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VIVEKANANDA INSTITUTE OF TECHNOLOGY (EAST)

CHAPTER 1

1.1 INTRODUCTION:-

India is worlds largest democracy. It is perceived to be charismatic one as it

accommodates cultural, regional, economical, social disparities and still is able to stand on its

own. Fundamental right to vote or simply voting in elections forms the basis of Indian

democracy.

In India all earlier elections be it state elections or centre elections a voter used to cast his/her

vote to his/her favorite candidate by putting the stamp against his/her name and then folding the

ballot paper as per a prescribed method before putting it in the Ballot box. This is a long, time-

consuming process and very much prone to errors.

This situation continued till election scene was completely changed by electronic voting

machine. No more ballot paper, ballot boxes, stamping, etc. all this condensed into a simple

box called ballot unit of the electronic voting machine.

EVM is capable of saving considerable printing stationery and transport of large volumes of

electoral material. It is easy to transport, store, and maintain. It completely rules out the chance

of invalid votes. Its use results in reduction of polling time, resulting in fewer problems in

electoral preparations, law and order, candidates' expenditure, etc. and easy and

accurate counting without any mischief at the counting centre. It is also eco friendly.

Our EVM consists mainly of two units - (a) Control Unit (CU) and (b) Ballot Unit (BU) withcable for connecting it with Control unit. Both the units consists of one microcontroller (8052)

each. The CU consists of one LCD, one hex keypad and a couple of switches, while BU

consists of a candidate panel, a votecast panel and a buzzer, etc.

This project is based on assembly language programming. The software platform used in this

project are Keil uVision3 and CProgramming.

1 DEPARTMENT OF ELECTRONICS & COMMUNICATION


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1.2 BACKGROUND OF VOTING SYSTEM

1.2.1 DEMOCRACY AND VOTING

Democracy has come to be accepted as the most preferred form of political system all

over the world. However, the success of a democratic structure is to be judged by the successes

that can be solely attributed to this system. There are various challenges before democracy.

These are foundational challenges, challenge of expansion and deepening of democracy. All of

these are dependent on how the democracy is perceived by people who form the government,

participate in formation of government and are benefited by it.

As we all know that India is worlds largest democracy. It is perceived to be

charismatic one as it accommodates cultural, regional, economical, social disparities and still is

able to stand on its own. India follows a federal form of government. It means that governance

power is not residing with one authority, but is distributed at various levels. In India power is

distributed between states and central authority.

What forms the basis of such vast and complex system of governance?

One needs not to be an Einstein to guess the answer. It is fundamental right to vote or simply

voting in elections.

Indian constitution provide every adult above the age of 18 years irrespective of his/her

religion, region, caste, creed, color, economic status, education and sex the essential right to

vote and elect her/his candidate to represent her/him.

Hence voting can be termed as backbone of not just democracy in India but all aroundthe world. Voting can be done in various ways. In early Roman Empire voting used to be done

by raising hands in favor or against. In board rooms voting is done in similar way, some write

their vote down, some choose to speak, some choose to cast vote using latest technology.



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1.2.2 VOTING TECHNIQUES

In India all earlier elections be it state elections or centre elections a voter used to cast

his/her vote to his/her favorite candidate by putting the stamp against his/her name and thenfolding the ballot paper as per a prescribed method before putting it in the Ballot box. This is a

long, time-consuming process and very much prone to errors.

This method wanted voters to be skilled voters to know how to put a stamp, and

methodical folding of ballot paper. Millions of paper would be printed and heavy ballot boxes

would be loaded and unloaded to and from ballot office to polling station. All this continued till

election scene was completely changed by electronic voting machine. No more ballot paper,

ballot boxes, stamping, etc. all this condensed into a simple box called ballot unit of the

electronic voting machine.

The marking system of voting was introduced in 1962 to make it possible for a

substantial number of illiterate voters to indicate easily their preferences in choosing their

representatives. Over the years, there was a pronounced increase in the volume of work: crores

of ballot papers had to be printed and lakhs of ballot boxes had to be prepared, transported, and

kept in storage; and a great amount of time was taken up by the conduct of elections. To

overcome these difficulties, the Election Commission of India (ECI) thought of electronic

gadgets. The Electronics Corporation of India Ltd. (ECIL), Hyderabad, and Bharat Electronics

Ltd. (BEL), Bangalore, developed the electronic voting machine in 1981.

1.2.3 THE ELECTRONIC VOTING MACHINE

The complete EVM consists mainly of two units - (a) Control Unit and (b) Balloting

Unit with cable for connecting it with Control unit. A Balloting Unit caters upto 16 candidates.

Four Balloting Units linked together catering in all to 64 candidates can be used with one

control unit. The control unit is kept with the Presiding Officer and the Balloting Unit is used

by the voter for polling.

The Balloting Unit of EVM is a small Box-like device, on top of which each candidate

and his/her election symbol is listed like a big ballot paper. Against each candidate's name, a



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What Happens after Voting is over?

After the hour fixed for the close of the poll and the last voter has recorded his vote, the

EVM is closed so that no further recording of votes in the machine is possible. At the counting

place, only the control unit is required for ascertaining the result of poll at the polling station at

which the EVM was used. The balloting unit is not required. All this used to happen every time

election were held.

