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VISWAJYOTHI COLLEGE OF ENGINEERING

AND TECHNOLOGY

AUTOMATIC BUS ANNOUCMENT SYSTEM

MINI PROJECT REPORT DONE BY

GEORGE JOSEPH JIS K SUNNY

DEPARTMENT OF ELECTRONICS AND COMMUNICATION

ENGINEERING

BATCH 2008-2012

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VISWAJYOTHI COLLEGE OF ENGINEERINGAND TECHNOLOGY

AUTOMATIC BUS ANNOUCMENT SYSTEM

MINI PROJECT

Submitted in partial fulfillment for the requirement of the

Award of Degree of Bachelor of Technology in

Electronics and Communication Engineering of

Mahatma Gandhi University.

BY

GEORGE JOSEPH

DEPARTMENT OF ELECTRONICS AND COMMUNICATION

ENGINEERING

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BATCH 2008-2012

VISWAJYOTHI COLLEGE OF ENGINEERING

AND TECHNOLOGY

DEPARTMENT OF ELECTRONICS AND COMMUNICATIONENGINEERING

CERTIFICATE

This is to certify that this mini project report entitled AUTOMATIC BUS

ANNOUCMENT SYSTEMis the bonafide report of mini project work done by GEORGE JOSEPH of sixth

semester Electronics and Communication Engineering in partial fulfillment for the

requirement of the award of Bachelor of Technology in Electronics and CommunicationEngineering of Mahatma Gandhi University.

REG NO:67159

Mini Project CoordinatorHead of Dept.

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--------------------------------------------------------

Abstract

The main aim of our project is to demonstrate how to replace the announcer in bus

station,Airport, railway station etc.The project only shows a basic demonstration of it using the

latest technologies Such as RFID reader, various soft wares

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rt

CONTENTS

Introduction...6

Block Diagram7

Block Diagram Explanation..8

Circuit Diagram10

Circuit Diagram Explanation..12

PCB Design &Fabrication..25

PCB Layouts.28

Software.30

Advantages, Disadvantages, Applications 38

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Future Scope39

Conclusion40

INTRODUCTION

Embedded systems have already pervaded our lives in numerous ways. Their applications

remain limited only by the imagination of the developers who design them. The

embedded system is a combination of hardware, software and perhaps additional mechanical

or electrical parts designed to perform a specific function.

RFID stands for Radio Frequency Identification. RFID is a technology that usescommunication via electromagnetic waves to exchange data between a terminal and an object

such as a product, animal, or person for the purpose of identification and tracking. An RFID

consist of an RFID tag and an RFID receiver.

Our preliminary aim in this project is to build an automatic announcement system in bus

terminal. Heart of this project is MicrochipsPIC16F877A microcontroller. There are two

main units:- Electronic Control Unit & System Unit. The Electronic Control Unit consist of

an RFID tag, RFID reader, microcontroller,. The system unit consist of a computer system

and a public addressing system.

The bus contains a RFID tag which has information regarding the particular bus the RFID

Module senses the information in RFID tag and sends MicrochipsPIC16F877A

microcontroller the microcontroller sends it to the system via MAX232 which converts TTL

logic of PIC to RS 232 of the PC and vice versa

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BLOCK DIAGRAM

Passive

RFID

module

Info. From

RFID tag

Microchip's

PIC16F877A

microcontroller

system

Power

supply

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BLOCK DIAGRAM EXPLANATION

Power supply

It provides regulated power supply of5v and 12v with help oftransformer andrectifier the

block diagram of power supply is:

MicrocontrollerA microcontroller (sometimes abbreviated C, uC orMCU) is a small computer on a single

integrated circuit containing a processor core , memory , and programmable input /output

peripherals . Program memory in the form of NOR flash orOTP ROM is also often included

on chip , as well as a typically small amount ofRAM . Microcontrollers are designed for

embedded applications , in contrast to the microprocessors used in personal computers or

other general purpose applications . Microcontrollers are used in automatically controlled

products and devices, such as automobile engine control systems, implantable medicaldevices, remote controls, office machines, appliances, power tools, and toys. By reducing the

Transformer Rectifier Voltageregulator

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size and cost compared to a design that uses a separate microprocessor, memory, and

input/output devices, microcontrollers make it economical to digitally control even more

devices and processes.

