41Finger Print Based ATM and Locker System

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FINGER PRINT BASED ATM AND LOCKER SYSTEM FOR MODERN SECURED BANKS


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CONTENTS

NAME OF THE CHAPTER PAGE No.

1. Abbreviations 3

2. Abstract 4

3. Introduction 5

a. Biometric

i. What is Biometrics?

5

ii. Why go for Biometrics

6

iii. Why finger Print Biometric

8

iv. FP Patterns

9

4. Block Diagram

11

5. Block Diagram Explanation 12

6. Schematic

15


2






7. Schematic Explanation

16

8. Hardware Components

19

a. Microcontroller

19

b. FP scanner

42

c. MAX-232

46

d. EEPROM

51

e. Power Supply

59

f. LCD

74

g. Buzzer

77

h. Keypad

79

i. Locker system

83

i. DC motors

83


3






ii. H-Bridge

87

9. Circuit description 92

10. Software Concepts 94

a. KEIL IDE

94

b. EXPRESS SCH

105

c. Embedded C

106

11. Result 108

12. Future Scope 109

13. Conclusion 110

14. Bibliography 111


4






ABBREVIATIONS


5







SYMBOL NAME

ACC Accumulator

B B register

PSW Program status word

SP Stack pointer

DPTR Data pointer 2 bytes

DPL Low byte

DPH High byte

P0 Port0

P1 Port1

P2 Port2

P3 Port3

IP Interrupt priority control

IE Interrupt enable control

TMOD Timer/counter mode control

TCON Timer/counter control

T2CON Timer/counter 2 control

T2MOD Timer/counter mode2 control

TH0 Timer/counter 0high byte

TL0 Timer/counter 0 low byte

TH1 Timer/counter 1 high byte


TH2 Timer/counter 2 high byte


SCON Serial control

SBUF Serial data buffer

PCON Power control

RPS Regulated Power Supply

FP Finger Print

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INTRODUCTION

An embedded system is a special-purpose system in which the computer is

completely encapsulated by or dedicated to the device or system it controls. Unlike a

general-purpose computer, such as a personal computer, an embedded system

performs one or a few pre-defined tasks, usually with very specific requirements.

Since the system is dedicated to specific tasks, design engineers can optimize it,

reducing the size and cost of the product. Embedded systems are often mass-

produced, benefiting from economies of scale.

Biometrics:

What is Biometrics?

The study of automated identification, by use of physical or behavioral

traits.

Physical vs. Behavioral:

• Physical

– Fingerprint

– Iris

– Ear

– Face

– Retina

– Hands

• Behavioral

– Signature

– Walking gait


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http://en.wikipedia.org/wiki/Economies_of_scale

http://en.wikipedia.org/wiki/Personal_computer

http://en.wikipedia.org/wiki/Computer


– Typing patterns

• Both

– Voice

Why go for Biometrics?

Authentication – the process of verifying that a user requesting a

network resource is who he, she, or it claims to be, and vice versa.

Conventional authentication methods

something that you have – key, magnetic card or smartcard

something that you know – PIN or password

Biometric authentication uses personal features

something that you are

Advantages:

Biometrics has no risk of

Forgetting it

Loosing it

Getting it stolen

Getting it copied

Being used by anyone else.

Essential Properties of a Biometric

• Universal


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– Everyone should have the characteristic

• Uniqueness

– No two persons have the same characteristic

• Permanence

– Characteristic should be unchangeable

• Collectability

– Characteristic must be measurable

Biometric System Process Flow

Pattern Recognition


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• Description and classification of measurements taken from

physical or mental processes

• Examination of pattern characteristics

• Formulation of the recognition system

• Important part of any biometric system

Why Fingerprint biometry?

High Universality

A majority of the population (>96%) have legible

fingerprints

More than the number of people who possess passports,

license and IDs

High Distinctiveness

Even identical twins have different fingerprints (most

biometrics fail)

Individuality of fingerprints established through empirical

evidence

High Permanence

Fingerprints are formed in the fetal stage and remain

structurally unchanged through out life.

High Performance

One of the most accurate forms of biometrics available

Best trade off between convenience and security

High Acceptability

Fingerprint acquisition is non intrusive. Requires no training.

Advantages:


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• Uniqueness

• Surety over the Cards and Keypads

• Against to Cards Duplication, misplacement and

improper disclosure of password

• No excuses for RF/Magnetic Cards forget ness

• No need to further invest on the Cards Cost

• No need to further manage the Cards Writing Devices

Fingerprint Patterns

• Loops

– Ridge lines enter from one side and curve around to exit

from the same side

– 60-65% of population

• Whorls

– Rounded or circular ridge pattern

– 30-35% of population

• Arches

– Ridge lines enter from one side of print and exit out the other

– 5% of population


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12






BLOCK DIAGRAM:


Micro controller

LCD DisplayPower supply

FingerPrint

Module

MAX232

Key pad

EEPROM

BANK LOCKER

BUZZER

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BLOCK DIAGRAM EXPLANATION:

POWER SUPPLY

A variable regulated power supply, also called a variable bench power supply, is

one where you can continuously adjust the output voltage to your requirements.

Varying the output of the power supply is the recommended way to test a project after

having double checked parts placement against circuit drawings and the parts

placement guide. This type of regulation is ideal for having a simple variable bench

power supply. Actually this is quite important because one of the first projects a

hobbyist should undertake is the construction of a variable regulated power supply.

While a dedicated supply is quite handy e.g. 5V or 12V, it's much handier to have a

variable supply on hand, especially for testing. Most digital logic circuits and

processors need a 5 volt power supply. To use these parts we need to build a regulated

5 volt source. Usually you start with an unregulated power supply ranging from 9

volts to 24 volts DC (A 12 volt power supply is included with the Beginner Kit and

the Microcontroller Beginner Kit.). To make a 5 volt power supply, we use a LM7805

voltage regulator IC.

The LM7805 is simple to use. You simply connect the positive lead of your

unregulated DC power supply (anything from 9VDC to 24VDC) to the Input pin,

connect the negative lead to the Common pin and then when you turn on the power,

you get a 5 volt supply from the Output pin.

Finger Print Scanner:

A fingerprint sensor is an electronic device used to capture a digital image of

the fingerprint pattern. The captured image is called a live scan. This live scan is


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http://en.wikipedia.org/wiki/Digital_image

http://en.wikipedia.org/wiki/Electronics

http://en.wikipedia.org/wiki/Sensor

http://www.iguanalabs.com/mbkit.htm

http://www.iguanalabs.com/1stled.htm


digitally processed to create a biometric template (a collection of extracted features)

which is stored and used for matching.

It supports wide range of fingerprint sensor interoperability giving you a

freedom to select suitable sensor that most fits to your application. Furthermore, the

fingerprint data for enrollment and verification are compatible among different

sensors, even if they are based on different technologies. This feature of unification

presents application manufacturers and system integrators with much more flexibility

than ever before.

MAX- 232

To allow compatibility among data communication equipment made by various

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

Industries Association (EIA).This RS-232 standard is used in PCs and numerous types

of equipment .However, since the standard was set long before the advent of the TTL

logic family, its input and output voltage levels are not TTL compatible. In RS-232 ,a

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

For this reason, to connect any RS-232 to a microcontroller system we must use

voltage converters such as MAX232 to convert the TTL logic levels to the RS-232

voltage levels and vice versa.

So here we are using this MAX-232 to have compatibility between the Finger Print

Scanner and microcontroller.

Microcontroller:

A Micro controller consists of a powerful CPU tightly coupled with memory

RAM, ROM or EPROM), various I / O features such as Serial ports, Parallel Ports,

Timer/Counters, Interrupt Controller, Data Acquisition interfaces-Analog to Digital

Converter (ADC), Digital to Analog Converter (ADC), everything integrated onto a

single Silicon Chip.


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http://en.wikipedia.org/wiki/Feature_extraction

http://en.wikipedia.org/wiki/Digital_signal_processing


It does not mean that any micro controller should have all the above said

features on chip, Depending on the need and area of application for which it is

designed, The ON-CHIP features present in it may or may not include all the

individual section said above.

Any microcomputer system requires memory to store a sequence of

instructions making up a program, parallel port or serial port for communicating with

an external system, timer / counter for control purposes like generating time delays,

Baud rate for the serial port, apart from the controlling unit called the Central

Processing Unit

KEYPAD:

In this project we are using two types of keypads, one is the matrix keypad and the

other is the normal key for selecting the mode of operation.

Here we are doing all the transactions regarding bank like deposit, withdraw, etc. for

this transactions and for entering the password we are using the 4X4 Matrix keypad.

Using the normal keypad we are going to select the mode which we are going to

perform.

LCD:

This is the widely used output device to indicate the status. Here the transaction

details are clearly displayed on the LCD.

Buzzer:

This is the output device which we are using to indicate the unauthorized person.

LOCKER SYSTEM:


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Here we are demonstrating a DC motor as the Locker for the authorized persons in

the Locker system mode.

EEPROM:

This is the additional memory which we are using for the storage of the data for a

particular person.

SCHEMATIC:


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Schematic Explanation:

This schematic explanation includes the detailed pin connections of every

device with the microcontroller.

Let us see the pin connections of each and every device with the

microcontroller in detail.

Power Supply:

The main aim of this power supply is to convert the 230V AC into 5V DC in order to

give supply for the TTL or CMOS devices.

In this process we are using a step down transformer, a bridge rectifier, a smoothing

circuit and the RPS.

Transformer:

At the primary of the transformer we are giving the 230V AC supply. The

secondary is connected to the opposite terminals of the Bridge rectifier as the input.

From other set of opposite terminals we are taking the output to the rectifier.

The bridge rectifier converts the AC coming from the secondary of the

transformer into pulsating DC. The output of this rectifier is further given to the

smoother circuit which is capacitor in our project.

The smoothing circuit eliminates the ripples from the pulsating DC and gives

the pure DC to the RPS to get a constant DC voltage.

The RPS regulates the voltage as per our requirement.

LCD module:

This module is used to display the status of voter and the competitor.

This module consists of 8 data lines D0 – D7, which are connected to the 8 pins of

port0 (P0).


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Additionally this module is having 3 control lines namely RS, RW and EN, which are

connected to the port2 higher pins P2.7, P2.6 and P2.5 respectively.

And the supply connections are given from the Power supply output 7805 to the VCC

and VSS pins of the LCD.

Finger Print Scanner:

The finger print scanner which we are using in this project supports the RS-232

standard voltage levels where as our microcontroller supports TTL logic levels. To

interface this finger print scanner with the microcontroller we require a level

converter which is MAX-232 here.

MAX-232:

The connections from finger print scanner are:

The transmission line is connected to RS-232 input section and the receiver line is

connected to the RS-232 output section on the MAX-232 IC to convert these voltage

levels into TTL standards. And the concerned TTL logic levels are connected to the

microcontroller TXD and the RXD lines.

Scan key:

To enable the microcontroller to read the finger print present at the scanner we are

using a scan key. After placing the finger on the scanner press this scan key to follow

the further process.

Mode Keys:

The mode keys concerned to different modes are connected as:

Locker key is connected to P3.4

Passport verification key is connected to P3.5 and

The ATM mode key is connected to P3.6.

KEYPAD:


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The connections regarding this Keypad are given to Port1 entirely because it is a 4 X

4 matrix keypad.

Locker system:

The locker system which is a motor here is connected to P2.2 and P2.3 through H-

Bridge, which is used to rotate the motor in bi-direction.

EEPROM:

The data pin and the clock pin of this PROM SDA and SCL are connected to P2.0 and

P2.1 respectively.

Buzzer:

Here the buzzer is connected to P3.3 to indicate the wrong transaction or the wrong

passport.


