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CHAPTER-1

INTRODUCTION

CHIRALA ENGINEERING COLLEGE Page 1


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INTRODUCTION

1.1 Objective

All the time men/women are not available in such cases we use FIRE

FIGHTING ROBO with supervisory control to stop the fire accidents.The objective of

this project is to operate the robot to detect and to stop the fire.

1.2 Introduction to embedded systems

An embedded system is a special-purpose computersystem designed toperform one or a few dedicated functions, often with real-time computing constraints. It

is usually embedded as part of a complete device including hardware and mechanical

parts. In contrast, a general-purpose computer, such as a personal computer, can do

many different tasks depending on programming. Embedded systems control many of

the common devices in use today.

Since the embedded system is dedicated to specific tasks, designengineers can optimize it, reducing the size and cost of the product, or increasing the

reliability and performance. Some embedded systems are mass-produced, benefiting

from economies of scale.

Physically, embedded systems range from portable devices such as

digital watches and MP4 players, to large stationary installations like traffic lights,

factory controllers, or the systems controlling nuclear power plants. Complexity varies

from low, with a single microcontroller chip, to very high with multiple units,

peripherals and networks mounted inside a large chassis or enclosure.

In general, "embedded system" is not an exactly defined term, as many

systems have some element of programmability. For example, handheld computers

share some elements with embedded systems, such as the operating systems and

microprocessors which power them. But are not truly embedded systems, because

they allow different applications to be loaded and peripherals to be connected.

http://wiki/Computerhttp://wiki/Real-time_computinghttp://wiki/Personal_computerhttp://wiki/Economies_of_scalehttp://wiki/MP4_playerhttp://wiki/MP4_playerhttp://wiki/Traffic_lighthttp://wiki/Nuclear_power_planthttp://wiki/Microcontrollerhttp://wiki/Handheld_computerhttp://wiki/Real-time_computinghttp://wiki/Personal_computerhttp://wiki/Economies_of_scalehttp://wiki/MP4_playerhttp://wiki/Traffic_lighthttp://wiki/Nuclear_power_planthttp://wiki/Microcontrollerhttp://wiki/Handheld_computerhttp://wiki/Computer


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1.3 History of embedded systems

In the earliest years of computers in the 1930-40s, computers were

sometimes dedicated to a single task, but were far too large and expensive for most

kinds of tasks performed by embedded computers of today. Over time however, the

concept of programmable controllers evolved from traditional electromechanical

sequencers, via solid state devices, to the use of computer technology.

One of the first recognizably modern embedded systems was the Apollo

Guidance Computer, developed by Charles Stark Draper at the MIT Instrumentation

Laboratory. At the project's inception, the Apollo guidance computer was considered

the riskiest item in the Apollo project as it employed the then newly developed

monolithic integrated circuits to reduce the size and weight. An early mass-produced

embedded system was the Automatics D-17 guidance computer for the Minuteman

missile, released in 1961. It was built from transistorlogic and had a hard disk for main

memory. When the Minuteman II went into production in 1966, the D-17 was

replaced with a new computer that was the first high-volume use of integrated

circuits. This program alone reduced prices on quad nand gate ICs from $1000/each to

$3/each, permitting their use in commercial products.

Since these early applications in the 1960s, embedded systems have

come down in price and there has been a dramatic rise in processing power and

functionality. The first microprocessor for example, the Intel 4004, was designed for

calculators and other small systems but still required many external memory and

support chips. In 1978 National Engineering Manufacturers Association released a

"standard" for programmable microcontrollers, including almost any computer-basedcontrollers, such as single board computers, numerical, and event-based controllers.

