complet finalised

BORDER SECURITY USING WIRELESS INTEGRATED NETWORK (WINS) 2012

BORDER SECURITY USING WIRELESS INTEGRATED NETWORK (WINS)

A Project Report Submittedin Partial Fulfillment of the Requirements

for the Degree of

BACHELOR OF TECHNOLOGY

in

ELECTRONICS & COMMUNICATION ENGINEERING

by

Prashant Singh Harish Kumar Vishal Pathak

(2008UEC079) (2007UEC187) (2007UEC056)

Subham Chauhan Abhishek Jain

(2007UEC165) (2007UEC061)

Under the Supervision of

Mrs. (Er.) Avantika Sharma

DEPARTMENT OF ELECTRONICS & COMMUNICATION ENGINEERING

INSTITUTE OF ENGINEERING & TECHNOLOGY

MANGALAYATAN UNIVERSITY ALIGARH

April, 2012

Mangalayatan University 1


CERTIFICATE

Certified that Prashant Singh (2008UEC079), Harish Kumar (2007UEC187), Vishal

Pathak (2007UEC056), Subham Chauhan (2007UEC165), Abhishek Jain

(2007UEC061) has carried out the research work presented in this report entitled “Border

Security Using Wireless Integrated Network (WINS)” for the award of Bachelor of

Technology in Electronics & Communication Engineering from Mangalayatan

University, Aligarh under my supervision. The report embodies results of original work,

and studies are carried out by the student himself and the contents of the thesis do not form

the basis for the award of any other degree to the candidate or to anybody else from this or

any other University/Institution.

(Mrs. (Er.) Avantika Sharma)

Lecturer & Project Supervisor

Date:

(Dr. Sudhir Kumar Sharma)

Associate Professor & Head

Department of Electronics & Communication Engineering

Mangalayatan University, Aligarh-202125

Date:



DECLARATION

We hereby declare that this submission is our own work and that, to the best of our knowledge and belief, it contains no material previously published or written by another person nor material which to a substantial extent has been accepted for the award of any other degree or diploma of the university or other institute of higher learning, except where due acknowledgment has been made in the text.

Prashant Singh (2008UEC079)

Harish Kumar (2007UEC187)

Vishal Pathak (2007UEC056)

Subham Chauhan (2007UEC165)

Abhishek Jain (2007UEC061)

Date :



ACKNOWLEDGEMENT

It gives us a great sense of pleasure to present the report of the B. Tech Project undertaken during B. Tech. Final Year. We owe special debt of gratitude to Mrs. (Er.) Avantika Sharma, Department of Electronics & Communication Engineering, Institute of Engineering & Technology, Mangalayatan University, Aligarh for her constant support and guidance throughout the course of our work. Her sincerity, thoroughness and perseverance have been a constant source of inspiration for us. It is only her cognizant efforts that our endeavors have seen light of the day.

We also take the opportunity to acknowledge the contribution of Ass. Professor Sudhir Sharma, Head, Department of Electronics & Communication Engineering, Institute of Engineering & Technology, Mangalayatn University, Aligarh for his full support and assistance during the development of the project.

We also do not like to miss the opportunity to acknowledge the contribution of all faculty members of the department for their kind assistance and cooperation during the development of our project. Last but not the least, we acknowledge our friends for their contribution in the completion of the project.

Prashant Singh (2008UEC079)

Harish Kumar (2007UEC187)

Vishal Pathak (2007UEC056)

Subham Chauhan (2007UEC165)

Abhishek Jain (2007UEC061)



TABLE OF CONTENTS

Topic Page

CERTIFICATE ....................................................................................................... i

DECLARATION .....................................................................................................ii

ACKNOWLEDGEMENTS ....................................................................................iii

CHAPTER 1.INTRODUCTION

The Basic Concept ..............................................................................1

CHAPTER 2. Circuit Description………………………………………………….4

CHAPTER 3.Component Description…………………………………………7 CHAPTER 4. Basic Requirements Basic Requirments……………………………………………………..10

4.1 Pyro sensor…………………………………………………………….114.2 Camera………………………………………………………………...154.3 Gun……………………………………………………………………164.4 Relay…………………………………………………………………..174.5 Television……………………………………………………………...204.6 Transformer……………………………………………………………214.7 Buzzer…………………………………………………………………304.8 Stepper Motor…………………………………………………………324.9 Microcontroller………………………………………………………...354.10 Regulator……………………………………………………………...604.11 Switch………………………………………………………………….654.12 Crystals………………………………………………………………...754.13 Diode…………………………………………………………………..754.14 Reset Circuitry…………………………………………………………82

CHAPTER 5. Problem Description…………………………………………...85 CHAPTER 6. Conclusion……………………………………………………..87 CHAPTER 7. Future Advancement…………………………………………..89 CHAPTER 8. References……………………………………………………..91



CHAPTER- 1

INTRODUCTION



INTRODUCTION

Our project, BORDER SECURITY SYSTEMS, is based on the concept of WIRELESS

INTEGRATED NETWORK SENSORS (WINS).

WINS provides a new monitoring and control capability for the border of the country. It

requires a microwatt of power and produces a less amount of delay to detect the target. Hence

it is reasonably faster.

The border security is the applicable scope for the effort of security check of the border. This

provides with the programmatic outcomes required by the framework for establishing a

perfect security.

The effective border security gives us the power to see the potential threats on the extreme

lines. Thus, emerging as a helping hand for the nation’s security.

The project uses Motion Detector which is the constructional feature of the PIR Sensor. This

is an electronic device that measures IR light radiating from objects in its field of view and is

invisible to the human eye.

The project also uses the stepper motor to control the rotatory motion of the gun. As soon as

the detecting sensor activates, the camera, TV and motor gets activated automatically.

Shooting from the gun is governed according to the requirement that suits to the security

person. This all is operated by the microcontroller commands.

A Relay, operated by an electromagnet is used to switch ON the gun functioning. The Relay

is used to isolate one circuit from the other. The programmatic outcomes required by the

framework for establishing a perfect security.

The effective border security gives us the power to see the potential threats on the extreme

lines. Thus, emerging as a helping hand for the Nation’s security.