1.2.4 BOOTH CAPTURE

A remarkable advantage is that rigging is not possible with the EVMs. In the ballot

paper system, the intruders can mark hundreds of ballots and put them into the ballot box in a

matter of a few minutes. This is not possible in voting machines as the machine is designed to

be capable of recording a maximum of five votes per minute. (The pace of polling can be set to

any predetermined number before manufacturing.) Thus, even for recording about 100 bogus

votes it would take the booth captors 20 to 25 minutes, during which time the law and order

officials may intervene to stop the rot. Moreover, as soon as the presiding officer apprehends

any mischief, he can stop the poll by pressing the special switch after which no votes can be

recorded.

The presiding officer of the polling station is empowered to close the control unit of

the voting machine to ensure "that no further vote can be recorded." There is no possibility of

any bogus votes being polled after the close of the poll and during the transit of the machines

from the polling booth to the counting centre. A vote once recorded in an EVM cannot be

tampered with, whereas in the ballot paper system the votes marked and put into the box can be

pulled out and destroyed. The EVMs are capable of retaining the memory of the votes recorded

for a period of three years. If the machine is tampered with in any respect either during the poll

time or at any time before the counting of votes, which will be easily detectable so that a fresh

poll can be ordered.

The EVMs have following advantages:

the saving of considerable printing stationery and transport of large volumes of

electoral material,



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easy transportation, storage, and maintenance,

no invalid votes,

reduction in polling time, resulting in fewer problems in electoral preparations, law and

order, candidates' expenditure, etc. and

easy and accurate counting without any mischief at the counting centre

Eco friendly.

As a matter of interest, Diebold Accuvote System, is a smarter system over conventional

EVMs used in India.

It is a new system of voting adopted by US government is DIEBOLD. Diebold systemworks on Microsoft software; it has no seals on locks and panels to detect a tempering. It has a

keyboard interface (!!!) and the server was tested to have Blaster virus. One report on Wired

says a lady stumbled upon some files from Diebold, and found that the votes were stored in MS

Access files. It also has a PCMCIA Scandisk card for local storage. A touch screen GUI and a

network connection to send the results to a server after encrypting it with DES.



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CHAPTER 2

WORKING OF EVM BALLOT UNIT

2.1 INTRODUCTION:-

The EVM consist of two units: ballot unit (BU) and control unit (CU). Following figure

shows the complete EVM system, including the constituents of both units as well as the signals

exchanged between them.

Figure 2.1 Block diagram of EVM



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2.2 BLOCK DIAGRAM OF BALLOT UNIT

Figure 2.2: Block diagram of ballot unit

2.3 WORKING OF EVM BALLOT UNIT SYSTEM:-

To start with EVM Ballot unit is divided into 2 main sub sections:-

1) Motherboard board circuit

2) Vote cast LED and feedback panel.



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Fig 2.3 Circuit diagram of Ballot Unit

Explanation of each unit:-

1) Motherboard circuit:----

Motherboard circuitry consists of following components. :------

a) Microcontroller

b) Crystal Oscillatorc) Opto coupler

d) Buzzer



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Fig 2.4 Mother Board Circuit

e) Amplifier

f) Resistor and a capacitor network for reset circuit of microcontroller.

2) Vote cast LED panel -

A vote cast LED panel is a section which will be at the voters end for the voters to cast their

votes. Here there are following components:-

a) 8 push to on switch

b) 8 Red LEDs

c) 8 green LEDs



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Additionally one more red LED and push to on switch has been added for a machine

ready signal. Ideally this push to on switch is at the control panel but since here we have only a

ballot unit therefore this button is mounted on this panel.

General working of the combined circuit:-

The switch combination of the circuit is like this.

Fig 2.5 EVM Front Panel

Now as we can see that the port is connected just after the LED and resistor network, so

ideally when a 5 volt supply is being given to resistor and LED ,at the port we get 0 potential.

now every time when we push the button ,the microcontroller should read the push sequence.

So a high bit is given at ports 21 to 28.so when the button is pressed the LED will glow and the

circuit will get a ground. As a result the bit at the port will also change from high to low and

thus the microcontroller will easily identify the push to button switch and can easily predict the

vote. Now when the microcontroller identified the push to button switch it sends a feedback

signal at ports 1 to 8(green LEDs) and the buzzer. Due to internal programming of the

microcontroller there is a continuous sounding of the buzzer as well as lighting of the green

LED.



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Working of Buzzer section

When the button is pressed at the vote cast LED panel. Then a high signal will flow at pin

no.16.This will initiate the opto coupler.

Fig 2.6 Working Principle of Opto-Coupler

As shown in the fig., when initiated the LED in the optocoupler will glow and then here

the photons will be initiated. The amplifier in the optocoupler will change +5 volt supply into

-5 volt supply. The output of the optocoupler will be connected to the base of the amplifier.

The amplifier emitter side will be connected to the +5 volt supply. So the emitter base

junction will be forward biased. Thereby amplifying current. The output from the collector side

will be connected to the positive section of the buzzer. So then the buzzer will beep.

Now as there is delay of two seconds in the internal programming of the microcontroller

therefore the buzzer will beep for two seconds specifying that the vote has been counted.