As the cost of microprocessors and microcontrollers fell it became

feasible to replace expensive knob-based analog components such as potentiometers

and variable capacitors with up/down buttons or knobs read out by a microprocessor

even in some consumer products. By the mid-1980s, most of the common previously

external system components had been integrated into the same chip as the processorand this modern form of the microcontroller allowed an even more widespread use,

http://wiki/Programmable_controllershttp://wiki/Electromechanicalhttp://wiki/Apollo_Guidance_Computerhttp://wiki/Apollo_Guidance_Computerhttp://wiki/Charles_Stark_Draperhttp://wiki/Minuteman_(missile)http://wiki/Minuteman_(missile)http://wiki/Transistorhttp://wiki/Digital_circuithttp://wiki/Hard_diskhttp://wiki/Sheffer_strokehttp://wiki/Microprocessorhttp://wiki/Intel_4004http://wiki/Calculatorhttp://wiki/Analog_electronicshttp://wiki/Potentiometerhttp://wiki/Variable_capacitorhttp://wiki/Microcontrollerhttp://wiki/Programmable_controllershttp://wiki/Electromechanicalhttp://wiki/Apollo_Guidance_Computerhttp://wiki/Apollo_Guidance_Computerhttp://wiki/Charles_Stark_Draperhttp://wiki/Minuteman_(missile)http://wiki/Minuteman_(missile)http://wiki/Transistorhttp://wiki/Digital_circuithttp://wiki/Hard_diskhttp://wiki/Sheffer_strokehttp://wiki/Microprocessorhttp://wiki/Intel_4004http://wiki/Calculatorhttp://wiki/Analog_electronicshttp://wiki/Potentiometerhttp://wiki/Variable_capacitorhttp://wiki/Microcontroller


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which by the end of the decade were the norm rather than the exception for almost all

electronics devices.

The integration of microcontrollers has further increased the

applications for which embedded systems are used into areas where traditionally a

computer would not have been considered. A general purpose and comparatively low-

cost microcontroller may often be programmed to fulfill the same role as a large

number of separate components. Although in this context an embedded system is

usually more complex than a traditional solution, most of the complexity is contained

within the microcontroller itself. Very few additional components may be needed and

most of the design effort is in the software. The intangible nature of software makes it

much easier to prototype and test new revisions compared with the design and

construction of a new circuit not using an embedded processor

1.4 Classification of Embedded systems

Embedded systems are divided into,

1.Autonomous

2.Real-time

3.Networked and

4.Mobile categories.

Autonomous systems function in standalone mode. Many embedded

systems used for process control in manufacturing units and automobiles fall under

this category. In process control systems the inputs originate from transducers that

convert a physical quantity, such as temperature, into an electric signal. The systemoutput controls the device. In standalone systems, the deadlines or response times are

not critical. An air-conditioner can be set to turn on when the temperature reaches a

certain level. Measuring instruments and CD players are examples of autonomous

systems.

Real time systems are required to carry out specific tasks in a specified

amount of time. These systems are extensively used to carry out time critical tasks inprocess control. For instance, a boiler plant must open the valves if the pressure



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exceeds a particular threshold. If the job is not carried out in the stipulated time, a

catastrophe may result.

Networks embedded systems monitor plant parameters, such as

temperature, pressure, and humidity, and send the data over the network to a

centralized system for online monitoring. A network-enabled web camera monitoring

the plant floor transmits its video output to remote controlling organization.

Mobile gadgets need to store databases locally in their memory. These

gadgets imbibe powerful computing and communication capabilities to perform real

time as well as non-real time tasks and handle multimedia applications. The gadgets

embed powerful processor and OS, and a lot of money with minimal power

consumption.

1.5 Applications of embedded systems

Embedded systems have virtually entered every sphere of our lives,

right from the time we work out on trade mills in the gym, to the cars we drive today.

Embedded systems cover a broad range of products that generalization is difficult.

Some broad categories are

Aero Space and Defense electronics -Flight safety, flight management, fire

control.

Automotive - auto safety, braking and steering systems, car information

systems.

Broadcast and Entertainment - audio control systems, camera systems, DVD

players.

Consumer/Internet Applications - Handheld computers, internet hand held

devices, point-of-sale systems like ATM.

Medical Electronics - cardiovascular devices, real time imaging system

(patient monitoring systems).



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Mobile data infrastructures - wireless LANS, pagers, wireless phones, satellite

terminals (VSATs).

