Ambulance traffic controllerDOCUMENTS

ABSTRACT

This project deals with the control of traffic for an ambulance, it analyses the

number of vehicles passing in every track in order to the intelligent for existing

traffic light controller and through GSM it sends message to the user. In the present,

it is seen that lot of time is getting wasted due to fixed time limit which is flexible in

lanes with more traffic density and also it is problem for emergency cases like

ambulance. Due to wastage of time there may be loss. Now by this project we can

save time of the people by continuously monitoring the vehicles passing on the

road. This monitoring is done thought 24 hours in a timeslot of 15 to 30 s after

every time slot.

The monitoring task is performed by based on the IR sensors. IR Transmitter

is placed over the ambulance. IR Receivers placed in four sides of traffic lights.

When the vehicle crosses the target location the receiver receives IR signal it will

interrupt the Micro controller and it stop all Green signals and on Red signals at the

same time it will on green signal at the ambulance side to allow the ambulance to

move without waiting in signals. After ambulance gone microcontroller reset and

works in normal function. Also these IR pairs linked to the GSM modem sends a

message to the user about the density of the traffic on respected sides.

Title of the project : Microcontroller based intelligent ambulance

traffic controller and Navigation

Domain : Embedded Systems Design

Software : Embedded C, Keil c,

Microcontroller : AT89c52

Power Supply : +5V, 500mA Regulated Power Supply

Display : LED 5mm, 16 X 2 LCD

Crystal : 11.0592MHz

Communication Device : IR sensors, GSM modem

Applications : Traffic Signals

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CONTENTS

Chapters

1. Introduction

2. Overview Embedded Systems

2.1 What Is System?

2.2 Embedded System

2.3 Life Cycle

2.4 Software Design and Working of Embedded Systems

3. Block diagram and its brief description

3.1 Block Diagrams

3.2 Circuit description

3.3IC’s

3.31 AT 89c52

3.32 ULN 2008

3.33 555 Timer

3.4 Infrared led’s

3.5 Power supply description

3.6 Transistors

3.7 Resistors & Capacitor

4. Software Description and Project Code

4.1 Software Description

4.2 Project Code

5.Advantages & Limitations

6. Applications

7. Conclusion and further scope

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Introduction

This project deals with the control of traffic for an ambulance, it analyses the

number of vehicles passing in every track in order to the intelligent for existing

traffic light controller and sending message to the user. In the present, it is seen that

lot of time is getting wasted due to fixed time limit which is flexible in lanes with

more traffic density and also it is problem for emergency cases like ambulance. Due

to wastage of time there may be loss. Now by this project we can save time of the

people by continuously monitoring the vehicles passing on the road. This

monitoring is done thought 24 hours in a timeslot of 15 to 30 s after every time slot.

The monitoring task is performed by based on the IR sensors. IR Transmitter

is placed over the ambulance. IR Receivers placed in four sides of traffic lights.

When the vehicle crosses the target location the receiver receives IR signal it will

interrupt the Micro controller and it stop all Green signals and on Red signals at the

same time it will on green signal at the ambulance side to allow the ambulance to

move without waiting in signals. After ambulance gone microcontroller reset and

works in normal function.

Title of the project : Microcontroller based intelligent ambulance

traffic controller.

Domain : Embedded Systems Design

Software : Embedded C, Keil c,

Microcontroller : AT89c52

Power Supply : +5V, 500mA Regulated Power Supply

Display : LED 5mm, 16 X 2 LCD

Crystal : 11.0592MHz

Communication Device : IR sensors & GSM modem

Applications : Traffic Signals,

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Overview Embedded Systems

2.1 What Is A System?

A Systems Is Something That Maintains Its Existence And Functions

As A Whole Through The Interaction Of Its Parts. E.G. Body, Mankind, Access

Control, Etc

A System Is A Part Of The World That A Person Or Group Of Persons

During Some Time Interval And For Some Purpose Choose To Regard As A

Whole, Consisting Of Interrelated Components, Each Component Characterized By

Properties That Are Selected As Being Relevant To The Purpose.

System Constituents

2.2 Embedded System:

We Can Define An Embedded System As “A Computing Device, Built In

To A Device That Is Not A Computer, And Meant For Doing Specific Computing

Tasks”.

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An Embedded System Is A Special-Purpose Computer System Usually Built Into A

Environment Connected To Systems Through Sensors , Actuators And Other I/O

Interfaces.Embedded System Must Meet Timing & Other Constraints Imposed On

It By Environment

Typical Embedded System

Technically, There Are Prevalent And Common Characteristics Of

Embedded Systems. From A Programmer's Perspective The Following Components

Are Minimum: Central Processing Unit (Cpu), Random Access Memory (Ram),

Programmable Read Only Memory (Prom) Or Erasable Prom (Eprom), And

Input/Output (I/O) Space.

Micro-Processor:

The Cpu Is A Unit That Centrally Fetches And Processes A Set Of General

Purpose Instructions. The Cpu Instruction Set Includes Instructions For Data

Transfer Operations, Alu Operations, Stack Operations, I/P &O/P Operations And

Program Control Sequencing And Supervising Operations. Any Cpu Must Process

The Following Basic Functionality Units:

1. A Control Unit To Fetch And Control The Sequential Processing Of Given

Commands Or Instruction And For Communicating With The Rest Of The System.

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2. An Alu For The Arithmetic And Logic Operations On The Bytes Or Words. It

May Be Capable Of Processing 8,16,32or 64-Bit Words At An Instant.

3. A Microprocessor Is A Single Vlsi Chip That Has A Chip And May Also Have

Some Other Units That Are Additionally Present And That Result In Faster

Processing Of Instructions.

Microcontroller:

A Microcontroller Is A Single Chip Vlsi Unit (Also Called Microcomputer)

Which Though Having Limited Computational Capabilities Posses An Enhanced

I/P, O/P Capabilities And A Number Of On-Chip Functional Units Micro-

Controllers Are Particularly Suited For Use In Embedded Systems For Real Time

Applications With On-Chip Program Memory And Devices.

2.3 Life Cycle

Requirements

Finalize the Functional Requirement of the System That Has To Be Implemented

Analysis:

Analyze the Requirements and Finalise the System Requirements

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Design:

Based On The Requirements Design The System.

Hardware :

Proteus

Software

Implementation:

Based On The Hardware Design Make The Layout Of The Pcb And Design The

Routing

Get The Pcb Fabricated

Mount The Components On To The Pcb

Programming:

Use The Designated Tools For Programming The Microcontroller Or Processor

Whichever Is Selected

Atmel

Kiel ‘C’- Compiler

Uc Flash Programmer

Microchip :

Mplab Ide

Icd2

Atmel

GSM

Jtag / Flash Programmer

Testing/Debugging:

Hardware Debugging

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Software Debugging

Functionality Test

Packaging/Implementation

Mount The Module Into The Designed Enclosure

Install The Designed System In The Required Application Area

The Essence

An Embedded

System Is A

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Microcontroller-Based, Software Driven, Reliable, Real-Time Control System,

Autonomous, Or Human Or Network Interactive, Operating On Diverse Physical

Variables And In Diverse Environments And Sold Into A Competitive And Cost

Conscious Market.

2.4 Software Design and Working of Embedded Systems:

In The Design Of The Software, It Simply Has A Loop Called

Control Loop. The Loop Calls Subroutines. Each Subroutine Manages A Part Of

The Hardware Or Software. Interrupts Generally Set Flags, Or Update Counters

That Are Read By The Rest Of The Software.

A Simple Api Disables And Enables Interrupts. Done Right, It Handles Nested

Calls In Nested Subroutines, And Restores The Preceding Interrupt State In The

Outermost Enable. This Is One Of The Simplest Methods Of Creating An

Exokernel. There Is Some Sort Of Subroutine In The Loop To Manage A List Of

Software Timers, Using A Periodic Real Time Interrupt. When A

Timer Expires, An Associated Subroutine Is Run, Or Flag Is Set. Any Expected

Hardware Event Should Be Backed-Up With A Software Timer.

