1

BUS SAFETY SYSTEM FOR SCHOOL

CHILDREN

A PROJECT REPORT

Submitted by

P.KIRUTHIKA Reg.No.:12BEC062

E.KOWSALYA Reg.No.:12BEC064

V.NANDHITHA Reg.No.:12BEC087

N.R.NITHIYA Reg.No.:12BEC092

in partial fulfilment for the award of the degree

of

BACHELOR OF ENGINEERING

IN

ELECTRONICS AND COMMUNICATION ENGINEERING

KUMARAGURU COLLEGE OF TECHNOLOGY

(An Autonomous Institution Affiliated to Anna University, Chennai)

COIMBATORE- 641 049

ANNA UNIVERSITY:CHENNAI 600 025

APRIL 2016

2

BUS SAFETY SYSTEM FOR SCHOOL

CHILDREN

A PROJECT REPORT

Submitted by

P.KIRUTHIKA Reg.No.:12BEC062

E.KOWSALYA Reg.No.:12BEC064

V.NANDHITHA Reg.No.:12BEC087

N.R.NITHIYA Reg.No.:12BEC092

in partial fulfilment for the award of the degree

of

BACHELOR OF ENGINEERING

IN

ELECTRONICS AND COMMUNICATION ENGINEERING

KUMARAGURU COLLEGE OF TECHNOLOGY

(An Autonomous Institution Affiliated to Anna University ,Chennai)

COIMBATORE-641 049

ANNA UNIVERSITY:CHENNAI 600 025

APRIL 2016

3

BONAFIDE CERTIFICATE

Certifed that this project report titled “BUS SAFETY SYSTEM FOR

SCHOOL CHILDREN” is the bonafide work of Ms. P.KIRUTHIKA

[12BEC062], Ms. E.KOWSALYA [12BEC064], Ms. V.NANDHITHA

[12BEC087], Ms. N.R.NITHIYA [12BEC092], who carried out the project

work under my supervision. Certified further that to the best of my knowledge

the work reported herein does not form part of any other project or dissertation

on the basis of which a degree or award was conferred on an earlier occasion on

this or any other candidate.

SIGNATURE

Ms.M.SHANTHI M.E., (Ph.D.),

PROJECT SUPERVISOR

Department of ECE

Kumaraguru College of Technology

Coimbatore - 641 049

SIGNATURE

Dr. A. VASUKI M.E., Ph.D.,

HEAD OF THE DEPARTMENT

Department of ECE

Kumaraguru College of Technology

Coimbatore - 641 049

The candidates with Register No.: 12BEC062, 12BEC064, 12BEC087,

12BEC092 are examined by us in the project viva-voce held on .................

INTERNAL EXAMINER EXTERNAL EXAMINER

ACKNOWLEDGEMENT

We express our sincere thanks to the Management of Kumaraguru College

of Technology and Joint Correspondent Shri. Shankar Vanavarayar for the

kind support and for providing necessary facilities to carry out the project work.

We would like to express our sincere thanks to our beloved Principal

Dr.R.S.Kumar, Ph.D., Kumaraguru College of Technology, who encouraged

us in each and every step of the project.

We would like to thank Dr.A.Vasuki, Ph.D., Head of the Department,

Electronics and Communication Engineering, for her kind support and for

providing necessary facilities to carry out the project work.

We wish to thank with everlasting gratitude to our Project Coordinator

Ms.K.Anusha, M.E., AP-II, Department of Electronics and Communication

Engineering for his consistent support throughout the course of this project

work.

We are greatly privileged to express our deep sense of gratitude and

heartfelt thanks to our Project Guide Ms. M.Shanthi M.E.,(Ph.D.), Associate

Professor, Department of Electronics and Communication Engineering for

his/her expert counseling and guidance to make this project to a great deal of

success and also we wish to convey our regards to all teaching and non-

teaching staff of ECE Department for their help and cooperation.

Finally, we thank our parents and our family members for giving us the

moral support and abundant blessings in all of our activities and our dear friends

who helped us to endure our difficult times with their unfailing support and

warm wishes.

ABSTRACT

With the advancement of the crime rate, security is having its alarming

significance for school children‘s. The safety mechanism to the school bus and

to the children travelling from home to the school and resume back to home is a

standalone component to the parents and to the school management. This

project aims to provide the total security for school children. Each student is

tagged with unique code. The module is placed at the entrance and exit location

of the bus. Wireless communication technology RFID is used to inform the

status of the bus to the school principal. The student record will be sent to the

concerned parent before leaving the children entry point. The return information

is also informed to the parent using GSM technology. The results are

favourably good to meet the challenges of the security issues.

vi

LIST OF ABBREVIATION

PIC Peripheral Interface Controller

RAM Random Access Memory

SMS Short Message Service

ALU Arithmetic Logic Unit

RFID Radio Frequency Identification

GSM Global System for Mobile Communication

GPS Global Positioning System

LCD Liquid Crystal Display

DOS Disc Operating System

CMD Command

MCLR Master Clear

ICSP Incircuit Serial Programming

UART Universal Asynchronous Receiver/Transmitter

USB Universal Serial Bus

LED Light Emitting Diode

EPC Electronic Product Code

BAP Battery Assisted Passive Device

.

vii

LIST OF FIGURES

S.NO

FIGURES

Pg.NO.

2.1. BLOCK DIAGRAM

2

2.2. CIRCUIT DIAGRAM

3

2.3. BLOCK DIAGRAM OF PIC

5

2.4. PIN DIAGRAM OF PIC

6

2.5. STACK

7

2.6. BLOCK DIAGRAM POWER SUPPLY

12

2.7. CIRCUIT DIAGRAM OF POWER SUPPLY 14

2.8. MAX232

27

2.9. LCD PIN DIAGRAM

35

3.1. PICKIT1

37

3.2. PICKIT2

38

3.3. PICKIT3

40

8

TABLE OF CONTENTS

CHAPTER

CONTENTS

Pg.NO

NO

ABSTRACT

iv

LIST OF ABBREVIATIONS

v

LIST OF FIGURES

vi

1 INTRODUCTION

1

2 HARDWARE DESCRIPTION

2

2.1. BLOCK DIAGRAM

2

2.1.1. DESCRIPTION

2

2.2. CIRCUIT DIAGRAM

3

2.2.1. DESCRIPTION

3

2.3. PIC MICROCONTROLLER

4

2.3.1. PIC16F887

4

2.3.2. BLOCK DIAGRAM

5

2.3.3. PIN DIAGRAM

6

2.3.4. STACK

7

2.3.5. STATUS REGISTER

8

2.3.6. I/O PORTS

8

2.3.7. INSTRUCTION SET

10

2.4. POWER SUPPLY UNIT

11

2.4.1. BLOCK DIAGRAM

12

2.4.2 WORKING PRINCIPLE 12

2.5. RFID

15

2.5.1. RFID TAG

15

2.5.2. RFID READERS

18

9

2.6. RELAY

19

2.6.1. RELAY DRIVER CIRCUIT 20

2.7. GSM

21

2.7.1. MOBILE STANDARDS 22

2.7.2. SMS

22

2.7.3. ADVANTAGES OF GSM 23

2.7.4. APPLICATIONS OF GSM 24

2.8. SERIAL COMMUNICATION

25

2.8.1. RS232

25

2.8.2. MAX 232

26

2.9. GPS

27

2.9.1. CONCEPT OF GPS

28

2.9.2. POSITION CALCULATION 29

2.10. LCD DISPLAY

32

2.10.1. FEATURES OF LCD

33

2.10.2. PIN DIAGRAM

35

2.10.3. ADVANTAGES

36

2.10.4. APPLICATIONS 36

3 SOFTWARE DESCRIPTION

37

3.1. PIC KIT TOOL

37

3.2. MPLAB IDE

40

3.3. EMBEDDED C

42

4 WORKING

45

5 WORKING MODEL

46

6 CONCLUSION

47

REFERENCES

48

10

1.INTRODUCTION

School buses transfers millions of children daily in various countries around

the world. While there many issues that might disturb the parents regarding the

travel safety of school going children, the project intends to look into

introducing access safety in respect of school buses through bus safety system

that will help the school children‘s transportation in a secure and safer way. The

supervision of the regularity of students during their entry and exit from the bus

is difficult to be controlled by drivers, which led to endangering child safety.