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HARDWARE COMPONENTS

1. Microcontroller

2. Finger print scanner

3. MAX-232

4. EEPROM

5. Power supply

6. LCD module

7. Buzzer

8. Matrix Keypad

9. Locker system

Microcontroller:

INTRODUCTION:


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A Micro controller consists of a powerful CPU tightly coupled with memory

RAM, ROM or EPROM), various I / O features such as Serial ports, Parallel Ports,

Timer/Counters, Interrupt Controller, Data Acquisition interfaces-Analog to Digital

Converter (ADC), Digital to Analog Converter (ADC), everything integrated onto a

single Silicon Chip.

It does not mean that any micro controller should have all the above said

features on chip, Depending on the need and area of application for which it is

designed, The ON-CHIP features present in it may or may not include all the

individual section said above.

Any microcomputer system requires memory to store a sequence of

instructions making up a program, parallel port or serial port for communicating with

an external system, timer / counter for control purposes like generating time delays,

Baud rate for the serial port, apart from the controlling unit called the Central

Processing Unit

INTRODUCTION TO 8051MICROCONTROLLER

In 1981,Intel corporation introduced an 8 bit microcontroller called the 8051.This

microcontroller had 128 bytes of RAM,4K bytes of on-chip ROM, two timers, one

serial port, and 4 ports(each 8-bits wide)all on single chip. At that time it was also

referred to as a “system on a chip”.

The 8051 is an 8-bit processor, meaning that the CPU can

work on only 8-bits of data at a time. Data larger than 8-bits has to be broken into 8-

bit pieces to be processed by the CPU. The 8051 can have a maximum of 64K bytes

of ROM; many manufacturers have put only 4Kbytes on chip.

INTRODUCTION TO ATMEL MICROCONTROLLER

SERIES: 89C51 Family, TECHNOLOGY: CMOS


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The major Features of 8-bit Micro controller ATMEL 89C51:

8 Bit CPU optimized for control applications

Extensive Boolean processing (Single - bit Logic) Capabilities.

On - Chip Flash Program Memory

On - Chip Data RAM

Bi-directional and Individually Addressable I/O Lines

Multiple 16-Bit Timer/Counters

Full Duplex UART

Multiple Source / Vector / Priority Interrupt Structure

On - Chip Oscillator and Clock circuitry.

On - Chip EEPROM

Figure.1 Block Diagram


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COUNTERINPUTS

EXTERNALINTERRUPT

S

INTERRUPTCONTROL

ON-CHIPFLASH ON-CHIP

RAM

TIMER 1

TIMER 0

CPU

OSC BUSCONTROL

4 I/O PORTS

SERILPORT






Fig.1: Oscillator Connection.

The P89C51 provides the following standard features: 4K bytes of Flash, 128

bytes of RAM, 32 I/O lines, two 16-bit timer/counters, five vector two-level interrupt

architecture, a full duplex serial port, and on-chip oscillator and clock circuitry. In

addition, the P89C51 is designed with static logic for operation down to zero

frequency and supports two software selectable power saving modes. The Idle Mode

stops the CPU while allowing the RAM, timer/counters, serial port and interrupt

system to continue functioning. The Power-down Mode saves the RAM contents but

freezes the oscillator disabling all other chip functions until the next hardware reset.


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PO P2 P1 P3 TXD RXD






Memory Organization

Fig.3 Memory Structure of the 8051.


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External

EA = 0

External

EA = 1

External

FFFFH

0000

INTERNAL

FF

00

EXTERNAL

FFFFH

PROGRAM MEMORYDATA MEMORY

RD WRPSEN






Memory Organization

Program Memory

Figure 4 shows a map of the lower part of the program memory. After

reset, the CPU begins execution from location 0000H. As shown in fig.4, each

interrupt is assigned a fixed location in program memory. The interrupt causes the

CPU to jump to that location, where it executes the service routine. External Interrupt

0, for example, is assigned to location 0003H. If External Interrupt 0 is used, its

service routine must begin at location 0003H. If the interrupt is not used, its service

location is available as general purpose.


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Fig. 4 Program Memory.

Program memory addresses are always 16 bits wide, even though the actual amount o

program memory used may be less than 64Kbytes. External program execution

sacrifices two of the 8-bit ports, P0 and P2, to the function of addressing the program

memory.

Data Memory

The right half of Figure 3 shows the internal and external data memory spaces

available on Philips Flash microcontrollers. Fig.6 shows a hardware configuration for

accessing up to 2K bytes of external RAM. In this case, the CPU executes from

internal flash. Port0 serves as a multiplexed address/data bus to the RAM, and 3 lines

of Port 2 are used to page the RAM. The CPU generates RD and WR signals as

needed during external RAM accesses. You can assign up to 64K bytes of external www.1000projects.comwww.fullinterview.comwww.chetanasprojects.com

(0033)H

002BH

0023H

001BH

0013H

000BH

0003H

0000H

8 bytesINTERRUPT LOCATIONS

RESET

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data memory. External data memory addresses can be either 1 or 2bytes wide. One-

byte addresses are often used in conjunction with one or more other I/O lines to page

the RAM, as shown in Fig.6. Two-byte addresses can also be used, in which case the

high address byte is emitted at Port2.

Internal data memory addresses are always 1 byte wide, which implies an

address space of only 256bytes. However, the addressing modes for internal RAM can

infact accommodate 384 bytes. Direct addresses higher than 7FH access one memory

space and indirect addresses higher than 7FH access a different memory space. Thus,

Figure.7 shows the Upper 128 and SFR space occupying the same block of addresses,

80H through FFH, although they are physically separate entities. Figure.8 shows how

the lower 128 bytes of RAM are mapped. The lowest 32 bytes are grouped into 4

banks of 8 registers. Program instructions call out these registers as R0 through R7.

Two bits in the Program Status Word (PSW) select which register bank is in use. This

architecture allows more efficient use of code space, since register instructions are

shorter than instructions that use direct addressing.


ACCESSIBLE BY INDIRECT ADDRESSING

ONLY.

ACCESSIBLE BY DIRECT

ADDRESSING ONLY

ACCESSIBLE BY INDIRECT ADDRESSING AND DIRECT ADDRESSING

Fig.5 Internal Data Memory.

Upper 128

Lower 128

80H7FH

00

FFH FFH

80H

Special register function

PortsStatus and control bitsTimersRegistersStack pointerAccumulator(etc)

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Fig.6 the lower 128 bytes of Internal RAM

The next 16 bytes above the register banks form a block of bit-addressable memory

space. The microcontroller instruction set includes a wide selection of single-bit

instructions, and these instructions can directly address the 128 bits in this area. These

bit addresses are 00H through 7FH. All of the bytes in the Lower 128 can be accessed

by either direct or indirect addressing.

REGISTERS:

In the CPU, registers are used to store information temporarily. That

information could be a byte of data to be processed, or an address pointing to the data

to be fetched. The vast majority of 8051 registers are 8–bit registers. In the 8051

there is only one data type: 8bits. The 8bits of a register are should in the diagram

from the MSB(most significant bit) D7 to the LSB(least significant bit)D0. With an

8-bit data type, any data larger than 8bits must be broken into 8-bit chunks before it is

processed. Since there are a large number of registers in the 8051, we will

concentrate on some of the widely used general-purpose registers and cover special

registers in future chapters.


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D7 D6 D5 D4 D3 D2 D1 D0

The most widely used registers of the 8051 are A (accumulator), B, R0, R1,

R2, R3, R4, R5, R6, R7, DPTR (data pointer), and PC (program counter). All of the

above registers are 8-bits, except DPTR and the program counter. The accumulator,

register A, is used for all arithmetic and logic instructions.

SFRs (Special Function Registers)

Among the registers R0-R7 are part of the 128 bytes of RAM memory . what

about registers A,B, PSW, and DPTR? Do they also have addresses? The answer is

yes. In the 8051, registers A, B, PSW and DPTR are part of the group of registers

commonly referred to as SFR (special function registers). There are many special

function registers and they are widely used. The SFR can be accessed by the names

(which is much easier) or by their addresses. For example, register A has address

E0h, and register B has been ignited the address F0H, as shown in table.

Symbol Name Address

ACC Accumulator 0E0H

B B register 0F0H

PSW Program status word 0D0H

SP Stack pointer 81H

DPTR Data pointer 2 bytes

DPL Low byte 82H

DPH High byte 83H

P0 Port0 80H

P1 Port1 90H

P2 Port2 0A0H

P3 Port3 0B0H

IP Interrupt priority control 0B8H

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TMOD Timer/counter mode control 89H

TCON Timer/counter control 88H

T2CON Timer/counter 2 control 0C8H

T2MOD Timer/counter mode2 control 0C9H

TH0 Timer/counter 0high byte 8CH

TL0 Timer/counter 0 low byte 8AH

TH1 Timer/counter 1 high byte 8DH

TL1 Timer/counter 1 low byte 8BH

TH2 Timer/counter 2 high byte 0CDH

TL2 Timer/counter 2 low byte 0CCH

RCAP2H T/C 2 capture register high byte 0CBH

RCAP2L T/C 2 capture register low byte 0CAH

SCON Serial control 98H

SBUF Serial data buffer 99H

PCON Power control 87H


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PIN CONFIGURATION:

Pin Diagram of AT89C51

Pin Description

VCC

Pin 40 provides supply voltage to the chip. The voltage source is +5v.


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GND Pin 20 is the ground.

Ports 0, 1, 2 and 3

As shown in pin diagram, the four ports P0, P1, P2, and P3 each use of 8 pins,

making the 8-bit ports. All the ports upon Reset are configured as input, since P0-P3

have FFH on them.

Port 0

Port 0 occupies a total of 8 pins (pins 32-33). It can be used for input or

output. Port0 is also designated as AD0-AD7, allowing it to be used for both address

and data. When connecting an 8051/31 to an external memory, port 0 provides both

address and data. The 8051 multiplexes address and data through port 0 to save pins.

ALE=0, it provides data D0-D7, but when ALE=1, it has address A0-A7. Therefore,

ALE is used for de-multiplexing address and data with the help of a 74LS373 latch.

In the 8051-based systems where there is no external memory connection, the pins of

P0 must be connected externally to a 10k –ohm pull-up resistor. This is due to the

fact that P0 is an Open drain, Unlike P1, P2, P3. Open drain is a term used for MOS

chips in the same way that open collector is used for TTL chips. In many systems

using the 8751, 89C51, or DS89C4x0 chips, we normally connect P0 to pull-up

resistors. With external pull-up resistors connected to P0, it can be used as a simple

I/O port, just like P1 and P2. In contrast to Port 0, ports p1, p2, and p3 do not need

any pull-up resistors since they already have pull-up resistors internally. Upon reset,

ports p1, p2, ad p3 are configured as input ports.

Port 1

Port 1 occupies a total of 8-pins (pins1-8). It can be used as input or output.

In contrast to port 0, this port does not need any pull-up resistors since it already has

pull-up resistors internally. Upon reset, port1 is configured as an input port.

Port 2

Port 2 occupies a total 8 pins (pins 21-28). It can be used as input or output.

However, in 8031-based systems, port2 is also designated as A8-A15, indicating its

dual function. Since an 8051/31 is capable of accessing 64K bytes of external

memory, it needs a path for the 16 bits of the address. While P0 provides the lower 8


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bits via A0-A7, it is the job of p2 is used for the upper 8 bits of the 16-bit address, and

it cannot be used for I/O. Just like P1, port 2 does not need any pull-up resistors since

it already has pull-up resistors internally. Upon reset, port2 is configured as an input

port.

Port 3

Port 3 occupies a total of 8 pins (pins 10-17). It can be used as input or output. P3

does not need any pull-up resistors, just as P1 and P2 did not. Although Port 3 is

configured as an input port upon reset, this is not the way it is most commonly used.