Hardware Events Fail About Once In A Trillion Times. State Machines May Be

Implemented With A Function-Pointer Per State-Machine (In C++, C Or Assembly,

Anyway). A Change Of State Stores A Different Function Into The Pointer. The

Function Pointer Is Executed Every Time The Loop Runs. Many Designers Read

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Each Io Device Once Per Loop, And Storing The Result So The Logic Acts On

Consistent Values.

3.1BLOCK DIAGRAM

BLOCK DIAGRAM FOR TRAFFIC CONTROLLER By

AMBULANCE

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3.2Circuitdiagrams

3.2.1 Power Supply Circuit:

3.2.2 Control Circuit:

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3.2.3 IR Tx CKT

3.2.4 IR Rx CKT

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3.2.5 WORKING:

The working of the circuit mainly comprises of four sections. They are:

1. Power Supply Circuit

2. Control Circuit

3. IR Transmitter

4. IR Receiver

1. Regulated Power Supply:

The power supply circuit comprises of a Transformer, Rectifier,

Filter (Smoothing) & Regulator.

The Transformer used is a 12v, 1A step-down transformer which is used

for reducing the single phase AC supply of 230v to 12v. This is done so

because the rectifier which we are using cannot withstand for such high

currents and voltages.

The Rectifier comprises of four diodes which is called as full wave bridge

rectifier. A rectifier is a device, which consists of diodes, is used for

converting alternating current into direct current.

The filter section comprises of a Capacitor which is used for reducing the

harmonics/ripple content present if any in the circuit after rectification

process. This is done so because the output of rectifier is pulsating DC.

A voltage regulator is an electrical regulator designed to automatically

maintain a constant voltage level.

2. Control Circuit:

The control circuit comprises of a microcontroller, relay driver and LED’s,

max232 and GSM. The microcontroller is the heart of the circuit. This

takes the inputs and gives the respective output according to the

command given to it.

The input from the controller comes from IR receiver circuit. According to

the input the controller activates the relays through relay driver. And

hence for the information to be given to the person/ambulance is done

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by making automatically ON of Lights and sending a message to the

respective person about the intensity of traffic through GSM.

The message is sent through GSM via serial communication i.e.;max232.

This follows a protocol called as RS232 through which serial

communication between devices is done. Accordingly as per the

intensity of the traffic on respective side , the GSM modem sends a

message to the user.

When the ambulance is arriving at a signal, the green light is given

automatically through the communication between IR transmitter and IR

receiver. When the communication between IR transmitter and receiver

is going on then there will be green signal given automatically as the

transmitter circuit is connected to the microcontroller.

3. IR Transmitter:

The supply to the transmitter is given through a 9v battery.

The transmitter circuit consists of 555 timer and IR transmitter.

The IR transmitter continuously transmits the rays.

The 555 timer will be astable mode of operation.

4. IR Receiver:

The supply to the transmitter is given through a 9v battery.

The receiver circuit consists of 555 timer and IR receiver.

The IR receiver continuously checks out for the IR transmitter rays.

The 555 timer will be monostable mode of operation.

When these rays are detected by the IR receiver, then the signal is passed

to microcontroller and then the controller makes the necessary action to

be taken i.e., it will make green lights ON and leaves the traffic of that

particular side where ambulance is present.

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3.31MICRO CONTROLLERS(AT89c52)

Microprocessors vs. Microcontrollers:

• Microprocessors are single-chip CPUs used in microcomputers.

• Microcontrollers and microprocessors are different in three main aspects:

hardware architecture, applications, and instruction set features.

• Hardware architecture: A microprocessor is a single chip CPU while a

microcontroller is a single IC contains a CPU and much of remaining circuitry of a

complete computer (e.g., RAM, ROM, serial interface, parallel interface, timer,

interrupt handling circuit).

• Applications: Microprocessors are commonly used as a CPU in computers while

microcontrollers are found in small, minimum component designs performing

control oriented activities.

• Microprocessor instruction sets are processing Intensive.

• Their instructions operate on nibbles, bytes, words, or even double words.

• Addressing modes provide access to large arrays of data using pointers and

offsets.

• They have instructions to set and clear individual bits and perform bit operations.

• They have instructions for input/output operations, event timing, enabling and

setting priority levels for interrupts caused by external stimuli.

• Processing power of a microcontroller is much less than a microprocessor.

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Difference between 8051 and 8052:

The 8052 microcontroller is the 8051's "big brother." It is a slightly more powerful

microcontroller, sporting a number of additional features which the developer may

make use of:

256 bytes of Internal RAM (compared to 128 in the standard 8051).

A third 16-bit timer, capable of a number of new operation modes and 16-bit

reloads.

Additional SFRs to support the functionality offered by the third timer.

AT89S52:

Features:

• Compatible with MCS-51 Products

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

– Endurance: 1000 Write/Erase Cycles

• 4.0V to 5.5V Operating Range

• Fully Static Operation: 0 Hz to 33 MHz

• Three-level Program Memory Lock

• 256K Internal RAM

• 32 Programmable I/O Lines

• 3 16-bit Timer/Counters

• Eight Interrupt Sources

• Full Duplex UART Serial Channel

• Low-power Idle and Power-down Modes

• Interrupt Recovery from Power-down Mode

• Watchdog Timer

• Dual Data Pointer

• Power-off Flag

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DESCRIPTION OF MICROCONTROLLER 89S52:

The AT89S52 is a low-power, high-performance CMOS 8-bit

micro controller with 8Kbytes of in-system programmable Flash

memory. The device is manufactured

Using Atmel’s high-density nonvolatile memory technology and

is compatible with the industry-standard 80C51 micro controller. The

on-chip Flash allows the program memory to be reprogrammed in-

system or by a conventional nonvolatile memory programmer. By

combining a versatile 8-bit CPU with in-system programmable flash

one monolithic chip; the Atmel AT89c52 is a powerful micro controller,

which provides a highly flexible and cost-effective solution to many

embedded control applications.

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ARCHITECTURE OF MICROCONTROLLER (89S52)

The AT89S52 provides the following standard features: 8K

bytes of Flash, 256 bytes of RAM, 32 I/O lines, Watchdog timer, two

data pointers, three 16-bit timer/counters, full duplex serial port, on-chip

oscillator, and clock circuitry. In addition, the AT89S52 is designed

with static logic for perationdown 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 interrupt

Or hardware reset.

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PIN DESCRIPTION OF MICROCONTROLLER 89C52

VCC: Supply voltage.

GND: Ground.

Port 0:

Port 0 is an 8-bit open drain bi-directional I/O port. As an output

port, each pin can sink eight TTL inputs. When 1sare written to port 0

pins, the pins can be used as high impedance inputs. Port 0 can also be

configured to be the multiplexed low order address/data bus during

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

internal pull-ups. Port 0 also receives the code bytes during Flash

programming and outputs the code bytes during program verification.

External pull-ups are required during program verification

Port 1

Port 1 is an 8-bit bi-directional I/O port with internal pull-ups. The Port 1

Output buffers can sink/source four TTL inputs. When 1s are written to Port 1

pins, they are pulled high by the internal pull-ups and can be used as inputs. In

addition, P1.0 and P1.1 can be configured to be the timer/counter 2 external

count input

(P1.0/T2) and the timer/counter 2 trigger input P1.1/T2EX),

respectively, as shown in the following table. Port 1 also receives the

low-order address bytes during Flash programming and verification.

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Port : 2

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

Port 2 output buffers can sink/source four TTL inputs. When 1s are

written to Port 2 pins, they are pulled high by the internal pull-ups and

can be used as inputs. Port 2 emits the high-order address byte during

fetches from external program memory and during accesses to external

data memory that use 16-bit addresses (MOVX @DPTR). In this

application, Port 2 uses strong internal pull-ups when emitting 1s.

During accesses to external data memory that use 8-bit addresses

(MOVX @ RI), Port 2emits the contents of the P2 Special Function

Register. Port 2 also receives the high-order address bits and some

control signals during Flash programming and verification.

Port : 3

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

output buffers can sink/source four TTL inputs. When 1s are writt 1s are written to

Port 3 pins, they are pulled high by the internal pull-ups and can be used as inputs.

As inputs, Port 3 pins that are externally being pulled low will source current (IIL)

because of the pull-ups. Port 3 also serves the functions of various special features

of the AT89S52, as shown in the following table.

Port 3 also receives some control signals for Flash programming

And verification.