The phenomenon of forgetting kids on the bus is one of the problems suffered

by the children, which has increased significantly in recent years. This has often

led to the death of many students on account of suffocation due to the lack of

attention of derivers. This project, through entry and exit recordings, aims to

create a suitable environment by following certain set of criteria of security and

safety for school bus that will have a positive impact on the student and their

family. The project proposed a bus safety system which was designed to control

the entering/exiting of students from the bus. This system does several tasks,

including identifying personal information (Eg. Name) of each student using

RFID tag, which will exchange the data with the RFID reader via radio waves,

and displaying student count into LCD display. This will let the driver to know

the number of students inside the bus and the students who departed from the

bus. Moreover, the system has an emergency system that will alert in case if

there is a child inside the bus after the bus stops at the destination by sending an

SMS to the school management via GSM modem. In addition, if the bus depart

and arrive successful from the source to destination, it will inform the

management through an SMS about its successful departure and arrival. The

key novel feature of the proposed methodology is the use of energy efficient

11

systems to support the tasks. The same data can be used to assess the time of

departure and arrival, number of students travels each day.

2.HARDWARE DESCRIPTION

2.1. BLOCK DIAGRAM

The complete block diagram of our project is as follows:

Fig.2.1. Block diagram

2.1.1. DESCRIPTION

The RFID card information is sensed using the RFID reader which is

matched with the pre-defined information in the embedded system and the card

information is displayed using a display unit. GSM and embedded system is

serially connected and the required conversion is performed by the level

RFID

CARD1

RFID

CARD3

RFID CARD2

EMBEDDED

SYSTEM

LEVEL

CONVERTER

GSM

POWER SUPPLY

GPS

RFID READER

DISPLAY

DRIVER

RFID

CARD4

12

converter. A driver is used to switch between the RFID reader and GPS. A

power supply unit is used to supply power to all the modules.

2.2. CIRCUIT DIAGRAM

The connections are made as per the given circuit diagram.

Fig.2.2. Circuit diagram

2.2.1. DESCRIPTION

The power supply unit is used to supply 5V to PIC Micro-Controller and

12V to all other modules. The 16x2 LCD display, two relays, MAX232 are

interfaced to PIC Micro-Controller through the interfacing pins. MAX232

13

performs the required level conversion among PIC, relay1, relay2 and GSM.

Relay1 switches between GPS and GSM. Relay2 switches between RFID reader

and Relay1. The LCD displays the RFID card information.

2.3. PIC MICROCONTROLLER

PIC is a family of Harvard architecture microcontrollers made by

Microchip Technology, derived from the PIC1640 originally developed by

General Instrument's Microelectronics Division. The name PIC initially referred

to "Peripheral Interface Controller". PICs are popular with developers and

hobbyists alike due to their low cost, wide availability, large user base,

extensive collection of application notes, availability of low cost or free

development tools, and serial programming (and re-programming with flash

memory) capability.

2.3.1 PIC16F887

Separate code and data spaces (Harvard architecture)

A small number of fixed length instructions

Most instructions are single cycle execution (4 clock cycles), with single

delay cycles upon branches and skips

A single accumulator (W), the use of which (as source operand) is

implied (i.e. is not encoded in the opcode)

All RAM locations function as registers as both source and/or destination

of math and other functions.

A hardware stack for storing return addresses

A fairly small amount of addressable data space (typically 256 bytes),

extended through banking

Watchdog timer.

Analog-to-digital converters (up to ~1.0 MHz).

14

Data space mapped CPU, port, and peripheral registers

2.3.2. BLOCK DIAGRAM

Fig.2.3.Block diagram of PIC

15

2.3.3. PIN DIAGRAM

Fig.2.4. Pin diagram of PIC

Program Memory map and stack for the PIC16F887

The PIC16F887 has a 13-bit program counter capable of addressing an 8K x

14 (0000h-1FFFh) program memory space. This 8x14 memory space is broken

into 4 pages of 2k x 14 each. Page # Memory location within a page A12 A11

A10 A9 A8 A7 A6 A5 A4 A3 A2 A1 A0 Accessing a location above these

boundaries will cause a wrap-around within the first 8K x 14 space. The Reset

16

vector is at memory location 0000h and the interrupt vector is at memory

location 0004h.

2.3.4. STACK

PICs have a hardware call stack, which is used to save return addresses. The

hardware stack is not software accessible on earlier devices, but this changed

with the 18 series devices.

Hardware support for a general purpose parameter stack was lacking in early

series, but this greatly improved in the 18 series, making the 18 series

architecture more friendly to high level language compilers.

Fig.2.5 Stack

17

2.3.5. STATUS REGISTER

The STATUS register contains:

The arithmetic status of the ALU

The Reset status

The bank select bits for data memory (GPR and SFR)

It is recommended to use the BCF and BSF instructions for bit manipulation

and the MOVWF instruction for byte manipulation of the STATUS register.

register BSF

Move content of W register to the STATUS register.

2.3.6. I/O PORTS

The 16F887 provides various PORT I/O pins – These can be Used to interface

to the ―outside world‖. A total of 35 I/O pins are provided by the 16F887 and

are divided into various PORTS.

PORT: A B C D E

PINS: 8 8 8 8 3

The I/O pins can be individually programmed to be either inputs or outputs.

Many of the I/O pins are shared with another functionality. One needs to

program the 16F887 for the desired functionality.

PORTA and the TRISA Register

18

The RA4 pin is a Schmitt Trigger input and an open drain output. All other

RA port pins have TTL input levels and full CMOS output drivers. All pins

have data direction bits (TRIS registers) which can configure these pins as

output or input .Setting a TRISA register bit puts the corresponding output

driver in a hi-impedance mode. Clearing a bit in the TRISA register puts the

contents of the output latch on the selected pin(s).

The ANSEL register is used to configure the Input mode of an I/O pin to

analog. Setting the appropriate ANSEL bit high will cause all digital reads on

the pin to be read as ‗0‘ and allow analog functions on the pin to operate

correctly.

PORTB and the TRISB Register:

PORTB is an 8-bit wide bi-directional port. The corresponding data direction

register is TRISB. Setting a bit in the TRISB register puts the corresponding

output driver in a high-impedance input mode. Clearing a bit in the TRISB

register puts the contents of the output latch on the selected pins.

