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GSM BASED WIRELESS ROBOT

SUBMITTED BY

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TABLE OF CONTENTS

CHAPTER ONE: INTRODUCTION

1.1 Introduction

1.2 Methodology

1.3 Scope of Work

1.4 Aims of the GSM ROBOT CONTROL

1.5 Objectives of the GSM ROBOT CONTROL

CHAPTER TWO: THEORETICAL BACKGROUND AND LITERATURE REVIEW

2.0 Theoretical Background

2.1 GSM Architecture

2.2 Technical Details

2.3 Main Cellular Standards

2.4 GSM Frequencies

2.5 Network Structure

2.6 Subscriber Identity Module (SIM)

2.7 Literature Review

2.8 GSM Security

2.9 Circuit Diagram of the GSM ROBOT CONTROL and Power Supply

CHAPTER THREE: DESIGN AND CONSTRUCTION

3.1 GSM Modem

3.1.1 Accessing GSM MODEM using Microsoft HyperTerminal

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3.2 Testing of GSM Modem

3.3 List of Important AT Commands

3.4 Microcontroller – MODEM Interfacing

3.4.1. DTE and DCE

3.4.2. RS-232

3.4.3. RTS/CTS Handshaking

3.4.4. Specifying Baud Rate, Parity & Stop bits

3.4.5 DCE Baud Rates

CHAPTER FOUR: TESTS, RESULTS, AND DISCUSSION

4.1 Testing a DB-9 RS-232 serial port in HyperTerminal

4.2 Testing and Observations

4.3 Operational Flowchart

4.4 Initializations

4.4.1 Serial transfer using TI and RI flags

4.4.2 Validity Check

4.4.3 Display

4.5 Programmer

4.6 Simulator

4.6 Burner

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4.7 Components List

CHAPTER FIVE: RECOMMENDATION AND CONCLUSION

5.1 Conclusion

5.2 Problems Encountered

5.2 Future Improvement

5.3 Recommendation

REFERENCES

APPENDIX A: USER’S MANUAL

APPENDIX B: TROUBLESHOOTING MANUAL

APPENDIX C: PROGRAM FLOWCODE

APPENDIX D: CONSTRUCTION STAGES

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CHAPTER ONE

INTRODUCTION

GSM and GPRS based Designs have developed another

innovative and Public utility product for mass communication

[1]. This is a Robot Control Device which control the Robot

through messages received as SMS or GPRS Packets and also

send acknowledgement of task. Such Devices can be used at

different areas of the human being life. Such offices, houses,

factories etc. Sent command from Mobiles or PCs to these

devices for move the motor left, right, stop. These devices are

designed to remotely control the Robot from anywhere and

anytime. Wireless communication has announced its arrival on

big stage and the world is going mobile [2]. We want to control

everything and without moving an inch. This remote control

Robot Control device is possible through Embedded Systems.

The use of “Embedded System in Communication” has given

rise to many interesting applications that ensures comfort and

safety to human life [3]. The main aim of the project will be to

design a SMS electronic Robot Control toolkit which can

replace the traditional Robot Control Devices. The toolkit

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receives the SMS, validates the sending Mobile Identification

Number (MIN) and perform the desired operation after

necessary code conversion. The system is made efficient by

SIMs so that the SMS can be received by number of devices

boards in a locality using techniques of time division multiple

access.

The main components of the toolkit include microcontroller,

GSM modem. These components are integrated with the device

board and thus incorporate the wireless features. The GSM

modem receives the SMS. The AT commands are serially

transferred to the modem. In return the modem transmits the

stored message through the wireless link. The microcontroller

validates the SMS and then perform specific task on the device.

The microcontroller used in this case is ATMEL AT89S52

.Motorola W220 is used as the GSM modem. In this prototype

model, LCD display is used for simulation purpose. The results

presented in the thesis support the proper functionalities and

working of the system. The timing diagram suggests the

response of the modem to various AT (attention) commands.

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1.2 METHODOLOGY

The method used to carry out this project is the principle of

serial communication in collaboration with embedded systems.

This is a very good project for Industries. This project has a

Robot Control, which will be used as the electronic device, and

also a GSM modem, which is the latest technology used for

communication between the mobile and the embedded devices.

System will work like when the user wants to on/off the

device; he has to send the message in his mobile defining the

messages and then the password of the system to the number of

the subscriber identity module (SIM) which is inserted in the

display system MODEM. Then, the MODEM connected to the

display system will receive the SMS, the microcontroller inside

the system is programmed in such a way that when the modem

receives any message the microcontroller will read the message

from serial headphone and verify for the password, if the

password is correct then it will start performing desire task.

1.3 Scope of Work

I will use liquid crystal display for displaying the message; I will

also use GSM modem (Motorola W220) as an interface between

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mobile and microcontroller. I will send message from any phone

irrespective of the GSM network to the modem connected to the

programmable device using a password. The message will get

by the GSM Modem of the device and do specific task.

1.4 AIMS OF THE GSM ELECTRONIC ROBOT

CONTROL

Uses: This is a very useful and innovative project you can

use this project in industries to control the robot for

different tasks.

1.5 OBJECTIVES OF THE GSM ELECTRONIC

ROBOT CONTROL

Programming of the mobile phone with AT (Attention)

command sequence

Interfacing the programming chip with the personal

computer

Interfacing the programmable chip with the Robot.

Interfacing of the mobile phone with the programmable

chip

Sending messages from the remote phone to control device.

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BLOCK DIAGRAM

89S52

REGULATED POWER SUPPLY

GSM MODEM

LCD

L293D

BUZZER

DC

MOTORS

MOBILE PHONES

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CIRCUIT DIAGRAM

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COMPONENT LIST

WIRELESS ROBOT – CONTROL

Name Capacity Quantity Code

Regulator 7805 1 U1

Regulator 7812 1 U3

Capacitor 1000µf 1 C1

Capacitor 10µf 1 C2

Ceramic Capacitor 22pf 2 C3,C4

Diode 4 D1,D2,D3,D4

Push Button 1

Mobile Phone 1

DC MOTOR 100rpm 2

LCD 16*2 1

40 Pin Base 1 U2

16 Pin Base 1 U4

8051(AT89S52) 1

L293D 1

Oscillator 11.0592mhz 1 X1

LED 1 D5

Resistance 220Ω 1 R1

Resistance 1k 1 R3

Resistance 10k 1 R2

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CHAPTER TWO

THEORETICAL BACKGROUND AND LITERATURE

REVIEW

2.0 Theoretical Background

GSM (Global System for Mobile communications: originally

from GROUPE Special Mobile) is the most popular standard for

mobile phones in the world. Its promoter, the GSM Association,

estimates that 80% of the global mobile market uses the

standard. GSM is used by over 3 billion people across more than

212 countries and territories [4]. Its ubiquity makes international

roaming very common between mobile phone operators

enabling subscribers to use their phones in many parts of the

world. GSM differs from its predecessors in that both signaling

and speech channels are digital, and thus is considered a second

generation (2G) mobile phone system [5]. This has also meant

that data communication was easy to build into the system.