Working of vote signal switch



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27 }

To start with, here we will allot high signal to ports 2 and 3.The ports 2 and 3 are connected to

vote-cast push to on button section and opto-coupler section respectively. Then we will enter

into loops which will continuous in nature as depicted in line 10.Then the microcontroller

checks if the ready signal is high or not. If the signal is high then the program will be hung

itself up there but if the signal changes from high to low then the microcontroller will change

the LED pin status to low and then the LED will glow. Again when the microcontroller

traverses through line 14 it will check whether port 2 is high or not. If it is high then the

program will hung itself up there, but if it is low then it will turn the LED off by putting high at

LED pin. Again it will a lot low at buzzer pin so that the buzzer will buzz. After that delay loop

will start which will give a delay of 2 seconds.



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CHAPTER 3

BASIC COMPONENT

3.1 MICROCONTROLLER:-

3.1.1 INTRODUCTION

Circumstances that we find ourselves in today in the field of microcontrollers had their

beginnings in the development of technology of integrated circuits. This development has made

it possible to store hundreds of thousands of transistors into one chip. That was a prerequisitefor production of microprocessors, and the first computers were made by adding external

peripherals such as memory, input-output lines, timers and other. Further increasing of the

volume of the package resulted in creation of integrated circuits. These integrated circuits

contained both processor and peripherals. That is how the first chip containing a

microcomputer, or what would later be known as a microcontroller came about.

3.1.2 DEFINITION OF A MICROCONTROLLER

Microcontroller, as the name suggests, are small controllers. They are like single chip

computers that are often embedded into other systems to function as processing/controlling

unit. For example, the remote control you are using probably has microcontrollers inside that

do decoding and other controlling functions. They are also used in automobiles, washing

machines, microwave ovens, toys ... etc, where automation is needed.

The key features of microcontrollers include:

High Integration of Functionality

Microcontrollers sometimes are called single-chip computers because they have on-chip

memory and I/O circuitry and other circuitries that enable them to function as small

standalone computers without other supporting circuitry.

Field Programmability, Flexibility

Microcontrollers often use EEPROM or EPROM as their storage device to allow field

programmability so they are flexible to use. Once the program is tested to be correct



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then large quantities of microcontrollers can be programmed to be used in embedded

systems.

Easy to Use

Assembly language is often used in microcontrollers and since they usually

follow RISC architecture, the instruction set is small. The development package of

microcontrollers often includes an assembler, a simulator, a programmer to "burn" the

chip and a demonstration board. Some packages include a high level language compiler

such as a C compiler and more sophisticated libraries.

Most microcontrollers will also combine other devices such as:

A Timer module to allow the microcontroller to perform tasks for certain time periods.

A serial I/O port to allow data to flow between the microcontroller and other devices

such as a PC or another microcontroller.

An ADC to allow the microcontroller to accept analogue input data for processing.

Fig 3.1.1: Showing a typical microcontroller device and its different

subunits

The heart of the microcontroller is the CPU core. In the past this has traditionally been based

on an 8-bit microprocessor unit.



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3.1.3 PIN DIAGRAM OF MICROCONTROLLER 8952 :-

Fig 3.1.2 Pin Diagram of 8952 Microcontroller

3.1.4 PIN DESCRIPTION OF 8952 MICROCONTROLLER:-1.VCC :- Supply voltage.

2.GND :-Ground.

3.Port 0 :-Port 0 is an 8-bit open drain bi-directional I/O port. As an output port, each pin can

sink eight TTL inputs. When 1s are written to port 0 pins, the pins can be used as high

impedance inputs.Port 0 can also be configured to be the multiplexed loworder address/data

bus during accesses to external program and data memory. In this mode, P0 has internal

pullups. Port 0 also receives the code bytes during Flash programming and outputs the code

bytes during program verification. External pullups are required during program verification.



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4.Port 1 :-Port 1 is an 8-bit bi-directional I/O port with internal pullups. The Port 1 output

buffers can sink/source four TTL inputs. When 1s are written to Port 1 pins, they are pulled

high by the internal pullups and can be used as inputs. As inputs, Port 1 pins that are externally

being pulled low will source current (IIL) because of the internal pullups. In addition, P1.0 and

P1.1 can be configured to be the timer/counter 2 external count input (P1.0/T2) and the

timer/counter 2 trigger input (P1.1/T2EX), respectively, as shown in the following table. Port 1

also receives the low-order address bytes during Flash programming and verification.

5. Port 2 :-Port 2 is an 8-bit bi-directional I/O port with internal pullups. The Port 2 output



being pulled low will source current (IIL) because of the internal pullups. Port 2 emits the high-

order address byte during fetches from external program memory and during accesses to

external data memory that use 16-bit addresses (MOVX @ DPTR). In this application, Port 2

uses strong internal pull-ups when emitting 1s. During accesses to external data memory that

use 8-bit addresses (MOVX @ RI), Port 2 emits the contents of the P2 Special Function

Register. Port 2 also receives the high-order address bits and some control signals during Flash

programming and verification.

6. Port 3:- Port 3 is an 8-bit bi-directional I/O port with internal pullups. The Port 3 output



being pulled low will source current (IIL) because of the pullups. Port 3 also serves the

functions of various special features of the AT89C52. Port 3 also receives some control signals

for Flash programming and verification.

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

resets the device.