Radio frequency identification (RFID reader)

Radio-frequency identification (RFID) is atechnology that uses communication

via electromagnetic waves to exchange data between a terminal and an object such as a

product , animal , or

person for the purpose of identification and tracking . Some tags can be read from several

meters away and beyond the line of sight of the reader .Radio-frequency identification

involves interrogators (also known as readers), and tags (also known as labels).

The RFID reader senses the information stored in the RFID tag which is located in the bus

Radio-frequency identification (RFID tag)

Most RFID tags contain at least two parts. One is an integrated circuit for storing

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

other specialized functions . The other is an antenna for receiving and transmitting the signal .

There are three types of RFID tags: passive RFID tags, which have no power source and

require an external electromagnetic field to initiate a signal transmission, active RFID tags,

which contain a battery and can transmit signals once an external source ( Interrogator ) has

been successfully identified , and battery assisted passive ( BAP ) RFID tags , which require an

external source to wake up but have significant higher forward link capability providing

greater range .

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RFID has many applications; for example, it is used in enterprise supply chain management

to improve the efficiency of inventory tracking and management

.

System

The system announces the information send from the PIC via max232 to public

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Circuit diagram

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CIRCUIT DIAGRAM EXPLANATION

Transformer & Rectifier circuit

The transformer is used to step down the down the 230v AC to 6v AC and the rectifier is used

to convert AC into DC

Voltage regulator section

A regulated power supply is an embedded circuit, or stand alone unit, the function of which is

to supply a stable voltage (or less often current), to a circuit or device that must be operated

within certain power supply limits. The output from the regulated power supply may be

alternating or unidirectional, but is nearly always DC (Direct Current).Usually a voltage

regulator IC is used for generating a fixed voltage a voltage regulator IC called 78xx is used

for this. The 78xx (also sometimes known as LM78xx) series of devices is a family of self-

contained fixed linear voltage regulatorintegrated circuits. The 78xx family is a very popularchoice for many electronic circuits which require a regulated power supply, due to their ease

of use and relative cheapness. When specifying individual ICs within this family, the xx is

replaced with a two-digit number, which indicates the output voltage the particular device is

designed to provide (for example, the 7805 has a 5 volt output, while the 7812 produces 12

volts).78xx is positive voltage ICSs

79xx is negative voltage regulator Ics

Microcontroller

A microcontroller (sometimes abbreviated C, uC orMCU) is a small computer on a single

integrated circuit containing a processor core , memory , and programmable input /output

peripherals . Program memory in the form of NOR flash orOTP ROM is also often included

on chip , as well as a typically small amount ofRAM . Microcontrollers are designed for

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embedded applications , in contrast to the microprocessors used in personal computers or

other general purpose applications .

Microcontrollers are used in automatically controlled products and devices, such as

automobile engine control systems, implantable medical devices, remote controls, office

machines, appliances, power tools, and toys. By reducing the size and cost compared to a

design that uses a separate microprocessor, memory, and input/output devices,

microcontrollers make it economical to digitally control even more devices and processes.

Mixed signal microcontrollers are common, integrating analog components needed to control

non-digital electronic systems.Microcontrollers are used in automatically controlled products

and devices, such as automobile engine control systems, implantable medical devices, remote

controls, office machines, appliances, power tools, and toys. By reducing the size and cost

compared to a design that uses a separate

microprocessor, memory, and input/output devices, microcontrollers make it economical to

digitally control even more devices and processes. Mixed signal microcontrollers are

common, integrating analog components needed to control non-digital electronic

systems.Microcontrollers are used in automatically controlled products and devices, such as

automobile engine control systems, implantable medical devices, remote controls, office

machines, appliances, power tools, and toys. By reducing the size and cost compared to a

design that uses a separate microprocessor, memory, and input/output devices,

microcontrollers make it economical to digitally control even more devices and processes.

Mixed signal microcontrollers are common, integrating analog components needed to control

non-digital electronic systems.Microcontrollers are used in automatically controlled products

and devices, such as automobile engine control systems, implantable medical devices, remote

controls, office machines, appliances, power tools, and toys. By reducing the size and cost

compared to a design that uses a separate microprocessor, memory, and input/output devices,

microcontrollers make it economical to digitally control even more devices and processes.