Port 3 has the additional function of providing some extremely important signals such

as interrupts. The below table provides these alternate functions of P3. This is

information applies to both 8051 and 8031 chips.

Alternate Functions of PORT3

Port 3 also receives some control signals for Flash programming and verification.

RST

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

resets the device.

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Prior to each reading from external memory, the microcontroller will set the

lower address byte (A0-A7) on P0 and immediately after that activates the output

ALE. Upon receiving signal from the ALE pin, the external register (74HCT373 or

74HCT375 circuit is usually embedded) memorizes the state of P0 and uses it as an

address for memory chip. In the second part of the microcontroller’s machine cycle, a

signal on this pin stops being emitted and P0 is used now for data transmission (Data

Bus). In this way, by means of only one additional (and cheap) integrated circuit, data

multiplexing from the port is performed. This port at the same time used for data and

address transmission.

PSEN

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

AT89C51 is executing code from external program memory, PSEN is activated twice

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

to external data memory.

EA/VPP

External Access. EA must be strapped to GND in order to enable the device to fetch

code from external program memory locations starting at 0000H up to FFFFH. 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, for parts

that require 12-volt VPP.

XTAL1 and XTAL2

The 8051 has an on-chip oscillator but requires an external clock to run it.

Most often a quartz crystal oscillator is connected to inputs XTAL1 (pin19) and

XTAL2 (pin18). The quartz crystal oscillator connected to XTAL1 and XTAL2 also

needs two capacitors of 30pf value. One side of each capacitor is connected to the

ground as shown in fig1.

It must be noted that there are various speeds of the 8051 family. Speed refers

to the maximum oscillator frequency connected to XTAL. For example, a 12-MHz

chip must be connected to a crystal with 12 MHz frequency of no more than 20 MHz.


36






When the 8051 is connected to a crystal oscillator and is powered up, we can observe

the frequency on the XTAL2 pin using the oscilloscope.

If you decide to use a frequency source other than a crystal oscillator, such as

a TTL oscillator, it will be connected to XTAL1; XTAL2 is left unconnected. As

shown in fig2.

Fig(1) XTAL connection to 8051 fig2. XTAL connection to an External clock

source

Tab 6.2.2 Status of External Pins

TIMERS


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On-chip timing/counting facility has proved the capabilities of the

microcontroller for implementing the real time application. These includes pulse

counting, frequency measurement, pulse width measurement, baud rate generation,

etc,. Having sufficient number of timer/counters may be a need in a certain design

application. The 8051 has two timers/counters. They can be used either as timers to

generate a time delay or as counters to count events happening outside the

microcontroller. Let discuss how these timers are used to generate time delays and we

will also discuss how they are been used as event counters.

BASIC RIGISTERS OF THE TIMERS

Both Timer 0 and Timer 1 are 16 bits wide. Since the 8051 has an 8-bit

architecture, each 16-bit timer is accessed as two separate registers of low byte and

high byte.

TIMER 0 REGISTERS

The 16-bit register of Timer 0 is accessed as low byte and high byte. the low

byte register is called TL0(Timer 0 low byte)and the high byte register is referred to

as TH0(Timer 0 high byte).These register can be accessed like any other register, such

as A,B,R0,R1,R2,etc.for example, the instruction ”MOV TL0, #4F”moves the value

4FH into TL0,the low byte of Timer 0.These registers can also be read like any other

register.

TH0 TL0


38

D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0






TIMER 1 REGISTERS

Timer 1 is also 16-bit register is split into two bytes, referred to as TL1

(Timer 1 low byte) and TH1 (Timer 1 high byte).these registers are accessible n the

same way as the register of Timer 0.

TMOD (timer mode) REGISTER

Both timers 0 and 1 use the same register, called TMOD, to set the various

timer operation modes. TMOD is an 8-bit register in which the lower 4 bits are set

aside for Timer 0 and the upper 4 bits for Timer 1.in each case; the lower 2 bits are

used to set the timer mode and the upper 2 bits to specify the operation.

TCON Register:

TCON controls the timer/counter operations. The lower four bits of TCON cater to

interrupt functions, but the upper four bits are for timer operations. The details of the

TCON register are shown below.


39






MSB LSB

Serial Communication:

Computers can transfer data in two ways: parallel and serial. In

parallel data transfers, often 8 or more lines (wire conductors) are used to transfer data

to a device that is only a few feet away. Examples of parallel transfers are printers

and hard disks; each uses cables with many wire strips. Although in such cases a lot

of data can be transferred in a short amount of time by using many wires in parallel,

the distance cannot be great. To transfer to a device located many meters away, the

serial method is used. In serial communication, the data is sent one bit at a time, in

contrast to parallel communication, in which the data is sent a byte or more at a time.

Serial communication of the 8051 is the topic of this chapter. The 8051 has serial

communication capability built into it, there by making possible fast data transfer

using only a few wires.

Serial data communication uses two methods, asynchronous and synchronous.

The synchronous method transfers a block of data at a time, while the asynchronous

method transfers a single byte at a time.

The 8051 transfers and receives data serially at many different baud rates. The

baud rate in the 8051 is programmable. This is done with the help of Timer1. The

8051 divides the crystal frequency by 12 to get the machine cycle frequency. In the

case of XTAL=11.0592MHZ, the machine cycle frequency is 921.6 KHz

(11.0592MHz/12=921.6KHz). The 8051’s serial communication UART circuitry

divides the machine cycle frequency of 921.6 kHz divided by 32 once more before it

is used by Timer 1 to set the Baud rate.

SBUF register


TF1 TR1 TF0 TR0 IE1 IT1 IE0 IT0

40






SBUF is an 8-bit register used solely for serial communication in the

8051. For a byte of data to be transferred via the TXD line, it must be placed in the

SBUF register. Similarly, SBUF holds the byte of data when it is received by the

8051’s RXD line. SBUF can be accessed like any other register in the 8051.

SCON (serial control) register

The SCON register is an 8-bit register used to program the start bit, stop bit,

and data bits of data framing, among other things.

The following describes various bits of the SCON register.

SM0 SM1 SM2 REN TB8 RB8 TI RI

BAUD RATE CALCULATION:

Internal timer stages are as fallows

Divided by X box can be replaced with T1 timer so that by changing the value of

timer we can obtain the required baud rate.

Let XClk = 11.0592 MHz

Baud Rate = (XClk / 12 / 16 / 2 / X)


41






For attaining 9600 baud Rate,

X can be calculated as

= 11.0592 x 106 / 12 / 16 / 2 / 9600

= 3

So set the 2’s Complement of 3 in Timer 1 so that we can achieve 9600 baud rates.

Note: Assuming 8-bit Auto reload mode and 8-bit variable baud rate modes.

Doubling the baud rate in the 8051:

There are two ways to increase the baud rate to data transfer in the 8051.

1. Use a higher- frequency crystal.

2. Change a bit in the PCON register, shown below.

SMOD -- -- -- GF1 GF0 PD IDL

Option1 is not feasible in many situations since the system crystal is fixed.

More

Importantly, it is not feasible because the new crystal may not be compatible

with the IBM PC serial COM port’s baud rate. Therefore, we will explore option2.

there is a software way to double the baud rate of the 8051 while the crystal frequency

is fixed. This is done with the register called PCON (power control). The PCON

register is an 8-bit register. Of the 8 bits, some are unused, and some are used for the

power control capability of the 8051. The bit that is used for the serial communication

is D7, the SMOD (serial mode) bit. When the 8051 is powered up, D7 (SMOD) of

this PCON register is zero. We can set it to high by software and thereby double the

baud rate.

INTERRUPTS:

A single microcontroller can serve several devices. There are two ways to do that:

INTERRUPTS or POLLING.


42






POLLING:

In polling the microcontroller continuously monitors the status of a given device;

when the status condition is met, it performs the service .After that, it moves on to

monitor the next device until each one is serviced. Although polling can monitor the

status of several devices and serve each of them as certain condition are met.

INTERRUPTS:

In the interrupts method, whenever any device needs its service, the device notifies

the microcontroller by sending it an interrupts signal. Upon receiving an interrupt

signal, the microcontroller interrupts whatever it is doing and serves the device. The

program associated with the interrupts is called the interrupt service routine (ISR).or

interrupt handler.

Six Interrupts in the 8051:

In reality, only five interrupts are available to the user in the 8051, but many

manufacturers’ data sheets state that there are six interrupts since they include

reset .the six interrupts in the 8051 are allocated as above.

1. Reset. When the reset pin is activated, the 8051 jumps to address location

0000.this is the power-up reset.

2. Two interrupts are set aside for the timers: one for Timer 0 and one for Timer

1.Memory location 000BH and 001BH in the interrupt vector table belong to

Timer 0 and Timer 1, respectively.

3. Two interrupts are set aside for hardware external harder interrupts. Pin

number 12(P3.2) and 13(P3.3) in port 3 are for the external hardware

interrupts INT0 and INT1,respectively.These external interrupts are also


43






referred to as EX1 and EX2.Memory location 0003H and 0013H in the

interrupt vector table are assigned to INT0 and INT1, respectively.

4. Serial communication has a single interrupt that belongs to both receive and

transmit. The interrupt vector table location 0023H belongs to this interrupt.

Registers:

Interrupt Enable Register

D7 D6 D5 D4 D3 D2 D1 D0

Interrupt priority upon rest:

When the 8051 is powered up, the priorities are assigned according to the below table.

in the below table we see, for example, that if external hardware interrupts 0 and 1 are

activated at the same time, external interrupt 0 (INT0) is responded to first. Only after

INT0 has been serviced is INT1 serviced, since INT1 has the lower priority. In reality,

the priority scheme in the table is nothing but an internal polling sequence in which

the 8051 polls the interrupts in the sequence listed in the below table and responds

accordingly.

8051/52 Interrupt Priority upon Reset

Highest to Lowest Prioritywww.1000projects.comwww.fullinterview.comwww.chetanasprojects.com

44

EA -- ET2 ES ET1 EX1 ET0 EX0






External Interrupt 0 (INT0)

Timer Interrupt 0 (TF0)

External Interrupt 1 (INT1)

Timer Interrupt 1 (TF1)

Serial Communication (RI+TI)

Timer 2(8052 only) TF2

Setting interrupts priority with the IP register

We can alter the sequence of above Table by assigning a higher priority to any one of

the interrupts. This is done by programming a register called IP (interrupt

priority).below diagram shows the bits of IP register. Upon power-up reset, the IP

register contain all 0s, making the priority sequence based on the above table. To give

a higher priority to any of the interrupt, we make the corresponding bit in the IP

register high.

D7 D0


45

-- -- PT2 PS PT1 PX1 PT0 PX0






FINGER PRINT SCANNER:

NITGEN FIM 3030:

A fingerprint sensor is an electronic device used to capture a digital image of

the fingerprint pattern. The captured image is called a live scan. This live scan is


46





http://en.wikipedia.org/wiki/Digital_image

http://en.wikipedia.org/wiki/Electronics



digitally processed to create a biometric template (a collection of extracted features)

which is stored and used for matching.

General Descriptions

FIM30 is an evolutionary standalone fingerprint recognition module consisted of optic

sensor and processing board. As CPU and highly upgraded algorithm are embedded

into a module, it provides high recognition ratio even to small size, wet, dry, calloused

fingerprint. High speed 1: N identification and 1: N verification.

FIM 30 has functions of fingerprint enrollment, identification, partial and entire

deletion and reset in a single board, it does not require connection with a separate PC,

thereby offering convenient development environment.

Off-line functionality stores logs on the equipment memory (up to 100 fingerprints)

and it’s identified using search engine from the internal algorithm.