8. ALE/PROG:- Address Latch Enable is an output pulse for latching the low byte of the

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

during Flash programming. In normal operation, ALE is emitted at a constant rate of 1/6 the

oscillator frequency and may be used for external timing or clocking purposes. Note, however,

that one ALE pulse is skipped during each access to external data memory. If desired, ALE

operation can be disabled by setting bit 0 of SFR location 8EH. With the bit set, ALE is active

only during a MOVX or MOVC instruction. Otherwise, the pin is weakly pulled high. Setting

the ALE-disable bit has no effect if the microcontroller is in external execution mode.



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9.PSEN:-Program Store Enable is the read strobe to external program memory. When the

AT89C52 is executing code from external program memory, PSEN is activated twice each

machine cycle, except that two PSEN activations are skipped during each access to external

data memory.

10.EA/VPP:-External Access Enable. EA must be strapped to GND inorder to enable the

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

Note, however, that if lock bit 1 is programmed, EA will be internally latched on reset.

EA should be strapped to VCC for internal program executions. This pin also receives the 12-

volt programming enable voltage (VPP) during Flash programming when 12-volt programming

is selected.

11.XTAL1 :-Input to the inverting oscillator amplifier and input to the internal clock operating

circuit.

12.XTAL2: -Output from the inverting oscillator amplifier.

3.1.5 MEMORY UNIT

Memory is part of the microcontroller whose function is to store data.

The easiest way to explain it is to describe it as one big closet with lots of drawers. If we

suppose that we marked the drawers in such a way that they can not be confused, any of their

contents will then be easily accessible. It is enough to know the designation of the drawer and

so its contents will be known to us for sure.

Figure 3.1.3: Simplified model of a memory unit



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Memory components are exactly like that. For a certain input we get the contents of a certain

addressed memory location and that's all. Two new concepts are brought to us: addressing and

memory location. Memory consists of all memory locations, and addressing is nothing but

selecting one of them. This means that we need to select the desired memory location on one

hand, and on the other hand we need to wait for the contents of that location. Besides reading

from a memory location, memory must also provide for writing onto it. This is done by

supplying an additional line called control line. We will designate this line as R/W (read/write).

Control line is used in the following way: if r/w=1, reading is done, and if opposite is true then

writing is done on the memory location. Memory is the first element, and we need a

few operation of our microcontroller.

The amount of memory contained within a microcontroller varies between different

microcontrollers. Some may not even have any integrated memory (e.g. Hitachi 6503, now

discontinued). However, most modern microcontrollers will have integrated memory. The

memory will be divided up into ROM and RAM, with typically more ROM than RAM.

Typically, the amount of ROM type memory will vary between around 512 bytes and 4096

bytes, although some 16 bit microcontrollers such as the Hitachi H8/3048 can have as much as

128 Kbytes of ROM type memory.

ROM type memory, as has already been mentioned, is used to store the program code. ROM

memory can be ROM (as in One Time Programmable memory), EPROM, or EEPROM.

The amount of RAM memory is usually somewhat smaller, typically ranging between 25 bytes

to 4 Kbytes.

RAM is used for data storage and stack management tasks. It is also used for register stacks (as

in the microchip PIC range of microcontrollers).

3.1.6 CENTRAL PROCESSING UNIT

Let add 3 more memory locations to a specific block that will have a built in capability to

multiply, divide, subtract, and move its contents from one memory location onto another. The



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Fig 3.1.5: Showing connection between memory and central

unit using buses

As far as functionality, the situation has improved, but a new problem has also appeared: we

have a unit that's capable of working by itself, but which does not have any contact with the

outside world, or with us! In order to remove this deficiency, let's add a block which contains

several memory locations whose one end is connected to the data bus, and the other hasconnection with the output lines on the microcontroller which can be seen as pins on the

electronic component.

3.1.8 INPUT-OUTPUT UNIT

Those locations we've just added are called "ports". There are several types of ports: input,output or bidirectional ports. When working with ports, first of all it is necessary to choose

which port we need to work with, and then to send data to, or take it from the port.



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Figure 3.1.6: Simplified input-output unit communicating with

external world

When working with it the port acts like a memory location. Something is simply being written

into or read from it, and it could be noticed on the pins of the microcontroller.

3.2 VOLTAGE REGULATOR:-

Description :-The MC78XX/LM78XX/MC78XXA series of three terminal positive

regulators are available in the TO-220/D-PAK package and with several fixed output voltages,

making them useful in a wide range of applications. Each type employs internal current

limiting thermal shut down and safe operating area protection, making it essentially

indestructible. If adequate heat sinking

is provided, they can deliver over 1A output current Although designed primarily as fixed

voltage regulators, these devices can be used with external components to obtain adjustablevoltages and currents.

Features Output Current up to 1A

Output Voltages of 5, 6, 8, 9, 10, 12, 15, 18, 24V

Thermal Overload Protection

Short Circuit Protection

Output Transistor Safe Operating Area Protection



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3.3 LED:-

Fig 3.3.1 LED

3.3.1 INTRODUCTION

Alight-emitting diode(LED) is asemiconductorlight source. LEDs are used as indicator

lamps in many devices, and are increasingly used forlighting. Introduced as a practical

electronic component in 1962,early LEDs emitted low-intensity red light, but modern versions

are available across thevisible,ultravioletandinfraredwavelengths, with very high

brightness.