2.1 GSM Architecture

GSM is a complex system and difficult to understand. The

Mobile Station (MS) refers to the mobile equipment [6]. The

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Base Station Subsystem controls the radio link with the Mobile

Station. The Network Subsystem performs main functions such

as switching of calls between mobile users, mobility

management operations, and proper operation and setup of a

network [7]. These functions are controlled by the Mobile

Services Switching Center (MSC).

2.2 TECHNICAL DETAILS

GSM is a cellular network, which means that mobile phones

connect to it by searching for cells in the immediate vicinity.

2.3 MAIN CELLULAR STANDARDS

YEAR STANDARD MOBILE

TELEPHONE

SYSTEM

TECHNO

LOGY

PRIMARY

MARKETS

1981 NMT540 NORDIC MOBILE

TELEPHONY

ANALOG

UE

EUROPE,MIDDL

E EAST

1985 TACS TOTAL ACCESS

COMMUNUNICATION

SYSTEM

ANALOG

UE

EUROPE AND

CHINA

1986 NMT900 NORDIC MOBILE ANALOG EUROPE,

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TELEPHONY UE MIDDLE EAST

1991 GSM GLOBAL SYSTEM FOR

MOBILE

COMMUNICATION

DIGITAL WORLD-WIDE

1991 TDMA TIME DIVISION

MULTIPLE ACCESS

DIGITAL AMERICA

1993 CDMA CODE DIVISION

MULTIPLE ACCESS

DIGITAL NORTH

AMERICA,

KOREA

1992 GSM 1800 GLOBAL SYSTEM FOR

MOBILE

COMMUNICATION

DIGITAL EUROPE

1994 PDC PERSONAL DIGITAL

CELLULAR

DIGITAL JAPAN

1995 PCS 1900 PERSONAL

COMPUTER SERVICES

DIGITAL NORTH

AMERICA

2001 GSM 800 GLOBAL SYSTEM FOR

MOBILE

COMMUNICATION

DIGITAL NORTH

AMERICA

2006-TILL

DATE

GSM 450 GLOBAL SYSTEM FOR

MOBILE

COMMUNICATION

DIGITAL WORLD-WIDE

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2.4 GSM FREQUENCIES

GSM networks operate in a number of different frequency

ranges (separated into GSM frequency ranges for 2G and UMTS

frequency bands for 3G). Most 2G GSM networks operate in the

900 MHz or 1800 MHz bands. Some countries in the Americas

(including Canada and the United States) use the 850 MHz and

1900 MHz bands because the 900 and 1800 MHz frequency

bands were already allocated. Most 3G GSM networks in

Europe operate in the 2100 MHz frequency band [9]

2.5 NETWORK STRUCTURE

The network behind the GSM seen by the customer is large and

complicated in order to provide all of the services which are

required.

The Base Station Subsystem (the base stations and their

controllers).

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The Network and Switching Subsystem (the part of the

network most similar to a fixed network). This is

sometimes also just called the core network.

The GPRS Core Network (the optional part which allows

packet based Internet connections).

All of the elements in the system combine to produce many

GSM services such as voice calls and SMS.

2.6 SUBSCRIBER IDENTITY MODULE (SIM)

One of the key features of GSM is the Subscriber Identity

Module, commonly known as a SIM card. The SIM is a

detachable smart card containing the user's subscription

information and phone book. This allows the user to retain his or

her information after switching handsets [10]. Alternatively, the

user can also change operators while retaining the handset

simply by changing the SIM. Some operators will block this by

allowing the phone to use only a single SIM, or only a SIM

issued by them; this practice is known as SIM locking, and is

illegal in some countries [11].

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2.7 LITERATURE REVIEW

This project is an implementation to the idea of the wireless

communication between a mobile phone and a microcontroller.

Currently the main work that has been done on this proposed

system is through serial port to the computer but not wireless. If

they want to control the GENERATOR, they have to go to the

remote area and change the rotation and one /off the

GENERATOR. But in this new design, the systems need not be

reprogrammed to control GENERATOR changing the

programming of microcontroller. The user will send SMS from

his phone and he will be able to control the GENERATOR.

2.8 GSM SECURITY

GSM was designed with a moderate level of security. The

system was designed to authenticate the subscriber using a pre-

shared key and challenge-response. Communications between

the subscriber and the base station can be encrypted.

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Fig. 2.2 Block Diagram

As we see in the above figure, there are at least three interfacing

circuits, MAX-232 with Microcontroller, LCD display with

microcontroller, and MAX-232 with GSM MODEM.

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HARDWARE DISCRIPTION

POWER SUPPLY:

Power supply is a reference to a source of electrical power. A

device or system that supplies electrical or other types of

energy to an output load or group of loads is called a power

supply unit or PSU. The term is most commonly applied to

electrical energy supplies, less often to mechanical ones, and

rarely to others.

Here in our application we need a 5v DC power supply for all

electronics involved in the project. This requires step down

transformer, rectifier, voltage regulator, and filter circuit for

generation of 5v DC power. Here a brief description of all the

components is given as follows:

TRANSFORMER:

A transformer is a device that transfers electrical energy from

one circuit to another through inductively coupled conductors —

the transformer's coils or "windings". Except for air-core

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transformers, the conductors are commonly wound around a

single iron-rich core, or around separate but magnetically-

coupled cores. A varying current in the first or "primary"

winding creates a varying magnetic field in the core (or cores) of

the transformer. This varying magnetic field induces a varying

electromotive force (EMF) or "voltage" in the "secondary"

winding. This effect is called mutual induction.

If a load is connected to the secondary circuit, electric charge

will flow in the secondary winding of the transformer and

transfer energy from the primary circuit to the load connected in

the secondary circuit.

The secondary induced voltage VS, of an ideal transformer, is

scaled from the primary VP by a factor equal to the ratio of the

number of turns of wire in their respective windings:

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By appropriate selection of the numbers of turns, a transformer

thus allows an alternating voltage to be stepped up — by making

NS more than NP — or stepped down, by making it

BASIC PARTS OF A TRANSFORMER

In its most basic form a transformer consists of:

A primary coil or winding.

A secondary coil or winding.

A core that supports the coils or windings.

Refer to the transformer circuit in figure as you read the

following explanation: The primary winding is connected to a

60-hertz ac voltage source. The magnetic field (flux) builds up

(expands) and collapses (contracts) about the primary winding.