Evolutionary standalone fingerprint recognition module FIM30 is ideal for on-line

applications, because allows ASCII commands to manage the device from the host.

On-line functionality, fingerprints to verify (1:1) or identify (1: N) can be stored on

non volatile memory, or be sent by RS-232 port.

Features

On-line and off-line fingerprint identification incorporated

Identification rate 1:1 and 1:N; FAR: 1/100.000 y FRR: 1/1.000

Algorithm and high hardness optical sensor

It provides high recognition ratio even to small size, wet, dry, calloused

fingerprint.

Fast acquisition of difficult finger types under virtually any condition.


47





http://en.wikipedia.org/wiki/Feature_extraction

http://en.wikipedia.org/wiki/Digital_signal_processing


Memory capacity for 100 fingerprints

Memory events: up to 2,000 authentications

Access host can be protected by fingerprint or password

It offers convenient development environment.

Two communication ports: RS-232 or host ( on-line applications )

ASCII protocol

Supply voltage: 5V

Small size and robust durability, it has longer life span.

This FIM 3030 is going to have the Optical Sensor to Enroll and Identify the Finger

Print.

Optical sensor

Optical fingerprint imaging involves capturing a digital image of the print

using visible light. This type of sensor is, in essence, a specialized digital camera. The

top layer of the sensor, where the finger is placed, is known as the touch surface.

Beneath this layer is a light-emitting phosphor layer which illuminates the surface of

the finger. The light reflected from the finger passes through the phosphor layer to an

array of solid state pixels (a charge-coupled device) which captures a visual image of

the fingerprint. A scratched or dirty touch surface can cause a bad image of the

fingerprint. A disadvantage of this type of sensor is the fact that the imaging

capabilities are affected by the quality of skin on the finger. For instance, a dirty or

marked finger is difficult to image properly. Also, it is possible for an individual to

erode the outer layer of skin on the fingertips to the point where the fingerprint is no

longer visible. It can also be easily fooled by an image of a fingerprint if not coupled

with a "live finger" detector. However, unlike capacitive sensors, this sensor

technology is not susceptible to electrostatic discharge damage.


48





http://en.wikipedia.org/wiki/Charge-coupled_device

http://en.wikipedia.org/wiki/Solid_state_(electronics)

http://en.wikipedia.org/wiki/Digital_camera

http://en.wikipedia.org/wiki/Visible_light


Target Application

Door-lock system

Safe Box

Simple Access Controller

Vehicle Control

ATM ,And more

Block Diagram

RS-232C communication data consist of 8-bit data, no parity, 1-bit start-bit and 1-bit

stop-bit.

Interfacing:


49






Here this FIM 3030 supports the serial communication protocol which is RS-232. we

are interfacing serially by converting the TTL logic into RS-232 standards and vice

versa.

For this hardware interfacing we are using MAX-232 as a level converter for reading

and writing data.

MAX-232:

Introduction:

Serial RS-232 (V.24) communication works with voltages (-15V ... -3V

for high [sic]) and +3V ... +15V for low [sic]) which are not compatible with normal

computer logic voltages. On the other hand, classic TTL computer logic operates

between 0V ... +5V (roughly 0V ... +0.8V for low, +2V ... +5V for high). Modern

low-power logic operates in the range of 0V ... +3.3V or even lower.

So, the maximum RS-232 signal levels are far too high for computer logic electronics,

and the negative RS-232 voltage for high . Therefore, to receive serial data from an

RS-232 interface the voltage has to be reduced, and the low and high voltage level

inverted. In the other direction (sending data from some logic over RS-232) the low

logic voltage has to be "bumped up", and a negative voltage has to be generated, too.

Logic Voltages

All this can be done with conventional analog electronics, e.g. a particular power

supply and a couple of transistors or the once popular 1488 (transmitter) and 1489

(receiver) ICs. However, since more than a decade it has become standard in amateur

electronics to do the necessary signal level conversion with an integrated circuit (IC)

from the MAX232 family (typically a MAX232A or some clone). In fact, it is hard to

find some

The MAX232 & MAX232A


50






The MAX 232 translates RS232 voltages to TTL voltages. RS232 represent a binary 1

or HI anywhere between –3V to –12V, a zero logic or LOW, between 3V and 12V.

TTL in the other hand responds to 0 to 2.1V as logic zero and 2.8V to 5V as a HI. The

MAX 232 provides voltage translation so the TTL PIC 16F84 can understand the

messages sent to it from the computer. A serial cable is also provided to connect the

MAX232 to the PC and jumper cables to connect the MAX232 to the micro

controller.

The MAX232 from Maxim was the first IC which in one package contains the

necessary drivers (two) and receivers (also two), to adapt the RS-232 signal voltage

levels to TTL logic. It became popular, because it just needs one voltage (+5V) and

generates the necessary RS-232 voltage levels (approx. -10V and +10V) internally.

This greatly simplified the design of circuitry. Circuitry designers no longer need to

design and build a power supply with three voltages (e.g. -12V, +5V, and +12V), but

could just provide one +5V power supply, e.g. with the help of a simple 78x05

voltage converter.

MAX232 (A) DIP Package

DIP Package of MAX 232A


51






A Typical Application

The MAX232 (A) has two receivers (converts from RS-232 to TTL voltage levels)

and two drivers (converts from TTL logic to RS-232 voltage levels). This means only

two of the RS-232 signals can be converted in each direction.

There are not enough drivers/receivers in the MAX232 to also connect the DTR,

DSR, and DCD signals. Usually these signals can be omitted when e.g.

communicating with a PC's serial interface. If the DTE really requires these signals

either a second MAX232 is needed, or some other IC from the MAX232 family can

be used (if it can be found in consumer electronic shops at all). An alternative for

DTR/DSR is also given below.

Maxim's data sheet explains the MAX232 family in great detail, including the pin

configuration and how to connect such an IC to external circuitry. This information

can be used as-is in own design to get a working RS-232 interface. Maxim's data just

misses one critical piece of information: How exactly to connect the RS-232 signals

to the IC. So here is one possible example:

MAX232 to RS232 DB9 Connection as a DCE

MAX232 Pin Nbr. MAX232 Pin Name Signal Voltage DB9 Pin

7 T2out CTS RS-232 7

8 R2in RTS RS-232 8

9 R2out RTS TTL n/a

10 T2in CTS TTL n/a

11 T1in TX TTL n/a

12 R1out RX TTL n/a

13 R1in RX RS-232 2

14 T1out TX RS-232 3


52






15 GND GND 0 5

Connections between MAX 232 & RS 232

In addition one can directly wire DTR (DB9 pin 4) to DSR (DB9 pin 6) without going

through any circuitry. This gives automatic (brain dead) DSR acknowledgement of an

incoming DTR signal.

Sometimes pin 6 of the MAX232 is hard wired to DCD (DB9 pin 1). This is not

recommended. Pin 6 is the raw output of the voltage pump and inverter for the -10V

voltage. Drawing currents from the pin leads to a rapid breakdown of the voltage, and

as a consequence to a breakdown of the output voltage of the two RS-232 drivers. It is

better to use software which doesn't care about DCD, but does hardware-handshaking

via CTS/RTS only. The circuitry is completed by connecting five capacitors to the IC

as it follows. The MAX232 needs 1.0µF capacitors, the MAX232A needs 0.1µF

capacitors. MAX232 clones show similar differences. It is recommended to consult

the corresponding data sheet. At least 16V capacitor types should be used. If

electrolytic or tantalic capacitors are used, the polarity has to be observed. The first

pin as listed in the following table is always where the plus pole of the capacitor

should be connected to. External Capacitors The 5V power supply is connected

to+5V: Pin 16 GND: Pin 15

MAX232(A) external Capacitors

Capacitor + Pin - Pin Remark

C1 1 3

C2 4 5

C3 2 16

C4 GND 6

This looks non-intuitive, but because pin 6 is

on -10V, GND gets the + connector, and not the

-


53






C5 16 GND

Drawbacks of MAX232:

The MAX-232 chip receives data from the receiver, and converts it to the

standard RS-232 data format that can be read in by a serial port on a personal

computer or workstation.

For the RS-232 interface, a standard MAX232 chip is used for level

conversion. Both use the on chip USART and thus the same firmware.

CONNECTIONS IN MAX 232:

If you wanted to do a general RS-232 connection, you could take a bunch of long

wires and solder them directly to the electronic circuits of the equipment you are

using, but this tends to make a big mess and often those solder connections tend to

break and other problems can develop. To deal with these issues, and to make it easier

to setup or take down equipment, some standard connectors have been developed that

is commonly found on most equipment using the RS-232 standards

EEPROM (24C02):

FEATURES

• Low power CMOS

— Active current less than 2 mA

— Standby current less than 8 mA

• Hardware writes protection

— Write control pin

• Internally organized as 256 x 8

• Two-wire serial interface

— Bidirectional data transfer protocol

• 8-Byte page-write mode


54






— Minimized total write time per byte

• Automatic word address incrementing

— Sequential register read

• Self-timed write cycle

— Maximum write cycle time of 10 ms

• 400 KHz Compatibility

Endurance: 1, 000,000 cycles per byte

• 8-pin PDIP, TSSOP, MSOP or SOIC packages

• Filtered inputs for noise suppression

OVERVIEW

The IS24C02 is a low cost 2,048-bit serial EEPROM. It is fabricated using ISSI’s

advanced CMOS EEPROM technology and operates from a single supply. The

IS24C02 is internally organized as a 256 x 8 memory bank. The IS24C02 features a

serial interface and software protocol allowing operation on a simple 2-wire bus. Up

to eight IS24C02s may be connected to the 2-wire bus by programming the A0, A1,

and A2 inputs.

PIN CONFIGURATION

PIN DESCRIPTIONS

A0-A2 Address Inputs

SDA Serial Data I/O

SCL Serial Clock Input

WC Write Control Input


55






VCC Power

GND Ground

A0, A1, and A2 - The address inputs are used to set the least significant three bits of

the slave address. These inputs may be tied HIGH or LOW, or they may be actively

driven. These inputs allow up to eight IS24C02 devices to be connected together on

the bus. When left floating, A0,

A1 and A2 are pulled to ground. The default values are zeros.

Serial Data (SDA) - The SDA pin is a bidirectional pin used to transfer data into and

out of the device. Data may change only when SCL is LOW. It is an open-drain

output, and may be wire ORed with any number of open-drain or open-collector

outputs.

Serial Clock (SCL) - The SCL input is used to clock all data into and out of the

device. In the WRITE mode, data must remain stable when SCL is HIGH. In the

READ mode, data is clocked out on the falling edge of SCL.

Write Control (WC) - The Write Control input is used to disable any attempt to write

to the memory. When HIGH, the memory is protected; when LOW, the write function

is normal. The part can be read independent of the state of WC pin. When not

connected, this pin will be pulled LOW.

ENDURANCE AND DATA RETENTION

The IS24C02 is designed for applications requiring high endurance write cycles and

unlimited read cycles. It provides 10 years of secure data retention, with or without

power applied, after the execution of 1,000,000 write cycles.

APPLICATIONS

The IS24C02 is ideal for high volume applications requiring low power and low

density storage. This device uses a low-cost, space-saving 8-pin plastic package.


56






Candidate applications include robotics, alarm devices, electronic locks, meters and

instrumentation.

GENERAL DESCRIPTION

The IS24C02 features a SERIAL communication, and supports bidirectional data

transmission protocol allowing operation on a simple two-wire bus between the

different devices connected somewhere on the system bus. The two-wire bus is

defined as a serial data line (SDA), and a serial clock line (SCL).