The project uses Motion Detector which is the constructional feature of the PIR Sensor. This

is an electronic device that measures IR light radiating from objects in its field of view and is

invisible to the human eye.

The project also uses the stepper motor to control the rotatory motion of the gun. As soon as

the detecting sensor activates, the camera, TV and motor gets activated automatically.

Shooting from the gun is governed according to the requirement that suits to the security

person. This all is operated by the microcontroller commands.

A Relay, operated by an electromagnet is used to switch ON the gun functioning. The Relay

is used to isolate one circuit from the other.

A Step down Transformer is also used that lowers down the voltage from 220 volts AC to 12

volts. This is done as the stepper motor needs the 12 volts voltage for its functioning.

A Microcontroller from the family of 8051 is used which is interfaced with the stepper

motor. Thus the functioning of all the equipments is controlled by the microcontroller. As this

is a computer-on-a-chip.

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

they control.



CHAPTER-2

CIRCUIT DESCRIPTION



Circuit Description

It is the schematic of our first test circuit. The PIC's output lines are first buffered by a

4050 hex buffer chip, and are then connected to an NPN transistor. The transistor

used, TIP120, is actually a NPN Darlington (it is shown as a standard NPN). The

TIP120’s act like switches, activating one stepper motor coil at a time.



Due to a inductive surge created when a coil is toggled, a standard 1N4001 diode is

usually placed across each transistor as shown in the figure, providing a safe way of

dispersing the reverse current without damaging the transistor. Sometimes called a

snubbing diode. The TIP120 transistors do not need an external snubbing diode

because they have a built in diode.

So the diodes shown in the drawing are the internal diodes in the TIP120 transistors.

The simplest way to operate a stepper motor with a PIC is with the full step pattern

shown in Table 1. Each part of the sequence turns on only one transistor at a time, one

after the other. After the sequence is completed, it repeats infinitely until power is

removed.

Q1 Q2 Q3 Q4

+ - - -

- + - -

- - + -

- - - +



CHAPTER: 3

COMPONENT LIST



COMPONENT LIST

1. Capacitance

1000µf : 3

10µf : 1

27þf : 3

2. Diode

IN4007 : 12

3. LED : 8

4. Resistance

470Ω : 8

10KΩ : 1

1KΩ : 5

5. Stepper Motor Coil : 4

6. Switch : 4

7. Transistor :

NPN : 5

PNP : 7



CHAPTER: 4

BASIC REQUIREMENTS

BASIC REQUIREMENTS



1. Pyro sensor

2. Camera

3. Gun

4. Relay

5. Television

6. Step Down Transformer

7. Buzzer

8. Stepper Motor

9. Micro Controller

10. Regulator

11. Switch

12. Crystal Used

13. Diode

14. Reset Circuitry

4.1 Pyro sensors



A PIR sensor, or Passive Infrared sensor, is a type of detector that is capable of detecting

infrared light emitting from objects within its field of view. PIR sensors differ from other

infrared sensors because they are only able to receive infrared waves rather than being able to

emit and receive them. Because all objects emit infrared (electromagnetic waves that travel

with heat), PIR sensors are able to detect objects that are in front of them. In fact, PIR sensors

can see many things that humans cannot.

PIR sensors are made of pyroelectric (or thermoelectric) materials and usually contain lenses

or mirrors in order to focus the infrared light for maximum reception. As infrared light comes

in contact with the pyroelectric material, which is usually a thin sheet, it creates an electrical

current that can be measured to determine the intensity of the infrared light (depth perception)

and the direction that it came from.

PIR sensors are made of pyroelectric (or thermoelectric) materials and usually contain lenses

or mirrors in order to focus the infrared light for maximum reception. As infrared light comes

in contact with the pyroelectric material, which is usually a thin sheet, it creates an electrical

current that can be measured to determine the intensity of the infrared light (depth perception)

and the direction that it came from.

Fig1:pyro sensors

Working:



A passive infrared detection and conversion circuit, comprising:

a. a pyrosensor

b. a current amplifier coupled with said pyrosensor

c. a capacitor coupled with said amplifier

d. a signal processor circuit coupled with said capacitor and being operable to charge

said capacitor to a first voltage level and to measure a capacitor discharge time, said

capacitor discharge time being the time required for said capacitor to discharge from

said first voltage level to a second voltage level, and being further operable to

generate an electrical control signal responsive to a variation in said capacitor

discharge time which corresponds to a significant motion event.

The passive infrared detection and conversion circuit wherein, when said pyrosensor is

exposed to infrared motion, it generates a transient current and wherein said capacitor

discharge time corresponds to said transient current.

The passive infrared detection and conversion circuit wherein said signal processor circuit

includes logic operable to compare said capacitor discharge time with a long term average

capacitor discharge time, and wherein said signal processor circuit generates said electrical

control signal only when said capacitor discharge time deviates from said long-term average

capacitor discharge time by a predetermined threshold amount.

The passive infrared detection and conversion circuit wherein said logic of said signal

processor circuit is further operable to calculate and update said long term average capacitor

discharge time based on said capacitor discharge time such that said logic filters out

unwanted background signals.

The passive infrared detection and conversion circuit wherein said logic calculates and

updates said long term average capacitor discharge time by adding a value corresponding to

the difference between said long term average capacitor discharge time and said capacitor

discharge time to said long term average capacitor discharge time.



The passive infrared detection and conversion circuit wherein said current amplifier is a

transistor.

A method for selectively generating a control signal corresponding to motion of an infrared

emitting body, comprising the steps of:

a. Charging a capacitor to a first voltage level;

b. Generating a current corresponding to said infrared motion by means of a pyrosensor;

c. Transmitting said current through a current amplifier;

d. Discharging said capacitor;

e. Measuring a capacitor discharge time, said capacitor discharge time being the time

required for said capacitor to discharge from said first voltage level to a second voltage

level;

f. sensing a significant motion event by a pyrosensor and generating a transient current

responsive thereto;

g. Delivering said current to said capacitor causing a variation in said discharge time; and

h. Generating an electrical control signal responsive to said variation in said capacitor

discharge time.