The expanding and contracting magnetic field around the

primary winding cuts the secondary winding and induces an

alternating voltage into the winding. This voltage causes

alternating current to flow through the load. The voltage may be

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stepped up or down depending on the design of the primary and

secondary windings.

THE COMPONENTS OF A TRANSFORMER

Two coils of wire (called windings) are wound on some type of

core material. In some cases the coils of wire are wound on a

cylindrical or rectangular cardboard form. In effect, the core

material is air and the transformer is called an AIR-CORE

TRANSFORMER. Transformers used at low frequencies, such

as 60 hertz and 400 hertz, require a core of low-reluctance

magnetic material, usually iron. This type of transformer is

called an IRON-CORE TRANSFORMER. Most power

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transformers are of the iron-core type. The principle parts of a

transformer and their functions are:

The CORE, which provides a path for the magnetic lines of

flux.

The PRIMARY WINDING, which receives energy from

the ac source.

The SECONDARY WINDING, which receives energy

from the primary winding and delivers it to the load.

The ENCLOSURE, which protects the above components

from dirt, moisture, and mechanical damage.

BRIDGE RECTIFIER

A bridge rectifier makes use of four diodes in a bridge

arrangement to achieve full-wave rectification. This is a widely

used configuration, both with individual diodes wired as shown

and with single component bridges where the diode bridge is

wired internally.

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BASIC OPERATION

According to the conventional model of current flow originally

established by Benjamin Franklin and still followed by most

engineers today, current is assumed to flow through electrical

conductors from the positive to the negative pole. In actuality,

free electrons in a conductor nearly always flow from the

negative to the positive pole. In the vast majority of

applications, however, the actual direction of current flow is

irrelevant. Therefore, in the discussion below the conventional

model is retained.

In the diagrams below, when the input connected to the left

corner of the diamond is positive, and the input connected to the

right corner is negative, current flows from the upper supply

terminal to the right along the red (positive) path to the output,

and returns to the lower supply terminal via the blue (negative)

path.

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When the input connected to the left corner is negative, and the

input connected to the right corner is positive, current flows

from the lower supply terminal to the right along the red path to

the output, and returns to the upper supply terminal via the blue

path.

In each case, the upper right output remains positive and lower

right output negative. Since this is true whether the input is AC

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or DC, this circuit not only produces a DC output from an AC

input, it can also provide what is sometimes called "reverse

polarity protection". That is, it permits normal functioning of

DC-powered equipment when batteries have been installed

backwards, or when the leads (wires) from a DC power source

have been reversed, and protects the equipment from potential

damage caused by reverse polarity.

Prior to availability of integrated electronics, such a bridge

rectifier was always constructed from discrete components.

Since about 1950, a single four-terminal component containing

the four diodes connected in the bridge configuration became a

standard commercial component and is now available with

various voltage and current ratings.

OUTPUT SMOOTHING

For many applications, especially with single phase AC where

the full-wave bridge serves to convert an AC input into a DC

output, the addition of a capacitor may be desired because the

bridge alone supplies an output of fixed polarity but

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continuously varying or "pulsating" magnitude (see diagram

above).

The function of this capacitor, known as a reservoir capacitor (or

smoothing capacitor) is to lessen the variation in (or 'smooth')

the rectified AC output voltage waveform from the bridge. One

explanation of 'smoothing' is that the capacitor provides a low

impedance path to the AC component of the output, reducing the

AC voltage across, and AC current through, the resistive load. In

less technical terms, any drop in the output voltage and current

of the bridge tends to be canceled by loss of charge in the

capacitor. This charge flows out as additional current through

the load. Thus the change of load current and voltage is reduced

relative to what would occur without the capacitor. Increases of

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voltage correspondingly store excess charge in the capacitor,

thus moderating the change in output voltage / current.

The simplified circuit shown has a well-deserved reputation for

being dangerous, because, in some applications, the capacitor

can retain a lethal charge after the AC power source is removed.

If supplying a dangerous voltage, a practical circuit should

include a reliable way to safely discharge the capacitor. If the

normal load cannot be guaranteed to perform this function,

perhaps because it can be disconnected, the circuit should

include a bleeder resistor connected as close as practical across

the capacitor. This resistor should consume a current large

enough to discharge the capacitor in a reasonable time, but small

enough to minimize unnecessary power waste.

Because a bleeder sets a minimum current drain, the regulation

of the circuit, defined as percentage voltage change from

minimum to maximum load, is improved. However in many

cases the improvement is of insignificant magnitude.

The capacitor and the load resistance have a typical time

constant τ = RC where C and R are the capacitance and load

resistance respectively. As long as the load resistor is large

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enough so that this time constant is much longer than the time of

one ripple cycle, the above configuration will produce a

smoothed DC voltage across the load.

In some designs, a series resistor at the load side of the capacitor

is added. The smoothing can then be improved by adding

additional stages of capacitor–resistor pairs, often done only for

sub-supplies to critical high-gain circuits that tend to be

sensitive to supply voltage noise.

The idealized waveforms shown above are seen for both voltage

and current when the load on the bridge is resistive. When the

load includes a smoothing capacitor, both the voltage and the

current waveforms will be greatly changed. While the voltage is

smoothed, as described above, current will flow through the

bridge only during the time when the input voltage is greater

than the capacitor voltage. For example, if the load draws an

average current of n Amps, and the diodes conduct for 10% of

the time, the average diode current during conduction must be

10n Amps. This non-sinusoidal current leads to harmonic

distortion and a poor power factor in the AC supply.

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In a practical circuit, when a capacitor is directly connected to

the output of a bridge, the bridge diodes must be sized to

withstand the current surge that occurs when the power is turned

on at the peak of the AC voltage and the capacitor is fully

discharged. Sometimes a small series resistor is included before

the capacitor to limit this current, though in most applications

the power supply transformer's resistance is already sufficient.

Output can also be smoothed using a choke and second

capacitor. The choke tends to keep the current (rather than the

voltage) more constant. Due to the relatively high cost of an

effective choke compared to a resistor and capacitor this is not

employed in modern equipment.

Some early console radios created the speaker's constant field

with the current from the high voltage ("B +") power supply,

which was then routed to the consuming circuits, (permanent

magnets were then too weak for good performance) to create the

speaker's constant magnetic field. The speaker field coil thus

performed 2 jobs in one: it acted as a choke, filtering the power

supply, and it produced the magnetic field to operate the

speaker.

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REGULATOR IC (78XX)

It is a three pin IC used as a voltage regulator. It converts

unregulated DC current into regulated DC current.

Normally we get fixed output by connecting the voltage

regulator at the output of the filtered DC (see in above diagram).

It can also be used in circuits to get a low DC voltage from a

high DC voltage (for example we use 7805 to get 5V from 12V).