CHAPTER-2



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BLOCK DIAGRAM

BLOCK DIAGRAM


Micro

controller

89C51

RF

Receiver

Relay(blower)

Light

sensor


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Fig:2.1block diagram of fire fighting robot

CIRCUIT DIGRAM


DC

Motor(right

wheel)

IR Sensor

DC Motor

(left wheel)


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+

-

U 2

L M 3 8 6

3

2

5

6

14 8

7

5 V

5 v

1 2 V

Q 3

B C 5 4 8

U 5

L 2 9 3

2

7

1 0

1 5

1

9

3

6

1 1

1 4

1 6

8

1 A

2 A

3 A

4 A

1 / 2 E N

3 / 4 E N

1 Y

2 Y

3 Y

4 Y

V C C 1

V C C 2

1 0 K

1 u c

7 8 0 5

Q 1

B C 5 4 7

1 0 k

1 0 K

1 0 K

1 2 V

B A T T E R Y

1 0 0 k

1 2 v

5 V

2 2 k

1 . 2 k

1 0 k

Y 1

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C A P

1 0 K

C 4

C A P

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U 1

8 0 5 1

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3 0

4 0

3 1

1 9

1 8

9

3 9

3 83 7

3 6

3 5

3 4

3 3

3 2

1

2

3

4

5

6

7

8

2 1

2 22 3

2 4

2 5

2 6

2 7

2 8

1 0

1 1

1 2

1 3

1 4

1 5

1 6

1 7

P S E N

A L E

V C C

E A

X 1

X 2

R S T

P 0 . 0 / A D 0

P 0 . 1 / A D 1

P 0 . 2 / A D 2P 0 . 3 / A D 3

P 0 . 4 / A D 4

P 0 . 5 / A D 5

P 0 . 6 / A D 6

P 0 . 7 / A D 7

P 1 . 0

P 1 . 1

P 1 . 2

P 1 . 3

P 1 . 4

P 1 . 5

P 1 . 6

P 1 . 7

P 2 . 0 / A 8

P 2 . 1 / A 9

P 2 . 2 / A 1 0P 2 . 3 / A 1 1

P 2 . 4 / A 1 2

P 2 . 5 / A 1 3

P 2 . 6 / A 1 4

P 2 . 7 / A 1 5

P 3 . 0 / R X D

P 3 . 1 / T X D

P 3 . 2 / I N T 0

P 3 . 3 / I N T 1

P 3 . 4 / T 0

P 3 . 5 / T 1

P 3 . 6 / W R

P 3 . 7 / R D

5 V

C 3

c 1

1

2

5 V

+

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L M 3 8 6

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5 V

5 V

2 2 0 K

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I N 4 0 0 7

R L 1

R E L A Y S P S T

4

3

1

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+

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L M 3 8 6

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Fig 2.2 circuit diagram

Circuit Operation

When we switch on the robot, it will initialize in auto mode and starts moving.

For robot movement, two dc motors are used. To move forward, both the wheels

rotated with same speed. To turn left or right, corresponding wheel is stopped. L293driver is used to drive the DC motors. Two outputs of this driver can form into one H-

bridge and it can drive the motor in both the directions. The LDR is used to sense the

fire. It varies the resistance according to the light. It is connected in potential divider

using another 10K fixed resistor. Whenever light falls on it, it drops the voltage. This

voltage is compared using comparator against a threshold voltage set by preset. If the

voltage across LDR is less then threshold, the output is LOW else the output is high.

This signal is interfaced to controller. The controller operates the water jet relay

according to the input. The water jet is having another DC motor coupled to water



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tank. When the motor rotates, the pressure build up in the tank and water pumps out

of it through a nozzle.

For manual mode of operation, a remote is designed with another micro

controller interfaced with LCD, keys and RF receiver. The robot is interfaced with RF

receiver. ASK modules with 433MHz carrier is used for RF communication. When

we power up the remote, it scans the keys. If press up & down key together, it

toggles between manual and auto mode. In manual mode, if press each key, the robot

performs each operation like, moving forward, moving reverse, left , right and

releasing water. In this mode it doesnt take LDR feedback.