The ANSELH register is used to configure the input mode of a PORTB I/O

pin to analog. Setting the appropriate ANSELH bit high will cause all digital

reads on the pin to be read as ‗0‘ and allow analog functions on the pin to

operate correctly. All of the PORTB pins are individually configurable as an

interrupt-on-change pin. Control bits IOCB<7:0> enable or disable the interrupt

function for each pin. For enabled interrupt-on-change pins, the present value is

compared with the old value latched on the last read of PORTB to determine

which bits have changed or mismatched the old value. The ‗mismatch‘ outputs

of the last read are ORed together to set the PORTB Change Interrupt flag bit

(RBIF) in the INTCON register. A mismatch condition will continue to set flag

bit RBIF. Reading or writing PORTB will end the mismatch condition and

allow flag bit RBIF to be cleared.

19

PORTC and the TRISC Register:

PORTC is an 8-bit bi-directional port. Each pin is individually configurable

as an input or output through the TRISC register. PORTC pins have Schmitt

Trigger input buffers. When enabling peripheral functions, care should be taken

in defining TRIS bits for each PORTC pin. Some peripherals override the TRIS

bit to make a pin an output, while other peripherals override the TRIS bit to

make a pin an input.

PORTD and the TRISD Register:

PORTD is an 8-bit port with Schmitt Trigger input buffers. Each pin is

individually configurable as an input or output.

PORTE register:

PORTE provides a 3-bit wide, bidirectional port on RE0, RE1, and RE2

pins. The exception is RE3, which is input only and its TRISE bit will always

read as ‗1‘. The corresponding data direction register is TRISE (1 input, 0

output). Reading the PORTE register reads the status of the pins, whereas

writing to it will write to the PORT latch. The TRISE register controls the

PORTE pin output drivers, even when they are being used as analog inputs. The

user should ensure the bits in the TRISE register are maintained set when using

them as analog inputs. I/O pins configured as analog input always read ‗0‘. The

ANSEL register must be initialized to configure an analog channel as a digital

input. Pins configured as analog inputs will read ‗0‘.

2.3.7. INSTRUCTION SET

A PIC's instructions vary from about 35 instructions for the low-end PICs to

over 80 instructions for the high-end PICs. The instruction set includes

instructions to perform a variety of operations on registers directly, the

20

accumulator and a literal constant or the accumulator and a register, as well as

for conditional execution, and program branching.

To load a constant, it is necessary to load it into W before it can be moved into

another register. On the older cores, all register moves needed to pass through

W, but this changed on the "high end" cores.PIC cores have skip instructions

which are used for conditional execution and branching. The skip instructions

are: 'skip if bit set', and, 'skip if bit not set'. Because cores before PIC18 had

only unconditional branch instructions, conditional jumps are implemented by a

conditional skip (with the opposite condition) followed by an unconditional

branch. Skips are also of utility for conditional execution of any immediate

single following instruction.

PIC instructions fall into 5 classes: Operation on W with 8-bit immediate

("literal") operand. E.g. movlw (move literal to W), andlw (AND literal with

W). One instruction peculiar to the PIC is retlw, load immediate into W and

return, which is used with computed branches to produce lookup tables.

Operation with W and indexed register. The result can be written to either the

W register (e.g. addwfreg,w). or the selected register (e.g. addwfreg,f). The

latter are usedto perform conditional branches. The usual ALU status flags are

available in a numbered register so operations such as "branch on carry clear"

are possible. Control transfers. Other than the skip instructions previously

mentioned, there are only two:goto and call.

2.4. POWER SUPPLY UNIT

The ac voltage, typically 220V rms, is connected to a transformer, which

steps that ac voltage down to the level of the desired dc output. A diode rectifier

then provides a full-wave rectified voltage that is initially filtered by a simple

capacitor filter to produce a dc voltage. This resulting dc voltage usually has

some ripple or ac voltage variation.

21

A regulator circuit removes the ripples and also remains the same dc value

even if the input dc voltage varies, or the load connected to the output dc

voltage changes. This voltage regulation is usually obtained using one of the

popular voltage regulator IC units.

2.4.1. BLOCK DIAGRAM

Fig,2.6:Block diagram of Power supply

2.4.2 WORKING PRINCIPLE

Transformer

The potential transformer will step down the power supply voltage (0-

230V) to (0-6V) level. Then the secondary of the potential transformer will be

connected to the precision rectifier, which is constructed with the help of op–

amp. The advantages of using precision rectifier are it will give peak voltage

output as DC, rest of the circuits will give only RMS output.

Bridge rectifier

When four diodes are connected as shown in figure, the circuit is called as

bridge rectifier. The input to the circuit is applied to the diagonally opposite

corners of the network, and the output is taken from the remaining two corners.

Let us assume that the transformer is working properly and there is a positive

potential, at point A and a negative potential at point B. the positive potential at

point A will forward bias D3 and reverse bias D4.

TRANSFORMER

RECTIFIER

FILTER

IC REGULATOR

LOAD

22

The negative potential at point B will forward bias D1 and reverse D2. At

this time D3 and D1 are forward biased and will allow current flow to pass

through them; D4 and D2 are reverse biased and will block current flow. The

path for current flow is from point B through D1, up through RL, through D3,

through the secondary of the transformer back to point B. this path is indicated

by the solid arrows. Waveforms (1) and (2) can be observed across D1 and D3.

One-half cycle later the polarity across the secondary of the transformer

reverse, forward biasing D2 and D4 and reverse biasing D1 and D3. Current

flow will now be from point A through D4, up through RL, through D2, through

the secondary of T1, and back to point A. This path is indicated by the broken

arrows. Waveforms (3) and (4) can be observed across D2 and D4. The current

flow through RL is always in the same direction. In flowing through RL this

current develops a voltage corresponding to that shown waveform (5). Since

current flows through the load (RL) during both half cycles of the applied

voltage, this bridge rectifier is a full-wave rectifier.

One advantage of a bridge rectifier over a conventional full-wave rectifier is

that with a given transformer the bridge rectifier produces a voltage output that

is nearly twice that of the conventional full-wave circuit.

This may be shown by assigning values to some of the components shown in

views A and B. assume that the same transformer is used in both circuits. The

peak voltage developed between points X and y is 1000 volts in both circuits. In

the conventional full-wave circuit shown—in view A, the peak voltage from the

center tap to either X or Y is 500 volts. Since only one diode can conduct at any

instant, the maximum voltage that can be rectified at any instant is 500 volts.

The maximum voltage that appears across the load resistor is nearly-but

never exceeds-500 v0lts, as result of the small voltage drop across the diode. In

the bridge rectifier shown in view B, the maximum voltage that can be rectified

is the full secondary voltage, which is 1000 volts. Therefore, the peak output

voltage across the load resistor is nearly 1000 volts. With both circuits using the

23

same transformer, the bridge rectifier circuit produces a higher output voltage

than the conventional full-wave rectifier circuit.

IC voltage regulator

Voltage regulators comprise a class of widely used ICs. Regulator IC units

contain the circuitry for reference source, comparator amplifier, control device,

and overload protection all in a single IC. IC units provide regulation of either a

fixed positive voltage, a fixed negative voltage, or an adjustably set voltage.

The regulators can be selected for operation with load currents from hundreds of

milli amperes to tens of amperes, corresponding to power ratings from milli

watts to tens of watts.