There are two types of voltage regulators 1. fixed voltage

regulators (78xx, 79xx) 2. variable voltage regulators (LM317)

In fixed voltage regulators there is another classification 1. +ve

voltage regulators 2. -ve voltage regulators POSITIVE

VOLTAGE REGULATORS This include 78xx voltage

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regulators. The most commonly used ones are 7805 and 7812.

7805 gives fixed 5V DC voltage if input voltage is in (7.5V,

20V).

THE CAPACITOR FILTER

The simple capacitor filter is the most basic type of power

supply filter. The application of the simple capacitor filter is

very limited. It is sometimes used on extremely high-voltage,

low-current power supplies for cathode ray and similar electron

tubes, which require very little load current from the supply. The

capacitor filter is also used where the power-supply ripple

frequency is not critical; this frequency can be relatively high.

The capacitor (C1) shown in figure 4-15 is a simple filter

connected across the output of the rectifier in parallel with the

load.

Full-wave rectifier with a capacitor filter.

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When this filter is used, the RC charge time of the filter

capacitor (C1) must be short and the RC discharge time must be

long to eliminate ripple action. In other words, the capacitor

must charge up fast, preferably with no discharge at all. Better

filtering also results when the input frequency is high; therefore,

the full-wave rectifier output is easier to filter than that of the

half-wave rectifier because of its higher frequency.

For you to have a better understanding of the effect that filtering

has on Eavg, a comparison of a rectifier circuit with a filter and

one without a filter is illustrated in views A and B of figure 4-

16. The output waveforms in figure 4-16 represent the unfiltered

and filtered outputs of the half-wave rectifier circuit. Current

pulses flow through the load resistance (RL) each time a diode

conducts. The dashed line indicates the average value of output

voltage. For the half-wave rectifier, Eavg is less than half (or

approximately 0.318) of the peak output voltage. This value is

still much less than that of the applied voltage. With no

capacitor connected across the output of the rectifier circuit, the

waveform in view A has a large pulsating component (ripple)

compared with the average or dc component. When a capacitor

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is connected across the output (view B), the average value of

output voltage (Eavg) is increased due to the filtering action of

capacitor C1.

UNFILTERED

Half-wave rectifier with and without filtering.

FILTERE

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The value of the capacitor is fairly large (several microfarads),

thus it presents a relatively low reactance to the pulsating current

and it stores a substantial charge.

The rate of charge for the capacitor is limited only by the

resistance of the conducting diode, which is relatively low.

Therefore, the RC charge time of the circuit is relatively short.

As a result, when the pulsating voltage is first applied to the

circuit, the capacitor charges rapidly and almost reaches the

peak value of the rectified voltage within the first few cycles.

The capacitor attempts to charge to the peak value of the

rectified voltage anytime a diode is conducting, and tends to

retain its charge when the rectifier output falls to zero. (The

capacitor cannot discharge immediately.) The capacitor slowly

discharges through the load resistance (RL) during the time the

rectifier is non-conducting.

The rate of discharge of the capacitor is determined by the value

of capacitance and the value of the load resistance. If the

capacitance and load-resistance values are large, the RC

discharge time for the circuit is relatively long.

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A comparison of the waveforms shown in figure 4-16 (view A

and view B) illustrates that the addition of C1 to the circuit

results in an increase in the average of the output voltage (Eavg)

and a reduction in the amplitude of the ripple component (Er)

which is normally present across the load resistance.

Now, let's consider a complete cycle of operation using a half-

wave rectifier, a capacitive filter (C1), and a load resistor (RL).

As shown in view A of figure 4-17, the capacitive filter (C1) is

assumed to be large enough to ensure a small reactance to the

pulsating rectified current. The resistance of RL is assumed to be

much greater than the reactance of C1 at the input frequency.

When the circuit is energized, the diode conducts on the positive

half cycle and current flows through the circuit, allowing C1 to

charge. C1 will charge to approximately the peak value of the

input voltage. (The charge is less than the peak value because of

the voltage drop across the diode (D1)). In view A of the figure,

the heavy solid line on the waveform indicates the charge on C1.

As illustrated in view B, the diode cannot conduct on the

negative half cycle because the anode of D1 is negative with

respect to the cathode. During this interval, C1 discharges

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through the load resistor (RL). The discharge of C1 produces the

downward slope as indicated by the solid line on the waveform

in view B. In contrast to the abrupt fall of the applied ac voltage

from peak value to zero, the voltage across C1 (and thus across

RL) during the discharge period gradually decreases until the

time of the next half cycle of rectifier operation. Keep in mind

that for good filtering, the filter capacitor should charge up as

fast as possible and discharge as little as possible.

Figure 4-17A. - Capacitor filter circuit (positive and negative

half cycles). POSITIVE HALF-CYCLE

Figure 4-17B. - Capacitor filter circuit (positive and negative

half cycles). NEGATIVE HALF-CYCLE

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Since practical values of C1 and RL ensure a more or less

gradual decrease of the discharge voltage, a substantial charge

remains on the capacitor at the time of the next half cycle of

operation. As a result, no current can flow through the diode

until the rising ac input voltage at the anode of the diode exceeds

the voltage on the charge remaining on C1. The charge on C1 is

the cathode potential of the diode. When the potential on the

anode exceeds the potential on the cathode (the charge on C1),

the diode again conducts, and C1 begins to charge to

approximately the peak value of the applied voltage.

After the capacitor has charged to its peak value, the diode will

cut off and the capacitor will start to discharge. Since the fall of

the ac input voltage on the anode is considerably more rapid

than the decrease on the capacitor voltage, the cathode quickly

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become more positive than the anode, and the diode ceases to

conduct.

Operation of the simple capacitor filter using a full-wave

rectifier is basically the same as that discussed for the half-wave

rectifier. Referring to figure 4-18, you should notice that

because one of the diodes is always conducting on. either

alternation, the filter capacitor charges or discharges during each

half cycle. (Note that each diode conducts only for that portion

of time when the peak secondary voltage is greater than the

charge across the capacitor.)

Figure 4-18. - Full-wave rectifier (with capacitor filter).

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Another thing to keep in mind is that the ripple component (E r)

of the output voltage is an ac voltage and the average output

voltage (Eavg) is the dc component of the output. Since the filter

capacitor offers relatively low impedance to ac, the majority of

the ac component flows through the filter capacitor. The ac

component is therefore bypassed (shunted) around the load

resistance, and the entire dc component (or Eavg) flows through

the load resistance. This statement can be clarified by using the

formula for XC in a half-wave and full-wave rectifier. First, you

must establish some values for the circuit.

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As you can see from the calculations, by doubling the frequency

of the rectifier, you reduce the impedance of the capacitor by

one-half. This allows the ac component to pass through the

capacitor more easily. As a result, a full-wave rectifier output is

much easier to filter than that of a half-wave rectifier.