The protocol defines any device that sends data onto the SDA bus as a transmitter,

and the receiving device as a receiver. The device controlling the data transmission is

named MASTER device, and the controlled device is named SLAVE device. In all

cases, the IS24C02 will be a slave device, since it never initiates any data transfers.

Up to eight IS24C02 can be connected to the bus. Device's physical address inputs A0-A2

must be connected to either VCC or GND. When left floating, A0, A1 and A2 are

pulled to ground. The default values are zeros.

Following a START condition, the MASTER (transmitter) device must initiate the

“Device Addressing Byte” including device type identifier, device address, and a read

or write operation to select a slave device (receiver) connected to the system bus. The

receiver will then respond with an Acknowledge by pulling the SDA line LOW. The

Acknowledge is used to indicate successful data transfers. The transmitting device

will release the data bus (SDA goes HIGH) after transmitting eight bits (one data bit

is transferred at the falling edge of each clock cycle). During the ninth clock cycle, the

receiver will pull the SDA line LOW to acknowledge the transmitter that it received

the eight bits of data.

DEVICE OPERATION


57






START and STOP Conditions

Both SDA and SCL lines remain HIGH when the SDA bus is not busy. A HIGH-to-

LOW transition of SDA line, while SCL is HIGH, is defined as the START condition.

A LOW to- High transition of SDA line, while SCL is HIGH, is defined as the STOP

condition.

Data Validity Protocol

One data bit is transferred during each clock cycle. The data on the SDA line must

remain stable during the HIGH period of the clock cycle, because changes on SDA

line during the SCL HIGH period will be interpreted as START or STOP control

signals.

Device Addressing Byte Definitions

The most significant four bits of Device Addressing Byte (Bit 7 to Bit 4) are defined

as the device type identifier. For IS24C02, this is fixed as 1010. The next three

significant address bits (Bit 3 to Bit 1) address a particular device. Up to eight

IS24C02 devices can be connected on the bus.


58






These eight addresses are defined by the state of the A0, A1, and A2 inputs. The last

bit Bit 0 defines the write or read operation to be performed. When set to “1”, a

READ operation is selected; when set to “0” a WRITE operation is selected.

WRITE OPERATION

Byte Write

For a WRITE operation, the IS24C02 requires another 8-bit data word address

following the Device Addressing Byte and Acknowledgement. This data word

address provides access to any one of the 256 data words of device's memory array.

Upon receipt of the data word address, the IS24C02 responds with an Acknowledge

on SDA, and waits for the next 8-bit data word, then again responding with an

Acknowledge. The master device terminates the Byte Write Operation by generating a

STOP condition; afterward the IS24C02 begins the internal WRITE cycle to the

nonvolatile memory array. Refer to Write Cycle Timing. All inputs are disabled

during this write cycle and the device will not respond to any requests from the

master.

Page Write


59






The IS24C02 is capable of 8-byte page- WRITE operation. A page-WRITE is

initiated in the same manner as a byte write, but instead of terminating the internal

write cycle after the first data word is transferred, the master device can transmit up to

7 more words. After the receipt of each data word, the IS24C02 responds immediately

with an Acknowledge on SDA line, and the four lower order data word address bits

are internally incremented by one while the four higher order bits of the data word

address remain constant. If the master device should transmit more than 8 words,

prior to issuing the STOP condition, the address counter will “roll over,” and the

previously written data will be overwritten. All inputs are disabled until completion of

the internal WRITE cycle.

Acknowledge Polling

Once the internal write cycle has started and the IS24C02 inputs are disabled,

acknowledge polling can be initiated. This involves sending a start condition followed

by the Device Addressing Byte. The read/write bit is representation of the operation

desired. Only if the internal write cycle has been completed will the IS24C02 respond

with acknowledge on the SDA bus allowing the read or write sequence to continue.

READ OPERATION

READ operations are initiated in the same manner as WRITE operations, except that

the read/write bit of the device addressing byte is set to “1”. There are three READ

operation options: current address read, random address read and sequential read.

Current Address Read

The IS24C02 contains an internal address counter which maintains the address of the

last data word accessed, incremented by one. For example, if the previous operation

either a read or write operation addressed to the address location n, the internal

address counter would increment to address location n+1. When the IS24C02 receives

the Device Addressing Byte with a READ operation (read/write bit set to “1”), it will

respond an Acknowledge and transmit the 8-bit data word stored at address location

n+1. If the Current Address READ operation only accesses a single byte of data, the

master device terminates the Current Address READ operation by pulling


60






Acknowledge HIGH (lack of Acknowledge) indicating the last data word to be read,

followed by a STOP condition.

Random Access Read

Random Address READ operation allows the master device to access any memory

location in a random fashion. This operation involves a two-step process. First, the

master device generates a START condition and initiates Device Addressing Byte

with a dummy WRITE operation (read/write bit sets to “0”), followed by the address

of the data word the master device is to READ. This procedure stores the desired

address of data word to the internal address counter of the IS24C02.

After the data word address Acknowledge is received by the master device, the master

device now initiates a CURRENT ADDRESS READ by sending Device Addressing

Byte with a READ operation (read/write bit sets to “1”). The IS24C02 responds with

an Acknowledge and transmits the eight data bits stored at the address location where

the master device is to READ. At this point, the master device terminates the

operation by pulling Acknowledge HIGH (lack of Acknowledge) indicating the last

data word to be read, followed by a STOP condition.

Sequential Read


61






Sequential Reads can be initiated as either a Current Address Read or Random

Address Read. The first data word is transmitted as with the other byte read modes,

the master device now responds with an ACKnowledge indicating that it requires

additional data from the IS24C02. The IS24C02 continues to output data for each

ACKnowledge received. the master device terminates the sequential READ operation

by pulling ACKnowledge HIGH (lack of ACKnowledge) indicating the last data word

to be read, followed by a STOP condition.

The data output is sequential; with the data from address n followed by the date from

address n+1 ... etc. The address-counter increments by one automatically, allowing the

entire memory contents to be serially read during sequential read operation. When the

memory address boundary (address 255) is reached, the address counter “rolls over”

to address 0, and the IS24C02 continues to output data for each Acknowledge

received.

REGULATED POWER SUPPLY:

DESCRIPTION

A variable regulated power supply, also called a variable bench power supply,

is one where you can continuously adjust the output voltage to your requirements.

Varying the output of the power supply is the recommended way to test a project after


62






having double checked parts placement against circuit drawings and the parts

placement guide.

This type of regulation is ideal for having a simple variable bench power

supply. Actually this is quite important because one of the first projects a hobbyist

should undertake is the construction of a variable regulated power supply. While a

dedicated supply is quite handy e.g. 5V or 12V, it's much handier to have a variable

supply on hand, especially for testing.

Most digital logic circuits and processors need a 5-volt power supply. To use

these parts we need to build a regulated 5-volt source. Usually you start with an

unregulated power supply ranging from 9 volts to 24 volts DC .To make a 5 volt

power supply, we use a LM7805 voltage regulator IC (Integrated Circuit). The IC is

shown below.

CIRCUIT FEATURES:

Brief description of operation: Gives out well regulated +5V output, output current

capability of 100 mA


63






Circuit protection: Built-in overheating protection shuts down output when regulator

IC gets too hot

Circuit complexity: Very simple and easy to build

Circuit performance: Very stable +5V output voltage, reliable operation

Availability of components: Easy to get, uses only very common basic components

Design testing: Based on datasheet example circuit, I have used this circuit

succesfully as part of many electronics projects

Applications: Part of electronics devices, small laboratory power supply

Power supply voltage: Unreglated DC 8-18V power supply

Power supply current: Needed output current + 5 mA

Component costs: Few dollars for the electronics components + the input

transformer cost.

CIRCUIT DIAGRAM

This 5V dc acts as Vcc to the microcontroller. The excess voltage is dissipated as

heat via an Aluminum heat sink attached to the voltage regulator.


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POWER SUPPLY DESIGN

power supply—A device for the conversion of available power of one set of

characteristics to meet specified requirements. Typical application of power supplies

includes converting raw input power to a controlled or stabilized voltage and/or

current for the operation of electronic equipment.

Power supplies belong to the field of power electronics, the use of

electronics for the control and conversion of electrical power. A power supply is

sometimes called a power converter and the process is called power conversion. It is

also sometimes called a power conditioner and the process is called power

conditioning.

There are many types of power supplies. Most are designed to convert

high voltage AC mains electricity to a suitable low voltage supply for electronics

circuits and other devices. A power supply can be broken down into a series of

blocks, each of which performs a particular function. The power supplies used in our

project, Digital Control of Three-Phase Induction Motor are +5V and+12V.

These power supplies can be designed by a simple circuit

arrangement consisting of bridge rectifier (here we used diodes connected in bridge

arrangement called the Diode Bridge), Capacitive or inductive filter, regulator (7812

for +12V and 7805 for +5V), resistor and Light Emitting Diode (LED) and

transformer. The purpose of each component in the power supply design circuit

shown in the schematic (drawn using Express SCH) is described below:

TRANSFORMER:


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Transformer is basically a one that transforms. A device used to transfer electric

energy from one circuit to another, especially a pair of multiply wound, inductively

coupled wire coils that affect such a transfer with a change in voltage, current, phase,

or other electric characteristic. In other words Transformers convert AC electricity

from one voltage to another with little loss of power.

Transformers work only with AC and this is one of the reasons why mains electricity

is AC. If the output voltage of a transformer is greater than the input voltage, it is

called a step-up transformer. If the output voltage of a transformer is less than the

input voltage it is called a step-down transformer. Most power supplies use a step-

down transformer to reduce the dangerously high mains voltage (230V in UK) to a

safer low voltage.

The input coil is called the primary and the output coil is called the secondary. There

is no electrical connection between the two coils; instead they are linked by an

alternating magnetic field created in the soft-iron core of the transformer. The two

lines in the middle of the circuit symbol shown below represent the core Transformers

waste very little power so the power out is (almost) equal to the power in. Note that as

voltage is stepped down current is stepped up.


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The ratio of the number of turns on each coil, called the turns ratio, determines the

ratio of the voltages. A step-down transformer has a large number of turns on its

primary (input) coil, which is connected to the high voltage mains supply, and a small

number of turns on its secondary (output) coil to give a low output voltage.

Turns Ratio = Vp / Vs = Np / Ns and

Power Out = Power In i.e., Vs * Is =Vp * Ip

Where, Vp =Primary (input) voltage

Np =Number of turns on primary coil

Ip =Primary (input) current

Vs =Secondary (output) voltage

Ns =Number of turns on secondary coil

Is =Secondary (output) current

Uses of transformers


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Electric power transmission over long distances. The simplicity, reliability, and

economy of conversion of voltages by stationary transformers were the principal

factor in the selection of alternating current power transmission.

High-voltage direct-current HVDC power transmission systems. Large, specially

constructed power transformers are used for electric arc furnaces used in steel

making.

Rotating transformers are designed so that one winding turns while the other

remains stationary. These can pass power or radio signals from a stationary

mounting to a rotating mechanism, or radar antenna.

Sliding transformers can pass power or signals from a stationary mounting to a

moving part such as a machine tool head. See linear variable differential

transformer.

Some rotary transformers are precisely constructed in order to measure distances

or angles. Usually they have a single primary and two or more secondaries, and

electronic circuits measure the different amplitudes of the currents in the

secondaries. See synchro and resolver.

Small transformers are often used to isolate and link different parts of radio

receivers and audio amplifiers, converting high current low voltage circuits to low

current high voltage, or vice versa. See electronics and impedance matching. See

also isolation transformer and repeating coil.

