ug major project - wireless bomb detection robot

A Project Report

On

““ WWII RREELL EESSSS BBOOMM BB DDEETTEECCTTII OONN RROOBBOOTT””

Submitted in partial fulfillment of the requirements for the award of the degree of

BACHELOR OF TECHNOLOGY IN

ELECTRONICS AND COMMUNICATION ENGINEERING

BY

ADITYA BADAMI (097F1A0402)

TAMMADI BABU RAO (097F1A0405)

G. SRI SAI RATNA (097F1A0425)

Under the guidance of

Mrs. S. NIHARIKA

Asst. Professor

Department of ECE

DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING

VISHWA BHARATHI INSTITUTE OF TECHNOLOGY & SCIENCES

Approved by AICTE, New Delhi & Affiliated to JNTU, Hyderabad. Nadergul (V), Saroor Nagar (M), Ranga Reddy (Dist) A. P. – 501510

i

Date: __________________

DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING

CERTIFICATE

This is to certify that Project entitled “WIRELESS BOMB DETECTION ROBOT”

is a bonafide work carried out by ADITYA BADAMI (097F1A0402), TAMMADI

BABU RAO (097F1A0405), G. SRI SAI RATNA (097F1A0425) in partial fulfillment

for the award of Bachelor of Technology in Department of ECE, “VISHWA

BHARATHI INSTITUTE OF TECHNOLOGY AND SCIENCES” , Hyderabad

during the year 2009-2013 under my supervision and guidance. The result embodied

in this Project Work has not been submitted to any other University or Institute for the

award of any Degree

INTERNAL GUIDE HEAD OF THE DEPARTMENT

Mrs. S. NIHARIKA (Asst. Professor) Mr.C.ASHOK VISHNU

PRINCIPAL EXTERNAL EXAMINER

iii

DECLARATION

We the undersigned, declare that the project title entitled “WIRELESS BOMB

DETECTION ROBOT” carried out at “WINEYARD TECHNOLOGIES” is

original and is being submitted to the Department of ECE “VISHWA BHARATHI

INSTITUTE OF TECHNOLOGY AND SCIENCES” , Hyderabad towards partial

fulfillment for the award of Bachelor of Technology.

We, declare that, the result embodied in the Project work has not been submitted to

any other University or Institute for the award of any Degree.

Date: ADITYA BADAMI (097F1A0402)

Place: Hyderabad TAMMADI BABU RAO (097F1A0405)

G. SRI SAI RATNA (097F1A0425)

iv

ACKNOWLEDGEMENT

The completion of this project work gives us an opportunity to convey our gratitude to

all those who have helped us to reach a stage where we have the confidence to launch

our career in the competitive world in the field of ELECTRONICS AND

COMMUNICATION ENGINEERING.

We express our sincere thanks to “Dr. D.MAHESHWAR REDDY” Principal,

“VISHWA BHARATHI INSTITUTE OF TECHNOLOGY AND SCIENC ES”

for providing all necessary facilities in completing our project report.

We express our sense of gratitude to Mr. C.ASHOK VISHNU Head of Department

of ECE, who encouraged us to select the project and completion of this project with

providing necessary facilities

Our honest thankfulness to Mrs. S. NIHARIKA , (Internal Guide) for her kind help

and for giving us the necessary guidance and valuable suggestions in completing this

project work and in preparing this report.

We take the opportunity to express gratitude to the Management, Teaching and Non

teaching Staff of “VISHWA BHARATHI INSTITUTE OF TECHNOLOGY AND

SCIENCES” for their kind co-operation during the period of my Study.

Finally, we would like to thank our parents & friends for their continuous

encouragement and support during the entire course of this project work.

`

v

ABSTRACT

The aim of our project is to design a wireless robot for bomb surveillance and

detection with a metal detector and to diffuse it by using a mobile jammer.

This is an interesting robot that can be controlled by hand gestures and by an

RF remote. This can be moved in forward and reverse direction using geared motors

of 60RPM. Also this robot can take sharp turnings towards left and right directions.

This project uses Arduino MCU as its controller. A high sensitive induction type

metal detector is designed using colpitts oscillator principle and fixed to this robot.

Also a mobile phone signal isolator is interfaced to the kit.

When the robot is moving on a surface, the system produces a beep sound

when Bomb is detected. Simultaneously a signal is fed to the jammer section to

switch on the jammer. This jammer diffuses the bomb by jamming the mobile signal

of GSM or CDMA or 3G networks.

The RF modules used here are STT-433 MHz Transmitter, STR-433 MHz

Receiver, HT12E RF Encoder and HT12D RF Decoder. The three switches are

interfaced to the RF transmitter through RF Encoder. The encoder continuously reads

the status of the switches, passes the data to the RF transmitter and the transmitter

transmits the data. This project uses 9V battery. This project is much useful for mines

detection and surveillance applications.

vi

LIST OF CONTENTS

TITLE PAGE NO

Certificate from the Department i

Certificate from the Organization ii

Declaration iii

Acknowledgement iv

Abstract v

Table of Contents vi

List of Figures viii

List of Tables ix

CHAPTER-1: INTRODUCTION 1 CHAPTER-2: BLOCK DIAGRAM 4 2.1 Transmitter block 4 2.2 Receiver block 5 2.3 Hardware implementation 6

CHAPTER-3: HARDWARE DETAILS 8 3.1 Power supply 8 3.2 Accelerometer 9 3.3 Encoder HT12E 11 3.4 RF Technology 12 3.5 Decoder HT12D 13 3.6 Mobile Jammer 14 3.7 Metal Detector 16 3.8 Buzzer 16 3.9 Liquid Crystal Display 17 3.10 DC Motor 18 3.11 H-Bridge 21 3.12 Microcontroller 24 CHAPTER-4: WIRELESS COMMUNICATION 26 4.1 Introduction 26 4.2 Properties of RF 27 4.3 Brief description of RF 27 4.4 Different RF Ranges and Applications 28 4.5 RF Transmitter STT-433MHZ 29 4.6 RF Receiver STR-433MHZ 31 4.7 RF Advantages 33

vii

4.8 RF Disadvantages 33 4.7 Interfacing of RF Transmitter with AT89S52 34 4.8 Interfacing of RF Receiver with ARDUINO 34

CHAPTER-5: MEMS TECHNOLOGY 35 5.1 MEMS Introduction 35 5.2 Accelerometer 38 5.3 Interfacing of MEMS sensor with Microcontroller 41 CHAPTER-6: MICROCONTROLLER 42 6.1 Introduction 42 6.2 Features 42 6.3 PIN Description of AT89S52 43 6.4 ARDUINO 46 6.5 ATmega328 Microcontroller 49 CHAPTER-7: SOFTWARE DETAILS 52 7.1 KEIL Software 52 7.2 PROLOAD 54 7.3 ARDUINO Software tools 55

CHAPTER-8: SCHEMATIC REPRESENTATION 60 8.1 Schematic representation of Transmitter 60 8.2 Schematic representation of Receiver 61 CHAPTER-9: APPLICATIONS AND ADVANTAGES 62 9.1 Applications 62 9.2 Advantages 62 CHAPTER-10: RESULT 63

CHAPTER-11: CONCLUSION AND FUTURE SCOPE 66 REFERENCES 67

APPENDIX

viii

LIST OF FIGURES

FIG NO. DESCRIPTION PAGE NO.

FIG 3.1 Components of RPS 8 FIG 3.2 Accelerometer 9 FIG 3.3 G-Whiz 10 FIG 3.4 Encoder PIN diagram 11 FIG 3.5 RF Transmitter and 12 FIG 3.6 Decoder PIN Diagram 13 FIG 3.7 Mobile Jammer 14 FIG 3.8 Jammer Signal 15 FIG 3.9 Buzzer 17 FIG 3.10 LCD display 17 FIG 3.11 Two Pole DC Motor 18 FIG 3.12 Rotation DC Motor 19 FIG 3.13 Three Pole DC Motor 20 FIG 3.14 DC Motor 20 FIG 3.15 Circuit of H-Bridge 21 FIG 3.16 Block Diagram of H-Bridge 23 FIG 3.17 PIN Connection 24 FIG 4.1 RF Transmitter 29 FIG 4.2 Applications 30 FIG 4.3 RF Receiver 31 FIG 4.4 PIN Diagram of RF Receiver 31 FIG 4.5 Digital Data PIN 32 FIG 5.1 Components of MEMS 35 FIG 5.2 Accelerometer 38 FIG 5.3 The Piezo electric Accelerometer 38 FIG 5.4 G-Whiz 39 FIG 5.5 Surface Micro Machined Accelerometer 40 FIG 6.1 AT89S52 PIN Diagram 43 FIG 6.2 Arduino Board 46 FIG 6.3 Arduino PIN diagram 47 FIG 6.4 AT mega PIN diagram 50

ix

LIST OF TABLES

TABLE NO. DESCRIPTION PG NO. Table 3.1 Encoder PIN Description 12 Table 3.2 Decoder PIN Description 13 Table 3.3 H-Bridge 22 Table 3.4 Absolute Maximum Ratings 23 Table 4.1 Different RF Ranges and Applications 28 Table 6.1 Port 1 44 Table 6.2 Port 3 45

WIRELESS BOMB DETECTION ROBOT ECE

VISHWA BHARATHI INSTITUTE OF TECHNOLOGY & SCIENCES (VBITS) Page 1

CHAPTER-1

INTRODUCTION

1.1 INTRODUCTION TO PROJECT

A Robot is a mechatronics device which also includes resourcefulness or autonomy.