Remember, the smaller the XC of the filter capacitor with respect

to the load resistance, the better the filtering action. Since

the largest possible capacitor will provide the best filtering.

Remember, also, that the load resistance is an important

consideration. If load resistance is made small, the load current

increases, and the average value of output voltage (Eavg)

decreases. The RC discharge time constant is a direct function of

the value of the load resistance; therefore, the rate of capacitor

voltage discharge is a direct function of the current through the

load. The greater the load current, the more rapid the discharge

of the

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capacitor, and the lower the average value of output voltage. For

this reason, the simple capacitive filter is seldom used with

rectifier circuits that must supply a relatively large load current.

Using the simple capacitive filter in conjunction with a full-

wave or bridge rectifier provides improved filtering because the

increased ripple frequency decreases the capacitive reactance of

the filter capacitor.

CIRCUIT DIAGRAM OF POWER SUPPLY

45

DIODE

The diode is a p-n junction device. Diode is the component

used to control the flow of the current in any one direction. The

diode widely works in forward bias.

Diode When the current flows from the P to N direction. Then it

is in forward bias. The Zener diode is used in reverse bias

function i.e. N to P direction. Visually the identification of the

diode`s terminal can be done by identifying he silver/black line.

The silver/black line is the negative terminal (cathode) and the

other terminal is the positive terminal (cathode).

APPLICATION

•Diodes: Rectification, free-wheeling, etc

•Zener diode: Voltage control, regulator etc.

46

•Tunnel diode: Control the current flow, snobbier circuit, etc

RESISTORS

The flow of charge through any material encounters an

opposing force similar in many respects to mechanical friction

.this opposing force is called resistance of the material .in some

electric circuit resistance is deliberately introduced in form of

resistor. Resistor used fall in three categories , only two of

which are color coded which are metal film and carbon film

resistor .the third category is the wire wound type ,where value

are generally printed on the vitreous paint finish of the

component. Resistors are in ohms and are represented in Greek

letter omega, looks as an upturned horseshoe. Most electronic

circuit require resistors to make them work properly and it is

obliviously important to find out something about the different

types of resistors available. Resistance is measured in ohms, the

symbol for ohm is an omega ohm. 1 ohm is quite small for

electronics so resistances are often given in kohm and Mohm.

Resistors used in electronics can have resistances as low as 0.1

ohm or as high as 10 Mohm.

47

FUNCTION

Resistor restrict the flow of electric current, for example a

resistor is placed in series with a light-emitting diode(LED) to

limit the current passing through the LED.

TYPES OF RESISTORS

FIXED VALUE RESISTORS

It includes two types of resistors as carbon film and metal film

.These two types are explained under

CARBON FILM RESISTORS

During manufacture, at in film of carbon is deposited onto a

small ceramic rod. The resistive coating is spiraled away in an

automatic machine until the resistance between there two ends

of the rods is as close as possible to the correct value. Metal

leads and end caps are added, the resistors is covered with an

48

insulating coating and finally painted with colored bands to

indicate the resistor value

Carbon Film Resistors

Another example for a Carbon 22000 Ohms or 22 Kilo-Ohms

also known as 22K at 5% tolerance: Band 1 = Red, 1st digit

Band 2 = Red, 2nd digit Band 3 = Orange, 3rd digit, multiply

with zeros, in this case 3 zero's Band 4 = Gold, Tolerance, 5%

METAL FILM RESISTORS

Metal film and metal oxides resistors are made in a similar way,

but can be made more accurately to within ±2% or ±1% of their

nominal vale there are some difference in performance between

these resistor types, but none which affects their use in simple

circuit.

49

WIRE WOUND RESISTOR

A wire wound resistor is made of metal resistance wire, and

because of this, they can be manufactured to precise values.

Also, high wattage resistors can be made by using a thick wire

material. Wire wound resistors cannot be used for high

frequency circuits. Coils are used in high frequency circuit. Wire

wound resistors in a ceramic case, strengthened with special

cement. They have very high power rating, from 1 or 2 watts to

dozens of watts. These resistors can become extremely hot when

used for high power application, and this must be taken into

account when designing the circuit.

TESTING

Resistors are checked with an ohm meter/millimeter. For a

defective resistor the ohm-meter shows infinite high reading.

CAPACITORS

In a way, a capacitor is a little like a battery. Although they

work in completely different ways, capacitors and batteries both

store electrical energy. If you have read How Batteries Work ,

50

then you know that a battery has two terminals. Inside the

battery, chemical reactions produce electrons on one terminal

and absorb electrons at the other terminal.

BASIC

Like a battery, a capacitor has two terminals. Inside the

capacitor, the terminals connect to two metal plates separated by

a dielectric. The dielectric can be air, paper, plastic or anything

else that does not conduct electricity and keeps the plates from

touching each other. You can easily make a capacitor from two

pieces of aluminum foil and a piece of paper. It won't be a

particularly good capacitor in terms of its storage capacity, but it

will work.

In an electronic circuit, a capacitor is shown like this:

51

When you connect a capacitor to a battery, here’s what happens:

•The plate on the capacitor that attaches to the negative terminal

of the battery accepts electrons that the battery is producing.

•The plate on the capacitor that attaches to the positive terminal

of the battery loses electrons to the battery.

TESTING

To test the capacitors, either analog meters or specia

l digital meters with the specified function are used. The non-

electrolyte capacitor can be tested by using the digital meter.

Multi – meter mode : Continuity Positive probe : One end

Negative probe : Second end Display : `0`(beep sound

occur) `OL` Result : Faulty OK

52

LED

LED falls within the family of P-N junction devices. The light

emitting diode (LED) is a diode that will give off visible light

when it is energized. In any forward biased P-N junction there

is, with in the structure and primarily close to the junction, a

recombination of hole and electrons. This recombination

requires that the energy possessed by the unbound free electron

be transferred to another state. The process of giving off light by

applying an electrical source is called electroluminescence.

LED is a component used for indication. All the functions being

carried out are displayed by led .The LED is diode which glows

when the current is being flown through it in forward bias

53

condition. The LEDs are available in the round shell and also in

the flat shells. The positive leg is longer than negative leg.

DC MOTOR

DC Motor has two leads. It has bidirectional motion

If we apply +ve to one lead and ground to another motor

will rotate in one direction, if we reverse the connection the

motor will rotate in opposite direction.

If we keep both leads open or both leads ground it will not

rotate (but some inertia will be there).

If we apply +ve voltage to both leads then braking will

occurs.

54

H-BRIDGE

This circuit is known as H-Bridge because it looks like ” H”

Working principle of H-Bridge.