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PORTB and the TRISB Register

PORTB is an 8-bit wide, bidirectional port. The corresponding data direction register

is TRISB. Setting a TRISB bit (= 1) will make the corresponding PORTB pin an input (i.e.,

put the corresponding output driver in a High-Impedance mode). Clearing a TRISB bit (= 0)

will make the corresponding PORTB pin an output (i.e., put the contents of the output latch

on the selected pin). Three pins of PORTB are multiplexed with the In-Circuit Debugger

and Low-Voltage Programming function: RB3/PGM, RB6/PGC and RB7/PGD. Each of the

PORTB pins has a weak internal pull-up. A single control bit can turn on all the pull-ups.

This is performed by clearing bit RBPU (OPTION_REG).

The weak pull-up is automatically turned off when the port pin is configured as an output.

The pull-ups are disabled on a Power-on Reset.

Four of the PORTB pins, RB7:RB4, have an interruption- change feature. Only pins

configured as inputs can cause this interrupt to occur (i.e., any RB7:RB4 pin configured as

an output is excluded from the interruption- change comparison). The input pins (of

RB7:RB4) are compared with the old value latched on the last read of PORTB. The

mismatch outputs of RB7:RB4 are ORed together to generate the RB port change

interrupt with flag bit RBIF (INTCON). This interrupt can wake the device from Sleep.

The user, in the Interrupt Service Routine, can clear the interrupt in the following manner:

a) Any read or write of PORTB. This will end the mismatch condition.

b) Clear flag bit RBIF.

A mismatch condition will continue to set flag bit RBIF. Reading PORTB will end

the mismatch condition and allow flag bit RBIF to be cleared. The interrupt-on-change

feature is recommended for wake-up on key depression operation and operations where

PORTB is only used for the interrupt-on-change feature. Polling of PORTB is not

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recommended while using the interrupt-on-change feature. This interrupt-on-mismatch

feature, together with software configurable pull-ups on these four pins, allow easy interface

to a keypad and make it possible for wake-up on key depression. RB0/INT is an external

interrupt input pin and is configured using the INTEDG bit (OPTION_REG).

PORTC and the TRISC Register

PORTC is an 8-bit wide, bidirectional port. The corresponding data direction register

is TRISC. Setting a TRISC bit (= 1) will make the corresponding PORTC pin an input (i.e.,

put the corresponding output driver in a High-Impedance mode). Clearing a TRISC bit (= 0)

will make the corresponding PORTC pin an output (i.e., put the contents of the output latch

on the selected pin). PORTC is multiplexed with several peripheral functions (Table 4-5).

PORTC pins have Schmitt Trigger input buffers. When the I2C module is enabled, the

PORTC pins can be configured with normal I2C levels, or with SMBus levels, by

using the CKE bit (SSPSTAT). 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.

Since the TRIS bit override is in effect while the peripheral is enabled, read-modifywrite

instructions (BSF, BCF, XORWF) with TRISC as the destination, should be avoided. The

user should refer to the corresponding peripheral section for the correct TRIS bit settings.

PORTD and TRISD Registers

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

configurable as an input or output. PORTD can be configured as an 8-bit wide

microprocessor port (Parallel Slave Port) by setting control bit, PSPMODE (TRISE). In

this mode, the input buffers are TTL.

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PORTE and TRISE Register

PORTE has three pins (RE0/RD/AN5, RE1/WR/AN6 and RE2/CS/AN7) which are

individually configurable as inputs or outputs. These pins have Schmitt Trigger input

buffers. The PORTE pins become the I/O control inputs for the microprocessor port when

bit PSPMODE (TRISE) is set. In this mode, the user must make certain that the

TRISE bits are set and that the pins are configured as digital inputs. Also, ensure that

ADCON1 is configured for digital I/O. In this mode, the input buffers are TTL. Register 4-

1 shows the TRISE register which also controls the Parallel Slave Port operation. PORTE

pins are multiplexed with analog inputs. When selected for analog input, these pins will read

as 0s. TRISE controls the direction of the RE pins, even when they are being used as

analog inputs. The user must make sure to keep the pins configured as inputs when using

them as analog inputs

INTERRUPTS

The PIC16F87XA family has up to 15 sources of interrupt. The Interrupt Control

register (INTCON) records individual interrupt requests in flag bits. It also has individual

and global interrupt enable bits. A global interrupt enable bit, GIE (INTCON), enables (if

set) all unmasked interrupts or disables (if cleared) all interrupts. When bit GIE is enabled

and an interrupts flag bit and mask bit are set, the interrupt will vector immediately.