Balanced-to-unbalanced conversion. A special type of transformer called a balun

is used in radio and audio circuits to convert between balanced circuits and

unbalanced transmission lines such as antenna down leads. A balanced line is one

in which the two conductors (signal and return) have the same impedance to

ground: twisted pair and "balanced twin" are examples. Unbalanced lines include

coaxial cable sand strip-line traces on printed circuit boards. A similar use is for

connecting the "single ended" input stages of an amplifier to the high-powered

"push-pull" output stage.

Center tap transformers :


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In electronics, a center tap is a wire that is connected to a point half way along one of

the windings of a transformer, inductor or a resistor. Center taps are sometimes used

on inductors for the coupling of signals, although most tapings are not at the center

but usually near one end. In the case of resistors, tapping is usually done only with

potentiometers, and center tapping is just a special case of normal operation of these

devices.

RECTIFIERS:

Rectification is a process of conversion of AC to DC. Here, the AC of transformer

output is given to the rectifier input, which converts it to DC output. Basically, bridge

rectifiers or diodes arranged in bridge called Diode arrangement are used for power

supply design.

A bridge rectifier makes use of four diodes in a bridge arrangement to achieve full-

wave rectification. This is a widely used configuration, both with individual diodes

wired as shown and with single component bridges where the diode bridge is wired

internally

Current Flow in the Bridge Rectifier


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For both positive and negative swings of the transformer, there is a forward path

through the diode bridge. Both conduction paths cause current to flow in the same

direction through the load resistor, accomplishing full-wave rectification.

While one set of diodes is forward biased, the other set is reversing biased and

effectively eliminated from the circuit.

Diode Bridge:

A diode bridge is an arrangement of four diodes connected in a bridge circuit as

shown below, that provides the same polarity of output voltage for any polarity of the

input voltage. When used in its most common application, for conversion of


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alternating current (AC) input into direct current (DC) output, it is known as a bridge

rectifier. The diagram describes a diode-bridge design known as a full-wave rectifier

or Graetz circuit. This design can be used to rectify single phase AC when

No transformer center tap is available.

The essential feature of this arrangement is that for both polarities of the voltage at the

bridge input, the polarity of the output is constant. When the input connected at the

left corner of the diamond is positive with respect to the one connected at the right

hand corner, current flows to the right along the upper colored path to the output, and

returns to the input supply via the lower one.


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http://en.wikipedia.org/wiki/Image:Diodebridge1.png



When the right hand corner is positive relative to the left hand corner, current flows

along the upper colored path and returns to the supply via the lower colored path.

AC, half-wave and full wave rectified signals

In each case, the upper right output remains positive with respect to the lower right

one. Since this is true whether the input is AC or DC, this circuit not only produces

DC power when supplied with AC power: it also can provide what is sometimes

called "reverse polarity protection". That is, it permits normal functioning when

batteries are installed backwards or DC input-power supply wiring "has its wires

crossed" (and protects the circuitry it powers against damage that might occur without

this circuit in place).

Prior to availability of integrated electronics, such a bridge rectifier was always

constructed from discrete components. Since about 1950, a single four-terminal

component containing the four diodes connected in the bridge configuration became a

standard commercial component and is now available with various voltage and

current ratings.

Capacitor:


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A capacitor is a device that stores energy in the electric field created between a pair of

conductors on which equal but opposite electric charges have been placed. A

capacitor is occasionally referred to using the older term condenser.

A capacitor consists of two electrodes or plates, each of which stores an opposite

charge. These two plates are conductive and are separated by an insulator or

dielectric. The charge is stored at the surface of the plates, at the boundary with the

dielectric. Because each plate stores an equal but opposite charge, the total charge in

the capacitor is always zero.

The capacitor's capacitance (C) is a measure of the amount of charge (Q) stored on

each plate for a given potential difference or voltage (V) which appears between the

plates:

In SI units, a capacitor has a capacitance of one farad when one coulomb of charge

causes a potential difference of one volt across the plates. Since the farad is a very

large unit, values of capacitors are usually expressed in microfarads (µF), nanofarads

(nF) or Pico farads (pF).

The capacitance is proportional to the surface area of the conducting plate and

inversely proportional to the distance between the plates. It is also proportional to the

permittivity of the dielectric (that is, non-conducting) substance that separates the

plates.The capacitance of a parallel-plate capacitor is given by:

Where ε is the permittivity of the dielectric, A is the area of the plates and d is the

spacing between them.


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Capacitors are commonly used in power supplies where they smooth the output of a

full or half wave rectifier. They can also be used in charge pump circuits as the energy

storage element in the generation of higher voltages than the input voltage.

Capacitors are connected in parallel with the power circuits of most electronic devices

and larger systems (such as factories) to shunt away and conceal current fluctuations

from the primary power source to provide a "clean" power supply for signal or control

circuits. Audio equipment, for example, uses several capacitors in this way, to shunt

away power line hum before it gets into the signal circuitry. The capacitors act as a

local reserve for the DC power source, and bypass Ac currents from the power supply.

Capacitors are used in power factor correction. Such capacitors often come as three

capacitors connected as a three phase load. Usually, the values of these capacitors are

given not in farads but rather as a reactive power in volt-amperes reactive (VAr). The

purpose is to match the inductive loading of machinery which contains motors, to

make the load appear to be mostly resistive.

Capacitors are also used in parallel to interrupt units of a high-voltage circuit breaker

in order to distribute the voltage between these units. In this case they are called

grading capacitors. In schematic diagrams, a capacitor used primarily for DC charge

storage is often drawn vertically in circuit diagrams with the lower, more negative,

plate drawn as an arc. The straight plate indicates the positive terminal of the device;

if it is polarized Non-polarized electrolytic capacitors used for signal filtering are

typically drawn with two curved plates. Other non-polarized capacitors are drawn

with two straight plates.

Non-polarized fixed capacitor

A non-polarized ("non polar") capacitor is a type of capacitor that has no implicit

polarity -- it can be connected either way in a circuit. Ceramic, mica and some

electrolytic capacitors are non-polarized. You'll also sometimes hear people call them

"bipolar" capacitors.


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Polarized fixed capacitor

A polarized ("polar") capacitor is a type of capacitor that has implicit polarity -- it can

only be connected one way in a circuit. The positive lead is shown on the schematic

(and often on the capacitor) with a little "+" symbol. The negative lead is generally

not shown on the schematic, but may be marked on the capacitor with a bar or "-"

symbol. Polarized capacitors are generally electrolytes.

The simple capacitor filter is the most basic type of power supply filter. The

application of the simple capacitor filter is very limited. It is sometimes used on

extremely high-voltage, low-current power supplies for cathode ray and similar www.1000projects.comwww.fullinterview.comwww.chetanasprojects.com

75






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

filter is also used where the power-supply ripple frequency is not critical; this

frequency can be relatively high.

REGULATORS:

A regulator converts varying input voltage and produces a constant "regulated"

output voltage.

The linear regulator is the basic building block of nearly every

power supply used in electronics. The IC linear regulator is so easy to use that it is

virtually foolproof, and so inexpensive that it is usually one of the cheapest

components in an electronic assembly. A linear regulator operates by using a voltage-

controlled current source to force a fixed voltage to appear at the regulator output

terminal. Series every electronic circuit is designed to operate off of some supply

voltage, which is usually assumed to be constant. A voltage regulator provides this

constant DC output voltage and contains circuitry that continuously holds the output

voltage at the design value regardless of changes in load current or input voltage (this

assumes that the load current and input voltage are within the specified operating

range for the part).

Voltage regulators are available in a variety of outputs, typically 5

volts, 9 volts and 12 volts. The last two digits in the name indicate the output voltage.

The "LM78XX" series of voltage regulators are designed for positive input. For

applications requiring negative input the "LM79XX" is used.


76







Name Voltage

LM7805 + 5 volts

LM7809 + 9 volts

LM7812 + 12 volts

LM7905 - 5 volts

LM7909 - 9 volts

LM7912 - 12 volts

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LIQUID CRYSTAL DISPLAY

A liquid crystal display (LCD) is a thin, flat display device made up of any

number of color or monochrome pixels arrayed in front of a light source or reflector. Each

pixel consists of a column of liquid crystal molecules suspended between two transparent

electrodes, and two polarizing filters, the axes of polarity of which are perpendicular to

each other. Without the liquid crystals between them, light passing through one would be

blocked by the other. The liquid crystal twists the polarization of light entering one filter

to allow it to pass through the other.

Many microcontroller devices use 'smart LCD' displays to output visual

information. LCD displays designed around Hitachi's LCD HD44780 module, are

inexpensive, easy to use, and it is even possible to produce a readout using the 8x80

pixels of the display. They have a standard ASCII set of characters and mathematical

symbols.

For an 8-bit data bus, the display requires a +5V supply plus 11 I/O lines. For a 4-

bit data bus it only requires the supply lines plus seven extra lines. When the LCD display

is not enabled, data lines are tri-state and they do not interfere with the operation of the

microcontroller.

Data can be placed at any location on the LCD. For 16×2 LCD, the address locations are:

Address locations for a 2x16 line LCD

SIGNALS TO THE LCD

The LCD also requires 3 control lines from the microcontroller:

1) Enable (E)

This line allows access to the display through R/W and RS lines. When this line is low,

the LCD is disabled and ignores signals from R/W and RS. When (E) line is high, the

LCD checks the state of the two control lines and responds accordingly.

2) Read/Write (R/W)


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This line determines the direction of data between the LCD and microcontroller. When it

is low, data is written to the LCD. When it is high, data is read from the LCD.

3) Register select (RS)

With the help of this line, the LCD interprets the type of data on data lines. When it is

low, an instruction is being written to the LCD. When it is high, a character is being

written to the LCD.

Logic status on control lines:

• E - 0 Access to LCD disabled

- 1 Access to LCD enabled

• R/W - 0 Writing data to LCD

- 1 Reading data from LCD

• RS - 0 Instructions

- 1 Character

Writing and reading the data from the LCD:

Writing data to the LCD is done in several steps:

1) Set R/W bit to low

2) Set RS bit to logic 0 or 1 (instruction or character)

3) Set data to data lines (if it is writing)

4) Set E line to high

5) Set E line to low

Read data from data lines (if it is reading):

1) Set R/W bit to high

2) Set RS bit to logic 0 or 1 (instruction or character)

3) Set data to data lines (if it is writing)

4) Set E line to high

5) Set E line to low

PIN DESCRIPTION

Most LCDs with 1 controller has 14 Pins and LCDs with 2 controller has 16 Pins

(Two pins are extra in both for back-light LED connections).


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Pin diagram of 2x16 line LCD

Pin description of the LCD


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BUZZER:

A buzzer or beeper is a signaling device, usually electronic, typically used in

automobiles, household appliances such as a microwave oven, or game shows. It most

commonly consists of a number of switches or sensors 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 a cheap 8-ohm speaker. Nowadays, it is more popular to use a ceramic-

based piezoelectric sounder like a Sonalert 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.

Electronic symbol for buzzer.


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http://en.wikipedia.org/wiki/Electronic_symbol

http://en.wikipedia.org/wiki/Piezoelectric

http://en.wikipedia.org/wiki/Electric_bell

http://en.wikipedia.org/wiki/Sound


http://en.wikipedia.org/wiki/Switch

http://en.wikipedia.org/wiki/Game_show

http://en.wikipedia.org/wiki/Microwave_oven

http://en.wikipedia.org/wiki/Automobile

http://en.wikipedia.org/wiki/File:Buzzer-IEC-Symbol.svg

http://en.wikipedia.org/wiki/File:2007-07-24_Piezoelectric_buzzer.jpg


Metal disk with piezoelectric disk attached, as found in a buzzer

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 buzzer buttons which are identified as "plungers".

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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MATRIX KEYPAD

Keyboards and LCDs are the most widely used input/output devices of the 8051, and

a basic understanding of them is essential. In this section, we first discuss keyboard

fundamentals, along with key press and key detection mechanisms, Then we show

how a keyboard is interfaced to an 8051.