The method for selectively generating a control signal of further including the step of filtering

out background signals.

The method for selectively generating a control signal further including the steps of

calculating and updating a long term average capacitor discharge time corresponding to said

capacitor discharge time and wherein the step of filtering includes comparing said capacitor

discharge time to said long term average capacitor discharge time.

The method for selectively generating a control signal of wherein the steps of calculating and

updating include updating said long term average capacitor discharge time by adding a value



corresponding to the difference between said long term average capacitor discharge time and

said capacitor discharge time to said long term average capacitor discharge time.

The method for selectively generating a control signal of wherein the step of filtering further

includes the step of comparing said capacitor discharge time with said long term average

capacitor discharge time and generating said control signal if the difference between said

capacitor discharge time and said long term average capacitor discharge time exceeds a

predetermined threshold value.

A method for selectively generating a control signal, comprising the steps of:

a. charging a capacitor to a known first voltage level and allowing said capacitor to

discharge to a second known voltage level at a known discharge rate;

b. modifying the discharge rate of said capacitor in proportion to the current output from

an infrared motion detector;

c. measuring said modified discharge rate of said capacitor; and

d. generating a signal corresponding to said modified discharge rate of said capacitor.

The method for selectively generating a control signal of further including the step of

adjusting a signal threshold in accordance with said discharge rate of said capacitor to

compensate for background signals.

How is this time then calculated?

The speed with which a microcontroller executes instructions is determined by what is known

as the crystal speed. A crystal is a component connected externally to the microcontroller.

The crystal has different values, and some of the used values are 6MHZ, 10MHZ, and 11.059

MHz etc. Thus, a 10MHZ crystal would pulse at the rate of 10,000,000 times per second.

The time is calculated using the formula

No of cycles per second = Crystal frequency in HZ / 12. For a 10MHZ crystal the number of

cycles would be, 10,000,000/12=833333.33333 cycles.



This means that in one second, the microcontroller would execute 833333.33333 cycles.

Hardware Design

A system capable of detecting motion using a dual element PIR sensor using the

MSP430F2013 microcontroller. The MSP430F2013 provides all the required elements for

interfacing to the PIR sensor in a small footprint, using the integrated 16-bit Sigma-Delta

analog-to digital converter (ADC) and built-in front-end PGA (SD16_A). A simplified circuit

that is used to process the PIR sensor output signal is shown. The external components

consist of the bias resistor, RB, required for the sensor and two RC filters formed by R1/C1

and R2/C2. The R1/C1 filter serves as an anti-aliasing filter on the AX+ input.R2/C2 serves

to create a DC bias for the AX- input. With a small peak-to-peak sensor output of the PIR, , a

higher gain setting is required eliminating the possibility that AX- can be tied directly to

VSS. The sensor output signal after the ant aliasing filter is connected to AX+. Simple DC

bias is established for maintaining the input range requirements of the SD16_A By heavily

low pass filtering the sensor output before connecting to AX-.

Software Design:Analog sampling and data processing is kept to a minimum required to reliably detect

motion. If no motion was detected in the last measurement the SD16_A internal reference is

enabled and a new conversion is started. After the conversion is complete, the SD16_A ISR

is entered and the internal reference is disabled.

4.2 CAMERA

A camera is a device that records/stores images. These images may be still photographs or

moving images such as videos or movies. The term camera comes from the camera

obscura (Latin for "dark chamber"), an early mechanism for projecting images. The modern

camera evolved from the camera obscura.

Cameras may work with the light of the visible spectrum or with other portions of

the electromagnetic spectrum. A camera generally consists of an enclosed hollow with an

opening (aperture) at one end for light to enter, and a recording or viewing surface for

capturing the light at the other end. A majority of cameras have a lens positioned in front of


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

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

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

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

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

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

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

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


the camera's opening to gather the incoming light and focus all or part of the image on the

recording surface. Most 20th century cameras used photographic film as a recording surface,

while modern ones use an electronic camera sensor. The diameter of the aperture is often

controlled by a diaphragm mechanism, but some cameras have a fixed-size aperture.

4.3 GUN

Gun is a muzzle or breech-loaded projectile firing weapon. In modern parlance, gun is a

projectile weapon using hollow, tubular barrel with a closed end-the breech-as the means of

directing the projectile. Most guns are described by the types of the barrel used, the means of

firing, the purpose of the weapon used, the caliber or the commonly accepted name for a

particular variation.

In Military use, the term “GUN” refers primarily to direct fire weapons that capitalize on

their velocity for penetration and range. These weapons are breeched-loaded and built

primarily for long range fire with a low or almost flat ballistic area.

WORKING OPERATION:

As the semi-conductor technology is experiencing rapid growth, human life gets complicated

without “embedded system”. Nowadays these new technologies are introduced in the

equipments engaged in the battlefield to improve the safety of soldiers and also to ensure

combat effectiveness. Our scope is to develop a mechanism to automatically control the

movement of the air defense gun mounted on the tank. Air defense gun is mounted on the

loader’s hatch in the turret of the tank and is controlled by the loader .It is primarily used to

attack low flying armored vehicles. Presently the gunner has to expose himself to track the

enemy and attack the target and so he becomes vulnerable to external foes, added to it he has

to manually adjust the desired elevation and depression of the air defense gun.


http://en.wikipedia.org/wiki/Diaphragm_(optics)

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

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


BASIC REQUIREMENTS

The system should enable sighting of the target through a sight, aiming the target in hatch

closed condition by slewing and elevating/ depressing anti-aircraft gun The system should

enable the rotation of loader’s hatch in azimuth plane both in anti-clockwise and clockwise

direction through 360 degree. The movement of air defense gun in the vertical plane is from -

10 degree to +70 degree. The system also requires automatic stopping of gun movement if it

attains the extreme positions in the vertical plane.

TRIGGERA trigger is a mechanism that actuates the firing sequence of firearms, or a power tool.

Triggers almost universally consist of levers or buttons actuated by the index finger. Rare

variations use the thumb to actuate the trigger.

Firearms use triggers to initiate the firing of a cartridge in the firing chamber of the weapon.

This is accomplished by actuating a striking device through a combination of spring and

kinetic energy operating through a firing pin to strike and ignite the primer.