If switch (A1 and A2 )are on and switch (B1 and

B2) are off then motor rotates in clockwise

direction

55

If switch (B1 and B2 )are on and switch (A1 and

A2) are off then motor rotates in Anti clockwise

direction

we can use Transistor, mosfets as a switch ( Study

the transistor as a a switch)

H-Bridge I.C (L293D)

L293D is a H-Bridge I.C. Its contain two H-Bridge pair.

56

Truth Table

Input 1 Input 2 Result

0 0 No rotation

0 1 Clockwise rotation

1 0 Anti clockwise

rotation

1 1 break

Note:-

Connect motors pins on output 1 and output 2 and control

signal at input 1 and input 2 will control the motion

Connect another motor pins on output 3 and output 4 and

control signal at input3and input 4

Truth table for i/p 3 and i/p 4 is same as above shown

0 means 0 V or Low

1 means High or +5V

57

In Enable 1 and Enable 2 if you give high then you observe

hard stop in condition 0 0 and 11. Unless slow stop of

motor on low signal

Required Motor voltage has given on pin 8 (Vs) i.e 12V

DC – 24V DC

SCHEMATIC OF L293D WITH DC MOTOR

+ 15 V DC

MOTOR VOLTAGE

L293D

27

1015

19

361114

168

IN1IN2IN3IN4

EN1EN2

OUT1OUT2OUT3OUT4

VSSVS

+5V DC

DUAL H-BRIDGE

+ 5 V DC

DC MOTOR

12

DC MOTOR 1

2

58

CHAPTER THREE

3.1 GSM Modem

A GSM modem is a wireless modem that works with a GSM

wireless network. A wireless modem behaves like a dial-up

modem. The main difference between them is that a dial-up

modem sends and receives data through a fixed telephone line

while a wireless modem sends and receives data through radio

waves. Like a GSM mobile phone, a GSM modem requires a

SIM card from a wireless carrier in order to operate [11].

3.1.1 Accessing GSM MODEM using Microsoft

HyperTerminal

Microsoft HyperTerminal is a small program that comes with

Microsoft Windows. We use it to send AT commands to the

GSM modem. It can be found at Start -> Programs ->

Accessories -> Communications -> HyperTerminal. Before

programming our SMS application, it is required to check if the

GSM modem and SIM card are working properly first [12]. The

MS HyperTerminal is a handy tool when it comes to testing the

GSM device. It is a good idea to test the GSM devices

beforehand. When a problem occurs, sometimes it is difficult to

59

tell what causes the problem. The cause can be the program, the

GSM device or the SIM card. If GSM device and SIM card with

MS HyperTerminal are operating properly, then it is very likely

that the problem is caused by the program or other hardware

[12]. For Linux users, Mincom can be used instead of

HyperTerminal.

3.2 Testing of GSM Modem

To use MS HyperTerminal to send AT commands to the GSM

modem, the following procedure is followed

1. I put a valid SIM (MTN) card into the GSM modem. I obtain

a SIM card by subscribing to the GSM service of a wireless

network operator.

2. No need to install any driver for the GSM modem

3. Then I set up MS HyperTerminal by selecting Start ->

Programs -> Accessories -> Communications ->

HyperTerminal.

4. In the Connection Description dialog box (as shown in the

screenshot given below), I enter any file name and choose an

icon I like for the connection. Then I click the OK button.

. In the Connect To dialog box, choose the COM port that your

mobile phone or GSM modem is connecting to in the Connect

60

using combo box. I choose COM1 because my mobile phone is

connected to the COM1 port. Then click the OK button. Type

"AT" in the main window. A response "OK" will be returned

from the mobile phone or GSM modem. Type "AT+CPIN?" in

the main window. The AT command "AT+CPIN?" is used to

query whether the mobile phone or GSM modem is waiting for a

PIN (personal identification number, i.e. password). If the

response is "+CPIN: READY", it means the SIM card does not

require a PIN and it is ready for use. If my SIM card requires a

PIN, you need to set the PIN with the AT command

"AT+CPIN=<PIN>".

[

3.3 List of Important AT Commands

After successfully testing the MODEM for its correct

operational state, I then set the MODEM parameters like Baud

rate, Echo off etc to enable easier access via a microcontroller

which I used in this project. The following are the

ATCOMMAND used for programming the gsm modem

Example: Changing and saving parameters

AT+IPR=9600[Enter] Transfer rate to 9600bps

61

AT&W [Enter] save parameters

AT+CMGF means convert the message to machine instruction

format

AT+CPMS means selection of SMS memory

AT+CMGR means read message from a given memory location

AT+CMGD means delete message from a given memory

location.

3.4 Microcontroller – Modem Interfacing

3.4.1. DTE and DCE

The terms DTE and DCE are very common in the data

communications market. DTE is short for Data Terminal

Equipment and DCE stands for Data Communications

Equipment. As the full DTE name indicates this is a piece of

device that ends a communication line, whereas the DCE

provides a path for communication. Let's say I have a computer

on which wants to communicate with the Internet through a

modem and a dial-up connection. To get to the Internet I tell my

modem to dial the number of my provider. After my modem has

dialed the number, the modem of the provider will answer my

62

call and I will hear a lot of noise. Then it becomes quiet and I

see my login prompt or my dialing program tells me the

connection is established. Now I have a connection with the

server from my provider and I can surf the Internet [13].

3.5 Microcontroller – LCD Interfacing

Above is the quite simple schematic. The LCD panel’s Enable

and Register Select is connected to the Control Port. The Control

Port is an open collector / open drain output. Therefore by

incorporating the two 10K external pull up resistors, the circuit

is more portable for a wider range of computers, some of which

may have no internal pull up resistors. I make no effort to place

the Data bus into reverse direction. Therefore I had wire the R/W

line of the LCD panel, into write mode. This will cause no bus

conflicts on the data lines. As a result I cannot read back the

63

LCD’s internal Busy Flag which tells us if the LCD has

accepted and finished processing the last instruction [20]. This

problem is overcome by inserting known delays into my

program. The 10k Potentiometer controls the contrast of the

LCD panel. Nothing fancy here.

I used a power supply of 5volt. The user may select whether the

LCD is to operate with a 4-bit data bus or an 8- bit data bus. If a

4-bit data bus is used, the LCD will require a total of 7 data

lines. If an 8-bit data bus is used, the LCD will require a total of

11 data lines [20]. LCD with 8-bit data bus is used for this

design. The three control lines are EN, RS, and RW. EN line

must be raised/lowered before/after each instruction sent to the

LCD regardless of whether that instruction is read or write text

or instruction. In short, I manipulate EN when communicating

with the LCD.