2.1 Microcontroller

Fig:2.3 pin diagram of micro controller

Microcontrollers are destined to play an increasingly important role in

revolutionizing various industries and influencing our day to day life more strongly

than one can imagine. Since its emergence in the early 1980's the microcontroller has

been recognized as a general purpose building block for intelligent digital systems.



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It is finding using diverse area, starting from simple children's toys to

highly complex spacecraft. Because of its versatility and many advantages, the

application domain has spread in all conceivable directions, making it ubiquitous.

As a consequence, it has generate a great deal of interest andenthusiasm among students, teachers and practicing engineers, creating an acute

education need for imparting the knowledge of microcontroller based system design

and development. It identifies the vital features responsible for their tremendous

impact, the acute educational need created by them and provides a glimpse of the

major application area.

A microcontroller is a complete microprocessor system built on a

single IC. Microcontrollers were developed to meet a need for microprocessors to be

put into low cost products. Building a complete microprocessor system on a single

chip substantially reduces the cost of building simple products, which use the

microprocessor's power to implement their function, because the microprocessor is a

natural way to implement many products.

This means the idea of using a microprocessor for low cost products

comes up often. But the typical 8-bit microprocessor based system, such as one using

a Z80 and 8085 is expensive. Both 8085 and Z80 system need some additional

circuits to make a microprocessor system. Each part carries costs of money. Even

though a product design may requires only very simple system, the parts needed to

make this system as a low cost product.

To solve this problem microprocessor system is implemented with a

single chip microcontroller. This could be called microcomputer, as all the major parts

are in the IC. Most frequently they are called microcontroller because they are used

they are used to perform control functions.

The microcontroller contains full implementation of a standard

MICROPROCESSOR, ROM, RAM, I/0, CLOCK, TIMERS, and also SERIAL

PORTS. Microcontroller also called "system on a chip" or "single chip

microprocessor system" or chip computer. Micro suggests that the device is small,

and controller tells you that the device' might be used to control objects, processes, or

events. Another term to describe a microcontroller is embedded controller, because



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the microcontroller and its support circuits are often built into, or embedded in, the

devices they control.

Today microcontrollers are very commonly used in wide variety of

intelligent products. For example most personal computers keyboards andimplemented with a microcontroller.

It replaces Scanning, Debounce, Matrix Decoding, and Serial

transmission circuits. Many low cost products, such as Toys, Electric Drills,

Microwave Ovens, VCR and a host of other consumer and industrial products are

based on "computer on a chip".

A microcontroller is a Computer-On-A-Chip, or, if you prefer, a

single- microcontrollers.

2.2 Block and pin diagram of micro controller

Fig: 2.4block and pin diagram of microcontroller



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2.3 Pin description

VCC

Supply voltage.GND

Ground.

Port 0

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

each pin can sink eight TTL inputs. When 1s are written to port 0 pins, the pins can be

used as high impedance inputs. Port 0 may 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 bidirectional 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. As inputs, Port

1 pins that are externally being pulled low will source current (IIL) because of the

internal pull-ups. Port 1 also receives the low-order address bytes during Flash

programming and verification.

Port 2





internal pull-ups. 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 it uses strong internal pull-ups when

emitting 1s. During accesses to external data memory that use 8-bit addresses



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

also receives the high-order address bits and some control signals during Flash

programming and verification.

Port 3





pull-ups. Port 3 also serves the functions of various special features of the AT89C51

as listed below:Port 3 also receives some control signals for Flash programming and

verification

Table:2.1 tabular form for port3

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 output pulse for latching the low byte of the

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

(PROG) during Flash programming. In normal operation ALE is emitted at a constant

rate of 1/6 the oscillator frequency, and may be used for external timing or clocking

purposes. Note, however, that one ALE pulse is skipped during each access to

external Data Memory.