4.4 RELAY

A relay is an electrically operated switch. It is used to isolate one electrical circuit from

another. It allows a low current control circuits to make or break the electrically isolated high

current circuit path.



Fig 2: Development of magnetic field in a relay as a switch

Many relays use the electromagnet to operate a switching mechanism mechanically, but other

operating principles are also used.

Relays are used where it is necessary to control a circuit by a low power signal (with

complete electrical isolation between control and controlled circuits), or where several

circuits must be controlled by one signal.

Relays are extremely useful when we have a need to control a large amount of current and/or

voltage with a small electrical signal. The relay coil which produces the magnetic field may

only consume fraction of watt of power, while the contact is closed or opened by that

magnetic field may be able to conduct hundreds of times that amount of power to a load.

The basic relay consists of a coil and a set of contacts. The most common relay coil is a

length of magnet wire wrapped around a metal core. When voltage is applied to the coil, the

current passes through the wire and creates a magnetic field. This magnetic field pulls the

contacts together and holds them until the current flow in the coil has stopped.



Fig3: Relay Functioning

The coil voltage and the current carrying capability of the contacts are the major

specifications needed to be considered while selecting a relay.

The current rating on the relay contacts tells how much current can be passed through the

contacts without damage to the contacts.

BASIC DESIGN AND OPERATION:

A simple electromagnetic relay consists of a coil of wire surrounding a soft iron core, an iron

yoke which provides a low reluctance path for magnetic flux, a movable iron armature and

one or more sets of contacts. The armature is hinged to the yoke and mechanically linked to

one or more sets of contacts. It is held in place by a spring so that when the relay is de-

energizes there is an air gap in the magnetic circuit. The connection of the armature and the

yoke ensures continuity of the circuit between the moving contacts on the armature.

When an electric current is passed through the coil it generates the magnetic field that attracts

the armature, and the consequent movement of the contact(s) either makes or breaks the



connection with the fixed contact. If the set of contacts was closed when the relay was de-

energized, then the movement opens the contacts and breaks the connection and vice versa if

the contacts were open. When the current to the coil is switched off, the armature is returned

by a force, approximately half as strong as the magnetic force, to its relaxed position. Usually

this force is provided by a spring, but gravity is also used in industrial motor starters.

When the coil is energized by the direct current, a diode is often placed across the coil to

dissipate the energy from the collapsing magnetic field at deactivation which would rather

generate a voltage splice dangerous to semiconductor circuit components.

Fig 4 : An Electro-Mechanical Relay

4.5 Television

Television (TV) is a telecommunication medium for transmitting and receiving moving

images that can be monochromatic (shades of grey) or multi colored. Images are usually

accompanied by sound. "Television" may also refer specifically to a television set, television

programming, and television transmission.

Television has become a major medium of communication and source for home

entertainment. Television is put to varied use in industry, e.g., for surveillance in places

inaccessible to or dangerous for human beings; in science.

Television, transmission and reception of still or moving images by means of electrical

signals, especially by means of electromagnetic radiation energy radiated in the form of a


http://en.wikipedia.org/wiki/Transmission_(telecommunications)

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

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

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

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

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

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

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

http://en.wikipedia.org/wiki/Mass-media

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


wave as a result of the motion of electric charges. A moving charge gives rise to a magnetic

field, and if the motion is changing (accelerated), then the magnetic field varies .

A standard television set comprises multiple internal electronic circuits, including those for

receiving and decoding broadcast signals. A visual display device which lacks a tuner is

properly called a monitor, rather than a television. A television system may use different

technical standards such as digital television (DTV) and high-definition television (HDTV).

Television systems are also used for surveillance, industrial process control, and guiding of

weapons, in places where direct observation is difficult or dangerous.

Fig5: Wavelengths existing in a television

4.6 Transformer

A transformer is a static device that transfers electrical energy from one circuit to another

through inductively coupled conductors, the transformer's coils. A varying current in the first

or primary winding creates a varying magnetic flux in the transformer's core and thus a

varying magnetic field through the secondary winding. This varying magnetic field induces a

varying electromotive force (EMF) or "voltage" in the secondary winding. This effect is

called mutual induction.

If a load is connected to the secondary, an electric current will flow in the secondary winding

and electrical energy will be transferred from the primary circuit through the transformer to

the load. In an ideal transformer, the induced voltage in the secondary winding (Vs) is in


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

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

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

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

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

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

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

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

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

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

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

http://en.wikipedia.org/wiki/High-definition_television

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

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

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

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

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

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


proportion to the primary voltage (Vp), and is given by the ratio of the number of turns in the

secondary (Ns) to the number of turns in the primary (Np) as follows:

By appropriate selection of the ratio of turns, a transformer thus allows an alternating current

(AC) voltage to be "stepped up" by making Ns greater than Np, or "stepped down" by making

Ns less than Np.

In the vast majority of transformers, the windings are coils wound around a ferromagnetic

core, air-core transformers being a notable exception.

Discovery

Fig6: Discovery of principle of mutual induction

Faraday's experiment with induction between coils of wire

The phenomenon of electromagnetic induction was discovered independently by Michael

Faraday and Joseph Henry in 1831. However, Faraday was the first to publish the results of

his experiments and thus receive credit for the discovery.[2] The relationship between

electromotive force (EMF) or "voltage" and magnetic flux was formalized in an equation

now referred to as "Faraday's law of induction":


http://en.wikipedia.org/wiki/Faraday's_law_of_induction

http://en.wikipedia.org/wiki/Equation_(mathematics)




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

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

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


http://en.wikipedia.org/wiki/Transformer#Cores

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


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


http://en.wikipedia.org/wiki/File:Induction_experiment.png

http://en.wikipedia.org/wiki/File:Induction_experiment.png


.

where the magnitude of the EMF in volts and ΦB is is the magnetic flux through the

circuit (in webers).

Faraday performed the first experiments on induction between coils of wire, including

winding a pair of coils around an iron ring, thus creating the first to roidal closed-core

transformer.