64

CHAPTER FOUR

4.2 Testing and Observations

After inclusion of the validation module in the program code, I

test the module with the device called universal programmer. In

this prototype I used only one valid number. With more memory

available three or four valid numbers can be included. When a

message is sent to number carried by the SIM of the MODEM,

the validation module of the program checks character by

character the sender’s number with the number stored in the

memory as the valid or authentic number. I then look for signals

on the TX and RX lines. What you see below on the left are the

signals on these lines with the ECHO being ON (ATE1). The

corresponding picture on the right depicts the modem response

after about 460 ms (variable as per message length: D) delay

with the new message

Test Result

12345 Please submit your

thesis

Please submit your thesis

12345 there will be a meeting There will be a meeting by

65

by 2pm 2pm

12345 I want to see Mr. Musa I want to see Mr. Musa

12345 I will not come to

school today

I will not come to school today

12345 please enemy alert Please enemy alert

12345 I am in India I am in India

12345 please hurry up Please hurry up

1234 I will be in office in the

next 30 minute

I will be in office in the next 30

minute

12345 is the password of the GSM electronic notice board.

Any message a user want to send has to be preceded by 12345

spaces the message. A user will then send the message to the

GSM number that is inside the Motorola c168

4.3 Initializations

The baud rate of the modem was set to be 9600 bps using the

HyperTerminal, The ECHO from the modem was turned off

using the command ATE0 at the HyperTerminal. For serial

transmission and reception to be possible both the DTE and

66

DCE should have same operational baud rates. Hence to set the

microcontroller at a baud rate of 9600bps, I set terminal count of

Timer 1 at 0FFh (clock frequency = 1.8432). The TCON and

SCON registers were set accordingly.

4.4.1 Serial transfer using TI and RI flags

After setting the baud rates of the two devices both the devices

are now ready to transmit and receive data in form of characters.

Transmission is done when TI flag is set and similarly data is

known to be received when the Rx flag is set. The

microcontroller then sends an AT command to the modem in

form of string of characters serially just when the TI flag is set.

After reception of a character in the SBUF register of the

microcontroller (response of MODEM with the read message in

its default format or ERROR message or OK message), the RI

flag is set and the received character is moved into the physical

memory of the microcontroller [22].

4.4.2 Validity Check

After serially receiving the characters the code then checks for

start of the sender’s number and then compares the number

character by character with the valid number pre stored in the

67

memory. Since we are employing just one valid number, we are

able to do the validation process dynamically i.e. without storing

the new message in another location in the memory. For more

than one valid numbers we would require more memory

locations to first store the complete (valid/invalid) message in

the memory and then perform the comparison procedure.

4.4.3 Display

After validity check the control flow goes into the LCD program

module to display the valid message stored in the memory. In

case of multiple valid numbers all invalid stored messages are

deleted by proper branching in the code to the “delete-message”

module.

4.4 Programmer

When we have to learn about a new computer we have to

familiarize about the machine capability we are using, and we

can do it by studying the internal hardware design (devices

architecture), and also to know about the size, number and the

size of the registers.

68

A microcontroller is a single chip that contains the processor

(the CPU), non-volatile memory for the program (ROM or

flash), volatile memory for input and output (RAM), a clock and

an I/O control unit. Also called a "computer on a chip," billions

of microcontroller units (MCUs) are embedded each year in a

myriad of products from toys to appliances to automobiles. For

example, a single vehicle can use 70 or more microcontrollers.

The following picture describes a general block diagram of

microcontroller.

89S52: The AT89S52 is a low-power, high-performance

CMOS 8-bit microcontroller with 8K bytes of in-system

programmable Flash memory. The device is manufactured using

Atmel’s high-density nonvolatile memory technology and is

compatible with the industry-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-grammar. By combining a versatile 8-bit CPU with

in-system programmable Flash on a monolithic chip, the Atmel

AT89S52 is a powerful microcontroller, which provides a highly

flexible and cost-effective solution to many, embedded control

69

applications. The AT89S52 provides the following standard

features: 8K bytes of Flash, 256 bytes of RAM, 32 I/O lines,

Watchdog timer, two data pointers, three 16-bit timer/counters, a

six-vector two-level interrupt architecture, a full duplex serial

port, on-chip oscillator, and clock circuitry. In addition, the

AT89S52 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

con-tents but freezes the oscillator, disabling all other chip

functions until the next interrupt

70

The hardware is driven by a set of program instructions, or

software. Once familiar with hardware and software, the user

can then apply the microcontroller to the problems easily.

The pin diagram of the 8051 shows all of the input/output

pins unique to microcontrollers:

71

The following are some of the capabilities of 8051

microcontroller.

Internal ROM and RAM

I/O ports with programmable pins

Timers and counters

Serial data communication

The 8051 architecture consists of these specific features:

16 bit PC &data pointer (DPTR)

72

8 bit program status word (PSW)

8 bit stack pointer (SP)

Internal ROM 4k

Internal RAM of 128 bytes.

4 register banks, each containing 8 registers

80 bits of general purpose data memory

32 input/output pins arranged as four 8 bit

ports: P0-P3

Two 16 bit timer/counters: T0-T1

Two external and three internal interrupt

sources Oscillator and clock circuits.

4.5 Simulator

KEIL Micro Vision is an integrated development environment

used to create software to be run on embedded systems (like a

microcontroller). It allows for such software to be written either

in assembly or C programming languages and for that software

to be simulated on a computer before being loaded onto the

microcontroller. The software used is c programming

73

μVision3 is an IDE (Integrated Development Environment)

that helps write, compile, and debug embedded programs. It

encapsulates the following components:

A project manager.

A make facility.

Tool configuration.

Editor.

74

A powerful debugger.

To create a GSM ENOTICE board project in uVision3:

1. Select Project - New Project.

2. Select a directory and enter the name of the project file.

3. Select Project –Select Device and select a device from

Device Database.

4. Create source files to add to the project

5. Select Project - Targets, Groups, and Files. Add/Files,

select Source Group1, and add the

Source files to the project.

6. Select Project - Options and set the tool options. Note that

when the target device is selected from the Device

Database all-special options are set automatically. Default

memory model settings are optimal for most applications.

7. Select Project - Rebuild all target files or Build target.

To create a new project, simply start micro vision and

select “Project”=>”New Project” from the pull–down menus.

In the file dialog that appears, a filename and directory was

chosen for the project. It is recommended that a new directory

75

be created for each project, as several files will be generated.

Once the project has been named, the dialog shown in the

figure below will appear, prompting the user to select a target

device. The chip being used is the “AT89S52,” which is listed

under the heading “Atmel”.

Next, Micro Vision was instructed to generate a HEX file

upon program compilation. A HEX file is a standard file format

for storing executable code that is to be loaded onto the

microcontroller. In the “Project Workspace” pane at the left,

right–click on “Target 1” and select “Options for ‘Target 1’

”.Under the “Output” tab of the resulting options dialog, ensure

that both the “Create Executable” and “Create HEX File”

options are checked. Then click “OK”.