A device with autonomy does its thing "on its own" without a human directly guiding

it moment-by-moment. Some authors would contend that all mechatronic devices are

robots, and that this book's restriction on robot entails only specialized software.

Robotics can be described as the current pinnacle of technical development.

Robotics is a confluence science using the continuing advancements of mechanical

engineering, material science, sensor fabrication, manufacturing techniques, and

advanced algorithms. The study and practice of robotics will expose a dabbler or

professional to hundreds of different avenues of study. For some, the romanticism of

robotics brings forth an almost magical curiosity of the world leading to creation of

amazing machines. A journey of a lifetime awaits in robotics.

Robotics can be defined as the science or study of the technology primarily

associated with the design, fabrication, theory, and application of robots. While other

fields contribute the mathematics, the techniques, and the components, robotics

creates the magical end product. The practical applications of robots drive

development of robotics and drive advancements in other sciences in turn. Crafters

and researchers in robotics study more than just robotics.

In this project we use a robot and it is controlled by hand gestures and these

hand movements are recognized by the hand gesture technology and based on the

movement of the hand the robot is moved in the respective direction i.e. either in

forward, backward, left or right. The benefits of such robots to these operations

include reduced personnel requirements, reduced fatigue, and access to otherwise

unreachable areas. Robotic search is useful since robots may be deployed in

dangerous environments without putting human responders at risk. This project is a

prototype which is widely used for military applications.



1.2 INTRODUCTION TO EMBEDDED SYSTEM:

An Embedded System is a combination of computer hardware and software, and

perhaps additional mechanical or other parts, designed to perform a specific function.

A good example is the microwave oven. Almost every household has one, and tens of

millions of them are used every day, but very few people realize that a processor and

software are involved in the preparation of their lunch or dinner.

This is in direct contrast to the personal computer in the family room. It too is

comprised of computer hardware and software and mechanical components (disk

drives, for example). However, a personal computer is not designed to perform a

specific function rather; it is able to do many different things. Many people use the

term general-purpose computer to make this distinction clear. As shipped, a general-

purpose computer is a blank slate; the manufacturer does not know what the customer

will do wish it. One customer may use it for a network file server another may use it

exclusively for playing games, and a third may use it to write the next great American

novel.

Frequently, an embedded system is a component within some larger system.

For example, modern cars and trucks contain many embedded systems. One

embedded system controls the anti-lock brakes, other monitors and controls the

vehicle's emissions, and a third displays information on the dashboard. In some cases,

these embedded systems are connected by some sort of a communication network, but

that is certainly not a requirement.

At the possible risk of confusing you, it is important to point out that a

general-purpose computer is itself made up of numerous embedded systems. For

example, my computer consists of a keyboard, mouse, video card, modem, hard drive,

floppy drive, and sound card-each of which is an embedded system.

Each of these devices contains a processor and software and is designed to

perform a specific function. For example, the modem is designed to send and receive

digital data over analog telephone line. That's it and all of the other devices can be

summarized in a single sentence as well.



If an embedded system is designed well, the existence of the processor and

software could be completely unnoticed by the user of the device. Such is the case for

a microwave oven, VCR, or alarm clock. In some cases, it would even be possible to

build an equivalent device that does not contain the processor and software. This

could be done by replacing the combination with a custom integrated circuit that

performs the same functions in hardware.

However, a lot of flexibility is lost when a design is hard-cooled in this way. It

is much easier, and cheaper, to change a few lines of software than to redesign a piece

of custom hardware.

1.3 MEMS TECHNOLOGY :

Micro-Electro-Mechanical Systems, or MEMS, is a technology that in its most

general form can be defined as miniaturized mechanical and electro-mechanical

elements (i.e., devices and structures) that are made using the techniques of micro

fabrication. The critical physical dimensions of MEMS devices can vary from well

below one micron on the lower end of the dimensional spectrum, all the way to

several millimeters.

Likewise, the types of MEMS devices can vary from relatively simple

structures having no moving elements, to extremely complex electromechanical

systems with multiple moving elements under the control of integrated

microelectronics. The one main criterion of MEMS is that there are at least some

elements having some sort of mechanical functionality whether or not these elements

can move.

The term used to define MEMS varies in different parts of the world. In the

United States they are predominantly called MEMS, while in some other parts of the

world they are called “Microsystems Technology” or “micro machined devices”.

Micro sensors and micro actuators are appropriately categorized as “transducers”,

which are defined as devices that convert energy from one form to another. In the case

of micro sensors, the device typically converts a measured mechanical signal into an

electrical signal.



CHAPTER-2

BLOCK DIAGRAM

2.1 TRANSMITTER BLOCK

LCD Display

Hand gesture recognizer-ACCELEROMETER

ENCODER

HT12E

RF Transmitter

STT - 433

AT89S52

Power supply to all Step down T/F

Bridge Rectifier

Filter Circuit

Regulator



2.2 RECEIVER BLOCK

Power supply to all sections

Lead acid

battery Regulator

H-Bridge

Geared Motor -

I

Geared Motor -

2

RF Decoder

RF Receiver

Reset

Power supply

Arduino

Metal Detector

Mobile Isolator

Buzzer



2.3 HARDWARE IMPLEMENTATION:

2.3.1 INTRODUCTION:

In this project we use a robot and it is controlled by hand gestures and these hand

movements are recognized by the hand gesture technology and based on the

movement of the hand the robot is moved in the respective direction i.e. either in

forward, backward, left or right. The benefits of such robots to these operations

include reduced personnel requirements, reduced fatigue, and access to otherwise

unreachable areas. Robotic search is useful since robots may be deployed in

dangerous environments without putting human responders at risk. This project is a

prototype which is widely used for military applications

2.3.2 COMPONENTS USED:

� Accelerometer

� AT89S52 Micro Controller

� Power Supply Unit

� LCD Display

� Buzzer

� RF Transmitter

� RF Receiver

� Arduino Micro Controller

� Motors

� Metal Detector

� Mobile Jammer

2.3.3 WORKING PROCEDURE:

The block diagram consists of data transmitter and data receiver blocks.

TRANSMITTER BLOCK:

As the overall system contains two microcontroller units, the function of

microcontrollers differ to each other, two different software programs are prepared to

function as data transmitter and data receiver.



The data transmitting unit consists of the following devices:

� Accelerometer

� AT89S52 micro controller

� Power Supply Unit

� RF Transmitter

� LCD Display

In our project, here we are using MEMS sensor i.e. accelerometer is given to

the port (P2.6- P2.7) of micro controller AT89S52.

The hand gesture given to accelerometer, this data is sent from AT89S52 to RF

transmitter from (P2.0- P2.3)

Simultaneously the direction of hand gesture made by accelerometer is

displayed on LCD which is interfaced with AT89S52 to the port (P1.0-P1.6).

RECEIVER BLOCK:

Similarly, the data receiving unit consists of the following devices:

� RF Receiver

� Arduino Microcontroller

� Motors

� Metal Detector

� Mobile Jammer

� Buzzer

The data which is transmitted from RF transmitter is received by RF receiver.

This information is sent to Arduino (ATMEGA 328).From Arduino the data is sent to

H-Bridge through Port (PC0-PC3) and the motor moves according to the hand

gesture made.

While the robot is moving, we have added a metal detector externally which

works on a separate battery. This metal detector is connected to buzzer as well as

mobile jammer. If metal detector detects the bomb, the buzzer makes the sound and

automatically mobile jammer is activated.



CHAPTER-3

HARDWARE DETAILS

3.1 POWER SUPPLY:

The input to the circuit is applied from the regulated power supply. The a.c. input i.e.,

230V from the mains supply is step down by the transformer to 12V and is fed to a

rectifier. The output obtained from the rectifier is a pulsating d.c voltage. So in order

to get a pure d.c voltage, the output voltage from the rectifier is fed to a filter to

remove any a.c components present even after rectification. Now, this voltage is given

to a voltage regulator to obtain a pure constant dc voltage.

Figure 3.1 Components of a regulated power supply

3.1.1 TRANSFORMER

Usually, DC voltages are required to operate various electronic equipment and these

voltages are 5V, 9V or 12V. But these voltages cannot be obtained directly. Thus the

a.c input available at the mains supply i.e., 230V is to be brought down to the required

voltage level.

This is done by a transformer. Thus, a step down transformer is employed to

decrease the voltage to a required level.



3.1.2 RECTIFIER

The output from the transformer is fed to the rectifier. It converts A.C. into pulsating

D.C. The rectifier may be a half wave or a full wave rectifier. In this project, a bridge

rectifier is used because of its merits like good stability and full wave rectification.

3.1.3 FILTER

Capacitive filter is used in this project. It removes the ripples from the output of

rectifier and smoothens the D.C. Output received from this filter is constant until the

mains voltage and load is maintained constant. However, if either of the two is varied,

D.C. voltage received at this point changes. Therefore a regulator is applied at the

output stage.

3.1.4 VOLTAGE REGULATOR

As the name itself implies, it regulates the input applied to it. A voltage regulator is an

electrical regulator designed to automatically maintain a constant voltage level. In this

project, power supply of 5V and 12V are required. In order to obtain these voltage

levels, 7805 and 7812 voltage regulators are to be used. The first number 78

represents positive supply and the numbers 05, 12 represent the required output

voltage levels.