Interfacing the Keyboard to the 8051

At the lowest level, keyboards are organized in a matrix of rows and columns. The

CPU accesses both rows and column through ports; therefore, with two 8-bit ports, an

8*8 matrix of keys can be connected to a microprocessor. When a key pressed, a row

and column make a connect; otherwise, there is no connection between row and

column. In IBM PC keyboards, a single micro controller (consisting of

microprocessor, RAM and EPROM, and several ports all on a single chip) takes care

of software and hardware interfacing of keyboard. In such systems it is the function of

programs stored in the EPROM of micro controller to scan the keys continuously,

identify which one has been activated, and present it to the motherboard. In this

section we look at the mechanism by which the 8051 scans and identifies the key.

Scanning and identifying the key

Figure13.5 shows a 4*4 matrix connected to two ports. The rows are connected to an

output port and the columns are connected to an input port. If no key has been

pressed, reading the input port will yield 1s for all columns since they are all

connected to high (Vcc) If all the rows are grounded and a key is pressed, one of the

columns will have 0 since the key pressed provides the path to ground. It is the


83






function of the micro controller to scan the keyboard continuously to detect and

identify the key pressed. How it is done is explained next.

Grounding rows and reading columns

To detect a pressed key, the micro controller grounds all rows by providing 0 to the

output latch, and then it reads the columns. If the data read from the columns is D3-

D0=1111, no key has been pressed and the process continues until a key press is

detected. However, if one of the column bits has a zero, this means that a key press

has occurred. For example, if D3-D0=1101, this means that a key in the D1 column

has been pressed. After a key press is detected, the micro controller will go through

the process of identifying the key. Starting with the top row, the micro controller

grounds it by providing a low to row D0 only; then it reads the columns. If the data

read is all1s, no key in that row is activated and the process is moved to the next row.


84






It grounds the next row, reads the columns, and checks for any zero. This process

continues until the row is identified. After identification of the row in which the key

has been pressed, the next task is to find out which column the pressed key belongs to.

This should be easy since the microcontroller knows at any time which row and

column are being accessed.

Assembly language program for detection and identification of key activation is given

below. In this program, it is assumed that P1 and P2 are initialized as output and

input, respectively. Program13.1 goes through the following four major stages:

1. To make sure that the preceding key has been released, 0s are output to all rows at

once, and the columns are read and checked repeatedly until all the columns are high.

When all columns are found to be high, the program waits for a short amount of time

before it goes to the next stage of waiting for a key to be pressed.

2) To see if any key is pressed, the columns are scanned over and over in an infinite

loop until one of them has a 0 on it. Remember that the output latches connected to

rows still have their initial zeros (provided in stage 1), making them grounded. After

the key press detection, it waits 20ms for the bounce and then scans the columns

again. This serves two functions: (a) it ensures that the first key press detection was

not an erroneous one due to spike noise, and(b) the 20ms delay prevents the same key

press from being interpreted as a multiple key press. If after the 20-ms delay the key

is still pressed, it goes to the next stage to detect which row it belongs to; otherwise, it

goes back into the loop to detect a real key press

3) To detect which row the key press belongs to, it grounds one row at a time,

reading the columns each time. If it finds that all columns are high, this means that the

key press cannot belong to that row; therefore, it grounds the next row and continues

until it finds the row the key press belongs to. Upon finding the row that the key press

belongs to, it sets up the starting address for the look-up table holding the scan codes

(or the ASCII value) for that row and goes to the next stage to identify the key.


85






4) To identify the key press, it rotates the column bits, one bit at a time, into the

carry flag and checks to see if it is low. Upon finding the zero, it pulls out the ASCII

code for that key from the look-up table; Otherwise, it increments the pointer to point

to the next element of the look-up table.

While the key press detection is standard for all keyboards, the process for

determining which key is pressed varies. The look-up table method shown in program

can be modified to work with any matrix up to 8*8.

There are IC chips such as National Semiconductors MM74C923 that incorporate

keyboard scanning and decoding all in one chip. Such chips use combinations of

counters and logic gates (No micro controller).

KEYPAD:

The keypad is the most widely used input device for microcontroller. Here we

are having two different sets of keypads one for entering the password and the other

for electing a person.

Any way here we are using a momentary NO switch which is open by default. When

ever we are pressing a key the concerned circuit will be closed and the resultant value

will be read by microcontroller and depends on our program the controller will takes

the further actions.

Schematic of momentary NO switch


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LOCKER SYSTEM:

DC Motor

DC motors are configured in many types and sizes, including brush

less, servo, and gear motor types. A motor consists of a rotor and a permanent

magnetic field stator. The magnetic field is maintained using either permanent

magnets or electromagnetic windings. DC motors are most commonly used in

variable speed and torque.

Motion and controls cover a wide range of components that in some

way are used to generate and/or control motion. Areas within this category include

bearings and bushings, clutches and brakes, controls and drives, drive components,

encoders and resolves, Integrated motion control, limit switches, linear actuators,

linear and rotary motion components, linear position sensing, motors (both AC and

DC motors), orientation position sensing, pneumatics and pneumatic components,

positioning stages, slides and guides, power transmission (mechanical), seals, slip

rings,solenoids,springs.

Motors are the devices that provide the actual speed and torque in a

drive system. This family includes AC motor types (single and multiphase motors,

universal, servo motors, induction, synchronous, and gear motor) and DC motors

(brush less, servo motor, and gear motor) as well as linear, stepper and air motors, and

motor contactors and starters.

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

A current-carrying conductor generates a magnetic field; when this is then placed in

an external magnetic field, it will experience a force proportional to the current in the www.1000projects.comwww.fullinterview.comwww.chetanasprojects.com

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http://encyclobeamia.solarbotics.net/articles/current.html


http://dc-motors.globalspec.com/Industrial-Directory/motor

http://dc-motors.globalspec.com/Industrial-Directory/motors













conductor, and to the strength of the external magnetic field. As you are well aware of

from playing with magnets as a kid, opposite (North and South) polarities attract,

while like polarities (North and North, South and South) repel. The internal

configuration of a DC motor is designed to harness the magnetic interaction between

a current-carrying conductor and an external magnetic field to generate rotational

motion.

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

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

magnet or winding with a "South" polarization).

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

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

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

magnets1. The stator is the stationary part of the motor -- this includes the motor

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

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

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

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

inside the stator (field) magnets.

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

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

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

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

commutator contacts, and energize the next winding. Given our example two-pole www.1000projects.comwww.fullinterview.comwww.chetanasprojects.com

88





http://encyclobeamia.solarbotics.net/articles/dc.html





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

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

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

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

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

exactly at the middle of its rotation (perfectly aligned with the field magnets), it will

get "stuck" there. Meanwhile, with a two-pole motor, there is a moment where the

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

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

damage motor components as well. Yet another disadvantage of such a simple motor

is that it would exhibit a high amount of torque” ripple" (the amount of torque it could

produce is cyclic with the position of the rotor).

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

the workings of one via an interactive animation (JavaScript required):

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

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


89







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

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

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

result of the coil windings' series wiring:

There's probably no better way to see how an average dc motor is put together,

than by just opening one up. Unfortunately this is tedious work, as well as requiring

the destruction of a perfectly good motor. This is a basic 3-pole dc motor, with 2

brushes and three commutator contacts.


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H-BRIDGE:

DC motors are typically controlled by using a transistor

configuration called an "H-bridge". This consists of a minimum of four mechanical or

solid-state switches, such as two NPN and two PNP transistors. One NPN and one

PNP transistor are activated at a time. Both NPN and PNP transistors can be activated


91





http://en.wikipedia.org/wiki/H-bridge


to cause a short across the motor terminals, which can be useful for slowing down the

motor from the back EMF it creates.

Basic Theory

H-bridge. Sometimes called a "full bridge" the H-bridge is so named because it has

four switching elements at the "corners" of the H and the motor forms the cross bar.

The key fact to note is that there are, in theory, four switching elements within the

bridge. These four elements are often called, high side left, high side right, low side

right, and low side left (when traversing in clockwise order).

The switches are turned on in pairs, either high left and lower right, or lower left and

high right, but never both switches on the same "side" of the bridge. If both switches

on one side of a bridge are turned on it creates a short circuit between the battery plus

and battery minus terminals. If the bridge is sufficiently powerful it will absorb that

load and your batteries will simply drain quickly. Usually however the switches in

question melt.

To power the motor, you turn on two switches that are diagonally opposed. In the

picture to the right, imagine that the high side left and low side right switches are

turned on.

The current flows and the motor begins to turn in a "positive" direction. Turn on the

high side right and low side left switches, then Current flows the other direction

through the motor and the motor turns in the opposite direction.

Actually it is just that simple, the tricky part comes in when you decide what to use

for switches. Anything that can carry a current will work, from four SPST switches,

one DPDT switch, relays, transistors, to enhancement mode power MOSFETs.

One more topic in the basic theory section, quadrants. If each switch can be controlled

independently then you can do some interesting things with the bridge, some folks


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http://en.wikipedia.org/wiki/Electromotive_force


call such a bridge a "four quadrant device" (4QD get it?). If you built it out of a single

DPDT relay, you can really only control forward or reverse. You can build a small

truth table that tells you for each of the switch's states, what the bridge will do. As

each switch has one of two states, and there are four switches, there are 16 possible

states. However, since any state that turns both switches on one side on is "bad"

(smoke issues forth: P), there are in fact only four useful states (the four quadrants)

where the transistors are turned on.

High Side Left High Side Right Low Side Left Low Side Right Quadrant Description

On Off Off On Forward Running

Off On On Off Backward Running

On On Off Off Braking

Off Off On On Braking

The last two rows describe a maneuver where you "short circuit" the motor which

causes the motors generator effect to work against itself. The turning motor generates

a voltage which tries to force the motor to turn the opposite direction. This causes the

motor to rapidly stop spinning and is called "braking" on a lot of H-bridge designs.

Of course there is also the state where all the transistors are turned off. In this case the

motor coasts freely if it was spinning and does nothing if it was doing nothing.

Implementation

1. Using Relays:


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A simple implementation of an H Bridge using four SPST relays is shown.

Terminal A is High Side Left, Terminal B is High Side Right, Terminal C is

Low Side Left and Terminal D is Low Side Right. The logic followed is

according to the table above.

Warning: Never turn on A and C or B and D at the same time. This will lead

to a short circuit of the battery and will lead to failure of the relays due to the

large current.

2. Using Transistors:

We can better control our motor by using transistors or Field Effect

Transistors (FETs). Most of what we have discussed about the relays H-Bridge

is true of these circuits. See the diagram showing how they are connected. You

should add diodes across the transistors to catch the back voltage that is

generated by the motor's coil when the power is switched on and off. This fly

back voltage can be many times higher than the supply voltage!

For information on building an H-Bridge using Transistors, have a look here.


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http://www.mcmanis.com/chuck/robotics/tutorial/h-bridge/bjt-bridge.html


Warning: If you don't use diodes, you could burn out your transistors. Also the

same warning as in the diode case. Don't turn on A and C or B and D at the

same time.

Transistors, being a semiconductor device, will have some resistance, which

causes them to get hot when conducting much current. This is called not being

able to sink or source very much power, i.e.: Not able to provide much current

from ground or from plus voltage.

Mosfets are much more efficient, they can provide much more current and not

get as hot. They usually have the fly back diodes built in so you don't need the

diodes anymore. This helps guard against fly back voltage frying your ICs.

To use Mosfets in an H-Bridge, you need P-Channel Mosfets on top because

they can "source" power, and N-Channel Mosfets on the bottom because then

can "sink" power.