A fixed three-terminal voltage regulator has an unregulated dc input voltage,

Vi, applied to one input terminal, a regulated dc output voltage, Vo, from a

second terminal, with the third terminal connected to ground. The series 78

regulators provide fixed positive regulated voltages from 5 to24 volts. Similarly,

the series 79 regulators provide fixed negative regulated voltages from 5 to 24

volts.

24

Fig. 2.7: Circuit diagram of Power supply

2.5. RFID

Radio-frequency identification is the use of a wireless non-contact system

that uses radio-frequency electromagnetic fields to transfer data from a tag

attached to an object, for the purposes of automatic identification and tracking.

Some tags require no battery and are powered by the electromagnetic fields

used to read them. Others use a local power source and emit radio waves

(electromagnetic radiation at radio frequencies). The tag contains electronically

stored information which can be read from up to several meters (yards) away.

Unlike a bar code, the tag does not need to be within line of sight of the reader

and may be embedded in the tracked object.

2.5.1. RFID TAG

RFID tags are used in many industries. An RFID tag attached to an

automobile during production can be used to track its progress through the

assembly line. Pharmaceuticals can be tracked through warehouses. Livestock

and pets may have tags injected, allowing positive identification of the animal.

RFID identity cards can give employees access to locked areas of a building,

and RF transponders mounted in automobiles can be used to bill motorists for

access to toll roads or parking.

Since RFID tags can be attached to clothing, possessions, or even implanted

within people, the possibility of reading personally-linked information without

consent has raised privacy concerns

25

Design

A radio-frequency identification system uses tags, or labels attached to the

objects to be identified. Two-way radio transmitter-receivers called

interrogators or readers send a signal to the tag and read its response. The

readers generally transmit their observations to a computer system running

RFID software or RFID middleware.

The tag's information is stored electronically in a non-volatile memory. The

RFID tag includes a small RF transmitter and receiver. An RFID reader

transmits an encoded radio signal to interrogate the tag. The tag receives the

message and responds with its identification information. This may be only a

unique tag serial number, or may be product-related information such as a stock

number, lot or batch number, production date, or other specific information.

RFID tags can be either passive, active or battery assisted passive. An active

tag has an on-board battery and periodically transmits its ID signal. A battery

assisted passive (BAP) has a small battery on board and is activated when in the

presence of a RFID reader. A passive tag is cheaper and smaller because it has

no battery. Instead, the tag uses the radio energy transmitted by the reader as its

energy source. The interrogator must be close for RF field to be strong enough

to transfer sufficient power to the tag. Since tags have individual serial numbers,

the RFID system design can discriminate several tags that might be within the

range of the RFID reader and read them simultaneously.

26

Tags may either be read-only, having a factory-assigned serial number that is

used as a key into a database, or may be read/write, where object-specific data

can be written into the tag by the system user. Field programmable tags may be

write-once, read-multiple; "blank" tags may be written with an electronic

product code by the user.

RFID tags contain at least two parts: an integrated circuit for storing and

processing information, modulating and demodulating a radio-frequency (RF)

signal, collecting DC power from the incident reader signal, and other

specialized functions; and an antenna for receiving and transmitting the signal.

Fixed readers are set up to create a specific interrogation zone which can be

tightly controlled. This allows a highly defined reading area for when tags go in

and out of the interrogation zone. Mobile readers may be hand-held or mounted

on carts or vehicles.

Tag Chip

The tag's chip or integrated circuit (IC) delivers performance, memory and

extended features to the tag. The chip is pre-programmed with a tag identifier

(TID), a unique serial number assigned by the chip manufacturer, and includes a

memory bank to store the items' unique tracking identifier (called an electronic

product code or EPC).

Tag Antennas

Tag antennas collect energy and channel it to the chip to turn it on. Generally,

the larger the tag antenna's area, the more energy it will be able to collect and

channel toward the tag chip, and the further read range the tag will have.

There is no perfect antenna for all applications. It is the application that

defines the antenna specifications. Some tags might be optimized for a

27

particular frequency band, while others might be tuned for good performance

when attached to materials that may not normally work well for wireless

communication (certain liquids and metals, for example). Antennas can be made

from a variety of materials; they can be printed, etched, or stamped with

conductive ink, or even vapour deposited onto labels.

Tags that have only a single antenna are not as reliable as tags with multiple

antennas. With a single antenna, a tag's orientation can result in ―dead zones‖,

or areas on the tag where incoming signals cannot be easily harvested to provide

sufficient energy to power on the chip and communicate with the reader. A tag

with dual antennas is able to eliminate these dead zones and increase its

readability but requires a specialized chip.

2.5.2. RFID READERS

An RFID reader, also known as an interrogator, is a device that provides the

connection between the tag data and the enterprise system software that needs

the information. The reader communicates with tags that are within its field of

operation, performing any number of tasks including simple continuous

inventorying, filtering (searching for tags that meet certain criteria), writing (or

encoding) to selected tags, etc.

The reader uses an attached antenna to capture data from tags. It then passes

the data to a computer for processing. Just like RFID tags, there are many

different sizes and types of RFID readers. Readers can be affixed in a stationary

position in a store or factory, or integrated into a mobile device such as a

portable, handheld scanner. Readers can also be embedded in electronic

equipment or devices, and in vehicles.

Reader Antennas

28

RFID readers and reader antennas work together to read tags. Reader

antennas convert electrical current into electromagnetic waves that are then

radiated into space where they can be received by a tag antenna and converted

back to electrical current. Just like tag antennas, there is a large variety of reader

antennas and optimal antenna selection varies according to the solution's

specific application and environment.

The two most common antenna types are linear- and circular-polarized

antennas. Antennas that radiate linear electric fields have long ranges, and high

levels of power that enable their signals to penetrate through different materials

to read tags. Linear antennas are sensitive to tag orientation; depending on the

tag angle or placement, linear antennas can have a difficult time reading tags.

Conversely, antennas that radiate circular fields are less sensitive to orientation,

but are not able to deliver as much power as linear antennas.

Choice of antenna is also determined by the distance between the RFID

reader and the tags that it needs to read. This distance is called read range.

Reader antennas operate in either a "near-field" (short range) or "far-field" (long

range). In near-field applications, the read range is less than 30 cm and the

antenna uses magnetic coupling so the reader and tag can transfer power. In

near-field systems, the readability of the tags is not affected by the presence of

dielectrics such as water and metal in the field.

In far-field applications, the range between the tag and reader is greater than

30 cm and can be up to several tens of meters. Far-field antennas utilize

electromagnetic coupling and dielectrics can weaken communication between

the reader and tags.

2.6. RELAY

A relay is an electrically operated switch. Many relays used

an electromagnet to operate a switching mechanism mechanically, but other

29

operating principles are also used. Relays are used where it is necessary to

control a circuit by a low-power signal (with complete electrical isolation

between control and controlled circuits), or where several circuits must be

controlled by one signal. The first relays were used in long distance telegraph

circuits, repeating the signal coming in from one circuit and re-transmitting it to

another. Relays were used extensively in telephone exchanges and early

computers to perform logical operations.

A type of relay that can handle the high power required to directly drive an

electric motor is called a contactor. Solid-state relays control power circuits

with no moving parts, instead using a semiconductor device to perform

switching. Relays with calibrated operating characteristics and sometimes

multiple operating coils are used to protect electrical circuits from overload or

faults; in modern electric power systems these functions are performed by

digital instruments still called "protective relays".