3.2 ACCELEROMETER

An accelerometer is an apparatus, either mechanical or electromechanical, for

measuring acceleration or deceleration - that is, the rate of increase or decrease in the

velocity of a moving object. Accelerometers are used to measure the efficiency of the

braking systems on road and rail vehicles; those used in aircraft and spacecraft can

determine accelerations in several directions simultaneously. There are also

accelerometers for detecting vibrations in machinery.

Figure 3.2 Accelerometer



3.2.1 G-WHIZ

The ADXL202 two-axis ý2-g accelerometer from Analog Devices is a good example

of a micro machine that’s making waves in the commercial market. More sensitive

than earlier airbag designs, it’s well suited for novel applications like two-axis tilt

sensing and inertial navigation. For instance, Microsoft is using the ’202 in their new

Freestyle Pro game controller, which senses body motion.

The basic principle of micro machined accelerometers is simple enough. A

tethered or "sprung" mass is forced into motion by an applied acceleration. The

distance that the mass moves, and thus the acceleration, is determined by differential

capacitance, as shown in figure.

Figure 3.3—G-Whiz

The principle may be simple, but the implementation is incredible, given the

intricacy of crafting it in silicon. Consider that the smallest detectable capacitance

change, 20 zF (yes, that’s "z" as in 10–21 F), corresponds to a 2-pm deflection! But

while it’s capable of resolving mere mg’s (thousandths of a g), the device can take a

500–1000-g hit and keep on ticking.

The use of a standard IC process means the same die can integrate signal-

conditioning and digitizing circuits, dispensing with the design hassles of dealing with

low-level analog signals. That makes the ADXL202 real easy to use. Just add power

(3–5.25 V, a mere 1 mA at that) and have at it with your favorite MCU or PLD.



3.3 ENCODER HT12E:

The encoder used here is HT12E from HOLTEK SEMICONDUCTORS INC. The

HT 12E Encoder ICs are series of CMOS LSIs for Remote Control system

applications. They are capable of Encoding 12 bit of information which consists of N

address bits and 12-N data bits. Each address/data input is externally trinary

programmable if bonded out.

3.3.1 PIN DIAGRAM:

Figure 3.4 Encoder pin diagram

3.3.2 PIN DESCRIPTION:



Table 3.1 Encoder Pin Description

3.4 RF TECHNOLOGY:

Radio frequency (RF) is a frequency or rate of oscillation within the range of about 3

Hz to 300 GHz. This range corresponds to frequency of alternating current electrical

signals used to produce and detect radio waves. Since most of this range is beyond the

vibration rate that most mechanical systems can respond to, RF usually refers to

oscillations in electrical circuits or electromagnetic radiation.

Radio frequency is a frequency or rate of oscillation within the range of about 3 Hz to

300 GHz. This range corresponds to frequency of alternating current electrical signals

used to produce and detect radio waves since most of this range is beyond the


oscillations in electrical circuits. RF is widely used because it does not require any

line of sight, less distortions and no interference.

Figure 3.5 RF Transmitter and RF Receiver



3.5 DECODER HT12D:

The decoder used is HT12D from HOLTEK SEMICONDUCTOR INC.

Figure 3.6 Decoder Pin diagram

Table 3.2 Decoder Pin Description



FEATURES

• Operating voltage: 2.4V~12V.

• Low power and high noise immunity CMOS technology.

• Low standby current.

• Capable of decoding 18 bits of information.

• Pairs with HOLTEK’s 318 series of encoders.

• 8~18 address pins.

• 0~8 data pins.

3.6 MOBILE JAMMER

• A portable cell phone jammer featured by universal and handheld design,

could blocking worldwide cell phone networks within 0.5-10 meters,

including GSM900MHz, GSM1800MHz, GSM850MHz/CDMA800MHz and

also 3G networks (UMTS / W-CDMA).

Figure 3.7 Mobile Jammer

• A mobile phone jammer is an instrument used to prevent cellular phones

from receiving signals from or transmitting signals to base stations. When

used, the jammer effectively disables cellular phones. These devices can be

used in practically any location, but are found primarily in places where a

phone call would be particularly disruptive because silence is expected.



OPERATION

• As with other radio jamming, cell phone jammers block cell phone use by

sending out radio waves along the same frequencies that cellular phones use.

This causes enough interference with the communication between cell phones

and towers to render the phones unusable. On most retail phones, the network

would simply appear out of range. Most cell phones use different bands to

send and receive communications from towers (called full duplexing).

Jammers can work by either disrupting phone to tower frequencies or tower to

phone frequencies. Smaller handheld models block all bands from 800MHz to

1900MHz within a 30-foot range (9 meters). Small devices tend to use the

former method, while larger more expensive models may interfere directly

with the tower. The radius of cell phone jammers can range from a dozen feet

for pocket models to kilometers for more dedicated units. The TRJ-89 jammer

can block cellular communications for a 5-mile (8 km) radius.

• Actually it needs less energy to disrupt signal from tower to mobile phone,

than the signal from mobile phone to the tower (also called base station),

because base station is located at larger distance from the jammer than the

mobile phone and that is why the signal from the tower is not so strong.

Figure 3.8 Jammer Signal

• Older jammers sometimes were limited to working on phones using only

analog or older digital mobile phone standards. Newer models such as the

double and triple band jammers can block all widely used systems (CDMA,



iDEN, GSM, et al.) and are even very effective against newer phones which

hop to different frequencies and systems when interfered with. As the

dominant network technology and frequencies used for mobile phones vary

worldwide, some work only in specific regions such as Europe or North

America.

• The jammer's effect can vary widely based on factors such as proximity to

towers, indoor and outdoor settings, presence of buildings and landscape, even

temperature and humidity play a role.

• There are concerns that crudely designed jammers may disrupt the functioning

of medical devices such as pacemakers. However, like cell phones, most of the

devices in common use operate at low enough power output (<1W) to avoid

causing any problems.

3.7 METAL DETECTOR:

• Metal detectors use electromagnetic induction to detect metal. Metal detector

can help you to find the metals buried deep in the ground. Uses include de-

mining (the detection of land mines), the detection of weapons such as knives

and guns, especially at airports, geophysical prospecting, archaeology and

treasure hunting. Metal detectors are also used to detect foreign bodies in food,

and in the construction industry to detect steel reinforcing bars in concrete and

pipes and wires buried in walls and floors.

• The simplest form of a metal detector consists of an oscillator producing an

alternating current that passes through a coil producing an alternating

magnetic field. If a piece of electrically conductive metal is close to the coil,

eddy currents will be induced in the metal, and this produces an alternating

magnetic field of its own. If another coil is used to measure the magnetic field

(acting as a magnetometer), the change in the magnetic field due to the

metallic object can be detected.

3.8 BUZZER:

An electric coil is wound on a plastic bobbin, the latter having a central sleeve within

which a magnetic core is slide ably positioned. One end of the sleeve is closed and



projects beyond the coil. An inverted cup-shaped housing surrounds the coil and

bobbin and has a central opening through which the closed end of the sleeve projects.

The core projects into the closed end of the sleeve beyond the margin of the

opening in the housing to augment the magnetic coupling between the housing and

the core. The open end of the housing is attached to a support bracket of magnetic

material, there being a spring between the bracket and bobbin normally urging the

core toward the closed end of the sleeve.

Figure 3.9 Buzzer

3.9 LIQUID CRYSTAL DISPLAY:

LCD stands for L iquid Crystal Display. LCD is finding wide spread use replacing

LEDs (seven segment LEDs or other multi segment LEDs).

These components are “specialized” for being used with the microcontrollers,

which means that they cannot be activated by standard IC circuits. They are used for

writing different messages on a miniature LCD.

Figure 3.10 LCD Display

A model described here is for its low price and great possibilities most

frequently used in practice. It is based on the HD44780 microcontroller (Hitachi) and

can display messages in two lines with 16 characters each.



It displays all the alphabets, Greek letters, punctuation marks, mathematical

symbols etc. In addition, it is possible to display symbols that user makes up on its

own. Automatic shifting message on display (shift left and right), appearance of the

pointer, backlight etc. are considered as useful characteristics.

3.10 DC MOTOR:

A DC motor is an electric motor that runs on direct current (dc) electricity.

3.10.1 DC MOTOR CONNECTIONS

Figure shows schematically the different methods of connecting the field and

armature circuits in a DC Motor. The circular symbol represents the armature circuit,

and the squares at the side of the circle represent the brush commutator system. The

direction of the arrows indicates the direction of the magnetic fields.

3.10.2 PRINCIPLES OF OPERATION:

In any electric motor, operation is based on simple electromagnetism. A current-

carrying conductor generates a magnetic field; when this is then placed in an external

magnetic field, it will experience a force proportional to the current in the conductor,

and to the strength of the external magnetic field. The internal configuration of a DC

motor is designed to harness the magnetic interaction between a current-carrying

conductor and an external magnetic field to generate rotational motion.

Let's start by looking at a simple 2-pole DC electric motor (here red represents

a magnet or winding with a "North" polarization, while green represents a magnet or

winding with a "South" polarization).