If desired, ALE operation can be disabled by setting bit 0 of SFR

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

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

no effect if the microcontroller is in external execution mode.

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 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. 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

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

operating circuit.

XTAL2

Output from the inverting oscillator amplifier. It should be noted that

when idle is terminated by a hard ware reset, the device normally resumes program



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execution, from where it left off, up to two machine cycles before the internal reset

algorithm takes control.

On-chip hardware inhibits access to internal RAM in this event, but

access to the port pins is not inhibited. To eliminate the possibility of an unexpected

write to a port pin when Idle is terminated by reset, the instruction following the one

that invokes Idle should not be one that writes to a port pin or to external memory.

2.4 Architecture of 89C51

Fig: 2.5 architecture of 89c51



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2.5Advantages of micro controller

If a system is developed with a microprocessor, the designer has to go

for external memory such as RAM, ROM or EPROM and peripherals and hence the

size of the PCB will be large enough to hold all the required peripherals. But, the

micro controller has got all these peripheral facilities on a single chip so development

of a similar system with a micro controller reduces PCB size and cost of the design.

One of the major differences between a micro controller and a

microprocessor is that a controller often deals with bits , not bytes as in the real world

application, for example switch contacts can only be open or close, indicators should

be lit or dark and motors can be either turned on or off and so forth.

2.6 Applications of Microcontrollers

Microcontrollers are designed for use in sophisticated real time

applications such as

1. Industrial Control

2. Instrumentation and

3. Intelligent computer peripherals

They are used in industrial applications to control

Motor

Robotics

Discrete and continuous process control In missile guidance and control

Telecommunication

Automobiles

For Scanning a keyboard

Driving an LCD

For Frequency measurements



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Period Measurements

2.7 Relay

Fig:2.6 relay

A relay is an electrically operated switch. Current flowing through the

coil of the relay creates a magnetic field which attracts a lever and changes the switch

contacts. The coil current can be on or off so relays have two switch positions and

they are double throw (changeover) switches. Relays allow one circuit to switch a

second circuit which can be completely separate from the first. For example a low

voltage battery circuit can use a relay to switch a 230V AC mains circuit. There is no

electrical connection inside the relay between the two circuits; the link is magnetic

and mechanical.

The coil of a relay passes a relatively large current, typically 30mA for

a 12V relay, but it can be as much as 100mA for relays designed to operate from

lower voltages. Most ICs (chips) cannot provide this current and a transistor is usually

used to amplify the small IC current to the larger value required for the relay coil. The

maximum output current for the popular 555 timer IC is 200mA so these devices can

supply relay coils directly without amplification.



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Fig: 2.7 outer view of realy

Relays are usually SPDT or DPDT but they can have many more sets

of switch contacts, for example relays with 4 sets of changeover contacts are readily

available. Most relays are designed for PCB mounting but you can solder wires

directly to the pins providing you take care to avoid melting the plastic case of the

relay. The animated picture shows a working relay with its coil and switch contacts.

You can see a lever on the left being attracted by magnetism when the coil is switched

on. This lever moves the switch contacts. There is one set of contacts (SPDT) in the

foreground and another behind them, making the relay DPDT.

The relay's switch connections are usually labeled COM, NC and NO.

COM = Common, always connect to this, it is the moving part of the switch.

NC = Normally Closed, COM is connected to this when the relay coil is off. NO = Normally Open, COM is connected to this when the relay coil is on.

2.7.1 Circuit description

This circuit is designed to control the load. The load may be

motor or any other load. The load is turned ON and OFF through relay. The relay ON

and OFF is controlled by the pair of switching transistors (BC 547). The relay is

connected in the Q2 transistor collector terminal. A Relay is nothing but



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electromagnetic switching device which consists of three pins. They are Common,

Normally close (NC) and Normally open (NO).

The relay common pin is connected to supply voltage. The

normally open (NO) pin connected to load. When high pulse signal is given to base of

the Q1 transistors, the transistor is conducting and shorts the collector and emitter

terminal and zero signals is given to base of the Q2 transistor. So the relay is turned

OFF state.