2.6.1. RELAY DRIVER CRICUIT

The relay driver circuit is enabled certain time duration only, such

enable pulse is depended by delay programming of microcontroller, here darling

circuit has been two transistors made connection of cascade network, if input is

set to base of the first transistor, then that is turn on and emitter current of that

turn the another one. Hereby the circuit is closed through coil and second

transistor, now the energized coil is controls the contactors that are change the

normally open to close and normally closed to open connection. The enabled

signal is not essential after energized that coil because transistor collector

current maintains the transistors in saturation state continuously.

The induction effect may be affect the indication components and

another thing, so diode is connected across the coil which can prevents the

30

chopping effect the inverse magnitude of magnetic field shorted across from

coil.

2.7. GSM

GSM is one of the widely used mobile standards. GSM is Global System

for Mobile Communication. As the name specifies, it enables the mobile users

to interact all over the world at any time. GSM was actually designed to be

platform independent. Because GSM provides a common standard, cellular

subscribers can use their telephones over the entire GSM area which includes all

the countries around the world where the GSM system is used. In addition, the

GSM provides user services such as high-speed data communication, facsimile

and a Short Message Service (SMS). The GSM technical specifications are

also designed to work with other standards as it guarantees standard interfaces.

Finally a key aspect of GSM is that the specifications are open ended and can be

built upon to meet the future requirements.

31

2.7.1. MOBILE STANDARDS

The primary purpose of a standard for mobile communication is to specify

how mobile phone calls are to be handled by a mobile network.

This specification includes the following.

The signals to be transmitted and received by the mobile phone.

The format of these signals.

The interaction of the network nodes.

The basic network services which should be available to mobile

subscribers.

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The basic network structure.

2.7.2. SMS

SMS stands for Short Message Service. It is a technology that enables the

sending and receiving messages between the mobile phones. The SMS was

included in the GSM (Global System for Mobile Communication) standards

right at the beginning. Later it was ported to wireless technologies like CDMA

and TDMA. The GSM and SMS standards were originally developed by the

ETSI. ETSI is the abbreviation for European Telecommunications Standards

Institute. Now the 3GPP (Third Generation Partnership Project) is

responsible for the development of GSM and SMS standards.

As suggested by the name ―Short Message Service” the amount of data that

can be supported by an SMS is very limited. One SMS message can contain at

most 140 bytes.

2.7.3. ADVANTAGES OF GSM

SMS is a great success all over the world. SMS messaging is one of the most

important revenues of the wireless carriers. The number of messages exchanged

every day is very enormous.

Some of the reasons behind the popularity of the SMS are described below.

SMS messages can be sent and read at any time

Nowadays most of the persons have a mobile phone and carries it most of the

time. With a mobile phone, we can send and read messages at any time and at

any place be it at the home, bus, office etc.

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SMS messages can be sent to an offline mobile phone

Unlike a phone call we can send the message to our friend when he / she has

switched of the mobile phone or he /she is in the place where the wireless signal

is temporarily unavailable. The SMS system of the mobile network operator

will store the message and later send it to our friend.

SMS messages are less disturbing

Unlike a phone call, we need not read or reply an SMS message immediately.

Besides reading and writing the messages do not make any noise. We need not

attend the messages urgently as we do in case of an urgent phone call.

SMS messages can be exchanged over different wireless carriers

SMS technology is a very mature technology. Not only can we exchange the

messages with the mobile users of same wireless carriers but also with the

mobile users of different wireless carriers. So the 100% GSM phones support

Short Message Service.

2.7.4. APPLICATIONS OF GSM

There are many different kinds of SMS applications on the market today and

many others can be developed. Applications in which the SMS messaging can

be utilized are virtually unlimited. Some of the applications are described

below.

Person-to-Person Text Messaging

Person to person text messaging is the most commonly used SMS application.

Here, a person types a text message to his friend using the keypad of his mobile

phone and then inputs the mobile phone number of the recipient and clicks the

Send option on the screen to send the message out. When the recipient mobile

34

phone receives the sent text message, it will notify the user by giving out a

sound or a vibration. The recipient can then read and respond either

immediately or at any time later.

Provision of information

It is another popular application of the SMS technology. Many content

providers make use of the SMS text messages to send the information such as

news, weather report and financial data to their subscribers. Many of these

information services are not free.

Downloading

SMS can be used as a transport medium of wireless downloads since it carries

binary data. Objects such as pictures, wallpapers, and logos can be encoded in

one or more SMS messages depending upon the object‘s size. Like information

services wireless download services are also not free.

Alerts and Notifications

SMS is a very suitable technology for delivering alerts and notifications of

important events. This is because of two reasons:

A mobile phone is a device that is carried by its owner most of the

time. Whenever an SMS text message is received, the mobile phone

will notify you by giving out a sound or by vibrating. You can check

what the SMS text message contains immediately.

SMS technology allows the "push" of information. This is different

from the "pull" model where a device has to poll the server regularly

in order to check whether there is any new information. The "pull"

model is less suitable for alert and notification applications, since it

wastes bandwidth and increases server load.

2.8. SERIAL COMMUNICATION

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Serial data is any data that is sent one bit at a time using a single electrical

signal. In contrast, parallel data is sent 8, 16, 32, or even 64 bits at a time using

a signal line for each bit. Data that is sent without the use of a master clock is

said to be asynchronous serial data.

2.8.1. RS 232

Several communications standards exist for the transfer of asynchronous

serial data. Common PC's transfer data using the EIA RS-232C (also known as

V.28 or V.24). Updated versions of this standard include RS-232D and

EIA/TIA-232E, but most literature still refers to the RS-232C or RS-232

standard. The baud rate for a serial connection is the number of bits that are

transmitted per second. It is specified in bits/second or baud. For example, a 110

baud serial link transfers 110 bits of data per second.

Data transfer rate

The rate of data transfer in serial data communication is stated in bps(bits per

second). Another widely used terminology for bps is baud rate. Baud rate is

defined as the number of signal changes per second. In modems, there are

occasions when a single change of signal transfers several bits of data. As far as

the conductor wire is concerned, the baud rate and bps are the same. It must be

noted that in asynchronous serial data communication, the baud rate is generally

limited to 100,000 bps.

RS232 Standards

To allow compatibility among data communication equipment made by

various manufactures, an interfacing standard called RS232 was set by the

Electronics Industries Association (EIA) in 1960. RS232 is the most widely

used serial I/O interfacing standard.

2.8.2. MAX 232

36

Since the RS232 standard was set long before the advent of the TTL logic

family, its input and output voltage levels are not TTL compatible. In RS232, a

1 bit is represented by -3 to -25 V, while a 0 bit is +3 to +25 V, making -3 to +3

undefined. For this reason, to connect any Rs232 to a microcontroller system we

must use voltage convertors such as MAX232 to convert any RS232 the TTL

logic levels to the RS232 voltage level, and vice versa. MAX232 IC chips are

commonly referred to as line drivers. MAX 232 converts the RS232‘s signals to

the TTL voltage levels that will be acceptable to the 8051‘s TxD and RxD pins.

The MAX232 converts from RS232 voltage levels to TTL voltage levels, and

vice versa. One advantage of the MAX232 chip is that it uses a +5 V power

source which is the same as the source voltage for the 8051. In other words,

with a single +5 V power supply we can power both the 8051 and MAX232,

with no need for the dual power supplies that are common in many older

systems.