Figure 3.11 Two Pole DC Motor

Every DC motor has six basic parts -- axle, rotor (a.k.a., armature), stator,

commutator, field magnet(s), and brushes. In most common DC motors (and all that



Beamers will see), the external magnetic field is produced by high-strength permanent

magnets. The stator is the stationary part of the motor -- this includes the motor

casing, as well as two or more permanent magnet pole pieces. The rotor (together with

the axle and attached commutator) rotates with respect to the stator. The rotor consists

of windings (generally on a core), the windings being electrically connected to the

commutator. The above diagram shows a common motor layout -- with the rotor

inside the stator (field) magnets.

The geometry of the brushes, commutator contacts, and rotor windings are

such that when power is applied, the polarities of the energized winding and the stator

magnet(s) are misaligned, and the rotor will rotate until it is almost aligned with the

stator's field magnets. As the rotor reaches alignment, the brushes move to the next

commutator contacts, and energize the next winding. Given our example two-pole

motor, the rotation reverses the direction of current through the rotor winding, leading

to a "flip" of the rotor's magnetic field, driving it to continue rotating.

In real life, though, DC motors will always have more than two poles (three is

a very common number). In particular, this avoids "dead spots" in the commutator.

You can imagine how with our example two-pole motor, if the rotor is exactly at the

middle of its rotation (perfectly aligned with the field magnets), it will get "stuck"

there. Meanwhile, with a two-pole motor, there is a moment where the commutator

shorts out the power supply (i.e., both brushes touch both commutator contacts

simultaneously). This would be bad for the power supply, waste energy, and damage

motor components as well. Yet another disadvantage of such a simple motor is that it

would exhibit a high amount of torque "ripple" (the amount of torque it could produce

is cyclic with the position of the rotor).

Figure 3.12 Rotation DC Motor



So since most small DC motors are of a three-pole design, let's tinker with the

workings of one via an interactive animation.

Figure 3.13 Three Pole DC motor

You'll notice a few things from this -- namely, one pole is fully energized at a

time (but two others are "partially" energized). As each brush transitions from one

commutator contact to the next, one coil's field will rapidly collapse, as the next coil's

field will rapidly charge up (this occurs within a few microsecond). We'll see more

about the effects of this later, but in the meantime you can see that this is a direct

result of the coil windings' series wiring:

Figure 3.14 DC Motor

The use of an iron core armature (as in the Mabuchi, above) is quite common,

and has a number of advantages. First off, the iron core provides a strong, rigid

support for the windings -- a particularly important consideration for high-torque

motors. The core also conducts heat away from the rotor windings, allowing the

motor to be driven harder than might otherwise be the case. Iron core construction is

also relatively inexpensive compared with other construction types. But iron core

construction also has several disadvantages. The iron armature has a relatively high



inertia which limits motor acceleration. This construction also results in high winding

inductances which limit brush and commutator life.

In small motors, an alternative design is often used which features a 'coreless'

armature winding. This design depends upon the coil wire itself for structural

integrity. As a result, the armature is hollow, and the permanent magnet can be

mounted inside the rotor coil. Coreless DC motors have much lower armature

inductance than iron-core motors of comparable size, extending brush and

commutator life.

3.11 H-BRIDGE:

Figure 3.15: Circuit of H-bridge

An H-bridge is an electronic circuit which enables DC electric motors to be run

forwards or backwards. These circuits are often used in robotics. H-bridges are

available as integrated circuits, or can be built from discrete components.

The two basic states of a H-bridge. The term "H-bridge" is derived from the

typical graphical representation of such a circuit. An H-bridge is built with four

switches (solid-state or mechanical). When the switches S1 and S4 (according to the

first figure) are closed (and S2 and S3 are open) a positive voltage will be applied

across the motor. By opening S1 and S4 switches and closing S2 and S3 switches, this

voltage is reversed, allowing reverse operation of the motor.

Using the nomenclature above, the switches S1 and S2 should never be closed

at the same time, as this would cause a short circuit on the input voltage source. The

same applies to the switches S3 and S4. This condition is known as shoot-through.



3.11.1 OPERATION:

The H-Bridge arrangement is generally used to reverse the polarity of the motor, but

can also be used to 'brake' the motor, where the motor comes to a sudden stop, as the

motors terminals are shorted, or to let the motor 'free run' to a stop, as the motor is

effectively disconnected from the circuit. The following table summarizes operation.

S1 S2 S3 S4 Result

1 0 0 1 Motor moves right

0 1 1 0 Motor moves left

0 0 0 0 Motor free runs

0 1 0 1 Motor brakes

Table 3.3: H-Bridge

3.11.2 H-BRIDGE DRIVER:

The switching property of this H-Bridge can be replace by a Transistor or a Relay or a

Mosfet or even by an IC. Here we are replacing this with an IC named L293D as the

driver whose description is as given below.

3.11.3 FEATURES:

• 600mA OUTPUT CURRENT CAPABILITY

• PER CHANNEL

• 1.2A PEAK OUTPUT CURRENT (non repetitive)

• PER CHANNEL

• ENABLE FACILITY

• OVERTEMPERATURE PROTECTION

• LOGICAL "0" INPUT VOLTAGE UP TO 1.5 V

• (HIGH NOISE IMMUNITY)

• INTERNAL CLAMP DIODES



3.11.4 DESCRIPTION:

The Device is a monolithic integrated high voltage, high current four channel driver

designed to accept standard DTL or TTL logic levels and drive inductive loads (such

as relays solenoids, DC and stepping motors) and switching power transistors. To

simplify use as two bridges each pair of channels is equipped with an enable input. A

separate supply input is provided for the logic, allowing operation at a lower voltage

and internal clamp diodes are included. This device is suitable for use in switching

applications at frequencies up to 5 kHz. The L293D is assembled in a 16 lead plastic

package which has 4 center pins connected together and used for heat sinking The

L293DD is assembled in a 20 lead surface mount which has 8 center pins connected

together and used for heat sinking.

3.11.5 BLOCK DIAGRAM:

Figure 3.16 Block Diagram of H-bridge

3.11.6 ABSOLUTE MAXIMUM RATINGS

Table 3.4: Absolute Maximum Ratings



3.11.7 PIN CONNECTIONS

Figure 3.17 PIN connections

3.12 MICROCONTROLLERS:

Microprocessors and microcontrollers are widely used in embedded systems products.

Microcontroller is a programmable device. A microcontroller has a CPU in addition

to a fixed amount of RAM, ROM, I/O ports and a timer embedded all on a single

chip. The fixed amount of on-chip ROM, RAM and number of I/O ports in

microcontrollers makes them ideal for many applications in which cost and space are

critical.

The Intel 8052 is Harvard architecture, single chip microcontroller (µC) which

was developed by Intel in 1980 for use in embedded systems. It was popular in the

1980s and early 1990s, but today it has largely been superseded by a vast range of

enhanced devices with 8052-compatible processor cores that are manufactured by

more than 20 independent manufacturers including Atmel, Infineon Technologies and

Maxim Integrated Products.

8052 is an 8-bit processor, meaning that the CPU can work on only 8 bits of

data at a time. Data larger than 8 bits has to be broken into 8-bit pieces to be

processed by the CPU. 8052 is available in different memory types such as UV-

EPROM, Flash and NV-RAM. The present project is implemented on Keil uVision.

In order to program the device, proload tool has been used to burn the program onto

the microcontroller.



3.12.1 ARDUINO:

Arduino is an open source electronics prototyping platform based on flexible, easy-to-

use hardware and software. It’s intended for artists, designers, hobbyists, and anyone

interested in creating interactive objects or environments. It’s an open-source physical

computing platform based on a microcontroller board, and a development

environment for writing software for the board.

In simple words, Arduino is a small microcontroller board with a USB plug to

connect to your computer and a number of connection sockets that can be wired up to

external electronics, such as motors, relays, light sensors, laser diodes, loudspeakers,

microphones, etc., They can either be powered through the USB connection from the

computer or from a 9V battery. They can be controlled from the computer or

programmed by the computer and then disconnected and allowed to work

independently.

Anyone can buy this device through online auction site or search engine. Since

the Arduino is an open-source hardware designs and create their own clones of the

Arduino and sell them, so the market for the boards is competitive.



CHAPTER-4

WIRELESS COMMUNICATION

4.1 WIRELESS COMMUNICATION INTRODUCTION:

Wireless communication, as the term implies, allows information to be exchanged

between two devices without the use of wire or cable. A wireless keyboard sends

information to the computer without the use of a keyboard cable; a cellular telephone

sends information to another telephone without the use of a telephone cable.

Changing television channels, opening and closing a garage door, and transferring a

file from one computer to another can all be accomplished using wireless technology.

In all such cases, information is being transmitted and received using electromagnetic

energy, also referred to as electromagnetic radiation. One of the most familiar sources

of electromagnetic radiation is the sun; other common sources include TV and radio

signals, light bulbs and microwaves. To provide background information in

understanding wireless technology, the electromagnetic spectrum is first presented

and some basic terminology defined.

4.1.1 WHAT IS RF?

Radio frequency (RF) is a frequency or rate of oscillation within the range of about 3

Hz to 300 GHz. This range corresponds to frequency of alternating current electrical

signals used to produce and detect radio waves. Since most of this range is beyond the


oscillations in electrical circuits or electromagnetic radiation

4.1.2 WHAT IS THE NEED FOR RF?

Radio frequency is a frequency or rate of oscillation within the range of about 3 Hz

to 300 GHz. This range corresponds to frequency of alternating current electrical

signals used to produce and detect radio waves since most of this range is beyond the


oscillations in electrical circuits. RF is widely used because it does not require any

line of sight, less distortions and no interference.