RST Reset input. A high on this pin for two machine cycles while

the oscillator is running resets the device.

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ALE/PROG

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

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

input (PROG) during Flash programming. In normal operation, ALE is emitted

at a constant rate of1/6 the oscillator frequency and may be used for external

timing or clocking purposes. Note, however, that one ALE pulse is skipped

during each access to external data Memory. If desired, ALE operation can be

disabled by setting bit 0 of SFR location

8EH. With the bit set, ALE is active only during a MOVX or MOVC

instruction. Otherwise, the pin is weakly pulled high. Setting the ALE-

disable bit has no effect if the micro controller is in external execution

mode.

PSEN :

Program Store Enable (PSEN) is the read strobe to external progra

m memory. When the AT89S52 is executing code from external

program memory, PSEN is activated twice each machine cycle, except

that two PSEN activations are skipped during each access to external

data memory.

EA/VPP :

External Access Enable. EA must be strapped to GND in order to

enable the device to fetch code from external program memory

locations starting at 0000H up to FFFFH.Note, however, that if lock bit

1 is programmed, EA will be internally latched on reset. A should be

strapped to VCC for internal program executions. This pin also receives

the 12-voltProgramming enables voltage (VPP) during Flash

programming.

XTAL1 :

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

operating circuit.

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XTAL2 : Output from the inverting oscillator amplifier.

Oscillator Characteristics

XTAL1 and XTAL2 are the input and output, respectively, of an

inverting amplifier that can be configured for use as an on-chip

oscillator, as shown in Figure 1. Either a quartz crystal or ceramic

resonator may be used. To drive the device from an External clock

source, XTAL2 should be left unconnected while XTAL1 is driven, as

shown in Figure 2.

Figure 1. Oscillator Connections

Special Function Register (SFR) Memory: -

Special Function Registers (SFR s) are areas of memory that

control specific functionality of the 8051 processor. For example, four

SFRs permit access to the 8051’s 32 input/output lines. Another SFR

allows the user to set the serial baud rate, control and access timers, and

configure the 8051’s interrupt system.

The Accumulator: The Accumulator, as its name suggests is used

as a general register to accumulate the results of a large number of

instructions. It can hold 8-bit (1-byte) value and is the most versatile

register.

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The “R” registers: The “R” registers are a set of eight registers that

are named R0, R1. Etc up to R7. These registers are used as auxiliary

registers in many operations.

The “B” registers: The “B” register is very similar to the

accumulator in the sense that it may hold an 8-bit (1-byte) value. Two

only uses the “B” register 8051 instructions: MUL AB and DIV AB.

The Data Pointer: The Data pointer (DPTR) is the 8051’s only user

accessible 16-bit (2Bytes) register. The accumulator, “R” registers are

all 1-Byte values. DPTR, as the name suggests, is used to point to data.

It is used by a number of commands, which allow the 8051 to access

external memory.

THE PROGRAM COUNTER AND STACK POINTER:

The program counter (PC) is a 2-byte address, which tells

the 8051 where the next instruction to execute is found in memory. The

stack pointer like all registers except DPTR and PC may hold an 8-bit (1-

Byte) value

ADDRESSING MODES:

An “addressing mode” refers that you are addressing a given

memory location. In summary, the addressing modes are as follows,

with an example of each:

Each of these addressing modes provides important

flexibility.

Immediate Addressing MOV A, #20 H

Direct Addressing MOV A, 30 H

Indirect Addressing MOV A, @R0

Indexed Addressing

a. External Direct MOVX A, @DPTR

b. Code In direct MOVC A, @A+DPTR

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Immediate Addressing:

Immediate addressing is so named because the value to

be stored in memory immediately follows the operation code in

memory. That is to say, the instruction itself dictates what value will be

stored in memory. For example, the instruction:

MOV A, #20H:

This instruction uses immediate Addressing because the

accumulator will be loaded with the value that immediately follows in

this case 20(hexadecimal). Immediate addressing is very fast since the

value to be loaded is included in the instruction. However, since the

value to be loaded is fixed at compile-time it is not very flexible.

Direct Addressing:

Direct addressing is so named because the value to be

stored in memory is obtained by directly retrieving it from another

memory location.

For example:

MOV A, 30h

This instruction will read the data out of internal RAM address

30(hexadecimal) and store it in the Accumulator. Direct addressing is

generally fast since, although the value to be loaded isn’t included in the

instruction, it is quickly accessible since it is stored in the 8051’s

internal RAM. It is also much more flexible than Immediate Addressing

since the value to be loaded is whatever is found at the given address

which may variable.

Also it is important to note that when using direct addressing

any instruction that refers to an address between 00h and 7Fh is

referring to the SFR control registers that control the 8051 micro

controller itself.

Indirect Addressing:

Indirect addressing is a very powerful addressing mode, which

in many cases provides an exceptional level of flexibility. Indirect

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addressing is also the only way to access the extra 128 bytes of internal

RAM found on the 8052. Indirect addressing appears as follows:

MOV A, @R0:

This instruction causes the 8051 to analyze Special Function

Register (SFR) Memory:

Special Function Registers (SFRs) are areas of memory that control

specific functionality of the 8051 processor. For example, four SFRs

permit access to the 8051’s 32 input/output lines. Another SFR allows

the user to set the serial baud rate, control and access timers, and

configure the 8051’s interrupt system.

Timer 2 Registers:

Control and status bits are contained in registers T2CON and

T2MOD for Timer 2 . The register pair (RCAP2H , RCAP2L) are the

Capture / Reload registers for Timer 2 in 16-bit capture mode or 16-bit

auto-reload mode .

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Article I. Interrupt Registers:

Article II. The individual interrupt enable bits are in the IE registe . Two

priorities can be set for each of the six interrupt sources in the IP register.

Article III.

Article IV. Timer 2

Article V. Timer 2 is a 16-bit Timer / Counter that can operate as either

a timer or an event counter. The type of operation is selected by bit C/T2 in

Article VI. the SFR T2CON . Timer 2 has three operating Modes :

capture , auto-reload ( up or down Counting ) , and baud rate generator . The

modes are selected by bits in T2CON . Timer 2 consists of two 8-bit

registers , TH2 and TL2 . In the Timer function , the TL2 register is

incremented every machine cycle . Since a machine cycle consists

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Article VII. of 12 oscillator periods, the count rate is 1/12 of the oscillator

frequency.In the Counter function , the register is incremented in response

to a 1-to-0 transition at its corresponding external input pin , T2 .When the

samples show a high in one cycle and a low in the next cycle, the count is

incremented . Since two machine cycles (24 Oscillator periods ) are required to

recognize 1-to-0 transition , the maximum count rate is 1 / 24 of the

oscillator frequency . To ensure that a given level is sampled at least once

before it changes , the level should be held for atleast one full machine

cycle .

Article VIII. Capture Mode

Article IX. In the capture mode , two options are selected by bit EXEN2

in T2CON . If EXEN2 = 0, Timer 2 is a 16-bit timer or counter which upon

overflow sets bit TF2 in T2CON . This bit can then be used to generate an

interrupt . If EXEN2 = 1 , Timer 2 performs the same operation , but a 1-to-0

transition at external input T2EX also causes the current value in TH2

and TL2 to be captured into RCAP2H and RCAP2L , respectively

Article X. Auto-reload (Up or Down Counter)

Article XI. Timer 2 can be programmed to count up or down when

configured in its 16-bit auto-reload mode. This feature is invoked by the

DCEN

(Down Counter Enable) bit located in the SFR T2MOD . Upon reset , the

DCEN bit is set to 0 so that timer 2 will default to count up.

When DCEN is set , Timer 2 can count up or down , depending on the value

of the T2EX pin . In this mode , two options are selected by bit EXEN2 in

T2CON . If EXEN2 = 0 , Timer 2 counts up to 0FFFFH and then sets the

TF2 bit upon overflow . If EXEN2 = 1 , a 16-bit

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Article XII. reload can be triggered either by an overflow or by a 1-to-0

transition at external input T2EX.

Article XIII. Baud Rate Generator

Article XIV. Timer 2 is selected as the baud rate generator by setting

TCLK and/or RCLK in T2CON . Note that the baud rates for transmit and

receive can be different if Timer 2 is used for the receiver or transmitter

and Timer 1 is used for the other function .The baud rates in Modes 1 and 3

aredetermined by Timer 2’s overflow rate according to the following equation

.