Individual interrupts can be disabled through their corresponding enable bits in

various registers. Individual interrupt bits are set regardless of the status of the GIE

bit. The GIE bit is cleared on Reset. The return from interrupt instruction, RETFIE, exits

the interrupt routine, as well as sets the GIE bit, which re-enables interrupts. The RB0/INT

pin interrupt, the RB port change interrupt and the TMR0 overflow interrupt flags are

contained in the INTCON register. The peripheral interrupt flags are contained in the

Special Function Registers, PIR1 and PIR2. The corresponding interrupt enable bits are

contained in Special Function Registers, PIE1 and PIE2, and the peripheral interrupt enable

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bit is contained in Special Function Register, INTCON. When an interrupt is responded to,

the GIE bit is cleared to disable any further interrupt, the return address is pushed onto the

stack and the PC is loaded with 0004h. Once in the Interrupt Service Routine, the source(s)

of the interrupt can be determined by polling the interrupt flag bits. The interrupt flag bit(s)

must be

cleared in software before re-enabling interrupts to avoid recursive interrupts. For external

interrupt events, such as the INT pin or PORTB change interrupt, the interrupt latency will

be three or four instruction cycles. The exact latency depends when the interrupt event

occurs. The latency is the same for one or two-cycle instructions. Individual interrupt flag

bits are set regardless of the status of their corresponding mask bit, PEIE bit or GIE bit.

INT INTERRUPT

External interrupt on the RB0/INT pin is edge triggered, either rising if bit INTEDG

OPTION_REG) is set or falling if the INTEDG bit is clear. When a valid edge appears

on the RB0/INT pin, flag bit, INTF (INTCON), is set. This interrupt can be disabled by

clearing enable bit, INTE (INTCON). Flag bit INTF must be cleared in software in the

Interrupt Service Routine before re-enabling this interrupt. The INT interrupt can wake-up

the processor from Sleep if bit INTE was set prior to going into Sleep. The status of global

interrupt enable bit, GIE, decides whether or not the processor branches to the interrupt

vector following wake-up.

TMR0 INTERRUPT

An overflow (FFh 00h) in the TMR0 register will set flag bit, TMR0IF

(INTCON). The interrupt can be enabled/disabled by setting/clearing enable bit,

TMR0IE (INTCON

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An input change on PORTB sets flag bit, RBIF (INTCON). The interrupt can be

enabled/disabled by setting/clearing enable bit, RBIE (INTCON).

KEY FEATURES PIC16F877A

Operating frequency DC 20 MHz

Resets (and delays) POR , BOR

(PWRT, OST)

Flash program memory

(14 bit words)

8K

Data memory(bytes) 368

EEPROM Data

Memory(bytes)

256

Interrupts 15

I/O ports Ports A, B, C, D, E

Timers 3

Capture/Compare/PWM

Modules

2

Serial Communications MSSP , USART

Parallel communications PSP

10-bit Analog to digital

modules

8 input channels

Analog Comparators 2

Instruction set 35 instructions

Packages 40 pin PDIP

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Context Saving During Interrupts

During an interrupt, only the return PC value is saved on the stack. Typically, users

may wish to save key registers during an interrupt (i.e., W register and Status register). This

will have to be implemented in software. For the PIC16F873A/874A devices, the register

W_TEMP must be defined in both Banks 0 and 1 and must be defined at the same offset

from the bank base address (i.e., If W_TEMP is defined at 0x20 in Bank 0, it must also be

defined at 0xA0 in Bank 1). The registers, PCLATH_TEMP and STATUS_TEMP, are only

defined in Bank 0. Since the upper 16 bytes of each bank are common in the

IC16F876A/877A devices, temporary holding registers, W_TEMP, STATUS_TEMP and

PCLATH_TEMP, should be placed in here. These 16 locations dont require banking and

therefore, make it easier for context save and restore.

ELEMENTS OF AN RFID SYSYTEM

RFID system consisting of 3 component

An antenna

RFID Reader

A transponder (RF tag) electronically programmed with unique information

RFID tag

An RFID tag is a microchip combined with an antenna in a compact package; the packaging

is structured to allow the RFID tag to be attached to an object to be tracked. "RFID" stands

for Radio Frequency Identification.