Basic principle:

The transformer is based on two principles:

First, that an electric current can produce a magnetic field (electromagnetism),

And, second that a changing magnetic field within a coil of wire induces a voltage across the

ends of the coil (electromagnetic induction). Changing the current in the primary coil changes

the magnetic flux that is developed. The changing magnetic flux induces a voltage in the

secondary coil.

Fig7: An ideal transformer



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



http://en.wikipedia.org/wiki/Toroid_(geometry)

http://en.wikipedia.org/wiki/Weber_(Wb)


http://en.wikipedia.org/wiki/File:Transformer3d_col3.svg


An ideal transformer is shown in the adjacent figure. Current passing through the primary

coil creates a magnetic field. The primary and secondary coils are wrapped around a core of

very high magnetic permeability, such as iron, so that most of the magnetic flux passes

through both the primary and secondary coils.

Induction law

The voltage induced across the secondary coil may be calculated from Faraday's law of

induction, which states that:

where Vs is the instantaneous voltage, Ns is the number of turns in the secondary coil and Φ is

the magnetic flux through one turn of the coil. If the turns of the coil are oriented

perpendicular to the magnetic field lines, the flux is the product of the magnetic flux density

B and the area A through which it cuts. The area is constant, being equal to the cross-sectional

area of the transformer core, whereas the magnetic field varies with time according to the

excitation of the primary. Since the same magnetic flux passes through both the primary and

secondary coils in an ideal transformer, the instantaneous voltage across the primary winding

equals

Taking the ratio of the two equations for Vs and Vp gives the basic equation for stepping up or

stepping down the voltage

Np/Ns is known as the turns ratio, and is the primary functional characteristic of any

transformer. In the case of step-up transformers, this may sometimes be stated as the

reciprocal, Ns/Np. Turns ratio is commonly expressed as an irreducible fraction or ratio: for

example, a transformer with primary and secondary windings of, respectively, 100 and 150

turns is said to have a turns ratio of 2:3 rather than 0.667 or 100:150.


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

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


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



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

http://en.wikipedia.org/wiki/Permeability_(electromagnetism)




Ideal power equation

Fig 8: Ideal transformer as a circuit element

If the secondary coil is attached to a load that allows current to flow, electrical power is

transmitted from the primary circuit to the secondary circuit. Ideally, the transformer is

perfectly efficient; all the incoming energy is transformed from the primary circuit to the

magnetic field and into the secondary circuit. If this condition is met, the incoming electric

power must equal the outgoing power:

giving the ideal transformer equation

Transformers normally have high efficiency, so this formula is a reasonable approximation.

If the voltage is increased, then the current is decreased by the same factor. The impedance in

one circuit is transformed by the square of the turns ratio. For example, if an impedance Zs is

attached across the terminals of the secondary coil, it appears to the primary circuit to have an

impedance of (Np/Ns)2Zs. This relationship is reciprocal, so that the impedance Zp of the

primary circuit appears to the secondary to be (Ns/Np)2Zp.

Detailed OperationMangalayatan University 30

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



http://en.wikipedia.org/wiki/File:Transformer_under_load.svg


The simplified description above neglects several practical factors, in particular the primary

current required to establish a magnetic field in the core, and the contribution to the field due

to current in the secondary circuit.

Models of an ideal transformer typically assume a core of negligible reluctance with two

windings of zero resistance.[31] When a voltage is applied to the primary winding, a small

current flows, driving flux around the magnetic circuit of the core. The current required to

create the flux is termed the magnetizing current; since the ideal core has been assumed to

have near-zero reluctance, the magnetizing current is negligible, although still required to

create the magnetic field.

The changing magnetic field induces an electromotive force (EMF) across each winding.

Since the ideal windings have no impedance, they have no associated voltage drop, and so the

voltages VP and VS measured at the terminals of the transformer, are equal to the

corresponding EMFs. The primary EMF, acting as it does in opposition to the primary

voltage, is sometimes termed the "back EMF". This is due to Lenz's law which states that the

induction of EMF would always be such that it will oppose development of any such change

in magnetic field.

Energy Loss

An ideal transformer would have no energy losses, and would be 100% efficient. In practical

transformers energy is dissipated in the windings, core, and surrounding structures. Larger

transformers are generally more efficient, and those rated for electricity distribution usually

perform better than 98%.

Transformer losses are divided into losses in the windings, termed copper loss, and those in

the magnetic circuit, termed iron loss. Losses in the transformer arise from:

Winding resistance


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

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

http://en.wikipedia.org/wiki/Lenz's_law

http://en.wikipedia.org/wiki/Counter-electromotive_force


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


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

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


Current flowing through the windings causes resistive heating of the conductors. At higher

frequencies, skin effect and proximity effect create additional winding resistance and losses.

Hysteresis losses

Each time the magnetic field is reversed, a small amount of energy is lost due to hysteresis

within the core. For a given core material, the loss is proportional to the frequency, and is a

function of the peak flux density to which it is subjected.

Eddy currents

Ferromagnetic materials are also good conductors, and a core made from such a material also

constitutes a single short-circuited turn throughout its entire length. Eddy currents therefore

circulate within the core in a plane normal to the flux, and are responsible for resistive

heating of the core material. The eddy current loss is a complex function of the square of

supply frequency and inverse square of the material thickness. Eddy current losses can be

reduced by making the core of a stack of plates electrically insulated from each other, rather

than a solid block; all transformers operating at low frequencies use laminated or similar

cores.


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


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

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

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

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

http://en.wikipedia.org/wiki/Proximity_effect_(electromagnetism)

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



Magnetostriction

Magnetic flux in a ferromagnetic material, such as the core, causes it to physically expand

and contract slightly with each cycle of the magnetic field, an effect known as

magnetostriction. This produces the buzzing sound commonly associated with transformers,

and can cause losses due to frictional heating.

Mechanical losses

In addition to magnetostriction, the alternating magnetic field causes fluctuating forces

between the primary and secondary windings. These incite vibrations within nearby

metalwork, adding to the buzzing noise, and consuming a small amount of power.

Stray losses

Leakage inductance is by itself largely lossless, since energy supplied to its magnetic fields is

returned to the supply with the next half-cycle. However, any leakage flux that intercepts

nearby conductive materials such as the transformer's support structure will give rise to eddy

currents and be converted to heat. There are also radiative losses due to the oscillating

magnetic field, but these are usually small.