The LED is based on thesemiconductor diode. When a diode is forward biased (switched

on),electronsare able torecombinewithholeswithin the device, releasing energy in the form

ofphotons. This effect is called

electroluminescence

and the

color

of the light (corresponding

to the energy of the photon) is determined by theenergy gapof the semiconductor. An LED is

usually small in area (less than 1 mm2), and integrated optical components are used to shape its

radiation pattern and assist in reflection.

LEDs present manyadvantagesover incandescent light sources including lowerenergy

consumption, longerlifetime, improved robustness, smaller size, faster switching, and greater

durability and reliance. However, they are relatively expensive and require more

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precisecurrentandheat managementthan traditional light sources. Current LED products for

general lighting are more expensive to buy than fluorescent lamp sources of comparable output.

They also enjoy use in applications as diverse as replacements for traditional light sources in

automotive lighting(particularlyindicators) and intraffic signals. The compact size of LEDs

has allowed new text and video displays and sensors to be developed, while their high

switching rates are useful in advanced communications technology.

3.3.2 PRACTICAL USE:-

The first commercial LEDs were commonly used as replacements forincandescent indicators,

and in seven-segment displays, first in expensive equipment such as laboratory and electronics

test equipment, then later in such appliances as TVs, radios, telephones, calculators, and even

watches (see list ofsignal applications). These red LEDs were bright enough only for use as

indicators, as the light output was not enough to illuminate an area. Later, other colors became

widely available and also appeared in appliances and equipment. As the LED materials

technology became more advanced, the light output was increased, while maintaining the

efficiency and the reliability to an acceptable level. The invention and development of the high

power white light LED led to use for illumination (see list of illumination applications). Most

LEDs were made in the very common 5 mm T1 and 3 mm T1 packages, but with increasingpower output, it has become increasingly necessary to shed excess heat in order to maintain

reliability, so more complex packages have been adapted for efficient heat dissipation.

Packages for state-of-the-art high power LEDs bear little resemblance to early LEDs.

http://en.wikipedia.org/wiki/Constant_currenthttp://en.wikipedia.org/wiki/Thermal_management_of_high-power_LEDshttp://en.wikipedia.org/wiki/Automotive_lightinghttp://en.wikipedia.org/wiki/LED#Indicators_and_signshttp://en.wikipedia.org/wiki/Traffic_signalhttp://en.wikipedia.org/wiki/Incandescencehttp://en.wikipedia.org/wiki/Seven-segment_displayhttp://en.wikipedia.org/wiki/Led#Indicators_and_signshttp://en.wikipedia.org/wiki/Led#Lightinghttp://en.wikipedia.org/wiki/Led#High_power_LEDshttp://en.wikipedia.org/wiki/File:LED,_5mm,_green_(en).svghttp://en.wikipedia.org/wiki/Constant_currenthttp://en.wikipedia.org/wiki/Thermal_management_of_high-power_LEDshttp://en.wikipedia.org/wiki/Automotive_lightinghttp://en.wikipedia.org/wiki/LED#Indicators_and_signshttp://en.wikipedia.org/wiki/Traffic_signalhttp://en.wikipedia.org/wiki/Incandescencehttp://en.wikipedia.org/wiki/Seven-segment_displayhttp://en.wikipedia.org/wiki/Led#Indicators_and_signshttp://en.wikipedia.org/wiki/Led#Lightinghttp://en.wikipedia.org/wiki/Led#High_power_LEDs


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Fig 3.3.2Parts of an LED

Fig 3.3.3 The inner workings of an LED

Fig 3.3.4 LED CHARACTERISTICS

3.3.3 COLOURS & MATERIALS:-

Conventional LEDs are made from a variety of inorganic semiconductor materials, the

following table shows the available colors with wavelength range, voltage drop and material:

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Colour Wavelength (nm) Voltage (V) Semiconductor Material

Red 610 < < 7601.63 < V


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Table 3.1 Led Colour S Materials

3.3.4 TYPES :-

Fig 3.3.5 Types of LED

LEDs are produced in a variety of shapes and sizes. The 5 mm cylindrical package (red, fifth

from the left) is the most common, estimated at 80% of world production. The color of the

plastic lens is often the same as the actual color of light emitted, but not always. For instance,

purple plastic is often used forinfrared LEDs, and most blue devices have clear housings.

There are also LEDs in SMT packages, such as those found onblinkiesand on cell phone

keypads

The main types of LEDs are miniature, high power devices and custom designs such as

alphanumeric or multi-color.

http://en.wikipedia.org/wiki/Infraredhttp://en.wikipedia.org/wiki/Surface-mount_technologyhttp://en.wikipedia.org/wiki/Blinky_(novelty)http://en.wikipedia.org/wiki/File:Verschiedene_LEDs.jpghttp://en.wikipedia.org/wiki/Infraredhttp://en.wikipedia.org/wiki/Surface-mount_technologyhttp://en.wikipedia.org/wiki/Blinky_(novelty)


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3.3.5 ELECTRICAL POLARITY :-

As with all diodes, current flows easily from p-type to n-type material. However, no current

flows and no light is produced if a small voltage is applied in the reverse direction. If the

reverse voltage becomes large enough to exceed thebreakdown voltage, a large current flows

and the LED may be damaged. If the reverse current is sufficiently limited to avoid damage, the

reverse-conducting LED is a useful noise diode.

3.3.6 ADVANTAGES :-

Efficiency: LEDs produce more light per watt than incandescent bulbs.