37

Fig.2.8. MAX 232

2.9. GPS

The Global Positioning System (GPS) is a global navigation satellite

system (GNSS) developed by the United States Department of Defence. It is the

only fully functional GNSS in the world. It uses a constellation of between 24

38

and 32 Medium Earth Orbit satellites that transmit precise microwave signals,

which allow GPS receivers to determine their current location, the time, and

their velocity. Its official name is NAVSTAR GPS.

2.9.1. CONCEPT OF GPS

A GPS receiver calculates its position by precisely timing the signals sent by

the GPS satellites high above the Earth. Each satellite continually transmits

messages containing the time the message was sent, precise orbital information

(the ephemeris), and the general system health and rough orbits of all GPS

satellites (the almanac). The receiver measures the transit time of each message

and computes the distance to each satellite. Geometric trilateration is used to

combine these distances with the location of the satellites to determine the

receiver's location. The position is displayed, perhaps with a moving map

display or latitude and longitude; elevation information may be included. Many

GPS units also show derived information such as direction and speed, calculated

from position changes.

39

It might seem three satellites are enough to solve for position, since space

has three dimensions. However a very small clock error multiplied by the very

large speed of light at which satellite signals propagate—results in a large

positional error.

2.9.2. POSITION CALCULATION

To provide an introductory description of how a GPS receiver works,

measurement errors will be ignored in this section. Using messages received

from a minimum of four visible satellites, a GPS receiver is able to determine

the satellite positions and time sent. The x, y, and z components of position and

the time sent are designated as where the subscript i is the satellite number and

has the value 1, 2, 3, or 4. Knowing the indicated time the message was

received, the GPS receiver can compute the indicated transit time, of the

message. Assuming the message travelled at the speed of light, c, the distance

travelled, can be computed as. Knowing the distance from GPS receiver to a

satellite and the position of a satellite implies that the GPS receiver is on the

surface of a sphere cantered at the position of a satellite. Thus we know that the

indicated position of the GPS receiver is at or near the intersection of the

surfaces of four spheres. In the ideal case of no errors, the GPS receiver will be

at an intersection of the surfaces of four spheres. The surfaces of two spheres, if

they intersect in more than one point, intersect in a circle. A figure, Two Sphere

Surfaces Intersecting in a Circle, is shown below.

Two sphere surfaces intersecting in a circle

The article, trilateration, shows mathematically that two spheres intersecting

in more than one point intersect in a circle.

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A circle and sphere surface in most cases of practical interest intersects at

two points, although it is conceivable that they could intersect at one point—or

not at all. Another figure, Surface of Sphere Intersecting a Circle (not disk) at

Two Points, shows this intersection. The two intersections are marked with dots.

Again trilateration clearly shows this mathematically. The correct position of

the GPS receiver is the intersection that is closest to the surface of the earth for

automobiles and other near-Earth vehicles. The correct position of the GPS

receiver is also the intersection which is closest to the surface of the sphere

corresponding to the fourth satellite. (The two intersections are symmetrical

with respect to the plane containing the three satellites. If the three satellites are

not in the same orbital plane, the plane containing the three satellites will not be

a vertical plane passing through the centre of the Earth. In this case one of the

intersections will be closer to the earth than the other. The near-Earth

intersection will be the correct position for the case of a near-Earth vehicle. The

intersection which is farthest from Earth may be the correct position for space

vehicles.

A TYPICAL RECEIVER WITH INTEGRATED ANTENNA

Many GPS receivers can relay position data to a PC or other device using the

NMEA 0183 protocol, or the newer and less widely used NMEA 2000.

Although these protocols are officially defined by the NMEA, references to

these protocols have been compiled from public records, allowing open source

tools like GPS to read the protocol without violating intellectual property laws.

41

Other proprietary protocols exist as well, such as the SiRF and MTK protocols.

Receivers can interface with other devices using methods including a serial

connection, USB or Bluetooth.

Broadcast Signal

Each GPS satellite continuously broadcasts a Navigation Message at 50

bit/s giving the time-of-week, GPS week number and satellite health

information (all transmitted in the first part of the message), an ephemeris

(transmitted in the second part of the message) and an almanac (later part of the

message). The messages are sent in frames, each taking 30 seconds to transmit

1500 bits.

Transmission of each 30 second frame begins precisely on the minute and

half minute as indicated by the satellite's atomic clock according to Satellite

message format. Each frame contains 5 sub frames of length 6 seconds and with

300 bits. Each sub frame contains 10 words of 30 bits with length 0.6 seconds

each.

Words 1 and 2 of every sub frame have the same type of data. The first word

is the telemetry word which indicates the beginning of a sub frame and is used

by the receiver to synch with the navigation message. The second word is the

HOW or handover word and it contains timing information which enables the

receiver to identify the sub frame and provides the time the next sub frame was

sent.

Words 3 through 10 of sub frame 1 contain data describing the satellite clock

and its relationship to GPS time. Words 3 through 10 of sub frames 2 and 3,

contain the ephemeris data, giving the satellite's own precise orbit. The

ephemeris is updated every 2 hours and is generally valid for 4 hours, with

provisions for updates every 6 hours or longer in non-nominal conditions. The

time needed to acquire the ephemeris is becoming a significant element of the

42

delay to first position fix, because, as the hardware becomes more capable, the

time to lock onto the satellite signals shrinks, but the ephemeris data requires 30

seconds (worst case) before it is received, due to the low data transmission rate.

2.10. LCD DISPLAY

Liquid crystal cell displays (LCDs) are used in similar applications where

LEDs are used. These applications are display of display of numeric and

alphanumeric characters in dot matrix and segmental displays.

LCDs are of two types

I. Dynamic scattering type

II. Field effect type

The construction of a dynamic scattering liquid crystal cell. The liquid

crystal material may be one of the several components, which exhibit optical

properties of a crystal though they remain in liquid form. Liquid crystal is

layered between glass sheets with transparent electrodes deposited on the inside

faces.

When a potential is applied across the cell, charge carriers flowing through

the liquid disrupt the molecular alignment and produce turbulence. When the

liquid is not activated, it is transparent. When the liquid is activated the

molecular turbulence causes light to be scattered in all directions and the cell

appease to be bright. This phenomenon is called dynamic scattering.

The construction of a field effect liquid crystal display is similar to that of

the dynamic scattering type, with the exception that two thin polarizing optical

filters are placed at the inside of each glass sheet. The liquid crystal material in

the field effect cell is also of different type from employed in the dynamic

43

scattering cell. The material used is twisted nemayic type and actually twists the

light passing through the cell when the latter is not energised.

Liquid crystal cells are of two types:

i. Transmittive type

ii. Reflective type

In the transmittive type cell, both glass sheets are transparent, so that light

from a rear source is scattered in the forward direction when the cell is

activated.

In reflective type cell has a reflecting surface on one side of glass sheets.

The incident light on the front surface of the cell is dynamically scattered by an

activated cell. Both types of cells appear quite bright when activated even under

ambient light conditions.

The liquid crystals are light reflectors are transmitters and therefore they

consume small amounts of energy (unlike light generators). The seven segment

display, the current is about 25micro Amps for dynamic scattering cells and

300micro amps for field effect cells. Unlike LEDs which can work on d.c. the

LCDs require a.c. voltage supply. A typical voltage supply to dynamic

scattering LCD is 30v peak to peak with 50 Hz.