When low pulse is given to base of transistor Q1 transistor,

the transistor is turned OFF. Now 12v is given to base of Q2 transistor so the

transistor is conducting and relay is turned ON. Hence the common terminal and NO

terminal of relay are shorted. Now load gets the supply voltage through relay.

2.8 Light Sensor

Fig: 2.8 light sensor

2.8.1 Description

The internal components of a photoelectric control for a typical American

streetlight. The photo resistor is facing rightwards, and controls whether current flows

through the heater which opens the main power contacts. At night, the heater cools,

closing the power contacts, energizing the street light. It is basically light dependent

resistor. The heater/bimetal mechanism provides a built-in time-delay.

http://en.wikipedia.org/wiki/Streetlighthttp://en.wikipedia.org/wiki/File:Streetlight_control.jpghttp://en.wikipedia.org/wiki/File:LDR.jpghttp://en.wikipedia.org/wiki/Streetlight


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A photo resistor or light dependent resistor or cadmium sulfide (CdS) cell is a

resistorwhose resistance decreases with increasing incident light intensity. It can also

be referenced as a photoconductor.

A photo resistor is made of a high resistance semiconductor. If light falling on

the device is of high enough frequency,photons absorbed by the semiconductor give

bound electrons enough energy to jump into the conduction band. The resulting free

electron (and its hole partner) conduct electricity, thereby loweringresistance.

A photoelectric device can be either intrinsic or extrinsic. An intrinsic

semiconductor has its own charge carriers and is not an efficient semiconductor, e.g.

silicon. In intrinsic devices the only available electrons are in the valence band, andhence the photon must have enough energy to excite the electron across the entire

band gap. Extrinsic devices have impurities, also called do pants, added whose ground

state energy is closer to the conduction band; since the electrons do not have as far to

jump, lower energy photons (i.e., longer wavelengths and lower frequencies) are

sufficient to trigger the device. If a sample of silicon has some of its atoms replaced

by phosphorus atoms (impurities), there will be extra electrons available for

conduction. This is an example of an extrinsic semiconductor.

2.9 Introduction to DC motor

2.9.1 History:

One of the first electromagnetic rotary motors was invented by Michael

Faraday in 1821 and consisted of a free-hanging wire dipping into a pool of mercury.

A permanent magnet was placed in the middle of the pool. When a current was passed

through the wire, the wire rotated around the magnet, showing that the current gave

rise to a circular magnetic field around the wire. This motor is often demonstrated in

school physics classes, but brine is sometimes used in place of the toxic mercury. This

is the simplest form of a class of electric motors called homopolar motors. A later

refinement is the Barlow's Wheel.

The modern DC motor was invented by accident in 1873, when Znobe

Gramme connected a spinning dynamo to a second similar unit, driving it as a motor.

2.9.2 What is dc motor?

http://en.wikipedia.org/wiki/Resistorhttp://en.wikipedia.org/wiki/Electrical_resistancehttp://en.wikipedia.org/wiki/Semiconductorhttp://en.wikipedia.org/wiki/Frequencyhttp://en.wikipedia.org/wiki/Photonhttp://en.wikipedia.org/wiki/Photonhttp://en.wikipedia.org/wiki/Electronhttp://en.wikipedia.org/wiki/Conduction_bandhttp://en.wikipedia.org/wiki/Conduction_bandhttp://en.wikipedia.org/wiki/Electron_holehttp://en.wikipedia.org/wiki/Electrical_resistancehttp://en.wikipedia.org/wiki/Electrical_resistancehttp://en.wikipedia.org/wiki/Valence_bandhttp://en.wikipedia.org/wiki/Bandgaphttp://en.wikipedia.org/wiki/Dopantshttp://en.wikipedia.org/wiki/Resistorhttp://en.wikipedia.org/wiki/Electrical_resistancehttp://en.wikipedia.org/wiki/Semiconductorhttp://en.wikipedia.org/wiki/Frequencyhttp://en.wikipedia.org/wiki/Photonhttp://en.wikipedia.org/wiki/Electronhttp://en.wikipedia.org/wiki/Conduction_bandhttp://en.wikipedia.org/wiki/Electron_holehttp://en.wikipedia.org/wiki/Electrical_resistancehttp://en.wikipedia.org/wiki/Valence_bandhttp://en.wikipedia.org/wiki/Bandgaphttp://en.wikipedia.org/wiki/Dopants