Color: LEDs can emit light of an intended color without the use of color filters that

traditional lighting methods require. This is more efficient and can lower initial costs.

Size: LEDs can be very small (smaller than 2 mm2) and are easily populated onto

printed circuit boards.

On/Off time: LEDs light up very quickly. A typical red indicator LED will achieve fullbrightness in microseconds. LEDs used in communications devices can have even faster

response times.

Cycling: LEDs are ideal for use in applications that are subject to frequent on-off

cycling, unlike fluorescent lamps that burn out more quickly when cycled frequently,

orHID lamps that require a long time before restarting.

Dimming: LEDs can very easily be dimmed either by Pulse-width modulation or

lowering the forward current. Cool light: In contrast to most light sources, LEDs radiate very little heat in the form

ofIRthat can cause damage to sensitive objects or fabrics. Wasted energy is dispersed as

heat through the base of the LED.

Slow failure: LEDs mostly fail by dimming over time, rather than the abrupt burn-out

of incandescent bulbs.

Lifetime: LEDs can have a relatively long useful life. One report estimates 35,000 to

50,000 hours of useful life, though time to complete failure may be longer. Fluorescent

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tubes typically are rated at about 10,000 to 15,000 hours, depending partly on the

conditions of use, and incandescent light bulbs at 1,0002,000 hours.

Shock resistance: LEDs, being solid state components, are difficult to damage with

external shock, unlike fluorescent and incandescent bulbs which are fragile. Focus: The solid package of the LED can be designed to focus its light. Incandescent

and fluorescent sources often require an external reflector to collect light and direct it in a

usable manner.

Toxicity: LEDs do not contain mercury, unlike fluorescent lamps.

Disadvantages

High initial price: LEDs are currently more expensive, price per lumen, on an initial

capital cost basis, than most conventional lighting technologies. The additional expense

partially stems from the relatively low lumen output and the drive circuitry and power

supplies needed.

Temperature dependence: LED performance largely depends on the ambient

temperature of the operating environment. Over-driving the LED in high ambient

temperatures may result in overheating of the LED package, eventually leading to device

failure. Adequate heat-sinkingis required to maintain long life. This is especially importantwhen considering automotive, medical, and military applications where the device must

operate over a large range of temperatures, and is required to have a low failure rate.

Voltage sensitivity: LEDs must be supplied with the voltage above the threshold and a

current below the rating. This can involve series resistors or current-regulated power

supplies.

Light quality: Most cool-white LEDs have spectra that differ significantly from

ablack body radiator like the sun or an incandescent light. The spike at 460 nm and dip at500 nm can cause the color of objects to beperceived differently under cool-white LED

illumination than sunlight or incandescent sources, due to metamerism, red surfaces being

rendered particularly badly by typical phosphor based cool-white LEDs. However, the

color rendering properties of common fluorescent lamps are often inferior to what is now

available in state-of-art white LEDs.

Area light source: LEDs do not approximate a point source of light, but rather

a lambertian distribution. So LEDs are difficult to use in applications requiring a spherical

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frequencies forradio transmitters and receivers. The most common type of piezoelectric

resonator used is the quartz crystal, so oscillator circuits designed around them were called

"crystal oscillators".

Quartz crystals are manufactured for frequencies from a few tens ofkilohertz to tens ofmegahertz. More than two billion (2109) crystals are manufactured annually. Most are small

devices for consumer devices such as wristwatches, clocks, radios,computers, and cellphones.

Quartz crystals are also found inside test and measurement equipment, such as counters, signal

generators, and oscilloscopes.

3.4.1 OPERATION:-

A crystal is a solid in which the constituent atoms, molecules, orions are packed in a regularly

ordered, repeating pattern extending in all three spatial dimensions.

Almost any object made of an elastic material could be used like a crystal, with appropriate

transducers, since all objects have natural resonant frequencies of vibration. For

example, steel is very elastic and has a high speed of sound. It was often used in mechanical

filters before quartz. The resonant frequency depends on size, shape, elasticity, and the speed of

sound in the material. High-frequency crystals are typically cut in the shape of a simple,

rectangular plate. Low-frequency crystals, such as those used in digital watches, are typicallycut in the shape of a tuning fork. For applications not needing very precise timing, a low-

cost ceramic resonatoris often used in place of a quartz crystal.

When a crystal ofquartz is properly cut and mounted, it can be made to distort in an electric

field by applying a voltage to an electrode near or on the crystal. This property is known

aspiezoelectricity. When the field is removed, the quartz will generate an electric field as it

returns to its previous shape, and this can generate a voltage. The result is that a quartz crystal

behaves like a circuit composed of an inductor, capacitor and resistor, with a precise resonantfrequency.

Quartz has the further advantage that its elastic constants and its size change in such a way that

the frequency dependence on temperature can be very low. The specific characteristics will

depend on the mode of vibration and the angle at which the quartz is cut (relative to its

crystallographic axes). Therefore, the resonant frequency of the plate, which depends on its

size, will not change much, either. This means that a quartz clock, filter or oscillator will

remain accurate. For critical applications the quartz oscillator is mounted in a temperature-

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controlled container, called a crystal oven, and can also be mounted on shock absorbers to

prevent perturbation by external mechanical vibrations.