Next, a file must be added to the project that will contain

the project code. To do this, expand the “Target 1” heading,

right–click on the “Source Group 1” folder, and select “Add

files…” Create a new blank file (the file name should end in

“.c”), select it, and click “Add.” The new file should now appear

in the “Project Workspace” pane under the “Source Group 1”

76

folder. Double-click on the newly created file to open it in the

editor. To compile the program, first save all source files by

clicking on the “Save All” button, and then click on the

“Rebuild All Target Files” to compile the program as shown in

the figure below. If any errors or warnings occur during

compilation, they will be displayed in the output window at the

bottom of the screen. All errors and warnings will reference the

line and column number in which they occur along with a

description of the problem so that they can be easily located

[23].

When the program has been successfully compiled, it can

be simulated using the integrated debugger in Keil Micro

Vision. To start the debugger, select “Debug”=>”Start/Stop

Debug Session” from the pull–down menus.

At the left side of the debugger window, a table is

displayed containing several key parameters about the simulated

microcontroller, most notably the elapsed time (circled in the

figure below). Just above that, there are several buttons that

control code execution. The “Run” button will cause the

program to run continuously until a breakpoint is reached,

77

whereas the “Step Into” button will execute the next line of code

and then pause (the current position in the program is indicated

by a yellow arrow to the left of the code).

4.6 PRO51 BURNER SOFTWARE

PRO51 BURNER provides you with software burning tools for

8051 based Microcontrollers in their Flash memory. The 51

BURNER tools, you can burn AT89C/SXXXX series of

ATMEL

microcontrollers.

78

CHAPTER FIVE

5.1 Conclusion

The prototype of the GSM based Generator Control device was

efficiently designed. This prototype has facilities to be

integrated with a Generator thus making it truly mobile. The

toolkit accepts the SMS, stores it, validates it and perform

specific operations. The SMS is deleted from the phone each

time it is read, thus making room for the next SMS.

5.2 Problem Encountered

During soldering, many of the connection become short

cktd. So we desolder the connection and did soldering

again.

A leg of the crystal oscillator was broken during mounting.

So it has to be replaced.

LED`s get damaged when we switched ON the supply so

we replace it by the new one.

TROUBLESHOOT

Care should be taken while soldering. There should be no

shorting of joints.

Proper power supply should maintain.

79

5.2 Future Improvement

In my project I am sending messages through GSM network

and Control the home devices by utilizing AT

(ATTENTION) commands. The same principle can be

applied to display the message on electronics display board

appliances at a distant location.

Robots can be controlled in a similar fashion by sending the

commands to the robots. These commands are read by using

AT commands and appropriate action is taken. This can be

used for spy robots at distant locations, utilized by the

military to monitor movement of enemy troops.

Currently farmers have to manually put on or off pumps,

drippers etc by using electric switches. Using the principle of

AT commands we can put on or off these appliances

remotely.

5.3 Recommendation

It is highly recommended that electronic board should be

constructed for this new system (GSM electronic notice board)

80

REFERENCES

1. The 8051Microcontroller by Kenneth J. Ayala

2. The 8051 Microcontroller and Embedded Systems by

Muhammad Ali Mazidi.

3. Principles and Applications of GSM by Vijay Garg.

4. Artificial Intelligence – Elain Rich & Kevin Knight, Tata Mc

Graw Hill, 2nd Edition.

5. Artificial Intelligence – A Modern approach – Slaurt Russel

and Peter Norving, Pearson Education, 2nd Edition.

6. Introduction to Robotics – P.J.Mc Kerrow, Addisson Wesley,

USA, 1991 Bernard Sklar, Digital Communications:

Fundamentals and Applications, Prentice Hall, 2001.

7. A. Clark and R. Harun, Assessment of kalman-_lter channel

estimators for an HF radio link," IEE Proceedings, vol. 133,

pp. 513521, Oct 1986.

8. ETS 300 502. European Digital Cellular Telecommunication

System (Phase 2); Teleservices Supported by a GSM Public

Land Mobile Network (PLMN). European

Telecommunications Standards Institute. September 1994.

81

9. Matthew C. Valenti and Jian Sun, Chapter 12: Turbo Codes,

Handbook of RF and Wireless

10. GSM Multiple Access Scheme,

http://www.eecg.toronto.edu/~nazizi/gsm/ma/ William

Stallings Data and Computer Communications 7th Edition:

Chapter 9 Spread Spectrum, http://juliet.stfx.ca/~lyang/csci-

465/lectures/09-SpreadSpectrum-new.ppt

11. ETS 300 608. Digital Cellular Telecommunication System

(Phase 2); Specification of the Subscriber Identity Module-

Mobile Equipment (SIM-ME) Interface. European

Telecommunications Standards Institute. May 1998.

12. ETR 100. European Digital Cellular Telecommunication

System (Phase 2); Abbreviations and Acronyms. European

Telecommunications Standards Institute. April 1995.

13. Jörg Eberspächer and Hans-Jörg Vögel. GSM switching,

services and Protocols. John Wiley and Sons, 1999.

14. Klaus Vedder GSM: Security, Services, and SIM. State of

the art in Applied Cryptography. Course on Computer

Security and Industrial Cryptography. Leuven, Belgium, June

3-6, 1997.

82

15. J. Wu and A. H. Aghvami, \A new adaptive equalizer with

channel estimator for mobile radio communications," IEEE

Transactions on Vehicular Technology,

16. L. J. Cimini, Analysis and simulation of a digital mobile

channel using orthogonal frequency division multiplexing,"

IEEE Transactions on Communications, vol. 33, pp. 665675,

July 1985.

17. B. Saltzberg, Performance of an ancient parallel data

transmission system," IEEE Trans. Commun. Techno., pp.

805813, December 1967

18. M. Zimmermann and A. Kirsch, The AN/GSC-

10/KATHRYN variable rate data modem for HF radio," IEEE

Trans. Commun.Techn., vol. CCM15,16

19. Hardware and user manuals of the modem from

MOTOROLA C168

http://developer.motorola.com/getDocument.do?docId=65054

20. http://www.mobilegpsonline.com/downloads/GM28-

29%20Datasheet%20R1G.pdf

21. http://www.mobilegpsonline.com/GSMJC01Spec.pdf

22. http://www.visualgsm.com/wire_sms_index.htm

23. http://en.wikipedia.org/wiki/Gsm

83

For futher details regarding to software and hardware and any

further querie contact to the given address.

HBeonLabs

Off. No. 46, 1st Floor, Kadamba Complex

Gamma-I, Greater Noida (India) - 201308

Contact us:

+91-120-4298000

+91-9212314779

info@hbeonlabs.com

training@hbeonlabs.com

www. hbeonlabs.com

84