4.2 PROPERTIES OF RF:

Electrical currents that oscillate at RF have special properties not shared by direct

current signals. One such property is the ease with which it can ionize air to create a

conductive path through air. This property is exploited by 'high frequency' units used

in electric arc welding. Another special property is an electromagnetic force that

drives the RF current to the surface of conductors, known as the skin effect. Another

property is the ability to appear to flow through paths that contain insulating material,

like the dielectric insulator of a capacitor. The degree of effect of these properties

depends on the frequency of the signals.

4.3 BRIEF DESCRIPTION OF RF:

Radio frequency (abbreviated RF) is a term that refers to alternating current (AC)

having characteristics such that, if the current is input to an antenna, an

electromagnetic (EM) field is generated suitable for wireless broadcasting and/or

communications. These frequencies cover a significant portion of the electromagnetic

radiation spectrum, extending from nine kilohertz (9 kHz),the lowest allocated

wireless communications frequency (it's within the range of human hearing), to

thousands of gigahertz(GHz).When an RF current is supplied to an antenna, it gives

rise to an electromagnetic field that propagates through space. This field is sometimes

called an RF field; in less technical jargon it is a "radio wave." Any RF field has a

wavelength that is inversely proportional to the frequency. In the atmosphere or in

outer space, if f is the frequency in megahertz and sis the wavelength in meters, then s

= 300/f. The frequency of an RF signal is inversely proportional to the wavelength of

the EM field to which it corresponds. At 9 kHz, the free-space wavelength is

approximately 33 kilometers (km) or 21 miles (mi). At the highest radio frequencies,

the EM wavelengths measure approximately one millimeter (1 mm). As the frequency

is increased beyond that of the RF spectrum, EM energy takes the form of infrared

(IR), visible, ultraviolet (UV), X rays, and gamma rays. Many types of wireless

devices make use of RF fields. Cordless and cellular telephone, radio and television

broadcast stations, satellite communications systems, and two-way radio services all

operate in the RF spectrum.



Some wireless devices operate at IR or visible-light frequencies, whose

electromagnetic wavelengths are shorter than those of RF fields.

4.4 DIFFERENT RANGES PRESENT IN RF AND

APPLICATIONS IN THEIR RANGES

Frequency Frequency range

Distance Uses

Extremely low frequency 3 to 30 Hz 10,000 km to 100,000 km

Directly audible when converted to sound, communication with submarines

Super low frequency

30 to 300 Hz 1,000 km to 10,000 km

Directly audible when converted to sound, AC power grids (50 hertz and 60 hertz)

Ultra low frequency 300 to 3000 Hz

100 km to 1,000 km

Directly audible when converted to sound, communication with mines

Very low frequency

3 to 30 kHz 10 km to 100 km

Directly audible when converted to sound (below ca. 18-20 kHz; or "ultrasound" 20-30+ kHz)

Low frequency 30 to 300 kHz 1 km to 10 km

AM broadcasting, navigational beacons, low FER

Medium frequency 300 to 3000 kHz

100 m to 1 km

Navigational beacons, AM broadcasting, maritime and aviation communication

High frequency 3 to 30 MHz 10 m to 100 m

Shortwave, amateur radio, citizens' band radio

Very high frequency 30 to 300 MHz

1 m to 10 m FM broadcasting broadcast television, aviation, GPR

Ultra high frequency 300 to 3000 MHz

10 cm to 100 cm

Broadcast television, mobile telephones, , wireless networking, microwave ovens, GPR

Super high frequency

3 to 30 GHz

1 cm to 10 cm

Wireless networking, satellite links, microwave links, Satellite television, door openers.

Extremely high frequency 30 to 300 GHz

1 mm to 10 mm

Microwave data links, radio astronomy, remote sensing, advanced weapons systems, advanced security scanning

Table 4.1: Different RF ranges and Applications



4.5 RF TRANSMITTER STT-433MHz:

Figure 4.1: RF Transmitter

4.5.1 PIN DESCRIPTION:

GND

� Transmitter ground. Connect to ground plane

DATA

� Digital data input. This input is CMOS compatible and should be driven with CMOS

level inputs.

VCC

� Operating voltage for the transmitter. VCC should be bypassed with a .01uF ceramic

capacitor and filtered with a 4.7uF tantalum capacitor. Noise on the power supply

will degrade transmitter noise performance.

ANT

� 50 ohm antenna output. The antenna port impedance affects output power and

harmonic emissions. Antenna can be single core wire of approximately 17cm length

or PCB trace antenna.

4.5.2 FACTORS INFLUENCED TO CHOOSE STT-433MHz:

ABOUT THE TRANSMITTER:

• The STT-433 is ideal for remote control applications where low cost and

longer range is required.

• The transmitter operates from a1.5-12V supply, making it ideal for battery-

powered applications.



• The transmitter employs a SAW-stabilized oscillator, ensuring accurate

frequency control for best range performance.

• The manufacturing-friendly SIP style package and low-cost make the STT-

433 suitable for high volume applications.

FEATURES:

• 433.92 MHz Frequency

• Low Cost

• 1.5-12V operation

• Small size

APPLICATION:

Figure 4.2 Applications

The typical connection shown in the above figure cannot work exactly at all times

because there will be no proper synchronization between the transmitter and the

microcontroller unit. i.e., whatever the microcontroller sends the data to the

transmitter, the transmitter is not able to accept this data as this will be not in the radio

frequency range. Thus, we need an intermediate device which can accept the input

from the microcontroller, process it in the range of radio frequency range and then

send it to the transmitter. Thus, an encoder is used.



4.6 RF RECEIVER STR-433 MHZ:

Figure 4.3 RF Receiver

The data is received by the RF receiver from the antenna pin and this data is available

on the data pins. Two Data pins are provided in the receiver module. Thus, this data

can be used for further applications

Figure 4.4: PIN Diagram of RF receiver

PIN-OUT:

ANT

� Antenna input.

GND

� Receiver Ground. Connect to ground plane.



VCC (5V)

� VCC pins are electrically connected and provide operating voltage for the

receiver. VCC can be applied to either or both. VCC should be bypassed with

a .1µF ceramic capacitor. Noise on the power supply will degrade receiver

sensitivity.

DATA

� Digital data output.

This output is capable of driving one TTL or CMOS load. It is a CMOS compatible

output.

Figure 4.5: Digital Data PIN



4.7 RF ADVANTAGES:

1. No line of sight is needed.

2. Not blocked by common materials: It can penetrate most solids and pass

through walls.

3. Longer range.

4. It is not sensitive to the light.

5. It is not much sensitive to the environmental changes and weather conditions.

4.8 RF DISADVANTAGES:

1. Interference: communication devices using similar frequencies - wireless

phones, scanners, wrist radios and personal locators can interfere with

transmission

2. Lack of security: easier to "eavesdrop" on transmissions since signals are

spread out in space rather than confined to a wire

3. Higher cost than infrared

4. Federal Communications Commission(FCC) licenses required for some

products

5. Lower speed: data rate transmission is lower than wired and infrared

transmission.



4.9 INTERFACING OF RF TRANSMITTER WITH AT89S52:

4.10 INTERFACING OF RF RECEIVER WITH ARDUINO:



CHAPTER 5

MEMS TECHNOLOGY

5.1 MEMS INTRODUCTION:

MEMS stand for Micro-Electro Mechanical Systems. MEMS techniques allow both

electronic circuits and mechanical devices to be manufactured on a silicon chip,

similar to the process used for integrated circuits. This allows the construction of

items such as sensor chips with built-in electronics that are a fraction of the size that

was previously possible.

Micro electromechanical systems (MEMS) are small integrated devices or

systems that combine electrical and mechanical components. They range in size from

the sub micrometer (or sub micron) level to the millimeter level and there can be any

number, from a few to millions, in a particular system. MEMS extend the fabrication

techniques developed for the integrated circuit industry to add mechanical elements

such as beams, gears, diaphragms, and springs to devices.

Examples of MEMS device applications include inkjet-printer

cartridges, accelerometers miniature robots, micro engines, locks, inertial sensors,

micro transmissions, micro mirrors, micro actuators, optical scanners, fluid

pumps, transducers, and chemical, pressure and flow sensors. New applications are

emerging as the existing technology is applied to the miniaturization and integration

of conventional devices. These systems can sense, control, and activate mechanical

processes on the micro scale, and function individually or in arrays to generate effects

on the macro scale. The micro fabrication technology enables fabrication of large

arrays of devices, which individually perform simple tasks, but in combination can

accomplish complicated functions.



Figure 5.1 Components of MEMS

The MEMS industry has an estimated $10 billion market, and with a projected

10-20% annual growth rate, it is estimated to have a $34 billion market in 2002 [1].

Because of the significant impact that MEMS can have on the commercial and

defense markets, industry and the federal government have both taken a special

interest in their development.

IC fabrication is dependent upon sensors to provide input from the

surrounding environment, just as control systems need actuators (also referred to as

transducers) in order to carry out their desired functions. Due to the availability of

sand as a material, much effort was put into developing Si processing and

characterization tools. These tools are now being used to advance transducer

technology. Today's IC technology far outstrips the original sensors and actuators in

performance, cost and size.