3.4.2 MODELING:-

Electrical model

Fig 3.4.2 Electronic symbol for a piezoelectric crystal resonator

Fig 3.4.3 Schematic symbol and equivalent circuit for a quartz

crystal in an oscillator

3.5 TRANSISTORS:-

3.5.1 INTRODUCTION:-

In electronics, a transistor is a semiconductor device commonly used to

amplify or switch electronic signals. A transistor is made of a solid piece of a semiconductor

material, with at least three terminals for connection to an external circuit. A voltage or currentapplied to one pair of the transistors terminals changes the current flowing through another

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pair of terminals. Because the controlled (output) power can be much larger than the

controlling (input) power, the transistor provides amplification of a signal. The transistor is the

fundamental building block of modern electronic devices, and is used in radio, telephone,

computerand other electronic systems. Some transistors are packaged individually but most are

found in integrated circuits.

3.5.2 TYPES:-

The bipolar

junction

transistor

(BJT) was

the first type of transistor to be mass-produced. Bipolar transistors are so named because they

conduct by using both majority and minority carriers. The three terminals of the BJT are namedemitter, base and collector. Two p-n junctions exist inside a BJT: the base/emitter junction and

base/collector junction. "The [BJT] is useful in amplifiers because the currents at the emitter

and collector are controllable by the relatively small base current."In an NPN transistor

operating in the active region, the emitter-base junction is forward biased, and electrons are

injected into the base region. Because the base is narrow, most of these electrons will diffuse

into the reverse-biased base-collector junction and be swept into the collector; perhaps one-

hundredth of the electrons will recombine in the base, which is the dominant mechanism in the

base current. By controlling the number of electrons that can leave the base, the number of

electrons entering the collector can be controlled.


BJT

PNP NPN

Fig 3.5.1 Types of

transistor
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+ -

Fig 3.7.1 Symbol of Capacitor

Capacitors are like electron storage banks. If your circuit is running low, it will deliver

electrons to your circuit.

In our water analogy, think of this as a water tank with water always flowing in, but with

drainage valves opening and closing. Since capacitors take time to charge, and time to

discharge, they can also be used for timing circuits. Timing circuits can be used to generate

signals such as PWM or be used to turn on/off motors in solar powered BEAM robots.

Quick note, some capacitors are polarized, meaning current can only flow one direction

through them. If a capacitor has a lead that is longer than the other, assume the longer lead

must always connect to positive.

3.7.1 ELECTROLYTIC CAPACITOR:-

Fig 3.7.2 Electrolyte Capacitor

An electrolytic capacitor is a type ofcapacitorthat uses an ionic conducting liquid as one of its

plates. Typically with a larger capacitance per unit volume than other types, they are valuable

in relatively high-current and low-frequency electrical circuits. This is especially the case in

power-supply filters, where they store charge needed to moderate output voltage and current

fluctuations, in rectifieroutput. They are also widely used as coupling capacitors in circuits

where AC should be conducted but DC should not.

3.8 BUZZER :-

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Fig 3.8.1 Buzzer

A Buzzer or Beeper is a signaling device, usually electronic, typically used in automobiles,

household appliances such as microwave ovens, orgame shows.

It most commonly consists of a number ofswitches orsensors connected to a control unit that

determines if and which button was pushed or a preset time has lapsed, and usually illuminates

a light on the appropriate button or control panel, and sounds a warning in the form of a

continuous or intermittent buzzing or beeping sound.

Initially this device was based on an electromechanical system which was identical to

an electric bell without the metal gong (which makes the ringing noise). Often these units were

anchored to a wall or ceiling and used the ceiling or wall as a sounding board. Another

implementation with some AC-connected devices was to implement a circuit to make the AC

current into a noise loud enough to drive a loudspeaker and hook this circuit up to an 8-ohm

speaker. Nowadays, it is more popular to use a ceramic-basedpiezoelectric sounder which

makes a high-pitched tone. Usually these were hooked up to "driver" circuits which varied the

pitch of the sound or pulsed the sound on and off.

In game shows it is also known as a "lockout system" because when one person signals

("buzzes in"), all others are locked out from signalling. Several game shows have large buzzerbuttons which are identified as "plungers". The buzzer is also used to signal wrong answers and

when time expires on many game shows, such as Wheel of Fortune,Family Feud and The Price

is Right.

The word "buzzer" comes from the rasping noise that buzzers made when they were

electromechanical devices, operated from stepped-down AC line voltage at 50 or 60 cycles.

Other sounds commonly used to indicate that a button has been pressed are a ring or a beep.

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3.9 OPTO-COUPLER :-

3.9.1 INTRODUCTION:-

In electronics, an opto-isolator (or optical isolator, optical coupling

device, optocoupler,photocoupler, or photoMOS) is a device that uses a

short optical transmission path to transfer an electronic signal between elements of a circuit,

typically a transmitterand a receiver, while keeping them electrically isolatedsince the

electrical signal is converted to a light beam, transferred, then converted back to an electrical

signal, there is no need for electrical connection between the source and destination circuits.

Isolation between input and output is rated at 7500 Volt peak for 1 second for a typical

component costing less than 1 US$ in small quantities.

The opto-isolator is simply a package that contains both an infrared light-emitting diode (LED)

and a photo-detector such as a photosensitive silicon diode, transistor Darlington pair, orsilicon

controlled rectifier(SCR). The wave-length responses of the two devices are tailored to be as

identical as possible to permit the highest measure of coupling possible. Other circuitryfor

example an output amplifiermay be integrated into the package. An opto-isolator is usually

thought of as a single integrated package, but opto-isolation can also be achieved by using

separate devices.