Article XV. Modes 1 and 3 Baud Rates =Timer 2 Overflow Rate

Article XVI. 16

Article XVII.

Article XVIII. The timer operation is different for Timer 2 when it is used as

a baud rate generator .Normally ,as a timer , it increments every machine cycle

(at 1/12 the oscillator frequency).As a baud rate generator , however, it

increments every state time ( at 1/2 the oscillator frequency ) .

Article XIX. Timer 0

Timer 0 functions as either a timer or event counter in four modes of

operation . Timer 0 is controlled by the four lower bits of the TMOD

register and bits 0, 1, 4 and 5 of the TCON register

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Article XX. Mode 0 ( 13-bit Timer)

Article XXI. Mode 0 configures timer 0 as a 13-bit timer which is set

up as an 8-bit timer (TH0 register) with a modulo 32 prescaler

implemented with the lower five bits of the TL0 register . The upper three

bits of TL0 register are indeterminate and should be ignored . Prescaler

overflow increments the TH0 register.

Article XXII. Mode 1 ( 16-bit Timer )

Article XXIII. Mode 1 is the same as Mode 0, except that the Timer

register is being run with all 16 bits . Mode 1 configures timer 0 as a

16-bit timer with the TH0 and TL0 registers connected in cascade . The

selected input increments the TL0 register .

Article XXIV. Mode 2 (8-bit Timer with Auto-Reload)

Article XXV. Mode 2 configures timer 0 as an 8-bit timer ( TL0 register )

that automatically reloads from the TH0 register . TL0 overflow sets TF0

flag in the TCON register and reloads TL0 with the contents of TH0 ,

which is preset by software .

Article XXVI. Mode 3 ( Two 8-bit Timers )Mode 3 configures timer 0

so that registers TL0 and TH0 operate as separate 8-bit timers. This mode

is provided for applications requiring an additional 8-bit timer or counter .

Article XXVII.

Article XXVIII. Timer 1

Article XXIX. Timer 1 is identical to timer 0 , except for mode 3 ,

which is a hold-count mode .

Article XXX. Mode 3 ( Halt )

Article XXXI. Placing Timer 1 in mode 3 causes it to halt and hold its

count . This can be used to halt Timer 1 when TR1 run control bit is

not available i.e. , when Timer 0 is in mode 3 .

Article XXXII. Baud Rates :

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Article XXXIII. The baud rate in Mode 0 is fixed. The baud

rate in Mode 2 depends on the value of bit SMOD in Special Functio

Register PCON. If SMOD = 0 (which is its value on reset), the baud rate is

1/64 the oscillator frequency . If SMOD = 1, the baud rate is 1/32 the

oscillator frequency. In the 89S52 , the baud rates in Modes 1 and 3 are

determined by the Timer 1 overflow rate. In case of Timer 2 , these

baud rates can be determined by Timer 1 , or by Timer 2 , or by both

(one for transmit and the other for receive ).

Article XXXIV.

Article XXXV. TCON REGISTER :Timer/counter Control Register

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Article XXXVI. TMOD REGISTER : Timer/Counter 0 and 1 Modes

3.32ULN 2803A

ULN are used to interfacing between microcontroller and the led’s

Because the can not work with out them.The ULN2801A-ULN2805Aeach contain

eight dar-lington transistors with common emitters and integral suppression diodes

for inductive loads. Each darlington features a peak load current rating of 600mA

(500mA continuous) and can withstand at least 50V in the off state. Outputsmay be

paralleled for higher current capability. Five versions are available to simplify

interfacing to standard logic families : the ULN2801A is designed for general

purpose applications with a current limit resistor ; the ULN2802Ahas a 10.5kΩ

input resistor and zener for 14-25V PMOS ; the ULN2803A has a 2.7kΩ input

resistor for 5V TTL and CMOS ; the ULN2804A has a 10.5kΩ input resistor for 6-

15V CMOS and the ULN2805A is designed to sink a minimum of 350mA for

standard and Schottky TTL where higher output current is required. All types are

supplied in a 18-lead plastic DIP with a copperlead from and featurethe

convenientinputopposite-output pinout to simplify board layout.

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3.33 555 TIMER

555 is used for producing a clock (square wave) at a desired frequency. It can be used in various ways like the astable mode, monostable mode etc. Here, we deal with the astable operation of 555. Astable mode ensures that the 555 is self-triggered & so, it acts as a multi-vibrator. Let us look into the working of 555 in astable mode:

These are the connections

needed to make the 555 chip run in the ‘astable’ mode. The pin numbers are given in circles.

Note the right-most side of the figure, and consider all the connections with the pins as ‘open-circuits’. Ignore the rest of the circuit for a while.

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D1 - Circuit Connections to be made

This over-familiar circuit will majestically jump up. The Vc1 is the driving signal for this 555, connected at PIN 6, which is the THRESHOLD PIN. As soon as Vc1 reaches ⅔Vcc, then the output at PIN 3 goes low, and the capacitor starts discharging, via PIN 7 with Rb as the Resistor and ground as the other terminal. (Refer to the first image to see how it MIGHT happen.) When it reaches ⅓Vcc, the output at PIN 3 goes high, and the DISCHARGE PIN’s connection with ground is broken. The capacitor again starts charging, and the cycle is repeated. You need not bother yourself with how the Circuit is broken or established.

This graph gives the OUTPUT at PIN 3 and the input voltage at PIN 7.

D3- Output

D4- Internal Working of the 555

This is the internal working of the 555 timer. The chip derives its name from the three R’s on the top of the image, they all are 5 kΩ. Hence, the name 555.

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Now, let us see how we can set the 555 to work at the desired frequency by selecting the right combination of resistances & capacitances. Using the convention as in D1, From circuit analysis & mathematics, it can be obtained that:Frequency = 1.44/(RA + 2RB) * C1

Also, 555 can produce waves with duty cycle else than the 50 % cycle. The desired duty cycle can be worked out by using the result:Duty Cycle = (RA + RB) * 100/ (RA + 2RB)where duty cycle= Ratio of time period when the output is 1 to the time period when the output is 0

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3.4(IR) INFRARED TECHNOLOGY

Introduction:

Technically known as "infrared radiation", infrared light is part of the

electromagnetic spectrum located just below the red portion of normal visible light

– the opposite end to ultraviolet. Although invisible, infrared follows the same

principles as regular light and can be reflected or pass through transparent objects,

such as glass. Infrared remote controls use this invisible light as a form of

communications between themselves and home theater equipment, all of which

have infrared receivers positioned on the front. Essentially, each time you press a

button on a remote, a small infrared diode at the front of the remote beams out

pulses of light at high speed to all of your equipment. When the equipment

recognizes the signal as its own, it responds to the command.

But much like a flashlight, infrared light can be focused or diffused, weak or

strong. The type and number of emitters can affect the possible angles and range

your remote control can be used from. Better remotes can be used up to thirty feet

away and from almost any angle, while poorer remotes must be aimed carefully at

the device being controlled.

The light our eyes see is but a small part of a broad spectrum of

electromagnetic radiation. On the immediate high energy side of the visible

spectrum lies the ultraviolet, and on the low energy side is the infrared. The portion

of the infrared region most useful for analysis of organic compounds is not

immediately adjacent to the visible spectrum, but is that having a wavelength range

from 2,500 to 16,000 nm, with a corresponding frequency range from 1.9*1013 to

1.2*1014 Hz.( From http://hyperphysics.phy-astr.gsu.edu/hbase/ems3.html : the

frequency of infrared ranges from 0.003 - 4 x 1014 Hz or about 300 gigahertz to 400

terahertz.).

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Infrared imaging is used extensively for both military and civilian purposes.