It is important that the four quadrants of the H-Bridge circuits be turned on

and off properly. When there is a path between the positive and ground side of

the H-Bridge, other than through the motor, a condition exists called "shoot

through". This is basically a direct short of the power supply and can cause

semiconductors to become ballistic, in circuits with large currents flowing.

There are H-bridge chips available that are much easier, and safer, to use than

designing your own H-Bridge circuit.


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CIRCUIT DESCRIPTION

This section describes the flow of the project from time to time and the

internal operation of the circuit.

Up on the power on, the microcontroller initializes the finger print

module, LCD, keypad, and the Locker system to their initial states as

stated in the program which is loaded into the microcontroller.

Before starting the actual operation here we have to specify the mode

which we are using like ATM or Locker or for PASSPORT

verification.

After pressing any one of the keys specified the controller initializes to

that particular mode.

In any one of the modes, the FP module is waiting for a finger print to

be scanned and when we place the finger and press the scan key a low

logic will be read by that pin and controller starts comparison among

the finger prints available in the data base with the present finger print.

ATM mode: If the match found then the controller enables the matrix

keypad which further enables the process of transactions

During each key press the concerned port pin of the controller reads a

logic low signal to indicate a particular operation as specified.

If any one of he option key like DEPOSIT, WITHDRAW, MINI,

pressed the concerned data will automatically stored in the external


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memory through the SDA line through which controller is going to

access the information of the users.

Locker mode: If the match found then the controller enables the

matrix keypad which further enables the locker system operation.

PASSPORT verification: If the match found then the controller gets

the information of the particular person and will be displayed on the

LCD.

If the match not found in the data base then the keypad and the locker

are remain in the disabled state and it will be indicated.

All these process while transactions or any fault will be displayed on

the LCD to which microcontroller sends the data through the data lines

(D0 – D7).


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SOFTWARE CONCEPTS:

The software used for this project is:

KEIL IDE

EXPRESS SCH

Embedded C

KEIL IDE:


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Keil uVision is what the software we are using for the programming. In this software

editor we are writing the program in any of the languages like ASM or Embedded C.

µVision3 Overview

The µVision3 IDE is a Windows-based software development platform that combines

a robust editor, project manager, and makes facility. µVision3 integrates all tools

including the C compiler, macro assembler, linker/locator, and HEX file generator.

µVision3 helps expedite the development process of your embedded applications by

providing the following:

Full-featured source code editor,

Device database for configuring the development tool setting,

Project manager for creating and maintaining your projects,

Integrated make facility for assembling, compiling, and linking your

embedded applications,

Dialogs for all development tool settings,

True integrated source-level Debugger with high-speed CPU and peripheral

simulator,

Advanced GDI interface for software debugging in the target hardware and for

connection to Keil ULINK,

Flash programming utility for downloading the application program into Flash

ROM,

Links to development tools manuals, device datasheets & user’s guides.

The µVision3 IDE offers numerous features and advantages that help you quickly and

successfully develop embedded applications. They are easy to use and are guaranteed

to help you achieve your design goals.

Features:


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The µVision3 Simulator is the only debugger that completely simulates all

on-chip peripherals

The µVision3 Device Database automatically configures the development

tools for the target microcontroller.

Identical Target Debugger and Simulator User Interface.

µVision3 incorporates project manager, editor, and debugger in a single

environment.

Benefits:

Write and test application code before production hardware is available.

Investigate different hardware configurations to optimize the hardware design.

Sophisticated systems can be accurately simulated by adding your own

peripheral drivers.

Mistakes in tool settings are practically eliminated and tool configuration time

is minimized.

The same tool can be used for debugging and programming. No extra

configuration time required.

Accelerates application development. While editing, you may configure

debugger features. While debugging, you may make source code

modifications.

Steps to Create a PROJECT:


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µVision3 includes a project manager which makes it easy to design

applications for an ARM based microcontroller. You need to perform the following

steps to create a new project:

Select the Toolset (only required for ARM Projects).

Create Project File and Select CPU.

Project Workspace - Books.

Create New Source Files.

Add Source Files to the Project.

Create File Groups.

Set Tool Options for Target Hardware.

Configure the CPU Startup Code.

Build Project and Generate Application Program Code.

Create a HEX File for PROM Programming.

The detailed description to create a project will be discussed with snap shots below

for better understanding the tool.

SOURCE CODE

1. Click on the Keil uVision Icon on Desktop

2. The following fig will appear


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ms-its:C:%5CKeil%5CC51%5CHLP%5Cuv3.chm::/UV3_3_CreateHexFile.htm

ms-its:C:%5CKeil%5CC51%5CHLP%5Cuv3.chm::/UV3_3_BuildProject.htm

ms-its:C:%5CKeil%5CC51%5CHLP%5Cuv3.chm::/UV3_3_Config_Start_Code.htm

ms-its:C:%5CKeil%5CC51%5CHLP%5Cuv3.chm::/UV3_3_Tool_Options.htm

ms-its:C:%5CKeil%5CC51%5CHLP%5Cuv3.chm::/UV3_3_Create_File_Groups.htm

ms-its:C:%5CKeil%5CC51%5CHLP%5Cuv3.chm::/UV3_3_SourceFiles.htm

ms-its:C:%5CKeil%5CC51%5CHLP%5Cuv3.chm::/UV3_3_Create%20_Source_File.htm

ms-its:C:%5CKeil%5CC51%5CHLP%5Cuv3.chm::/UV3_3_BooksTab.htm

ms-its:C:%5CKeil%5CC51%5CHLP%5Cuv3.chm::/UV3_3_CreatePrjFile.htm

ms-its:C:%5CKeil%5CC51%5CHLP%5Cuv3.chm::/UV3_3_ARMToolset.htm


3. Click on the Project menu from the title bar

4. Then Click on New Project

5. Save the Project by typing suitable project name with no extension in u r

own folder sited in either C:\ or D:\


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6. Then Click on Save button above.

7. Select the component for u r project. i.e. Atmel……

8. Click on the + Symbol beside of Atmel


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9. Select AT89C51 as shown below

10. Then Click on “OK”

11. The Following fig will appear

12. Then Click either YES or NO………mostly “NO”www.1000projects.comwww.fullinterview.comwww.chetanasprojects.com

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13. Now your project is ready to USE

14. Now double click on the Target1, you would get another option “Source

group 1” as shown in next page.

15. Click on the file option from menu bar and select “new”


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16. The next screen will be as shown in next page, and just maximize it by

double clicking on its blue boarder.

17. Now start writing program in either in “C” or “ASM”

18. For a program written in Assembly, then save it with extension “. asm”

and for “C” based program save it with extension “ .C”


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19. Now right click on Source group 1 and click on “Add files to Group

Source”


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20. Now you will get another window, on which by default “C” files will

appear.

21. Now select as per your file extension given while saving the file

22. Click only one time on option “ADD”

23. Now Press function key F7 to compile. Any error will appear if so happen.


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24. If the file contains no error, then press Control+F5 simultaneously.

25. The new window is as follows

26. Then Click “OK”


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27. Now Click on the Peripherals from menu bar, and check your required port

as shown in fig below

28. Drag the port a side and click in the program file.

29. Now keep Pressing function key “F11” slowly and observe.

30. You are running your program successfully


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EXPRESS SCH:Express PCB is the software tool which consists two functionalities one regarding the

Circuit designing and the other for PCB designing.

Here we are using Express SCH for designing the circuit regarding the project.

Take a few minutes to acquaint yourself with the Express SCH program's display.

You will notice that there are two toolbars, one along the top and another along the

left side. At the bottom of the display is a status bar.

Drawing a Schematic

Express SCH is a very easy to use Windows application for drawing schematics.

While not required, we suggest that you draw a schematic for your circuit before

designing the PC board. By linking the schematic to the PCB, you will save time

designing and be less likely to make mistakes. You will also discover that the user

interface for Express SCH and Express PCB is so similar that after spending the few

minutes to learn one, the other will already be familiar.


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Embedded C:

What is an embedded system?

An embedded system is an application that contains at least one programmable

computer and which is used by individuals who are, in the main, unaware that the

system is computer-based.

Which programming language should you use?

Having decided to use an 8051 processor as the basis of your embedded system,

the next key decision that needs to be made is the choice of programming language. In

order to identify a suitable language for embedded systems, we might begin by

making the following observations:

Computers (such as microcontroller, microprocessor or DSP chips) only

accept instructions in ‘machine code’ (‘object codes’). Machine code is, by

definition, in the language of the computer, rather than that of the

programmer. Interpretation of the code by the programmer is difficult and

error prone.

All software, whether in assembly, C, C++, Java or Ada must ultimately be

translated into machine code in order to be executed by the computer.

Embedded processors – like the 8051 – have limited processor power and very

limited memory available: the language used must be efficient.

The language chosen should be in common use.

Summary of C language Features:

It is ‘mid-level’, with ‘high-level’ features (such as support for functions and

modules), and ‘low-level’ features (such as good access to hardware via pointers).

It is very efficient.


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It is popular and well understood.

Even desktop developers who have used only Java or C++ can soon

understand C syntax.

Good, well-proven compilers are available for every embedded processor (8-

bit to 32-bit or more).

Basic C program structure:

//- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

//Basic blank C program that does nothing

// Includes

//- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

#include <reg51.h> // SFR declarations

Void main (void)

{

While (1);

{

Body of the loop // Infinite loop

}

} // match the braces


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RESULT

After selecting the mode of operation, the optical sensor takes the finger print and

compares with the previously stored database. If the present finger prints matches

with any one of the previously stored data then the controller sends a signal to enable

the keypad.

For each key press a low logic value will be present at the concerned pin of the

microcontroller and by reading this value the controller will do the further actions as

specified in the program. The concerned transaction by the user is loaded in the

external memory in this case what we are using is EEPROM of 2K bytes at a

particular location in the memory.

All these functions which are performed by the user are simultaneously

displayed on the LCD. In case any of the finger print is not matched with the data the

Locker system is not opened and the Keypad is not enabled at all by giving the

indication in the form of buzzer.


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SCOPE FOR FURTHER DEVELOPMENT

1. The performance of the system can be further improved in terms of operating

speed, memory capacity by using the advanced controllers.

2. The storage memory of the particular user can be increased by interfacing the

controller to the PC for all these transactions.

3. The device can be made to perform better by providing the power supply with

the help of Battery to reduce the requirement of main AC supply.

4. A speaking voice alarm used to indicate the unauthorized person accessing the

ATM and the Locker system and to indicate the wrong Passport.

5. The system can be made to communicate with modems or mobile phones to

alert the user on every transaction in the ATM mode and to alert the

authorities in the Passport verification mode.


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CONCLUSION

A step by step approach in designing the microcontroller based system for securing

the transactions of the user and providing the security for the locker system and even

more for the PASSPORT verification using a finger print scanner has been followed.

The result obtained in providing the security is quite reliable in all the three modes.

The system has successfully overcome some of the aspects existing with the present

technologies, by the use of finger print Biometric as the authentication Technology.


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Bibliography

The 8051 Micro controller and Embedded Systems

-Muhammad Ali Mazidi

Janice Gillispie Mazidi

The 8051 Micro controller Architecture, Programming & Applications

-Kenneth J.Ayala

Fundamentals Of Micro processors and Micro computers

-B.Ram

Micro processor Architecture, Programming & Applications

-Ramesh S. Gaonkar

Electronic Components


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-D.V. Prasad

WEB Resources:

www.atmel.com

www.8051projects.com

www.microsoftsearch.com

www.geocities.com

www.alldatasheet.com

www.bioenable.com


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http://www.alldatasheet.com/

http://www.geocities.com/

http://www.microsoftsearch.com/

http://www.atmel.com/

41Finger Print Based ATM and Locker System

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