Equivalent Circuit

The physical limitations of the practical transformer may be brought together as an equivalent

circuit model (shown below) built around an ideal lossless transformer. Power loss in the

windings is current-dependent and is represented as in-series resistances Rp and Rs. Flux

leakage results in a fraction of the applied voltage dropped without contributing to the mutual

coupling, and thus can be modeled as reactances of each leakage inductance Xp and Xs in

series with the perfectly coupled region.

Iron losses are caused mostly by hysteresis and eddy current effects in the core, and are

proportional to the square of the core flux for operation at a given frequency. Since the core

flux is proportional to the applied voltage, the iron loss can be represented by a resistance RC

in parallel with the ideal transformer.


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A core with finite permeability requires a magnetizing current Im to maintain the mutual flux

in the core. The magnetizing current is in phase with the flux; saturation effects cause the

relationship between the two to be non-linear, but for simplicity this effect tends to be

ignored in most circuit equivalents. With a sinusoidal supply, the core flux lags the induced

EMF by 90° and this effect can be modeled as a magnetizing reactance (reactance of an

effective inductance) Xm in parallel with the core loss component. Rc and Xm are sometimes

together termed the magnetizing branch of the model. If the secondary winding is made open-

circuit, the current I0 taken by the magnetizing branch represents the transformer's no-load

current. The secondary impedance Rs and Xs is frequently moved (or "referred") to the

primary side after multiplying the components by the impedance scaling factor (Np/Ns)2.

Fig 9: Transformer equivalent circuit, with secondary impedances referred to the primary side

The resulting model is sometimes termed the "exact equivalent circuit", though it retains a

number of approximations, such as an assumption of linearity. Analysis may be simplified by

moving the magnetizing branch to the left of the primary impedance, an implicit assumption

that the magnetizing current is low, and then summing primary and referred secondary

impedances, resulting in so-called equivalent impedance.

The parameters of equivalent circuit of a transformer can be calculated from the results of

two transformer tests: open-circuit test and short-circuit test.

Application

A major application of transformers is to increase voltage before transmitting electrical

energy over long distances through wires. Wires have resistance and so dissipate electrical

energy at a rate proportional to the square of the current through the wire. By transforming


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

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

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

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

http://en.wikipedia.org/wiki/Permeability_(electromagnetism)

http://en.wikipedia.org/wiki/File:Transformer_equivalent_circuit.svg


electrical power to a high-voltage (and therefore low-current) form for transmission and back

again afterward, transformers enable economical transmission of power over long distances.

Consequently, transformers have shaped the electricity supply industry, permitting generation

to be located remotely from points of demand. All but a tiny fraction of the world's electrical

power has passed through a series of transformers by the time it reaches the consumer.

Transformers are also used extensively in electronic products to step down the supply voltage

to a level suitable for the low voltage circuits they contain. The transformer also electrically

isolates the end user from contact with the supply voltage.

Signal and audio transformers are used to couple stages of amplifiers and to match devices

such as microphones and record players to the input of amplifiers. Audio transformers

allowed telephone circuits to carry on a two-way conversation over a single pair of wires. A

balun transformer converts a signal that is referenced to ground to a signal that has balanced

voltages to ground, such as between external cables and internal circuits.

The principle of open-circuit (unloaded) transformer is widely used for characterisation of

soft magnetic materials, for example in the internationally standardised Epstein frame

method.

4.7 Buzzer

A buzzer or beeper is an audio signaling device, which may be mechanical,

electromechanical, or piezoelectric. Typical uses of buzzers and beepers include alarms,

timers and confirmation of user input such as a mouse click or keystroke.


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

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

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

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

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


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

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

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

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

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

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

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

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

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

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


http://en.wikipedia.org/wiki/Signal_(electrical_engineering)


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



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

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


http://en.wikipedia.org/wiki/Power_(physics)#Electrical_power


Fig10: A buzzer

Mechanical

A joy buzzer is an example of a purely mechanical buzzer.

Electromechanical

Early devices were based on an electromechanical system identical to an electric bell without

the metal gong. Similarly, a relay may be connected to interrupt its own actuating current,

causing the contacts to buzz. Often these units were anchored to a wall or ceiling to use it as a

sounding board. The word "buzzer" comes from the rasping noise that electromechanical

buzzers made piezoelectric

A piezoelectric element may be driven by an oscillating electronic circuit or other audio

signal source, driven with a piezoelectric audio amplifier. Sounds commonly used to indicate

that a button has been pressed are a click, a ring or a beep.

Uses

Annunciator panels

Electronic metronomes

Game shows

Microwave ovens and other household appliances


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

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

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

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

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

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

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

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

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

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


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

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

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


Sporting events such as basketball games

4.8 STEPPER MOTOR

Motion control, in electronic terms, means to accurately control the movement of an object

based on either speed, distance, load, inertia, rotation angle, synchronism or a combination of

all these factors. There are numerous types of motion control systems, including; Stepper

motor, Linear step motor, DC Brush, Brushless, Servo and more.

The stepper motor is an electromagnetic device that converts digital pulses into mechanical

shaft rotation.

Fig 11: A Stepper Motor

BASICS OF STEPPER MOTOR:

A stepper motor is a brushless, synchronous electric motor that can divide a full rotation into

a large number of steps. The motor position can be controlled precisely without any feedback


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mechanism as long as the motor is carefully sized to the application. These are similar to

switch reluctance motors (very large stepping motors with a reduced pole count).

MOTOR CONSTRUCTION:

The motor consists of multiple electrical windings wrapped in pairs around the outer

stationary portion of the motor. The inner portion consists of iron or magnetic disks mounted

on shaft and suspended on the bearings. The rotor has the projecting teeth which align with

the magnetic fields of the windings. When the coils are energized in sequence by direct

current, the teeth follow the sequence and rotate a discrete distance necessary to re-align with

the magnetic field.

The number of coil combinations and the number of teeth determine the steps (resolution) of

the motor.