Around 1982, the term micromachining came into use to designate the

fabrication of micromechanical parts (such as pressure-sensor diaphragms or

accelerometer suspension beams) for Si micro sensors. The micromechanical parts

were fabricated by selectively etching areas of the Si substrate away in order to leave

behind the desired geometries. Isotropic etching of Si was developed in the early

1960s for transistor fabrication. Anisotropic etching of Si then came about in 1967.

Various etch-stop techniques were subsequently developed to provide further process

flexibility.

These techniques also form the basis of the bulk micromachining processing

techniques. Bulk micromachining designates the point at which the bulk of the Si

substrate is etched away to leave behind the desired micromechanical elements [3].

Bulk micromachining has remained a powerful technique for the fabrication of

micromechanical elements. However, the need for flexibility in device design and



performance improvement has motivated the development of new concepts and

techniques for micromachining. Among these is the sacrificial layer technique, first

demonstrated in 1965 by Nathanson and Wickstrom [15], in which a layer of material

is deposited between structural layers for mechanical separation and isolation. This

layer is removed during the release etch to free the structural layers and to allow

mechanical devices to move relative to the substrate.

A layer is releasable when a sacrificial layer separates it from the substrate.

The application of the sacrificial layer technique to micromachining in 1985 gave rise

to surface micromachining.

Fabrication Technologies:

The three characteristic features of MEMS fabrication technologies are

miniaturization, multiplicity, and microelectronics. Miniaturization enables the

production of compact, quick-response devices. Multiplicity refers to the batch

fabrication inherent in semiconductor processing, which allows thousands or millions

of components to be easily and concurrently fabricated. Microelectronics provides the

intelligence to MEMS and allows the monolithic merger of sensors, actuators, and

logic to build closed-loop feedback components and systems. The successful

miniaturization and multiplicity of traditional electronics systems would not have

been possible without IC fabrication technology. Therefore, IC fabrication

technology, or micro fabrication, has so far been the primary enabling technology for

the development of MEMS. Micro fabrication provides a powerful tool for batch

processing and miniaturization of mechanical systems into a dimensional domain not

accessible by conventional (machining) techniques. Furthermore, micro fabrication

provides an opportunity for integration of mechanical systems with electronics to

develop high-performance closed-loop-controlled MEMS.

Advances in IC technology in the last decade have brought about

corresponding progress in MEMS fabrication processes. Manufacturing processes

allow for the monolithic integration of micro-electromechanical structures with

driving, controlling, and signal-processing electronics. This integration promises to

improve the performance of micromechanical devices as well as reduces the cost of

manufacturing, packing and instrumenting these devices.



Applications of MEMS:

• Pressure sensors

• Accelerometers

• Inertial sensors

• Micro engines

5.2 ACCELEROMETER

An accelerometer is an apparatus, either mechanical or electromechanical, for

measuring acceleration or deceleration - that is, the rate of increase or decrease in the

velocity of a moving object. Accelerometers are used to measure the efficiency of the

braking systems on road and rail vehicles; those used in aircraft and spacecraft can

determine accelerations in several directions simultaneously. There are also

accelerometers for detecting vibrations in machinery.

Figure 5.2: Accelerometer

The types of sensor used to measure acceleration, shock, or tilt include piezo film,

5.2.1 THE PIEZO ELECTRIC ACCELEROMETER:

Among the desirable features of the piezoelectric (PE) accelerometer are accuracy,

durability, large dynamic range, ease of installation, and long life span. Although

these devices cost more than other types, in many situations their benefits outweigh

the higher price. To provide useful data, PE accelerometers require proper signal

conditioning circuitry. We will briefly review the important characteristics of a PE

accelerometer and circuit techniques for signal conditioning. In particular, we will

examine an interface that will allow the accelerometer output's magnitude and

frequency to be measured by a microcontroller unit (MCU).



Figure 5.3 Piezo Electric Accelerometer

The PE accelerometer uses an internal PE element coupled with a loading

mass to form a single-degree-of-freedom "mass-spring" system. The accelerometer is

a charge-sensitive device; an instantaneous change in stress on the internal PE

element produces a charge at the accelerometer's output terminals that is proportional

to the applied acceleration.

5.2.2 G-WHIZ:

The ADXL202 two-axis ý2-g accelerometer from Analog Devices is a good example

of a micro machine that’s making waves in the commercial market. More sensitive

than earlier airbag designs, it’s well suited for novel applications like two-axis tilt

sensing and inertial navigation. For instance, Microsoft is using the ’202 in their new

Freestyle Pro game controller, which senses body motion.

The basic principle of micro machined accelerometers is simple enough. A

tethered or "sprung" mass is forced into motion by an applied acceleration. The

distance that the mass moves, and thus the acceleration, is determined by differential

capacitance, as shown in figure.

Figure 5.4—G-Whiz

The principle may be simple, but the implementation is incredible, given the

intricacy of crafting it in silicon. Consider that the smallest detectable capacitance



change, 20 zF (yes, that’s "z" as in 10–21 F), corresponds to a 2-pm deflection! But

while it’s capable of resolving mere mg’s (thousandths of a g), the device can take a

500–1000-g hit and keep on ticking.

The use of a standard IC process means the same die can integrate signal-

conditioning and digitizing circuits, dispensing with the design hassles of dealing with

low-level analog signals. That makes the ADXL202 real easy to use. Just add power

(3–5.25 V, a mere 1 mA at that) and have at it with your favorite MCU or PLD.

5.2.3 SURFACE MICRO-MACHINED ACCELEROMETERS:

In recent years, silicon micro-machined sensors have made tremendous advances in

terms of cost and level of on-chip integration for measurements such as acceleration

and/or vibration. These products provide the sensor and the signal conditioning

circuitry on chip, and require only a few external components. Some manufacturers

have taken this approach one step further by converting the analogue output of the

analogue signal conditioning to a digital format such as duty cycle. This method not

only lifts the burden of designing fairly complex analogue circuitry for the sensor, but

also reduces cost and board area. Micro-machined accelerometers are now being

incorporated into products such as joysticks and airbags, applications that were

previously impossible due to sensor price and or size. A surface micro-machined

device consists of springs, masses, and motion-sensing components. These sensors are

made with the standard IC processing techniques used in wafer fabrication facilities

Figure 5.5: Surface Micro-Machined Accelerometer



5.3 INTERFACING OF MEMS SENSOR WITH

MICROCONTROLLER :



CHAPTER-6

MICROCONTROLLER

6.1 MICROCONTROLLERS INTRODUCTION:

Microprocessors and microcontrollers are widely used in embedded systems products.

Microcontroller is a programmable device. A microcontroller has a CPU in addition

to a fixed amount of RAM, ROM, I/O ports and a timer embedded all on a single

chip. The fixed amount of on-chip ROM, RAM and number of I/O ports in

microcontrollers makes them ideal for many applications in which cost and space are

critical. The Intel 8052 is Harvard architecture, single chip microcontroller (µC)

which was developed by Intel in 1980 for use in embedded systems. It was popular in

the 1980s and early 1990s, but today it has largely been superseded by a vast range of

enhanced devices with 8052-compatible processor cores that are manufactured by

more than 20 independent manufacturers including Atmel, Infineon Technologies and

Maxim Integrated Products.

6.2 FEATURES:

• Compatible with MCS-51® Products

• 8K Bytes of In-System Programmable (ISP) Flash Memory

• 4.0V to 5.5V Operating Range

• Fully Static Operation: 0 Hz to 33 MHz

• Three-level Program Memory Lock

• 256 x 8-bit Internal RAM

• 32 Programmable I/O Lines

• Three 16-bit Timer/Counters

• Eight Interrupt Sources

• Full Duplex UART Serial Channel

• Low-power Idle and Power-down Modes

• Interrupt Recovery from Power-down Mode

• Watchdog Timer

• Dual Data Pointer

• Power-off Flag



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 programmer. 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 applications.

PIN DIAGRAM OF AT89S52:

Figure 6.1 AT89S52 PIN Diagram

6.3 PIN DESCRIPTIONS OF AT89S52

VCC

Supply voltage.

GND

Ground.



Port 0

Port 0 is an 8-bit open drain bidirectional I/O port.

Port 1

Port 1 is an 8-bit bidirectional I/O port with internal pullups. The Port 1 output buffers

can sink/source four TTL inputs.

Table 6.1: Port 1

Port 2

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

buffers can sink/source four TTL inputs. Port 2 also receives the high-order address

bits and some control signals during Flash programming and verification.

Port 3

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

buffers can sink/source four TTL inputs. Port 3 also serves the functions of various

special features of the AT89S52, as shown in the following table. Port 3 also receives

some control signals for Flash programming and verification.



Table 6.2: Port 3

RST

Reset input. A high on this pin for two machine cycles while the oscillator is running

resets the device.

ALE/PROG

Address Latch Enable (ALE) is an output pulse for latching the low byte of the

address during accesses to external memory. This pin is also the program pulse input

(PROG) during Flash programming.

PSEN

Program Store Enable (PSEN) is the read strobe to external program memory. When

the AT89S52 is executing code from external program memory, PSEN is activated

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

access to external data memory.