Military applications include target acquisition, surveillance, night vision, homing

and tracking. Non-military uses include thermal efficiency analysis, remote

temperature sensing, short-ranged wireless communication, spectroscopy, and

weather forecasting. Infrared astronomy uses sensor-equipped telescopes to

penetrate dusty regions of space, such as molecular clouds; detect cool objects such

as planets, and to view highly red-shifted objects from the early days of the universe

IR LED QED234:

FEATURES:

• Wave length is 940 nm

• Chip material =GaAs with AlGaAs window

• Package type: T-1 3/4 (5mm lens diameter)

• Matched Photo sensor: QSD122/123/124

• Medium Emission Angle, 40°

• High Output Power

• Package material and color: Clear, untainted, plastic

• Ideal for remote control applications

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Emitter/Detector Alignment:

Good alignment of the emitter and detector is important for good operation,

especially if the gap is large. This can be done with a piece of string stretched

between and in line with LED and phototransistor. A length of dowel or stiff wire

could be used to set the alignment. Another method that can be used for longer

distances is a laser pointer shone through one of the mounting holes.

For best results the height of the "beam" should be at coupler height and at an

angle across the tracks. The emitter could also be mounted above the track with the

phototransistor placed between the rails in locations such as hidden yards. Placing

the emitter and detector at an angle would again be helpful.

Emitter/Detector Alignment Methods

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A sample infrared remote controle setup:

Infrared Receiver (Pickup)

This device picks up the infrared signal from your remote control just like a

TV or VCR. It encodes the infrared signal into a signal suitable for transmission.

Receivers must be located in the room you wish to use the remote control. The wire

from the receiver to the connecting block needs at least three available conductors

and can be several hundred feet long. Both quad wire and category 5wire work fine.

See our IR receivers here.

Connecting Block

This is simply a place for all the parts to plug in or connect to. Connecting

blocks are usually classified based on the number of outputs (how many IR emitters

can connect to the block) Amplified connecting blocks can generally support more

outputs. All connecting blocks can support many IR receivers wired in parallel.

Connecting blocks are usually located near the equipment that is to be controlled,

along with the power supply and emitters. See our connecting blocks here.

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Infrared Emitters

IR Emitters generally "stick" onto the front of the device you want to

control. Therefore you need one emitter for each device. "Dual" emitters

have two emitters and one plug, so they only take up one jack of the connecting

block. "Blink" emitters blink visibly as well as infrared, so they are easier to

troubleshoot. All emitters come with long cords and extra double-stick tape. "Blast"

style emitters, where one emitter blinks into several devices, are usually less reliable

but can be used when the environment is tightly controlled and

Applications:

Infrared Filters

Night vision

Thermograph

Other imaging

Tracking

Heating

Communications

Spectroscopy

Meteorology

Climatology

Astronomy

Art history

Biological systems

Photobiomodulation

Health hazard

Article XXXVII. Light-emitting diode (LED)

A light-emitting diode (LED) (pronounced, or just /lɛd/), is an electronic

light source. The LED was first invented in Russia in the 1920s, and introduced in

America as a practical electronic component in 1962. Oleg Vladimirovich Losev

was a radio technician who noticed that diodes used in radio receivers emitted light

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when current was passed through them. In 1927, he published details in a Russian

journal of the first ever LED.

All early devices emitted low-intensity red light, but modern LEDs are available

across the visible, ultraviolet and infra red wavelengths, with very high brightness.

LEDs are based on the semiconductor diode. When the diode is forward biased

(switched on), electrons are able to recombine with holes and energy is released in

the form of light. This effect is called electroluminescence and the color of the light

is determined by the energy gap of the semiconductor. The LED is usually small in

area (less than 1 mm2) with integrated optical components to shape its radiation

pattern and assist in reflection.

LEDs present many advantages over traditional light sources including lower

energy consumption, longer lifetime, improved robustness, smaller size and faster

switching. However, they are relatively expensive and require more precise current

and heat management than traditional light sources.

Applications of LEDs are diverse. They are used as low-energy indicators but also

for replacements for traditional light sources in general lighting and automotive

lighting. The compact size of LEDs has allowed new text and video displays and

sensors to be developed, while their high switching rates are useful in

communications technology.

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(a) Application-specific variations

Flashing LEDs are used as attention seeking indicators without requiring external

electronics. Flashing LEDs resemble standard LEDs but they contain an integrated

multivibrator circuit inside which causes the LED to flash with a typical period of

one second. In diffused lens LEDs this is visible as a small black dot. Most flashing

LEDs emit light of a single color, but more sophisticated devices can flash between

multiple colors and even fade through a color sequence using RGB color mix

Bi-color LEDs are actually two different LEDs in one case. It consists of two

dies connected to the same two leads but in opposite directions. Current flow

in one direction produces one color, and current in the opposite direction

produces the other color. Alternating the two colors with sufficient

frequency causes the appearance of a blended third color. For example, a

red/green LED operated in this fashion will color blend to produce a yellow

appearance.

Tri-color LEDs are two LEDs in one case, but the two LEDs are connected

to separate leads so that the two LEDs can be controlled independently and

lit simultaneously. A three-lead arrangement is typical with one common

lead (anode or cathode).

RGB LEDs contain red, green and blue emitters, generally using a four-wire

connection with one common lead (anode or cathode).

Alphanumeric LED displays are available in seven-segment and starburst

format. Seven-segment displays handle all numbers and a limited set of

letters. Starburst displays can display all letters. Seven-segment LED

displays were in widespread use in the 1970s and 1980s, but increasing use

of liquid crystal displays, with their lower power consumption and greater

display flexibility, has reduced the popularity of numeric and alphanumeric

LED displays.

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(b) Advantages Efficiency LEDs produce more light per watt than incandescent bulbs.

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

filters that traditional lighting methods require. This is more efficient and

can lower initial costs.

Size: LEDs can be very small (smaller than 2 mm2and are easily populated

onto printed circuit boards.

On/Off time: LEDs light up very quickly. A typical red indicator LED will

achieve full brightness in microseconds. LEDs used in communications

devices can have even faster response times.

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

on-off cycling, unlike fluorescent lamps that burn out more quickly when

cycled frequently, or HID lamps that require a long time before restarting.

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

modulation or lowering the forward current.

Cool light: In contrast to most light sources, LEDs radiate very little heat in

the form of IR that can cause damage to sensitive objects or fabrics. Wasted

energy is dispersed as heat through the base of the LED.

Slow failure: LEDs mostly fail by dimming over time, rather than the

abrupt burn-out of incandescent bulbs.

Lifetime: LEDs can have a relatively long useful life. One report estimates

35,000 to 50,000 hours of useful life, though time to complete failure may

be longer. Fluorescent tubes typically are rated at about 10,000 to 15,000

hours, depending partly on the conditions of use, and incandescent light

bulbs at 1,000–2,000 hours.

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

damage with external shock, unlike fluorescent and incandescent bulbs

which are fragile.

Focus: The solid package of the LED can be designed to focus its light.

Incandescent and fluorescent sources often require an external reflector to

collect light and direct it in a usable manner.

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

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(c) Disadvantages High initial price: LEDs are currently more expensive, price per lumen, on

an initial capital cost basis, than most conventional lighting technologies.

The additional expense partially stems from the relatively low lumen output

and the drive circuitry and power supplies needed. However, when

considering the total cost of ownership (including energy and maintenance

costs), LEDs far surpass incandescent or halogen sources and begin to

threaten compact fluorescent lamps.

Temperature dependence: LED performance largely depends on the

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

high ambient temperatures may result in overheating of the LED package,

eventually leading to device failure. Adequate heat-sinking is required to

maintain long life. This is especially important when considering

automotive, medical, and military applications where the device must

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

failure rate.

Voltage sensitivity: LEDs must be supplied with the voltage above the

threshold and a current below the rating. This can involve series resistors or

current-regulated power supplies.

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

from a black body radiator like the sun or an incandescent light. The spike at

460 nm and dip at 500 nm can cause the color of objects to be perceived

differently under cool-white LED illumination than sunlight or incandescent

sources, due to metamerism, red surfaces being rendered particularly badly

by typical phosphor based cool-white LEDs. However, the color rendering

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

available in state-of-art white LEDs.

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

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

requiring a spherical light field. LEDs are not capable of providing

divergence below a few degrees. This is contrasted with lasers, which can

produce beams with divergences of 0.2 degrees or less.

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Blue Hazard: There is increasing concern that blue LEDs and cool-white

LEDs are now capable of exceeding safe limits of the so-called blue-light

hazard as defined in eye safety specifications such as ANSI/IESNA RP-

27.1-05: Recommended Practice for Photobiological Safety for Lamp and

Lamp Systems.