2.10.1. FEATURES OF LCD

1. Polarizing filter film with a vertical axis to polarize light as it enters.

2. Glass substrate with ITO electrodes. The shapes of these electrodes will

determine the shapes that will appear when the LCD is turned ON.

Vertical ridges etched on the surface are smooth.

3. Twisted nematic liquid crystal.

4. Glass substrate with common electrode film (ITO) with horizontal ridges

to line up with the horizontal filter.

44

5. Polarizing filter film with a horizontal axis to block/pass light.

6. Reflective surface to send light back to viewer. (In a backlit LCD, this

layer is replaced with a light source.)

A liquid crystal display (LCD) is a flat panel display, electronic visual

display, video display that uses the light modulating properties of liquid crystals

(LCs). LCs don‘t emit light directly.

They are used in a wide range of applications, including computer monitors,

television, instrument panels, aircraft cockpit displays, signage, etc. They are

common in consumer devices such as video players, gaming devices, clocks,

watches, calculators, and telephones. LCDs have displaced cathode ray tube

(CRT) displays in most applications. They are usually more compact,

lightweight, portable, less expensive, more reliable, and easier on the eyes. They

are available in a wider range of screen sizes than CRT and plasma displays,

and since they do not use phosphors, they cannot suffer image burn-in.

LCDs are more energy efficient and offer safer disposal than CRTs. Its low

electrical power consumption enables it to be used in battery-powered electronic

equipment. It is an electronically modulated optical device made up of any

number of segments filled with liquid crystals and arrayed in front of a light

source (backlight) or reflector to produce images in color or monochrome. The

most flexible ones use an array of small pixels. The earliest discovery leading to

the development of LCD technology, the discovery of liquid crystals, dates

from 1888. By 2008, worldwide sales of televisions with LCD screens had

surpassed the sale of CRT units.

45

2.10.2. PIN DIAGRAM

Fig.2.9. LCD diagram

PIN NO SYMBOL FUNCTION

1 Vss Ground terminal of

Module

2 Vdd Supply terminal of

Module, +

5v

3 Vo Power supply for

liquid crystal drive

4 RS Register select

RS=0…Instruction

register

RS=1…Data register

46

2.10.3. ADVANTAGES

1. Consume much lesser energy (i.e. low power) when compared to

LEDs.

2. Utilizes the light available outside and no generation of light.

3. Since very thin layer of liquid crystal is used, more suitable to act as

display elements (in digital watches, pocket calculators, ect.)

4. Since reflectivity is highly sensitive to temperature, used as

temperature measuring sensor.

5. Very cheap.

2.10.4. APPLICATIONS

1. Watches

2. Fax & Copy machines & Calculators

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3. SOFTWARE DESCRIPTION

3.1. PICkit Tool

Fig.3.1. PICkit 1

PICkit is a family of programmers for PIC microcontrollers made by

Microchip Technology. They are used to program and debug microcontrollers,

as well as program EEPROM. Some models also feature logic analyzer and

serial communications (UART) tool.

The people who develop open-source software for the PICkit use a mailing list

for collaboration.

PICkit 1

The PICkit 1 — introduced on March 31, 2003 for US $36 — was a

rudimentary USB programmer for PIC microcontrollers, produced by

Microchip Technology, the manufacturers of the PIC series of microcontrollers.

It was integrated into a demo board featuring 8 LEDs, a switch, and a

potentiometer. Its default program (explained in the documentation) rotates the

48

LEDs in series. The light display's direction and speed of rotation can be

changed with the button and potentiometer on the PICkit board.

PICkit 2

The PICkit 2 — introduced in May 2005 — replaced the PICkit 1. The most

notable difference between the two is that the PICkit 2 has a separate

programmer/debugger unit which plugs into the board carrying the chip to be

programmed, whereas the PICkit 1 was a single unit. This makes it possible to

use the programmer with a custom circuit board via an In Circuit Serial

Programming (ICSP) header. This feature is not intended for so-called

"production" programming, however.

The PICkit 2 uses an internal PIC18F2550 with Full Speed USB. The latest

PICkit 2 firmware allows the user to program and debug most of the 8 and 16

bit PICmicro and dsPIC members of the Microchip product line.

Fig.3.2. PIC kit 2

The PICkit 2 is open to the public, including its hardware schematic,

firmware source code (in C language) and application programs (in C#

language). End users and third parties can easily modify both the hardware and

49

software for enhanced features. e.g. GNU/Linux version of PICKit 2 application

software, DOS style CMD support, etc.

The PICkit 2 has a programmer-to-go (PTG) feature, which can download the

hex file and programming instructions into on-board memory (128K byte I2C

EEPROM or 256K byte I2C EEPROM), so that no PC is required at the end

application.

The Microchip version of PICkit 2 has a standard 128K byte memory. 256K

byte memory can be achieved by modifying the hardware or from third party.

Additionally, a 500 kHz three-channel logic analyser and a UART tool are

built into the PICKit 2. These features are missing from the PICkit 3.

Since release of V2.61, PICkit 2 PC software now support maximum 4M

bytes of memory for programmer-to-go feature. This modification makes the

PICKit 2 support 8x more memory than the PICKit 3. This enhancement has

been contributed by Au Group Electronics and the PICkit 2 firmware is also

reported to be submitted to Microchip PICkit 2 team in the middle of March

2009. Hopefully this enhancement will be integrated into future firmware

releases too.

PICkit 3

Microchip has gone on to manufacture the PICkit 3, a variation of the

PICkit 2 with the same form factor and a new translucent case. It features a

faster 16-bit PIC24F processor and a wider voltage regulation range. There are

some complaints of it not being as reliable as the Pickit 2.

50

Fig.3.3. PIC kit 3

Both PICkit 2 and PICkit 3 have internal, switch-mode voltage regulators.

This allows them, in the case of the PICkit 2, to generate voltages from 2.5 to 5

volts, or in the case of the PICkit 3, 2.5 to 5.5 volts, from 5V USB, at around

100mA. Both have options for calibrating the output with a multi meter, for

increased accuracy. Additionally, for some PICs, the MCLR programming

voltage can be generated, at around 13-14 volts. This voltage is required to

reprogram the flash memory.

3.2. MPLAB IDE

COMPONENTS OF MPLAB IDE

The MPLAB IDE has both built-in components and plug-in modules to

configure the system for a variety of software and hardware tools.

Project Manager

The project manager provides integration and communication between the

IDE and the language tools.

Editor

The editor is a full-featured programmer's text editor that also serves as a

window into the debugger.

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Assembler/Linker and Language Tools

The assembler can be used stand-alone to assemble a single file, or can be

used with the linker to build a project from separate source files, libraries and

recompiled objects. The linker is responsible for positioning the compiled code

into memory areas of the target microcontroller.

Debugger

The Microchip debugger allows breakpoints, single stepping, watch

windows and all the features of a modern debugger for the MPLAB IDE. It

works in conjunction with the editor to reference information from the target

being debugged back to the source code.

Execution Engines

There are software simulators in MPLAB IDE for all PIC micro MCU and

dsPIC DSC devices. These simulators use the PC to simulate the instructions

and some peripheral functions of the PIC micro MCU and dsPIC DSC devices.