EA/VPP

External Access Enable, EA must be strapped to GND in order to enable the device

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

FFFFH. This pin also receives the 12-volt programming enable voltage (VPP) during

Flash programming.

XTAL1

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

circuit.

XTAL2

Output from inverting oscillator amplifier.



SFRs (Special Function Registers):

SFRs are a kind of control table used for running and monitoring microcontroller’s

operating. Each of these registers, even each bit they include, has its name, address in

the scope of RAM and clearly defined purpose.

A Register (Accumulator)

This is a general-purpose register which serves for storing intermediate results during

operating

B Register:

B register is used during multiply and divide operations which can be performed only

upon numbers stored in the A and B registers.

6.4 ARDUINO

Arduino interface boards provide the engineers, artists, designers, hobbyists and

anyone who tinker with technology with a low-cost, easy-to-use technology to create

their creative, interactive objects, useful projects etc., A whole new breed of projects

can now be built that can be controlled from a computer.

Figure 6.2 Arduino board

Arduino is a open source electronics prototyping platform based on flexible,

easy-to-use hardware and software. It’s intended for artists, designers, hobbyists, and

anyone interested in creating interactive objects or environments. It’s an open-source

physical computing platform based on a microcontroller board, and a development

environment for writing software for the board.



In simple words, Arduino is a small microcontroller board with a USB plug to

connect to your computer and a number of connection sockets that can be wired up to

external electronics, such as motors, relays, light sensors, laser diodes, loudspeakers,

microphones, etc., They can either be powered through the USB connection from the

computer or from a 9V battery. They can be controlled from the computer or

programmed by the computer and then disconnected and allowed to work

independently. Anyone can buy this device through online auction site or search

engine. Since the Arduino is an open-source hardware designs and create their own

clones of the Arduino and sell them, so the market for the boards is competitive. The

name “Arduino” is reserved by the original makers. However, clone Arduino designs

often have the letters “duino” on the end of their name, for example, Freeduino or

DFRduino. The software for programming your Arduino is easy to use and also freely

available for Windows, Mac, and LINUX computers at no cost.

ARDUINO Board Pin diagram

Figure 6.3 Arduino Pin Diagram

6.4.1 THE ARDUINO PIN DESCRIPTION:

• VIN: The input voltage to the Arduino board when it's using an external power

source (as opposed to 5 volts from the USB connection or other regulated

power source). You can supply voltage through this pin, or, if supplying

voltage via the power jack, access it through this pin.



• 5V: The regulated power supply used to power the microcontroller and other

components on the board. This can come either from VIN via an on-board

regulator, or be supplied by USB or another regulated 5V supply.

• 3V3: A 3.3 volt supply generated by the on-board regulator. Maximum current

draw is 50 mA.

• GND. Ground pins.

• Serial: 0 (RX) and 1 (TX). Used to receive (RX) and transmit (TX) TTL serial

data. These pins are connected to the corresponding pins of the ATmega8U2

USB-to-TTL Serial chip.

• PWM: 3, 5, 6, 9, 10, and 11. Provide 8-bit PWM output with the analog Write

() function.

• LED: 13. There is a built-in LED connected to digital pin 13. When the pin is

HIGH value, the LED is on, when the pin is LOW, it's off.

• The Uno has 6 analog inputs, each of which provides 10 bits of resolution.

• Each of the 14 digital pins on the Uno can be used as an input or output, using

pin Mode(), digital Write(), and digital Read() functions

Digital pins:

• Pins 0 – 7: PORT D [0:7]

• Pins 8 – 13: PORT B [0:5]

• Pins 14 – 19: PORT C [0:5] (Arduino analog pins 0 – 5)

• digital pins 0 and 1 are RX and TX for serial communication

• digital pin 13 connected to the base board LED

Digital Pin I/O Functions:

• pin Mode(pin, mode)

• Sets pin to INPUT or OUTPUT mode

• digital Write(pin, value)

• Sets pin value to LOW or HIGH (0 or 1)



• int value = digital Read(pin)

• Reads back pin value (0 or 1)

Analog input:

• Analog input pins: 0 – 5

• Analog input functions

int Val = analog Read(pin)

Analog output:

• Generates a PWM output on digital pin (3, 5, 6, 9, 10, 11)

• Analog input functions

Analog Write (pin, value)

6.5 ATMEGA 328 Microcontrollers

The ATmega88 through ATmega328 microcontrollers are said by Atmel to be the

upgrades from the very popular ATmega8. They are pin compatible, but not

functionally compatible. The ATmega328 has 32kB of flash, where the ATmega8 has

8kB. Other differences are in the timers, additional SRAM and EEPROM, the

addition of pin change interrupts, and a divide by 8 presale for the system clock.

The schematic below shows the Atmel ATmega328 circuit as it was built on

the test board. The power supply is common and is shared between all of the

microcontrollers on the board. The ATmega328 is in a minimal circuit. It is using its

internal 8 MHz RC oscillator (divided by 8). The boot loader is programmed using the

ISP programming connector, and the Arduino sketches are uploaded via the 6-pin

header. Be aware that programming the Arduino boot loader into the ATmega88,

ATmega168, or ATmega328 microcontroller will change the clock fuses, requiring

the addition of an external crystal. The crystal shown on the schematic is

only required when the ATmega328 is going to be used as an Arduino, although it

may be desired in any real world application. I typically run them at 16 MHz, but they

will run as high as 20 MHz.



PIN DIAGRAM:

Figure 6.4: AT mega PIN diagram 6.5.1 PIN DESCRIPTIONS:

VCC: Digital supply voltage

GND: Ground

Port B (PB7:0) XTAL1/XTAL2/TOSC1/TOSC2

Port B is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for

each bit). The Port B output buffers have symmetrical drive characteristics with both

high sink and source capability. As inputs, Port B pins that are externally pulled low

will source current if the pull-up resistors are activated. The Port B pins are tri-stated

when a reset condition becomes active, even if the clock is not running.

Depending on the clock selection fuse settings, PB6 can be used as input to the

inverting Oscillator amplifier and input to the internal clock operating circuit.

Depending on the clock selection fuse settings, PB7 can be used as output from the

inverting Oscillator amplifier. If the Internal Calibrated RC Oscillator is used as chip

clock source, PB7.6 is used as TOSC2.1 input for the Asynchronous Timer/Counter2

if the AS2 bit in ASSR is set.



Port C (PC5:0)

Port C is a 7-bit bi-directional I/O port with internal pull-up resistors (selected for

each bit). The PC5..0 output buffers have symmetrical drive characteristics with both

high sink and source capability. As inputs, Port C pins that are externally pulled low

will source current if the pull-up resistors are activated. The Port C pins are tri-stated

when a reset condition becomes active, even if the clock is not running.

PC6/RESET

If the RSTDISBL Fuse is programmed, PC6 is used as an I/O pin. Note that the

electrical characteristics of PC6 differ from those of the other pins of Port C. If the

RSTDISBL Fuse is unprogrammed, PC6 is used as a Reset input. A low level on this

pin for longer than the minimum pulse length will generate a Reset, even if the clock

is not running.

Port D (PD7:0)

Port D is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for

each bit). The Port D output buffers have symmetrical drive characteristics with both

high sink and source capability.

AVCC

AVCC is the supply voltage pin for the A/D Converter, PC3:0, and ADC7:6. It should

be externally connected to VCC, even if the ADC is not used. If the ADC is used, it

should be connected to VCC through a low-pass filter.

AREF

AREF is the analog reference pin for the A/D Converter.

ADC7:6 (TQFP and QFN/MLF Package Only)

In the TQFP and QFN/MLF package, ADC7:6 serve as analog inputs to the A/D

converter. These pins are powered from the analog supply and serve as 10-bit ADC

channels.



CHAPTER-7

SOFTWARE DETAILS

7.1 KEIL SOFTWARE:

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

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

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

also supports C language code.

STEPS TO WRITE AN ASSEMBLY LANGUAGE PROGRAM IN

KEIL AND HOW TO COMPILE IT:

1. Install the Keil Software in the PC in any of the drives.

2. After installation, an icon will be created with the name “Keil uVision3”. Just

drag this icon onto the desktop so that it becomes easy whenever you try to

write programs in keil.

3. Double click on this icon to start the keil compiler.

4. A page opens with different options in it showing the project workspace at the

leftmost corner side, output window in the bottom and an ash colored space

for the program to be written.

5. Now to start using the keil, click on the option “project”.

6. A small window opens showing the options like new project, import project,

open project etc. Click on “New project”.

7. A small window with the title bar “Create new project” opens. The window

asks the user to give the project name with which it should be created and the

destination location. The project can be created in any of the drives available.

You can create a new folder and then a new file or can create directly a new

file.

8. After the file is saved in the given destination location, a window opens where

a list of vendors will be displayed and you have to select the device for the

target you have created.



9. The most widely used vendor is Atmel. So click on Atmel and now the family

of microcontrollers manufactured by Atmel opens. You can select any one of

the microcontrollers according to the requirement.

10. When you click on any one of the microcontrollers, the features of that

particular microcontroller will be displayed on the right side of the page. Click

on this microcontroller and have a look at its features. Now click on “OK” to

select this microcontroller.

11. A small window opens asking whether to copy the startup code into the file

you have created just now. Just click on “No” to proceed further.

12. Now you can see the TARGET and SOURCE GROUP created in the project

workspace.