Blue pollution: Because cool-white LEDs (i.e., LEDs with high color

temperature) emit much more blue light than conventional outdoor light

sources such as high-pressure sodium lamps, the strong wavelength

dependence of Rayleigh scattering means that cool-white LEDs can cause

more light pollution than other light sources. It is therefore very important

that cool-white LEDs are fully shielded when used outdoors. Compared to

low-pressure sodium lamps, which emit at 589.3 nm, the 460 nm emission

spike of cool-white and blue LEDs is scattered about 2.7 times more by the

Earth's atmosphere. Cool-white LEDs should not be used for outdoor

lighting near astronomical observatories.

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3.5 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 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 .

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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.

Circuit Features:

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

output, output current capability of 100 mA

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 successfully as part of many electronics

projects

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Block Diagram:

Circuit Diagram:

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Basic Power Supply Circuit:

Above is the circuit of a basic unregulated dc power

supply. A bridge rectifier D1 to D4 rectifies the ac from the

transformer secondary, which may also be a block rectifier such as

WO4 or even four individual diodes such as 1N4004 types. (See

later re rectifier ratings).

The principal advantage of a bridge rectifier is you do not

need a centre tap on the secondary of the transformer. A further

but significant advantage is that the ripple frequency at the output

is twice the line frequency (i.e. 50 Hz or 60 Hz) and makes filtering

somewhat easier.

As a design example consider we wanted a small

unregulated bench supply for our projects. Here we will go for a

voltage of about 12 - 13V at a maximum output current (IL) of

500ma (0.5A). Maximum ripple will be 2.5% and load regulation is

5%.

Now the RMS secondary voltage (primary is whatever is

consistent with your area) for our power transformer T1 must be

our desired output Vo PLUS the voltage drops across D2 and D4 (2

* 0.7V) divided by 1.414.

This means that Vsec = [13V + 1.4V] / 1.414 which equals about

10.2V. Depending on the VA rating of your transformer, the

secondary voltage will vary considerably in accordance with the

applied load. The secondary voltage on a transformer advertised

as say 20VA will be much greater if the secondary is only lightly

loaded.

If we accept the 2.5% ripple as adequate for our purposes

then at 13V this becomes 13 * 0.025 = 0.325 Vrms. The peak to

peak value is 2.828 times this value. Vrip = 0.325V X 2.828 = 0.92

V and this value is required to calculate the value of C1. Also

required for this calculation is the time interval for charging

pulses. If you are on a 60Hz system it it 1/ (2 * 60) = 0.008333

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which is 8.33 milliseconds. For a 50Hz system it is 0.01 sec or 10

milliseconds.

Remember the tolerance of the type of capacitor used here

is very loose. The important thing to be aware of is the voltage

rating should be at least 13V X 1.414 or 18.33. Here you would use

at least the standard 25V or higher (absolutely not 16V).With our

rectifier diodes or bridge they should have a PIV rating of 2.828

times the Vsec or at least 29V. Don't search for this rating because

it doesn't exist. Use the next highest standard or even higher. The

current rating should be at least twice the load current maximum

i.e. 2 X 0.5A or 1A. A good type to use would be 1N4004, 1N4006

or 1N4008 types.

These are rated 1 Amp at 400PIV, 600PIV and 1000PIV

respectively. Always be on the lookout for the higher voltage ones

when they are on special.

IC Voltage Regulators

Voltage regulators comprise a class of widely used ICs.

Regulator IC units contain the circuitry for reference source,

comparator amplifier, control device, and overload protection all in

a single IC. Although the internal construction of the IC is

somewhat different from that described for discrete voltage

regulator circuits, the external operation is much the same. IC

units provide regulation of either a fixed positive voltage, a fixed

negative voltage, or an adjustably set voltage.

A power supply can be built using a transformer connected

to the ac supply line to step the ac voltage to desired amplitude,

then rectifying that ac voltage, filtering with a capacitor and RC

filter, if desired, and finally regulating the dc voltage using an IC

regulator. The regulators can be selected for operation with load

currents from hundreds of mill amperes to tens of amperes,

corresponding to power ratings from mill watts to tens of watts.

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Three-Terminal Voltage Regulators:

Fixed Positive Voltage Regulators:

Vin

Vout

C1 C2

Fig shows the basic connection of a three-terminal voltage

regulator IC to a load. The fixed voltage regulator has an

unregulated dc input voltage, Vi, applied to one input terminal, a

regulated output dc voltage, Vo, from a second terminal, with the

third terminal connected to ground. While the input voltage may

vary over some permissible voltage range, and the output load

may vary over some acceptable range, the output voltage remains

constant within specified voltage variation limits. A table of

positive voltage regulated ICs is provided in table. For a selected

regulator, IC device specifications list a voltage range over which

the input voltage can vary to maintain a regulated output voltage

over a range of load current. The specifications also list the

amount of output voltage change resulting from a change in load

current (load regulation) or in input voltage (line regulation).

TABLE: Positive Voltage Regulators in 7800 series

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IN OUT78XX

GND

IC No. Output voltage(v) Maximum input voltage(v)

78057806780878107812781578187824

+5+6+8+10+12+15+18+24

35V

40V

3.6 Transistors

Transistors amplify current, for

example they can be used to amplify the small output current

from a logic IC so that it can operate a lamp, relay or other

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high current device. In many circuits a resistor is used to

convert the changing current to a changing voltage, so the

transistor is being used to

amplify voltage.

A transistor may be used as a switch (either fully on with maximum current, or fully

off with no current) and as an amplifier (always partly on). The amount of current

amplification is called the current gain, symbol hFE.

For further information please see the Transistor Circuits page.

Types of transistor

There are two types of standard transistors, NPN and PNP, with different circuit symbols. The letters refer to the layers of semiconductor material used to make the transistor. Most transistors used today are NPN because this is the easiest type to make from silicon. If you are new to electronics it is best to start by learning how to use NPN transistors.

The leads are labelled base (B), collector (C) and emitter (E).These terms refer to the internal operation of a transistor but they are not much help in understanding how a transistor is used, so just treat them as labels!

A Darlington pair is two transistors connected together to give a very high current gain.

In addition to standard (bipolar junction) transistors, there are field-effect transistors which are usually referred to as FETs. They have different circuit symbols and properties and they are not (yet) covered by this page.

Connecting

Transistors have three leads which must be connected the correct way round. Please take care with this because a wrongly connected transistor may be damaged instantly when you switch on.

If you are lucky the orientation of the transistor will be clear from the PCB or

Transistor circuit symbols

Transistor leads for some common case styles.

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stripboard layout diagram, otherwise you will need to refer to a supplier's catalogue to identify the leads.

The drawings on the right show the leads for some of the most common case styles.

Please note that transistor lead diagrams show the view from below with the leads towards you. This is the opposite of IC (chip) pin diagrams which show the view from above.

Heat sinks :Waste heat is produced in transistors due to the current flowing

through them. Heat sinks are needed for power transistors because they pass large currents. If you find that a transistor is becoming too hot to touch it certainly needs a heat sink! The heat sink helps to dissipate (remove) the heat by transferring it to the surrounding air.

For further information please see the Heat sinks page.

Testing a transistor:Transistors can be damaged by heat when soldering or

by misuse in a circuit. If you suspect that a transistor may be damaged there are two easy ways to test it:

(i) 1. Testing with a multimeterUse a multimeter or a simple tester (battery, resistor and LED) to check each pair of leads for conduction. Set a digital multimeter to diode test and an analogue multimeter to a low resistance range.

Test each pair of leads both ways (six tests in total):

Heat sink

Photograph © Rapid Electronics

Testing an NPN transistor

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The base-emitter (BE) junction should behave like a diode and conduct one way only.

The base-collector (BC) junction should behave like a diode and conduct one way only.

The collector-emitter (CE) should not conduct either way.

The diagram shows how the junctions behave in an NPN transistor. The diodes are reversed in a PNP transistor but the same test procedure can be used.