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The tag's antenna picks up signals from an RFID reader or scanner and then returns the

signal, usually with some additional data (like a unique serial number or other customized

information).

RFID tags can be very small - the size of a large rice grain. Others may be the size of a small

paperback book.

RFID Reader

An RFID reader is a device that is used to interrogate an RFID tag. The reader has an

antenna that emits radio waves; the tag responds by sending back its data.

A number of factors can affect the distance at which a tag can be read (the read range). The

frequency used for identification, the antenna gain, the orientation and polarization of the

reader antenna and the transponder antenna, as well as the placement of the tag on the object

to be identified will all have an impact on the RFID systems read range.

WORKING

The antenna emits radio signals to activate the tag and to read and write data to it.

The reader emits radio waves in ranges of anywhere from one inch to 100 feet or more,

depending upon its power output and the radio frequency used. When an RFID tag passes

through the electromagnetic zone, it detects the reader's activation signal.

The reader decodes the data encoded in the tag's integrated circuit (silicon chip) and the

data is passed to the host computer for processing.

The purpose of an RFID system is to enable data to be transmitted by a portable device,

called a tag, which is read by an RFID reader and processed according to the needs of a

particular application. The data transmitted by the tag may provide identification or location

information, or specifics about the product tagged, such as price, color, date of purchase, etc.

RFID technology has been used by thousands of companies for a decade or more. . RFID

quickly gained attention because of its ability to track moving objects. As the technology is

refined, more pervasive - and invasive - uses for RFID tags are in the works.

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A typical RFID tag consists of a microchip attached to a radio antenna mounted on a

substrate. The chip can store as much as 2 kilobytes of data.To retrieve the data stored on an

RFID tag, you need a reader. A typical

reader is a device that has one or more antennas that emit radio waves and receive signals

back from the tag. The reader then passes the information in digital form to a computer

system.

APPLICATIONS

Asset Tracking

It's no surprise that asset tracking is one of the most common uses of RFID.Companies can put RFID tags on assets that are lost or stolen often, that are underutilized or

that are just hard to locate at the time they are needed. Just about every type of RFID system

is used for asset management. NYK Logistics, a third-party logistics provider based in

Secaucus, N.J., needed to track containers at its Long Beach, Calif., distribution center. It

chose a real-time locating system that uses active RFID beacons to locate container to within

10 feet.

1. Manufacturing

RFID has been used in manufacturing plants for more than a decade. It's used to track

parts and work in process and to reduce defects, increase throughput and manage the

production of different versions of the same product.

2 .Supply Chain Management

RFID technology has been used in closed loop supply chains or to automate parts of

the supply chain within a company's control for years.As standards emerge, companies are

increasingly turning to RFID to track shipments among supply chain partners.

3. Retailing

Retailers such as Best Buy, Metro, Target, Tesco and Wal-Mart are in the forefront of

RFID adoption. These retailers are currently focused on improving supply chain efficiencyand making sure product is on the shelf when customers want to buy it.

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4. Payment Systems

RFID is all the rage in the supply chain world, but the technology is also catching on

as a convenient payment mechanism. One of the most popular uses of RFID today is to pay

for road tolls without stopping.

These active systems have caught on in many countries, and quick service restaurants are

experimenting with using the same active RFID tags to pay for meals at drive-through

windows.

5. Security and Access Control

RFID has long been used as an electronic key to control who has access to office

buildings or areas within office buildings. The first access control systems used low-

frequency RFID tags.

Recently, vendors have introduced 13.56 MHz systems that offer longer read range.

The advantage of RFID is it is convenient (an employee can hold up a badge to unlock a

door, rather than looking for a key or swiping a magnetic stripe card) and because there is no

contact between the card and reader, there is less wear and tear, and therefore less

maintenance.

As RFID technology evolves and becomes less expensive and more robust, it's likely

that companies and RFID vendors will develop many new applications to solve common andunique business problems.

MAX 232

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The MAX232 is an integrated circuit that converts signals from an RS-232 serial port to

signals suitable for use in TTL compatible digital logic circuits. The MAX232 is a dual

driver/receiver and typically converts the RX, TX, CTS and RTS signals.