13. Now click on “File” and in that “New”. A new page opens and you can start

writing program in it.

14. After the program is completed, save it with any name but with the .asm

extension. Save the program in the file you have created earlier.

15. You can notice that after you save the program, the predefined keywords will

be highlighted in bold letters.

16. Now add this file to the target by giving a right click on the source group. A

list of options open and in that select “Add files to the source group”. Check

for this file where you have saved and add it.

17. Right click on the target and select the first option “Options for target”. A

window opens with different options like device, target, output etc. First click

on “target”.

18. Since the set frequency of the microcontroller is 11.0592 MHz to interface

with the PC, just enter this frequency value in the Xtal (MHz) text area and put

a tick on the Use on-chip ROM. This is because the program what we write

here in the keil will later be dumped into the microcontroller and will be stored

in the inbuilt ROM in the microcontroller.

19. Now click the option “Output” and give any name to the hex file to be created

in the “Name of executable” text area and put a tick to the “Create HEX file”

option present in the same window. The hex file can be created in any of the

drives. You can change the folder by clicking on “Select folder for Objects”.



20. Now to check whether the program you have written is errorless or not, click

on the icon exactly below the “Open file” icon which is nothing but Build

Target icon. You can even use the shortcut key F7 to compile the program

written.

21. To check for the output, there are several windows like serial window,

memory window, project window etc. Depending on the program you have

written, select the appropriate window to see the output by entering into debug

mode.

22. The icon with the letter “d” indicates the debug mode.

23. Click on this icon and now click on the option “View” and select the

appropriate window to check for the output.

24. After this is done, click the icon “debug” again to come out of the debug

mode.

25. The hex file created as shown earlier will be dumped into the microcontroller

with the help of another software called Proload.

7.2 PROLOAD:

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

into hex code, that hex code has to be dumped into the microcontroller placed in the

programmer kit and this is done by the Proload. Programmer kit contains a

microcontroller on it other than the one which is to be programmed. This

microcontroller has a program in it written in such a way that it accepts the hex file

from the keil compiler and dumps this hex file into the microcontroller which is to be

programmed. As this programmer kit requires power supply to be operated, this

power supply is given from the power supply circuit designed above. It should be

noted that this programmer kit contains a power supply section in the board itself but

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

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

adapter connected to 230 V AC.

1. Install the Proload Software in the PC.

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

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



4. Now place the microcontroller in the GIF socket provided in the programmer

kit.

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

information like Hardware model, com port, device type, Flash size etc. Click

on browse option to select the hex file to be dumped into the microcontroller

and then click on “Auto program” to program the microcontroller with that

particular hex file.

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

bottom of the page. After this process is completed, remove the

microcontroller from the programmer kit and place it in your system board.

Now the system board behaves according to the program written in the

microcontroller.

7.3 ARDUINO SOFTWARE TOOLS

Arduino and Arduino Mega Software and Drivers Installation

This describes the installation of the Arduino IDE Development software and drivers

for the Windows Operating System. The images and description is based on

installation under Windows XP, but the process should be similar for Vista and

Windows 7. First we need to get the latest version of the Arduino software this can be

downloaded from the Arduino website

STEP 1:

Next, plug in your Arduino board to your computer with a USB cable and wait while

Windows detects the new device. Windows will fail to detect the device as it doesn't

know where the drivers are stored. You will get an error similar to the one right.

Select the Install from a list or specific location (Advanced) option and click next



STEP 2:

Now choose the location that the Arduino drivers are stored in. This will be in a

subfolder called drivers in your Arduino directory



STEP3:

After selecting next you may get a message like the one shown right.

Select Continue Anyway

STEP 4:

Windows should now have found the Arduino drivers. Click Finish to complete the installation



STEP 5:

The computer communicates with the Arduino board via a special serial port chip

built into the Arduino board. The Arduino IDE software needs to know the serial port

number that Windows has just allocated to it Open the Windows Control Panel and

select the System app. Click on the Hardware tab and then on the Device Manager

button. Click on the Ports (COM and LPT) option and note what COM port has been

allocated to the Arduino Board.

STEP 6:

Next, run the Arduino IDE application, which will be in c:\program files\arduino-0021 or similar Click on Tools | Serial Port and select the port number from above



STEP 7:

Next click on Tools | Board and select the type of board that you have

STEP 8:

Now try opening the Simple program from the example directory within the Arduino IDE, Verify/Compile it and upload it to your board. You should see the TX and RX leds on the board flash showing you that it is working. Finally the built in LED connected to Pin 13 will flash. That’s your first program running

Create a shortcut to the Arduino IDE and place it on your desktop



CHAPTER 8

SCHEMATIC REPRESENTATION

8.1 SCHEMATIC REPRESENTATION OF TRANSMITTER



8.2 SCHEMATIC REPRESENTATION OF RECEIVER:



RF RECEIVER

MOBILE JAMMER WITH METAL DETECTOR



CHAPTER-9

APPLICATIONS AND ADVANTAGES

9.1 APPLICATIONS:

� Defense: This project is useful in bomb detection and surveillance areas.

� Temples: A metal detection robot is used at sacred places & crowded areas

like shopping malls instead of men power .

� VIP security: A bomb diffusion robot with a CCTV camera can be used at

VIP’s houses for their security.

� Terrorist prone areas.

� Instead of manpower to detect landmines in combing operations, this project is

much helpful for mines detection.

9.2 ADVANTAGES:

� Spontaneous output.

� Long range.

� Not light sensitive.

� Line of sight not required.

� Not as sensitive to weather/environmental conditions



CHAPTER-10

RESULT

TRANSMITTER RECEIVER

INPUT: LCD DISPLAY:



OUTPUT:

WHEN METEL DETECTED:

INPUT OUTPUT

MOBILE JAMMER ACITVATED WHEN METAL DETECTED:



CHAPTER- 11

CONCLUSION & FUTURE SCOPE

10.1 CONCLUSION

This project presents the movement of the robot using Hand gesture technology which

runs on the 9V power supply. This project is been designed and implemented with

ARDUINO MCU in embedded system domain. Experimental work has been carried

out carefully. The result shows that higher efficiency is indeed achieved using the

embedded system. The proposed method is verified to be highly beneficial for the

security purpose.

10.2 FUTURE SCOPE

� Could be made to work on solar energy instead of battery source.

� For more spontaneous output including visual guidance, an image capturing

device of high resolution like movable camera could be fixed to the robot.

� The voice recognition security may also be developed in future.



REFERENCES:

1. Www. howstuffworks.com

2. Embedded System by Raj Kamal

3. 8051 Microcontroller and Embedded Systems by Mazzidi

4. Electronics Maker.

5. Electronics for you

6. Electrikindia

7. www.wikipedia.com

8. www.Electronic projects.com

APPENDIX

SOURCE CODE

TRANSMITTER :

#include<reg52.h> #include"I2C_MEM.c" #include"LCD4.h" sbit frw=P2^7; sbit lft=P2^6; sbit rht=P2^5; sbit bck=P2^4; void main() { LCD_init(); LCD_puts(0x80," I2C MEMS TEST "); MEMS_Init(); LCD_puts(0x80," Mem inited "); while (1) { x=RrByte_MEMS(0x00); y=RrByte_MEMS(0x01); z=RrByte_MEMS(0x02); Robo_Movements(x,y); } } Robo_Movements(unsigned char f_b,unsigned char l_r) { if((f_b>15&&f_b<35)) { LCD_puts(0x80," FORWARD "); frw=0; return; } else if(f_b<50&&f_b>35) { LCD_puts(0x80," BACKWARD "); bck=0; return;

} else if(l_r>15&&l_r<35) { LCD_puts(0x80," LEFT "); lft=0; return; } else if(l_r<50&&l_r>35) { LCD_puts(0x80," RIGHT "); rht=0; return; } else if((f_b<10 && l_r<10) || (f_b>100 && l_r>100)) { LCD_puts(0x80," STOP "); } }

RECEIVER:

//RF//////////////////// const int sw1=1; const int sw2=2; const int sw3=3; const int sw4=4; //////////////////////// //H-Bridge////////////// const int h1=5; const int h2=6; const int h3=11; const int h4=12; //////////////////////// int sw1State=0; int sw2State=0; int sw3State=0; int sw4State=0; int firesensState=0; void setup() { pinMode(sw1,INPUT); pinMode(sw2,INPUT); pinMode(sw3,INPUT); pinMode(sw4,INPUT); pinMode(h1,OUTPUT); pinMode(h2,OUTPUT); pinMode(h3,OUTPUT);

pinMode(h4,OUTPUT); } void loop() { if(sw1State==LOW) { digitalWrite(h1,HIGH); digitalWrite(h2,LOW); digitalWrite(h3,HIGH); digitalWrite(h4,LOW); } if(sw2State==LOW) { digitalWrite(h1,LOW); digitalWrite(h2,HIGH); digitalWrite(h3,LOW); digitalWrite(h4,HIGH); } if(sw3State==LOW) { digitalWrite(h1,HIGH); digitalWrite(h2,LOW); digitalWrite(h3,HIGH); digitalWrite(h4,HIGH); } if(sw4State==LOW) { digitalWrite(h1,HIGH); digitalWrite(h2,HIGH); digitalWrite(h3,HIGH); digitalWrite(h4,LOW); } }

ug major project - wireless bomb detection robot

Documents