(ii) 2. Testing in a simple switching circuit

Connect the transistor into the circuit shown on the right which uses the transistor as a switch. The supply voltage is not critical, anything between 5 and 12V is suitable. This circuit can be quickly built on breadboard for example. Take care to include the 10k resistor in the base connection or you will destroy the transistor as you test it!

If the transistor is OK the LED should light when the switch is pressed and not light when the switch is released.

To test a PNP transistor use the same circuit but reverse the LED and the supply voltage.

Some multimeters have a 'transistor test' function which provides a known base current and measures the collector current so as to display the transistor's DC current gain hFE.

Transistor codes :There are three main series of transistor codes used in the UK:

Codes beginning with B (or A), for example BC108, BC478 The first letter B is for silicon, A is for germanium (rarely used now). The second letter indicates the type; for example C means low power audio frequency; D means high power audio frequency; F means low power high frequency. The rest of the code identifies the particular transistor. There is no obvious logic to the numbering system. Sometimes a letter is added to the end (eg BC108C) to identify a special version of the main type, for example a higher current gain or a different case style. If a project specifies a higher gain version (BC108C) it must be used, but if the general code is given (BC108) any transistor with that code is suitable.

Codes beginning with TIP, for example TIP31A TIP refers to the manufacturer: Texas Instruments Power transistor. The letter at the end identifies versions with different voltage ratings.

A simple switching circuitto test an NPN transistor

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Codes beginning with 2N, for example 2N3053 The initial '2N' identifies the part as a transistor and the rest of the code identifies the particular transistor. There is no obvious logic to the numbering system.

Choosing a transistorMost projects will specify a particular transistor, but if necessary you can usually substitute an equivalent transistor from the wide range available. The most important properties to look for are the maximum collector current IC and the current gain hFE. To make selection easier most suppliers group their transistors in categories determined either by their typical use or maximum power rating.

To make a final choice you will need to consult the tables of technical data which are normally provided in catalogues. They contain a great deal of useful information but they can be difficult to understand if you are not familiar with the abbreviations used. The table below shows the most important technical data for some popular transistors, tables in catalogues and reference books will usually show additional information but this is unlikely to be useful unless you are experienced. The quantities shown in the table are explained below.

NPN transistors

Code StructureCasestyle

IC

max.VCE

max.hFE

min.Ptot

max.

Category(typical use)

Possiblesubstitutes

BC107 NPN TO18 100mA 45V 110 300mW Audio, low power

BC182 BC547

BC108 NPN TO18 100mA 20V 110 300mWGeneral purpose, low power

BC108C BC183 BC548

BC108C NPN TO18 100mA 20V 420 600mWGeneral purpose, low power

BC109 NPN TO18 200mA 20V 200 300mWAudio (low noise), low power

BC184 BC549

BC182 NPN TO92C 100mA 50V 100 350mWGeneral purpose, low power

BC107 BC182L

BC182L NPN TO92A 100mA 50V 100 350mWGeneral purpose, low power

BC107 BC182

BC547B NPN TO92C 100mA 45V 200 500mW Audio, low power

BC107B

BC548B NPN TO92C 100mA 30V 220 500mWGeneral purpose, low power

BC108B

BC549B NPN TO92C 100mA 30V 240 625mWAudio (low noise), low power

BC109

2N3053 NPN TO39 700mA 40V 50 500mW General BFY51

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purpose, low power

BFY51 NPN TO39 1A 30V 40 800mW

General purpose, medium power

BC639

BC639 NPN TO92A 1A 80V 40 800mW

General purpose, medium power

BFY51

TIP29A NPN TO220 1A 60V 40 30WGeneral purpose, high power

TIP31A NPN TO220 3A 60V 10 40WGeneral purpose, high power

TIP31C TIP41A

TIP31C NPN TO220 3A 100V 10 40WGeneral purpose, high power

TIP31A TIP41A

TIP41A NPN TO220 6A 60V 15 65WGeneral purpose, high power

2N3055 NPN TO3 15A 60V 20 117WGeneral purpose, high power

Please note: the data in this table was compiled from several sources which are not entirely consistent! Most of the discrepancies are minor, but please consult information from your supplier if you require precise data.

PNP transistors

Code StructureCasestyle

IC

max.VCE

max.hFE

min.Ptot

max.

Category(typical use)

Possiblesubstitutes

BC177 PNP TO18 100mA 45V 125 300mW Audio, low power

BC477

BC178 PNP TO18 200mA 25V 120 600mWGeneral purpose, low power

BC478

BC179 PNP TO18 200mA 20V 180 600mWAudio (low noise), low power

BC477 PNP TO18 150mA 80V 125 360mW Audio, low power

BC177

BC478 PNP TO18 150mA 40V 125 360mWGeneral purpose, low power

BC178

TIP32A PNP TO220 3A 60V 25 40WGeneral purpose, high power

TIP32C

TIP32C PNP TO220 3A 100V 10 40WGeneral purpose, high power

TIP32A

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Please note: the data in this table was compiled from several sources which are not entirely consistent! Most of the discrepancies are minor, but please consult information from your supplier if you require precise data.

Structure This shows the type of transistor, NPN or PNP. The polarities of the two types are different, so if you are looking for a substitute it must be the same type.

Case style There is a diagram showing the leads for some of the most common case styles in the Connecting section above. This information is also available in suppliers' catalogues.

IC max. Maximum collector current.

VCE max. Maximum voltage across the collector-emitter junction. You can ignore this rating in low voltage circuits.

hFE This is the current gain (strictly the DC current gain). The guaranteed minimum value is given because the actual value varies from transistor to transistor - even for those of the same type! Note that current gain is just a number so it has no units. The gain is often quoted at a particular collector current IC which is usually in the middle of the transistor's range, for example '100@20mA' means the gain is at least 100 at 20mA. Sometimes minimum and maximum values are given. Since the gain is roughly constant for various currents but it varies from transistor to transistor this detail is only really of interest to experts. Why hFE? It is one of a whole series of parameters for transistors, each with their own symbol. There are too many to explain here.

Ptot max. Maximum total power which can be developed in the transistor, note that a heat sink will be required to achieve the maximum rating. This rating is important for transistors operating as amplifiers, the power is roughly IC × VCE. For transistors operating as switches the maximum collector current (IC max.) is more important.

3.7Resistors& Capacitors

Resistors:

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The resistor's function is to reduce the flow of electric current.This symbol is used to indicate a resistor in a circuit diagram, known as a schematic.Resistance value is designated in units called the "Ohm." A 1000 Ohm resistor is typically shown as 1K-Ohm ( kilo Ohm ), and 1000 K-Ohms is written as 1M-Ohm ( megohm ).

There are two classes of resistors; fixed resistors and the variable resistors. They are also classified according to the material from which they are made. The typical resistor is made of either carbon film or metal film. There are other types as well, but these are the most common.The resistance value of the resistor is not the only thing to consider when selecting a resistor for use in a circuit. The "tolerance" and the electric power ratings of the resistor are also important.The tolerance of a resistor denotes how close it is to the actual rated resistence value. For example, a ±5% tolerance would indicate a resistor that is within ±5% of the specified resistance value.The power rating indicates how much power the resistor can safely tolerate. Just like you wouldn't use a 6 volt flashlight lamp to replace a burned out light in your house, you wouldn't use a 1/8 watt resistor when you should be using a 1/2 watt resistor.

The maximum rated power of the resistor is specified in Watts.Power is calculated using the square of the current ( I2 ) x the resistance value ( R ) of the resistor. If the maximum rating of the resistor is exceeded, it will become extremely hot, and even burn.Resistors in electronic circuits are typicaly rated 1/8W, 1/4W, and 1/2W. 1/8W is almost always used in signal circuit applications.When powering a light emitting diode, a comparatively large current flows through the resistor, so you need to consider the power rating of the resistor you choose.

Color code resistor's

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Color code ariations

Three band resistorsVery long ago, back in the 20th century, it was assumed that all resistors were 20 %, or worse, and thus didn't need any tolerance marking. Also, since the tolerance was so wide there was no need for more than two significant digits. These resistors are in the E3 or E6 series. If you stumble on one of these, call your local museum.

Four band resistorsMankind eventually learned to manufacture 10 % or even 5 % resistors and a tolerance marking had to be invented. There were still no need for more than two significant digits, and therefore four color bands did the trick. These resistors typically are in the E12 and E24 series.

