each type employs internal current limiting, thermal shut down and
safe operating area protection, making it essentially indestructible. If adequate heat sinking is
provided, they can deliver over 1A output current. Although designed primarily as fixed voltage
regulators, these devices can be used with external components to obtain adjustable voltages and
currents.
Features
• Output Current up to 1A.
• Output Voltages of 5, 6, 8, 9, 10, 12, 15, 18, 24V.
• Thermal Overload Protection.
• Short Circuit Protection.
• Output Transistor Safe Operating Area Protection.

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Positive Voltage Controller LM7805
Positive Voltage Controller (LM7805)

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2.5 OP-AMPLIFIER (LM324N)
Features
2-kV ESD Protection (K-Suffix Devices)
Wide Supply Range:
Single Supply - 3 V to 32 V
Dual Supplies - 1.5 V to 16 V
Low Supply-Current Drain Independent of Supply Voltage - 0.8 mA.

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Common-Mode Input Voltage Range Includes Ground, Allowing Direct Sensing Near
Ground
Low Input Bias and Offset Parameters:
Input Offset Voltage - 3 mV
A Versions- 2 mV
Input Offset Current - 2 nA
Input Bias Current - 20 nA
A Versions . . . 15 nA
Differential Input Voltage Range Equal to Maximum-Rated Supply Voltage 32 V
Open-Loop Differential Voltage Amplification- 100 V/mV
Internal Frequency Compensation
Op-Amplifier
These devices consist of four independent high-gain frequency-compensated operational
amplifiers that are designed specifically to operate from a single supply over a wide range of
voltages. Operation from split supplies also is possible if the difference between the two supplies
is 3 V to 32 V (3 V to 26 V for the LM2902), and VCC is at least 1.5 V more positive than the
input common-mode voltage. The low supply-current drain is independent of the magnitude of
the supply voltage.
Applications include transducer amplifiers, dc amplification blocks, and all the
conventional operational-amplifier circuits that now can be more easily implemented in single-
supply-voltage systems. For example, the LM124 can be operated directly from the standard 5-V
supply that is used in digital systems and easily provides the required interface electronics
without requiring additional ±15-V supplies.

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2.6 DIODE
The simplest semiconductor device is made up of a sandwich of p-type semi-conducting
material, with contacts provided to connect the p-type & n-type layers to an external circuit. This
is a Junction Diode. If the positive terminal of the battery is connected to the p-type material
(cathode) and the negative terminal to the n-type material (anode), a large current will flow. This
is called forward biasing. If the connections are reversed, a very little current will flow. This is
because under this condition, the p-type material will accept the electrons from the negative
terminal of the battery and the n-type material will give up its free electrons to the battery
resulting in the state of electrical equilibrium since the n-type material has no more electrons.
Thus there will be a small current to flow and the diode is called Reverse biased.
Thus the Diode allows direct current to pass only in one direction while blocking it in the other
direction. Power Diodes are used in converting AC current into DC current. In this, current will
flow freely during the first half cycle (forward biased) and practically not at all during the other
half cycle (reversed biased). This makes the diode an effective rectifier that converts AC current
into pulsating DC current. The signal diodes are used in radio circuits for the detection of radio
signals. Diodes are used in the circuit to control the voltage.
N P
Diode

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2.7 RESISTORS
Resistance is the property of a material offering opposition to current. It is measured in
Ohms. All conductors represent a certain amount of resistance as no conductor is 100% efficient.
To control the electron flow (current) in a predictable manner, we use resistors. Electronic
circuits use calibrated lumped resistance to control the flow of current. Resistances are of two
types: Fixed and Variable resistors. In fixed resistors, the value is fixed and cannot be varied
while in a variable resistance it can be varied using a knob.Resistor varieties are of many types:
(a) Carbon Composition
(b) Wire round and
(c) Special types.
The resistance values are determined by the color coding. Each resistor has four color stripes.
Resistors are of various power ratings that increases with increase in size
Colour Code
Black 0
Brown 1
Red 2
Orange 3
Yellow 4
Green 5
Blue 6
Violet 7
Grey 8
White 9

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First Color > first digit
Second Color > second digit
Third Color > Power of 10
Fourth Color > Tolerance (gold +5%, silver +10%, no color +20%)
2.8 BUZZER
The “Piezoelectric sound components” introduced herein operate on an innovative
principle utilizing natural oscillation of piezoelectric elements. These buzzers are offered in light
weight compact sizes from the smallest diameter of 12mm to large Piezo electric sounders.
Today piezoelectric sound components are used in many ways such as home appliances, OA
equipment, Audio equipment telephones etc. And they are widely applied for example in alarms,
speakers, telephone ringers, receivers, beep sounds etc.
PIEZO ELERTRIC BUZZER TYPES OF BUZZER