A stepper motor is a multi-pole brushless DC motor. These multiple coil pairs can be

connected either positive or negative resulting in four unique full steps. When the coils are

sequenced correctly, the motor rotates forward. When the sequence is reversed, the motor

rotates in reverse. When the sequence is held, the rotor locks (brakes) in place.

The amount of torque required to force the rotor from position is the holding or static torque.

If the rotor slips (step loss), it will align with the next available coil combination, either four

steps forward or four steps backward.



Fig 12: Electrical model of a Stepper Motor

INTERFACING:

Stepper motor is one of the commonly used motor for precise angular movement of all

motors, stepper motor is easiest to control. Its handling simplicity is hard to deny. All there to

do is to bring the sequence of rectangular pulses to one input of step controller and direction

information to another input.

The stepping motor consists of three basic elements, often combined with some type of user

interface (host computer, PLC or Dumb Terminal):



Fig 13: Basic Elements

The Indexer (or controller) is a microprocessor capable of generating step pulses and

direction signals for the driver. In addition, the indexer is typically required to perform many

other sophisticated command functions.

The Driver (or amplifier) converts the indexer command signals into the power necessary to

energize the motor windings. There are numerous types of drivers, with different

current/ampere ratings and construction technology. Not all drivers are suitable to run all

motors, so when designing a Motion Control System the driver selection process is critical.

4.9 MICROCONTROLLER

A microcontroller (sometimes abbreviated µC, uC or MCU) is a small computer on a single

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

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

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

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

other general purpose applications.

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

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

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

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

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

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

non-digital electronic systems.

Some microcontrollers may use Four-bit words and operate at clock rate frequencies as low

as 4 kHz, for low power consumption (mill watts or microwatts). They will generally have

the ability to retain functionality while waiting for an event such as a button press or other

interrupt; power consumption while sleeping (CPU clock and most peripherals off) may be

just nano watts, making many of them well suited for long lasting battery applications. Other


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http://en.wikipedia.org/wiki/Flash_memory#NOR_flash

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microcontrollers may serve performance-critical roles, where they may need to act more like

a digital signal processor (DSP), with higher clock speeds and power consumption.

A microcontroller can be considered a self-contained system with a processor, memory and

peripherals and can be used as an embedded system. The majority of microcontrollers in use

today are embedded in other machinery, such as automobiles, telephones, appliances, and

peripherals for computer systems. These are called embedded systems.

Types of microcontrollers

Parallax Propeller

Free scale 68HC11 (8-bit)

Intel 8051

Silicon Laboratories Pipelined 8051 Microcontrollers

ARM processors (from many vendors) using ARM7 or Cortex-M3 cores are generally

microcontrollers

STMicroelectronics STM8 (8-bit), ST10 (16-bit) and STM32 (32-bit)

Atmel AVR (8-bit), AVR32 (32-bit), and AT91SAM (32-bit)

Freescale ColdFire (32-bit) and S08 (8-bit)

Hitachi H8, Hitachi SuperH (32-bit)

Hyperstone E1/E2 (32-bit, First full integration of RISC and DSP on one processor

core [1996] [1])

Infineon Microcontroller: 8, 16, 32 Bit microcontrollers for automotive and industrial

applications[6]

MIPS (32-bit PIC32)

NEC V850 (32-bit)

NXP Semiconductors [2] LPC1000, LPC2000, LPC3000, LPC4000 (32-bit), LPC900,

LPC700 (8-bit)

PIC (8-bit PIC16, PIC18, 16-bit dsPIC33 / PIC24)


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

http://www.nxp.com/microcontrollers/

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

http://en.wikipedia.org/wiki/V850

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

http://en.wikipedia.org/wiki/Microcontroller#cite_note-5

http://en.wikipedia.org/wiki/List_of_common_microcontrollers#Infineon

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

http://en.wikipedia.org/wiki/Hitachi_H8

http://en.wikipedia.org/wiki/Freescale_S08

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

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

http://en.wikipedia.org/wiki/AT91SAM

http://en.wikipedia.org/wiki/AVR32

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

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

http://www.st.com/mcu/

http://en.wikipedia.org/w/index.php?title=ST10&action=edit&redlink=1

http://www.st.com/mcu/

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

http://en.wikipedia.org/wiki/ARM7

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

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

http://en.wikipedia.org/wiki/Intel_8051

http://en.wikipedia.org/wiki/Freescale_68HC11

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

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

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


PowerPC ISE

PSoC (Programmable System-on-Chip)

Rabbit 2000 (8-bit)

Texas Instruments Microcontrollers MSP430 (16-bit), C2000 (32-bit), and Stellaris

(32-bit)

Toshiba TLCS-870 (8-bit/16-bit)

XMOS XCore XS1 (32-bit)

Zilog eZ8 (16-bit), eZ80 (8-bit)

MICROCONTROLLER 8051

The Intel 8051 microcontroller is one of the most popular general purpose microcontrollers in

use today. The success of the Intel 8051 spawned a number of clones which are collectively

referred to as the MCS-51 family of microcontrollers, which includes chips from vendors

such as Atmel, Philips, Infineon, and Texas Instruments.

About the 8051

The Intel 8051 is an 8-bit microcontroller which means that most available operations are

limited to 8 bits. There are 3 basic "sizes" of the 8051: Short, Standard, and Extended. The

Short and Standard chips are often available in DIP (dual in-line package) form, but the

Extended 8051 models often have a different form factor, and are not "drop-in compatible".

All these things are called 8051 because they can all be programmed using 8051 assembly

language, and they all share certain features (although the different models all have their own

special features).

Some of the features that have made the 8051 popular are:

64 KB on chip program memory.


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http://en.wikipedia.org/wiki/TI_MSP430

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128 bytes on chip data memory (RAM).

4 register banks.

128 user defined software flags.

8-bit data bus

16-bit address bus

32 general purpose registers each of 8 bits

16 bit timers (usually 2, but may have more, or less).

3 internal and 2 external interrupts.

Bit as well as byte addressable RAM area of 16 bytes.

Four 8-bit ports, (short models have two 8-bit ports).

16-bit program counter and data pointer.