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Dc motor is an electric motor converts electrical energy into mechanical

motion. The reverse task that of converting mechanical motion into electrical energy,

is accomplished by a generator or dynamo. In many cases the two devices are

identical except for their application and minor construction details.

DC motors are used when there is positioning requirement and also changes in

load and torque. DC motors can be conveniently interfaced to Bipolar DAC, or MPUs

can generate PWM to control them.

The classic DC motor has a rotating ligature in the form of an electromagnet.

A rotary switch called a commutate reverses the direction of the electric current twice

every cycle, to flow through the armature so that the poles of the electromagnet pushand pull against the permanent magnets on the outside of the motor. As the poles of

the armature electromagnet pass the poles of the permanent magnets, the commutate

reverses the polarity of the armature electromagnet. During that instant of switching

polarity, inertia keeps the classical motor going in the proper direction. (See the

diagrams below.)

A simple DC electric motor. When the coil is powered, a magnetic field is generated

around the armature. The left side of the armature is pushed away from the left

magnet and drawn toward the right, causing rotation.

http://en.wikipedia.org/wiki/Image:Electric_motor_cycle_1.png


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The armature continues to rotate.

When the armature becomes horizontally aligned, the commutate reverses the

direction of current through the coil, reversing the magnetic field. The process then

repeats.

2.10 REGULATED POWER SUPPLY

The power supplies are designed to convert high voltage AC mains

electricity to a suitable low voltage supply for electronics circuits and other devices. ARPS (Regulated Power Supply) is the Power Supply with Rectification, Filtering

and Regulation being done on the AC mains to get a Regulated power supply for

Microcontroller and for the other devices being interfaced to it. A power supply can

by broken down into a series of blocks, each of which performs a particular function.

A d.c power supply which maintains the output voltage constant irrespective of a.c

mains fluctuations or load variations is known as Regulated D.C Power Supply

For example a 5V regulated power supply system as shown below:

http://en.wikipedia.org/wiki/Image:Electric_motor_cycle_3.pnghttp://en.wikipedia.org/wiki/Image:Electric_motor_cycle_2.png


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2.10.1 Transformer:

A transformer is an electrical device which is used to convert electrical

power from one Electrical circuit to another without change in frequency.

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. Step-up transformers increase in output voltage, step-down

transformers decrease in output voltage. Most power supplies use a step-down

transformer to reduce the dangerously high mains voltage to a safer low voltage. The

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



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mains supply, and a small number of turns on its secondary (output) coil to give a low

output voltage.

Fig:2.9 Electrical Transformer

Turns ratio = Vp/ VS = Np/NS

Power Out= Power In

VS X IS=VP X IP

Vp = primary (input) voltage

Np = number of turns on primary coil

Ip = primary (input) current

2.10.2 RECTIFIER:

A circuit which is used to convert a.c to dc is known as RECTIFIER. The

process of conversion a.c to d.c is called rectification

TYPES OF RECTIFIERS:

Half wave Rectifier

Full wave rectifier

1. Centre tap full wave rectifier.2. Bridge type full bridge rectifier.

Comparison of rectifier circuits:

Parameter

Type of Rectifier

Half wave Full wave Bridge

Number of diodes1 2 4

PIV of diodesVm 2Vm Vm

D.C output voltageVm/ 2Vm/ 2Vm/



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Vdc,at no-load0.318Vm 0.636Vm 0.636Vm

Ripple factor1.21 0.482 0.482

Ripple frequency F 2f 2f Rectification efficiency

0.406 0.812 0.812Transformer Utilization

Factor(TUF) 0.287 0.693 0.812

RMS voltage Vrms Vm/2 Vm/2 Vm/2

Full-wave Rectifier:

From the above comparison we came to know that full wave bridge rectifier

as more advantages than the other two rectifiers. So, in our project we are using full

wave bridge rectifier circuit.