The drivers provide RS-232 voltage level outputs (approx. 7.5 V) from a single + 5 V

supply via on-chip charge pumps and external capacitors. This makes it useful for

implementing RS-232 in devices that otherwise do not need any voltages outside the 0 V to

+ 5 V range, aspower supply design does not need to be made more complicated just for

driving the RS-232 in this case.

The receivers reduce RS-232 inputs (which may be as high as 25 V), to standard 5 V TTL

levels. These receivers have a typical threshold of 1.3 V, and a typical hysteresis of 0.5 V.

The later MAX232A is backwards compatible with the original MAX232 but may operate at

higherbaud rates and can use smaller external capacitors 0.1 F in place of the 1.0 F

capacitors used with the original deviceThe newer MAX3232 is also backwards compatible,

but operates at a broader voltage range, from 3 to 5.5 V.

Pin out of max232

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PCB DESIGN AND FABRICATION

After the designing and testing of the circuit, the next step is to mount the

circuit on the PCB and solder them properly. The PCB fabrication involves two steps:

Preparing the PCB drawing:

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The traditional method of making a PCB layout involves the complete

placement of parts, taking a photographic negative of the drawing, developing the image of

negative formed on the photosensitive copper plate and dissolving the excess by etching. For

small scale operation where large number of copies are not needed a cost saving procedure is

used. In this later conversion problem is overcome, also tracing of the circuit and fault finding

is made easy, as the PCB exactly matches the original circuit so that one does not have to

constantly look for positions to drill holes and place various components. Making the PCB

drawing involves some primary considerations such as placement of component on a piece of

paper, location of holes dividing diameter of various holes, the optimum area each component

should occupy, full utilization and prevention of overcrowding of components at a particularplace. For anchoring leads of components 1mm diameter holes and for fixing PCB pattern

total chassis of 3mm diameter holes are recommended. After this the sketch must be drawn.

The sketch is the mirror image of the PCB pattern desired. It shows the component placement

on the other side of the PCB laminate. The mirror image of this PCB pattern drawn on the

tracing paper will appear as the PCB pattern when viewed from the other side. To save time

and effort the sketch can be made on a paper itself right at the beginning. Alternatively the

PCB pattern can be drawn from the sketch with the help of carbon paper. A fresh carbon

paper may be placed upon a flat surface and covered with a plain sheet of paper. On this the

sketch is drawn with a ball pen or hard pencil. The mirror image of the sketch pen can be

obtained on lower sheet of the paper.

PCB fabrication:

An outline of the copper clad board is drawn on a paper and drawing is filled

onto it, making correct outlines of IC pins, resistors etc. The positive layout is also drawn

from that. For simplicity inch graph is used. This negative is transferred to the copper clad

board using enamel paint or nail polish. It is dried in sunlight. It is not advisable to rub or

touch the board to avoid scratching of the surface. Finally the board should be placed in the

etchant which is ferric chloride solution(FeCl3). FeCl3 is usually supplied in crystalline

form. It is dissolved in water to make solution of specific gravity 1.2. Etching is also a time

dependent process, for a fresh solution warmed upto 40 degree Celsius. Time taken should

be typically 10-15minutes. During this time the board should be agitated and checked to

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ascertain the state of etching. The board should be removed as soon as copper has cleared

all the areas affected by resistance. Failure will result in undercutting. Having completed

the etching process, the next step involves washing, cleaning and drying the PCB. Remove

the enamel paint by rubbing with a cloth soaked in thinner or turpentine. After that holes

are drilled on the sides. Now a coat of varnish is applied if necessary over the PCB to

prevent corrosion.

Soldering

Soldering is the process of joining metats by using lower melting point metal

or alloy with joining surface. Soldered joints will establish strong electrical connection

between component leads. The popularly used solders are alloys of tin and lead melt below

the melting point of tin.

Flux:

In order to make the surface accept the solder readily, the component terminal

should be free from oxides and other obstructing films. The leads should be cleaned

chemically or by abrasion using blades or knives. A small amount of lead coating can be done

on cleaned portion of lead using soldered iron. This process is called thinning. Zinc chloride

or Ammonium chloride or in combination is mostly used as fluxes. These are available in

petroleum jelly as paste flux. The residue which remains after soldering may be washed out

with more water accompanied by brushing.