Optional in-circuit emulators and in-circuit debuggers are also available to test

code as it runs in the applications hardware.

The MPLAB IDE provides the ability to

Create and edit source code using the built-in editor.

Assemble, compile and link source code.

Debug the executable logic by watching program flow with the built-in

simulator or in real time with in-circuit emulators or in-circuit debuggers.

Make timing measurements with the simulator or emulator.

View variables in Watch windows.

Program firmware into devices with device programmers

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The following minimum configuration is required to run MPLAB IDE:

• PC compatible Pentium class system

• Microsoft Windows 3.1x, Windows 95/98, and above

• 16 MB memory (32 MB recommended)

• 45 MB of hard disk space

3.3. EMBEDDED C

Embedded C uses most of the syntax and semantics of standard C, e.g.,

main() function, variable definition, data type declaration, conditional

statements (if, switch, case), loops (while, for), functions, arrays and strings,

structures and union, bit operations, macros, etc.

Necessity

During infancy years of microprocessor based systems, programs were

developed using assemblers and fused into the EPROMs. There used to be no

mechanism to find what the program was doing. LEDs, switches, etc. were used

to check for correct execution of the program. Some ‗very fortunate‘ developers

had In-Circuit Emulator's (ICE's), but they were too costly and were not quite

reliable as well. As time progressed, use of microprocessor-specific assembly-

only as the programming language reduced and embedded systems moved onto

C as the embedded programming language of choice. C is the most widely used

programming language for embedded processors/controllers. Assembly is also

used but mainly to implement those portions of the code where very high timing

accuracy, code size efficiency, etc. are prime requirements.

As assembly language programs are specific to a processor, assembly

language didn‘t offer portability across systems. To overcome this

disadvantage, several high level languages, including C, came up. Some other

53

languages like PLM, Modula-2, Pascal, etc. also came but couldn‘t find wide

acceptance. Amongst those, C got wide acceptance for not only embedded

systems, but also for desktop applications. Even though C might have lost its

sheen as a mainstream language for general purpose applications, it still has a

strong-hold in embedded programming. Due to the wide acceptance of C in

embedded systems, various kinds of support tools like compilers & cross-

compilers, ICE, etc. came up, and all this facilitated development of embedded

systems using C. Assembly language seems to be an obvious choice for

programming embedded devices. However, use of assembly language is

restricted to developing efficient codes in terms of size and speed. Also,

assembly codes lead to higher software development costs and code portability

is not there. Developing small codes are not much of a problem, but large

programs/projects become increasingly difficult to manage in assembly

language. Finding good assembly programmers has also become difficult.

Hence high level languages are preferred for embedded systems programming.

Advantages

It is small and simpler to learn, understand, program and debug.

Compared to assembly language, C code written is more reliable and

scalable, more portable between different platforms.

C compilers are available for almost all embedded devices in use today,

and there is a large pool of experienced C programmers.

Unlike assembly, C has advantage of processor-independence and is not

specific to any particular microprocessor/microcontroller or any system.

This makes it convenient for a user to develop programs that can run on

most of the systems.

As C combines functionality of assembly language and features of high

level languages, C is treated as a ‗middle-level computer language‘ or

‗high level assembly language‘.

54

It is fairly efficient.

It supports access to I/O and provides ease of management of large

embedded projects.

Java is also used in many embedded systems but Java programs require

the Java Virtual Machine (JVM), which consumes a lot of resources.

Hence it is not used for smaller embedded devices.

In Embedded we need read/write data on given address, so in C its Easy

to access and modify, because of its pointer concept.

Other High-level programming language like Pascal, FORTRAN also

provides some of the advantages.

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4. WORKING

When the engine is ignited, the school bus starts to move and the module

gets triggered on with the help of a power supply unit. The power supply unit

has a transformer (step-down), bridge rectifier and LM7805 IC. The transformer

is used to convert 230V AC power supply to 12V AC supply. The bridge

rectifier converts this AC power supply to DC voltage. IC LM7805 is used to

prevent the controller from the damage in case of any voltage fluctuations.

From this unit, the power supply is given to all other units. There is a provision

for noise filtering using ceramic capacitors.

There are two relays namely relay 1 and relay 2. Relay 1 has a connection

with RFID and GSM. Relay 2 is connected with both GPS and GSM. GSM is

serially connected to the PIC micro-controller with the help of an UART. As

GSM works on AC supply, the DC supply from the PIC microcontroller is

converted into the AC supply with the help of UART. Whenever the valid tag is

read, the reader is connected to the relay 1 and the connection between the relay

2 and GPS will be disconnected. As GPS is a continuous monitoring system the

last tracked location is sent to the microcontroller. The count of the number of

students getting into the bus is displayed on the LCD through the PIC micro

controller. Here we have used 16x2 LCD displays which has two rows and it

has 16 characters in each row which is used to display the student information

stored in the RFID tag. For the entry of each student into the bus, the student‘s

status with the location is sent to the respective parents with the help of GSM.

In the same way how the message reaches the parent when the student boarded

the bus, the message again reaches the parents even when they get down from

the bus. The student attendance is recorded in the controller which can be sent

to the management manually.

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5.WORKING MODEL

57

6. CONCLUSION

This project presents a system to monitor pick-up/drop-off of school children

to enhance the safety of children during the daily transportation from and to

school. The system consists of two main units, a bus unit and a school unit. The

bus unit the system is used to detect when a child boards or leaves the bus. This

information is communicated to the school unit that identifies which of the

children did not board or leave the bus and issues an alert message accordingly.

The system has a developed web-based database-driven application that

facilities its management and provides useful information about the children to

authorized personal. A complete prototype of the proposed system was

implemented and tested to validate the system functionality. The results show

that the system is promising for daily transportation safety.

58

REFERENCES

[1] Khaled Shaaban et.al ―5Smart Tracking System for School Buses

Using Passive RFID Technology to Enhance Child Safety‖ , Journal of Traffic

and Logistics Engineering, Vol 1( 2), pages: 191-196, Dec 2013.

[2] Seong-eun Yoo, Poh Kit Chong, Daeyoung Kim, ―School Zone Safety

System Based on Wireless Sensor Network‖, Journal of Sensors, Vol 9, Pages

5968-5988, July 2009.

[3] G. Bharathi, L.Rammurthy , ― Implementation of children tracking system

using ARM7 microcontroller‖, International Journal of Industrial Electronics

and Electrical Engineering, Volume-2(12): pages 18-21, Dec.-2014.

[4] V.SivaSankaran et.al , ― Advanced embedded system assisted GSM and

RFID based smart school management system‖ , International journal of

advanced research in electrical , Electronics and Instrumentation Engineering,

Vol 2(7): pages 3124-3128, July 2013.

[5] M. Navya, et.al , ― Android based children tracking system using voice

recognition‖, International journal of Computer science and information

technology,Vol 4 (1): pages 229-235, Jan 2015.

[6] Khaled Shaaban et.al, ―Smart Tracking System for School Buses Using

Passive RFID Technology to Enhance Child Safety ― , Journal of Traffic and

Logistics Engineering, Vol 1( 2): pages 191-196, Dec 2013.

[7] J.Saranya , J.Selvakumar, ―Implementation of Children Tracking System on

Android Mobile Terminals ― , International conference on Communication and

Signal Processing, April 3-5, 2013, India 9