Bridge Rectifier: 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.

A bridge rectifier makes use of four diodes in a bridge arrangement as shownin fig (a) 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.

Fig (A)



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Operation:

During positive half cycle of secondary, the diodes D2 and D3 are in

forward biased while D1 and D4 are in reverse biased as shown in the fig(b). The

current flow direction is shown in the fig (b) with dotted arrows.

FIG (B)

During negative half cycle of secondary voltage, the diodes D1 and D4 are

in forward biased while D2 and D3 are in reverse biased as shown in the fig(c). The

current flow direction is shown in the fig (c) with dotted arrows.

Fig(C)

2.10.3 VOLTAGE REGULATOR:

Voltage regulator ICs is available with fixed (typically 5, 12 and 15V) or

variable output voltages. The maximum current they can pass also rates them.

Negative voltage regulators are available, mainly for use in dual supplies. Mostregulators include some automatic protection from excessive current ('overload



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protection') and overheating ('thermal protection'). Many of the fixed voltage

regulators ICs have 3 leads and look like power transistors, such as the 7805 +5V 1A

regulator shown on the right. 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.

Fig 2.10 A Three Terminal Voltage Regulator

7805 Regulator:

The Bay Linear LM7805 is integrated linear positive regulator with three

terminals. The LM7805 offer several fixed output voltages making them useful in

wide range of applications. When used as a zener diode/resistor combination

replacement, the LM7805 usually results in an effective output impedanceimprovement of two orders of magnitude, lower quiescent current. The LM7805 is

available in the TO-252, TO-220 & TO-263packages,



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CHAPTER 3

RESULTS AND DISCUSSION



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RESULTS AND DISCUSSION

By using this procedure we designed a program and run successfully,

and it was implemented in the target.In this project we are successfully designed a robot to implement in the

application ofFIRE FIGHTING ROBOT.

3.1 Discussion

Here we just design a model to implement this application and the

major limitation is the sensitivity of the sensors what we are implemented. Here we

can able to detect up to few centimetres only. If we can increase the sensitivity of

sensors then we can use our system in real time applications like military, navy,

industries etc....

3.2 Advantages

1. Reduce the manpower to find out the fire

2. Economical3. Easy to implement

3.3 Applications

1. Manufacturing industries

2. Fireworks industries

3. Textiles

4. Military applications



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CHAPTER 4

CONCLUSION

4.Conclusion



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The proposed system based on Atmel microcontroller is found to be

more compact, user friendly and less complex, which can readily be used in order to

perform. Several tedious and repetitive tasks. Though it is designed keeping in mind

about the need for industry, it can extended for other purposes such as commercial &

research applications. Due to the probability of high technology (Atmel

microcontroller) used this FIRE FIGHTING ROBOT is fully software controlled

with less hardware circuit.

CHAPTER 5



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REFERENCES

References

1. Printed circuit boards-design & technology by Walter c boss



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2. Electrical estimating and costing-surjit singh (dhanpat rai & co).

3.Atmel corporation microcontroller Databook Oct 1995.4. 8051 microcontroller architecture and programming Kenath Ayala.

5.Michael Barr, Programming embedded systems in C &C++, TMH 19906.The 8051 Microcontroller and Embedded systems Muhammad Ali. Mazidi

and Janice Gillespie Mazidi.

Websites

www.atmel.com

www.microchip.com www.8052.com

www.beyondlogic.org

www.ctv.es/pckits/home.html

www.aimglobal.org

www.wikimapia.com

http://www.8052.com/http://www.beyondlogic.org/http://www.ctv.es/pckits/home.htmlhttp://www.8052.com/http://www.beyondlogic.org/http://www.ctv.es/pckits/home.html


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