Digital opto-isolators change the state of their output when the input state

changes; analog isolators produce an analog signal which reproduces the input.

3.9.2 CONFIGURATIONS :-

Fig 3.9.1 Schematic diagram of a very simple opto-isolator with anLED and phototransistor.

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3.10 PUSH TO ON SWITCH :-



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Fig 3.10.1 Push to on switch

A Push Switch or Push to make switch, allows electricity to flow between its two contacts

when held in. When the button is released, the circuit is broken. So it is called a non- latching

switch.

Other forms are push to break which, does the opposite. I.e when the button is not pressed,

electricity can flow, but when it is pressed the circuit is broken.

CHAPTER 4

PRINTED CIRCUIT BOARD

4.1 PRINTED CIRCUIT BOARDS

The use of miniaturization and sub miniaturization in electronic equipment design has been

responsible for the introduction of a new technique in inters component wiring and assembly

that is popularly known as printed circuit.

The printed circuit boards (PCBs) consist of an insulating substrate material with metallic

circuitry photo chemically formed upon that substrate. Thus PCB provides sufficient

mechanical support and necessary electrical connections for an electronic circuit.

Advantages of printed circuit boards: -

1) Circuit characteristics can be maintained without introducing variations inter

circuit capacitance.

2) Wave soldering or vapour phase reflow soldering can mechanize component

wiring and assembly.

3) Mass production can be achieved at lower cost.

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4) The size of component assembly can be reduced with corresponding

decrease in weight.

5) Inspection time is reduced as probability of error is eliminated.

4.2 TYPES OF PCBS: -

There are four major types of PCBs: -

1) Single sided PCB: - In this, copper tracks are on one side of the board, and are the

simplest form of PCB. These are simplest to manufacture thus have low production

cost.

2) Double sided PCB:- In this, copper tracks are provided on both sides of the substrate.

To achieve the connections between the boards, hole plating is done, which increase the

manufacturing complexity.

3) Multilayered PCB: - In this, two or more pieces of dielectric substrate material with

circuitry formed upon them are stacked up and bonded together. Electrically

connections are established from one side to the other and to the layer circuitry by

drilled holes, which are subsequently plated through copper.

4) Flexible PCB: - Flexible circuit is basically a highly flexible variant of the conventional

rigid printed circuit board theme.

4.3 PCB MANUFACTURING PROCESS: -

There are a number of different processes, which are used to

manufacture a PCB, which is ready for component assembly, from a copper clad base material.

These processes are as follows

4.3.1 PRE PROCESSING: - This consists of initial preparation of a copper clad laminate

ready for subsequent processing. Next is to drill tooling holes. Passing a board through rollers

performs cleaning operation.

4.3.2 PHOTOLITHOGRAPHY: This process for PCBs involves the exposure of a photo

resist material to light through a mask. This is used for defining copper track and land patterns.

4.3.3. ETCHING: -The etching process is performed by exposing the surface of the board to

an etchant solution which dissolves away the exposed copper areas .The different solutions

used are: FeCl, CuCl, etc.

4.3.4 DRILLING: Drilling is used to create the component lead holes and through holes in aPCB .The drilling can be done before or after the track areas have been defined.



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4.3.5 SOLDER MASKING: - It is the process of applying organic coatings selectively to

those areas where no solder wettings is needed .The solder mask is applied by screen-printing.

4.3.6 PRE METAL PLATING :The plating is done to ensure protection of the copper tracks

and establish connection between different layers of multiplayer boards. PCBs are stacked

before being taken for final assembly of components .The PCB should retain its solder ability.

4.3.7 BARE BOARD TESTING: - Each board needs to ensure that the required connections

exist, that there are no short circuits and holes are properly placed .The testing usually consists

of visual inspection and continuity testing.

4.4 PCB LAYOUT OF BALLOT UNIT:-

Fig 4.1 PCB Lay Out Of Mother Board Circuit



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Fig 4.2 PCB Lay Out of EVM Front Panel

CHAPTER

5

MICROCONTROLLER PROGRAMMING

C LANGUAGE CODE :-

#includevoid delay (unsigned int);sbit ready = P3^5;sbit buzzer = P3^6;sbit LED = P3^7;

void main (void){P2=0xFF;P3=0xFF;while(1){

while(ready==1);LED=0;while (P2==0xFF);LED=1;

buzzer=0;

P1=P2;delay(2000);



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P1=P2=P3=0xFF;}}void delay (unsigned int time){

unsigned int i,j;for (i=1;i


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FUTURE

SCOPE

Number of candidates could be increased by using other microcontroller or an 8255 IC.

It could be interfaced with printer to get the hard copy of the result almost instantly from

the machine itself.

It could also be interfaced with the personal computer and result could be stored in the

central server and its backup could be taken on the other backend servers.

Again, once the result is on the server it could be relayed on the network to various

offices of the election conducting authority. Thus our project could make the result available

any corner of the world in a matter of seconds

In days of using nonpolluting and environment friendly resources of energy,it could pose

a very good example.



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DATA SHEET OF TRANSISTOR BC 557:-



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project report 000000

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