Soldering Iron:

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This tool is used to melt solder and apply at the joint in the circuit. It operates

on 230V supply. The iron bit at the tip of it gets heated within few minutes. 50W or 25W

soldering iron are commonly used for soldering purposes.

Soldering Steps:

Make the layout of components in the circuit. Plug in the cord of soldering

iron into the mains to get it heated.

Straighten and remove the coating of component leads using a blade or knife.

Apply a little flux on the leads. Take a little solder on soldering iron and apply

the molten solder on the leads. Care must be taken to avoid the components

getting heated up.

Mount the components on PCB by bending the leads of components using

nose pliers.

Apply flux on the joints and solder the joints. Soldering must be done in

minimum to avoid the dry soldering and heating up of components.

Wash the residue using water and brush

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PCB Layouts

Bottom layer

Assembly top

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Top layer

Software

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#include "main.h"

#include "init.h"

//*************************************************************************

// Structure for wiegand data RFID1

//*************************************************************************

// data stucture for the 26 bit wiegand data receive

struct wiegand_data_rfid1

{

BYTE data1;

BYTE data2;

BYTE data3;

BYTE data4;

BYTE data5;

}wdata1;

struct wiegand_data_rfid1 *wiegand_data_str1_ptr;

BYTE *wiegand_data_ptr1;

//*************************************************************************

// Clear Structure Variables

//*************************************************************************

void clear_str_var1()

{

wdata1.data1=0; // clear the structure variables

wdata1.data2=0;

wdata1.data3=0;

wdata1.data4=0;

wdata1.data5=0;

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}

//;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

// Function Name : Data pack

// Details : It removes the parity bit and pack the data as 3 byte

//;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

//data packing function

//it will remove the parity at the starting and end of the 26 bit wiegand

data

void data_pack(BYTE *wiegand_data_ptr,BYTE Rfid)

{

BYTE *temp_ptr;

temp_ptr=wiegand_data_ptr; // wiegand data pointer initilizing

temp_ptr--;

for(i=0;i

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bit_set(*temp_ptr,0); // set the 0th bit of the buffer

}

else

{

rotate_left( temp_ptr, 1); //if low rotate the buffer 1bit

bit_clear(*temp_ptr,0); // clear the 0th bit of the buffer

}

}

temp_ptr=wiegand_data_ptr; // wiegand data pointer initilizing

putc('$'); //starting character

for(i=0;i

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if(input_state(pin_B4)^input_state(pin_B5)) //exor the data high pin and the data

low pin of RFID1

{

if(!input_state(pin_B4)) //if the data high pin is low

{

bit_high=1; //set the bit high flag

bit_set(*wiegand_data_ptr1,0); // set the 0th bit of the wiegand data buffer

}

else if(!input_state(pin_B5)) //if the data low pin is low

{

bit_low=1; //set the bit low flag

bit_clear(*wiegand_data_ptr1,0); // clear the 0th bit of the wiegand data

buffer

}

rotate_left( wiegand_data_ptr1, 1); // rotate the wiegand data buffer 1 bit for

next bit

bit_cnt1++; //incriment the bit count

Data_cnt1++; // wiegand data bit count incriment

}

if(bit_cnt1==8) //if one byte received

{

wiegand_data_ptr1++; //incrimet wiegand data structure pointer

bit_cnt1=0; //clear bit count

}

if(Data_cnt1==26) // wiegand data bits received =26(if using 26 bit

wiegand format)

{

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wiegand_data_ptr1=wiegand_data_str1_ptr; //initilize the wiegand data

stucture pointer

for( i=0;i

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Data_cnt1=0; //clear wiegand data bit count

bit_cnt1=0;

read_ok_Rfid1_flg=0;

}

}

}

ADVANTAGES

It replaces the announcer thereby reducing the monthly expenditure for the

announcer

Since the announcing messages are already pre recorded in a clear background, the

resultant announcement will be very much audible for the passengers.

It has improved accuracy.

It simplifies the traffic inside the bus stand .

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CONCLUSION

The advent of new high speed technology and the growing computer capacity provided

realistic opportunity for public addressing system. Our announcement system will replaces

the announcer in the bus terminal . The most innovative technology, zigbee can be used

efficiently for the wireless communication between the controller module and the system.

The main advantage is that it will give high performance and more reliable.

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