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PIEZO ELECTRIC BUZZER CIRCUIT
OSCILLATING SYSTEM
Basically the sound source of a piezoelectric sound component is a piezoelectric
diaphragm. A piezoelectric diaphragm consists of a piezoelectric ceramic plate which has
electrodes on both sides and a metal plate (Brass or stainless steel). A piezoelectric ceramic plate
is attached to a metal plate with adhesives. Figure shows the oscillating system of a piezoelectric
diaphragm. Applying D.C voltage between electrodes of a piezoelectric diaphragm causes
mechanical distortion due to piezoelectric effect. For a misshaped piezoelectric element, the
distortion of the piezoelectric element expands in a radial direction.
STRUCTURE OF PIEZOELECTRIC DIAPHRAGM
2.9 PRINTED CIRCUIT BOARD:
Printed Circuit Board is used for housing components to make a circuit. A PCB acts as a
base. It is used as it provides compactness, simplicity of servicing and ease of interconnection.

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There are single-sided, double sided and double sided with plated through hold (PYH) types of
PCBs.
The PCBs are made up of either phenolic paper based material or Glass epoxy material.
Both materials are available as laminate sheets with copper cladding.
PCBs have a copper cladding on either one or both sides. In both types of PCBs, this is
done by pasting a thin copper foil on the board during the curing process. PCBs are prepared in
sizes of 1-2 meter wide and up to 2 meter long. The thickness of the PCBs is 1.42 to 1.8 mm.
The copper deposited on these PCBs is about 0.2mm thick and weighs an ounce per square foot.
Printed Circuit Board

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CHAPTER 3
3.1 SOFTWARE DESCRIPTION
1. Click on the Keil uVision Icon on Desktop
2. The following fig will appear
3. Click on the Project menu from the title bar
4. Then Click on New Project

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5. Save the Project by typing suitable project name with no extension in your own folder
sited in either C: or D:
6. Then Click on Save button above.
7. Select the component for u r project. i.e. Atmel…
8. Click on the + Symbol beside of Atmel
9. Select AT89C51 as shown below

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10. Then Click on “OK”
11. The Following fig will appear
12. Then Click either YES or NO………mostly “NO”
13. Now your project is ready to USE
14. Now double click on the Target1, you would get another option “Source group 1” as shown
in next page.

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15. Click on the file option from menu bar and select “new”
16. The next screen will be as shown in next page, and just maximize it by double clicking on its
blue boarder.

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17. Now start writing program in either in “C” or “ASM”
18. For a program written in Assembly, then save it with extension “. asm” and for “C” based
program save it with extension “ .C”
19. Now right click on Source group 1 and click on “Add files to Group Source”

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20. Now you will get another window, on which by default “C” files will appear.
21. Now select as per your file extension given while saving the file
22. Click only one time on option “ADD”
23. Now Press function key F7 to compile. Any error will appear if so happen.

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24. If the file contains no error, then press Control+F5 simultaneously.
25. The new window is as follows
26. Then Click “OK”

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27. Now Click on the Peripherals from menu bar, and check your required port as shown in fig
below.
28. Drag the port a side and click in the program file
29. Now keep Pressing function key “F11” slowly and observe.
30. You are running your program successfully.

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3.2 SOURCE CODE
FOR AUTO DIALE HOME SECURITY
ORG 00H
MOV P1,#3CH
SETB P3.5 ;KEY
BEGIN: MOV P0,#0FFH
CLR P3.4 ;BUZZER OFF
CLR P2.6 ;INTER FACE WITH MODEM
STAY: JB P3.5,STAY ;KEY;
MOV P0,#0FFH;
CLR P3.4 ;BUZZER OFF;
CLR P2.6 ;DISMISS COMMECTION TO MODEM;
TEST FOR SENSOR OPEN
SENSOR1: JB P1.0,EXIT
SJMP SENSOR1
EXIT: MOV R4,#50
CLR P0.0
ACALL DELAY
ACALL DELAY
DJNZ R4,BLINK1
MOV P0,#0FEH
SETB P0.0
SENSOR2:JB P1.0,ENTRY
JB P1.0,SENSOR ON
JNB P1.1,SENSOR ON
JNB P1.2,SENSOR ON
SJMP SENSOR2
ACALL SIREN
ENTRY : MOV R5,#50
CLR P0.0
ACALL DELAY