Five band resistorsEngineers' appetite for precision led to the development of 2 % and 1 % or better resistors, and in order to keep the logarithmically constant difference between consecutive resistance values another significant digit had to be employed. But engineers also developed tools to paint tinier color bands, so that was not a problem. These resistors belong to the E48, E96 and E192 series.

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Section XXXVII.02 Six band resistors

Now that tolerances were in the sub-percent region, another factor had to be accounted for, namely temperature coefficient. Well, why not just throw in yet another color band? Good idea. Here it is.

There are also other uses of the sixth color band, for instance quality codes. These are, however, not well standardized and are therefore not part of the color code calculator.

Capacitor

Electronic capacitors are one of the most widely used electronic components. These electronic capacitors only allow alternating or changing signals to pass through them, and as a result they find applications in many different areas of electronic circuit design. There are a wide variety of types of capacitor including electrolytic, ceramic, tantalum, plastic, sliver mica, and many more. Each capacitor type has its own advantages and disadvantages can be used in different applications.

The choice of the correct capacitor type can have a major impact on any circuit. The differences between the different types of capacitor can mean that the circuit may not work correctly if the correct type of capacitor is not used. Accordingly a summary of the different types of capacitor is given below, and further descriptions of a variety of capacitor types can be reached through the related articles menu on the left hand side of the page below the main menu.

4.1 SOFTWARE DESCRIPTION

1. Click on the Keil uVision Icon on Desktop

2. The following fig will appear

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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

9. Select AT89C51 as shown below

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10. Then Click on “OK”

11. The Following fig will appear

12. Then Click either YES or NO………mostly “NO”

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.

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15. Click on the file option from menu bar and select “new”

16. The next screen will be as shown in next page, and just maximize it by

double clicking on its blue boarder.

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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”

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”

27. Now Click on the Peripherals from menu bar, and check your required

port as shown in fig below

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28. Drag the port a side and click in the program file.

29. Now keep Pressing function key “F11” slowly and observe.

You are running your program successfully

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4.2 Project Code

org 0000hljmp main ;main program

ORG 000BH

ljmp timer_0

org 0030hmain:

clr ie.7mov a,#00hmov p0,a ;data to ports=0mov p1,amov p2,a

mov 50h,a ;0.25 countermov 51h,a ;0.25 counter

setb p1.0 ;R1 LED ONsetb p1.3 ;R2 LED ONsetb p1.6 ;R3 LED ONsetb p2.1 ;R4 LED ON

setb p3.7setb p3.6setb p3.5setb p3.4acall delayclr p1.0 ;R1 LED OFFsetb p1.2 ;G1 LED ON

setb 00clr 01clr 02clr 03clr 04

mov tmod,#01h ;timer 0 mode 1mov tl0,#00hmov th0,#00h ;timer is loaded

with 0000mov ie,#10000011b ;timer 0 interruptsetb tr0

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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;MAIN PROGRAM;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;loop_inf:

jb p3.7,next1setb 00setb 04clr 01clr 02clr 03sjmp next_out

;;;;;;;;;;;;;;;;;;;;;;;;;;;;next1:

jb p3.6,next2setb 01setb 04clr 00clr 02clr 03sjmp next_out

;;;;;;;;;;;;;;;;;;;;;;;;;;;next2:

jb p3.5,next3setb 02setb 04clr 00clr 01clr 03sjmp next_out

;;;;;;;;;;;;;;;;;;;;;;;;;;;next3:

jb p3.4,next_outsetb 03setb 04clr 00clr 01clr 02sjmp next_out

;;;;;;;;;;;;;;;;;;;;;;;;;;next_out:

clr 04sjmp loop_inf

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;timer 0 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;timer_0:

clr tr0CLR IE.7

jb 04,out_siren

INC 50hmov a,50h

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CJNE a,#02H,OUT_IDMOV 50h,#00h

out_siren:jb 00,firstjb 01,secondjb 02,thirdjb 03,fourthljmp OUT_ID

;;;;;;;;;;;;;;first:

clr p1.2 ;G1 LED offsetb p1.1 ;Y1 LED ONacall delayclr p1.1setb p1.0 ;R1 LED ON

clr p1.3 ;R2 LED OFFsetb p1.5 ;G2 LED ONclr 00setb 01ljmp OUT_ID

;;;;;;;;;;;;;;;;second:

clr p1.5 ;G2 LED offsetb p1.4 ;Y2 LED ONacall delayclr p1.4setb p1.3 ;R2 LED ON

clr p1.6 ;R3 LED OFFsetb p2.0 ;G3 LED ONclr 01setb 02ljmp OUT_ID

;;;;;;;;;;;;;;;;;third:

clr p2.0 ;G3 LED offsetb p1.7 ;Y3 LED ONacall delayclr p1.7setb p1.6 ;R3 LED ON

clr p2.1 ;R4 LED OFFsetb p2.3 ;G4 LED ONclr 02setb 03ljmp OUT_ID

;;;;;;;;;;;;;;;;;fourth:

clr p2.3 ;G4 LED off

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setb p2.2 ;Y4 LED ONacall delayclr p2.2setb p2.1 ;R4 LED ON

clr p1.0 ;R1 LED OFFsetb p1.2 ;G1 LED ONclr 03setb 00

OUT_ID:mov th0,#00hmov tl0,#01hmov ie,#10000011bSETB TR0RETI

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

delay1: mov 70h,#0ffh mov 71h,#0fh

loop_2: djnz 70h,loop_2 djnz 71h,loop_2 ret

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; delay: mov 70h,#0ffh

mov 71h,#0ffh mov 72h,#05h

loop_1: djnz 70h,loop_1 djnz 71h,loop_1 djnz 72h,loop_1 ret

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

Advantages

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Resistance to external disturbances such as vibration, infrared radiation, ambient noise, and EMI radiation.

Reduce the traffic intensity

High signaling control

Less affected by target materials and surfaces, and not affected by color. Solid-state units have virtually unlimited, maintenance free

life. Can detect small objects over long operating distances. Reduction in time taken by the user to reach a particular.

LIMITATIONS

COST

BANDWIDTH

EFFICIENCY COST

COMPLEXITY

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Applications

Ambulance

VIPs vehicles

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CONCLUSION

The project “Microcontroller based intelligent ambulance traffic controller and

Navigation” has been successfully designed and tested. Integrating features of all

the hardware components used have developed it. Presence of every module has

been reasoned out and placed carefully thus contributing to the best working of the

unit.

Secondly, using highly advanced IC’s and with the help of growing technology the

project has been successfully implemented.

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FUTURE SCOPE

This system is a rapidly growing field and there are new and improved

strategies popping up all the time. For the most part these systems are all built

around the same basic structure, a central box that monitors several detectors and

perimeter guards and sounds an alarm when any of them are triggered.

This system is best for guiding the perimeter of a house or a business

center the points where an intruder would enter the building. In this system IR

sensor is used to detect the intrusion. Similarly the vibration and temperature

sensors recognize vibration disturbances and accidental fires respectively.

This project provides an efficient and economical security system.

This system finds applications in industries, banks and homes.

Incorporating the features discussed below can further enhance the system

1. This system can detect intrusion only at discrete points. This system

detection feature can be extended to scanning a complete area. Thus the

intrusion into the building can be detected with much more efficiently.

2. The redialing feature can also be incorporated such that if the call is not

put forward the first time, the auto dialer will dial the same number until

the call is successfully completed.

3. A pre-recorded voice message can delivered to the owner notifying him

about the intrusion into the premises.

4. The addition of the above discussed advancements certainly builds this

project into a much flexible and reliable security system.

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BIBLIOGRAPHY

1. The 8051 Microcontroller and Embedded Systems By Muhammad Ali Mazidi

2. Fundamentals Of Embedded Software By Daniel W Lewis

3..www.howsstuffworks.com

4. www.alldatasheets.com

5. www.electronicsforu.com

6. www.knowledgebase.com

7.www.8051 projectsinfo.com 8.Datasheets of Microcontroller AT89C52

9. Datasheets of 555 timer

10. Datasheets of TSAL 6200

11. Datasheets of TSOP 1356

12. Datasheets of BC 547

13. Datasheets of DTMF Generator UM 95089

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