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ACALL DELAY
DJNZ R5,BLINK2
SETB P0.0
JB P3.5,REPEATE
SIREN : SETB P3.4 ;BUZZER ON
SETB P2.6 ;INTER FACE WITH GSM MODEM
ACALL DELAY
ACALL DELAY
ACALL DELAY
ACALL DELAY
ACALL DELAY
ACALL DELAY
ACALL DELAY
SETB P2.7 ;REDIAL ON
ACALL DELAY
ACALL DELAY
ACALL DELAY
ACALL DELAY
ACALL DELAY
CLR P2.7 ;REDIAL OFF
KEY : JNB P3.5,KEY ;
MOV P1,#0FFH;
SETB P3.2 ;BUZZER OFF;
SETB P3.4 ;DISMISS COMMECTION
REPEATE: LJMP BEGIN
DELAY: MOV R2, #255
HERE2: MOV R3, #255
HERE: DJNZ R3, HERE
DJNZ R2, HERE2
RET
END

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CHAPTER 4
4.1 RESULTS
The circuit gives an exact simulation of switching of electrical appliances with the phone
as a mobile-remote. Using this circuit model we are able to switch four devices connected to it.
The circuit works extremely well for four devices although we can always enhance it for
implementing switching up to eight devices.
4.2 DISCUSSION
Our circuit, the “Auto Dialer Home Security System” is an excellent device for
contemporary home security and messaging system. The exact circuit for AC current devices
needs to have an external power supply. Further we can use the same circuit for up to eight
devices using the same IC. The relays used in the circuit are electro-mechanical and therefore it
may sometimes cause malfunctioning. For this purpose we can use newer Optocoupler that do
not need a physical connection between the circuit and the controlled device. In that mechanism
infra-red light ray is used between the actual base circuit and the device.
4.3 CONCLUSION
This device prototype which we have designed on an elementary level for exploring the
various ranges of possibility for the security of home and instant messaging in terms of any
unusual mishappening has stood with complete accuracy in terms of operation, delay in
activation, environment sustainability. The device works excellently well under simulated
conditions. The actual circuit based on this model will definitely prove to be a landmark success
in the field of home security and office security.

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4.4 SCOPE OF FUTURE ENHANCEMENTS
Our circuit model is the first step towards the new enhancements in wide ranging security
issues pertaining to various field from military to personal home security. Since we have
designed only a prototype to confirm the righteous way in which we are proceeding for
implementing our designs and ideas, hence we leave every possible situation for future
enhancements. Those few possible enhancements in the configuration of the circuit that will
bring about excellence are.
 Since we have implemented only two sensors for fire and intrusion sensing, hence we can
implement more sensors approximately up to 6 for e.g. Water level indicator, sensor to
detect any leakage of gas, we can also interface with fax machine & computer to sense
any incoming fax or email etc.
 A further enhancement which we can make is that we can use microprocessor
AT89S52&8086 instead of AT89C2501 for extending our range of security issues.
 In place of the traditional electro-mechanical relays, we can use contemporary Opto-
couplers. They are operated through infra red light rays. When a command for switching
is keyed in by the caller, the Opto- couplers will be activated by the circuit and only the
desired device is switched on.
 The device may be interfaced with a computer connected to a gsm modem. Thus, it is
possible to create a software simulation of the device.

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CHAPTER 4
5.1 REFERENCES
a) BOOKS REFERED
 Jillman J & Halkias C
 Jivan S. Parab
 Ron Manchini
 Ramakant A. Gaekwad
b) SOFTWARE USED
PCB Designing Software
Simulation software for Microcontroller AT89C51
Simulink software for circuit designing and analysis
Virtual Studio For Programming of GSM modem.
c) WEBSITES REFERED
1. www.atmel.com
2. www.pantechprojects.com
3. www.fairchildsemi.com
d) EXPANSES
S.No. Component Name Quantity Price (Rs.)
1 Micro Controller (AT89C2051) 1 150
2 Op-Amplifier (LM324N) 1 50
3 GSM Modem 1 3000
4 Sensors(IR&FIRE) 1 20
5 Three terminal Voltage regulator 1 35
6 IC 20&14 Pins Connector 1 10
7 Buzzer 1 20

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8 Serial mail connector 1 35
9 2 Pin Header cable 1 8
10 Soldering Iron 1 60
11 Variable Registers 2 14
Total 3402
Rest of Components are Provided by College