1 Microsecond instruction cycle with 12 MHz Crystal.

8051 models may also have a number of special, model-specific features, such as UARTs,

ADC, OpAmps, etc...



Fig 14: 8051 PIN DIAGRAM


http://en.wikibooks.org/wiki/File:Pinouts8051.jpg


PIN DESCRIPTION OF 8051

Ports:

There are 4 8-bit ports: P0, P1, P2 and P3.

PORT P0 (pins 32 to 39) PORT P0 can be used as a general purpose 8 bit port when no

external memory is present, but if external memory access is required then PORT P0 acts as a

multiplexed address and data bus that can be used to access external memory in conjunction

with PORT P2. P0 acts as AD0-AD7

PORT P1 (Pins 1 to 8): The port P1 is a general purpose input/output port which can be used

for a variety of interfacing tasks. The other ports P0, P2 and P3 have dual roles or additional

functions associated with them based upon the context of their usage.

PORT P2 (pins 21 to 28): PORT P2 can also be used as a general purpose 8 bit port when no

external memory is present, but if external memory access is required then PORT P2 will act

as an address bus in conjunction with PORT P0 to access external memory. PORT P2 acts as

A8-A15, as can be seen from fig 1.1

PORT P3 (Pins 10 to 17): PORT P3 acts as a normal IO port, but Port P3 has additional

functions such as, serial transmit and receive pins, 2 external interrupt pins, 2 external

counter inputs, read and write pins for memory access.

PIN 9: PIN 9 is the reset pin which is used reset the microcontroller’s internal registers and

ports upon starting up. (Pin should be held high for 2 machine cycles.)

PINS 18 & 19: The 8051 has a built-in oscillator amplifier hence we need to only connect a

crystal at these pins to provide clock pulses to the circuit.

PIN 40 and 20: Pins 40 and 20 are VCC and ground respectively. The 8051 chip needs +5V

500mA to function properly, although there are lower powered versions like the Atmel 2051

which is a scaled down version of the 8051 which runs on +3V.

PINS 29, 30 & 31: As described in the features of the 8051, this chip contains a built-in flash

memory. In order to program this we need to supply a voltage of +12V at pin 31. If external

memory is connected then PIN 31, also called EA/VPP, should be connected to ground to



indicate the presence of external memory. PIN 30 is called ALE (address latch enable), which

is used when multiple memory chips are connected to the controller and only one of them

needs to be selected. We will deal with this in depth in the later chapters. PIN 29 is called

PSEN. This is "program store enable". In order to use the external memory it is required to

provide the low voltage (0) on both PSEN and EA pins.

ARCHITECTURE OF 8051

Fig 15: Architecture of 8051


http://en.wikibooks.org/wiki/File:Intel_8051_arch.svg


Data and Program Memory

The 8051 Microprocessor can be programmed in PL/M, 8051 Assembly, C and a number of

other high-level languages. Many compilers even have support for compiling C++ for an

8051.

Program memory in the 8051 is read-only, while the data memory is considered to be

read/write accessible. When stored on EEPROM or Flash, the program memory can be

rewritten when the microcontroller is in the special programmer circuit.

Program Start Address

The 8051 starts executing program instructions from address 0000 in the program memory.

Direct Memory

The 8051 has 256 bytes of internal addressable RAM, although only the first 128 bytes are

available for general use by the programmer. The first 128 bytes of RAM (from 0x00 to

0x7F) are called the Direct Memory, and can be used to store data.

Special Function Register

The Special Function Register (SFR) is the upper area of addressable memory, from address

0x80 to 0xFF. A, B, PSW, DPTR are called SFR. This area of memory cannot be used for

data or program storage, but is instead a series of memory-mapped ports and registers. All

port input and output can therefore be performed by memory move operations on specified

addresses in the SFR. Also, different status registers are mapped into the SFR, for use in

checking the status of the 8051, and changing some operational parameters of the 8051.

SPECIAL FUNCTION REGISTER (SFR) ADDRESSES:

ACC ACCUMULATOR 0E0H

B B REGISTER 0F0H

PSW PROGRAM STATUS WORD 0D0H



SP STACK POINTER 81H

DPTR DATA POINTER 2 BYTES

DPL LOW BYTE OF DPTR 82H

DPH HIGH BYTE OF DPTR A0H

P3 PORT3 0B0H

TMODTIMER/COUNTER MODE CONTROL 89H

TCON TIMER COUNTER CONTROL 88H

TH0 TIMER 0 HIGH BYTE 8CH

TLO TIMER 0 LOW BYTE 8AH

TH1 TIMER 1 HIGH BYTE 8DH

TL1 TIMER 1 LOW BYTE 8BH

SCON SERIAL CONTROL 98H

SBUF SERIAL DATA BUFFER 99H

PCON POWER CONTROL 87H

Both timers are the 89c51 share the one register TMOD. 4 LSB bit for the timer 0 and 4 MSB

for the timer 1.



In each case lower 2 bits set the mode of the timer

Upper two bits set the operations.

GATE: Gating control when set. Timer/counter is enabled only while the INTX pin is

high and the TRx control pin is set. When cleared, the timer is enabled

whenever the TRx control bit is set

C/T: Timer or counter selected cleared for timer operation (input from internal

system clock)

M1 Mode bit 1

M0 Mode bit 0

M1 M0 MODEOPERATING MODE

0 0 0 13 BIT TIMER/MODE

0 1 1 16 BIT TIMER MODE

1 0 2 8 BIT AUTO RELOAD

1 1 3 SPLIT TIMER MODE

PSW (PROGRAM STATUS WORD)

CY PSW.7 CARRY FLAG

AC PSW.6 AUXILIARY CARRY

F0 PSW.5 AVAILABLE FOR THE USER FRO



GENERAL PURPOSE

RS1 PSW.4 REGISTER BANK SELECTOR BIT 1

RS0 PSW.3 REGISTER BANK SELECTOR BIT 0

0V PSW.2 OVERFLOW FLAG

-- PSW.1 USER DEFINABLE BIT

P PSW.0 PARITY FLAG SET/CLEARED BY HARDWARE



PCON REGISTER (NON BIT ADDRESSABLE)

If the SMOD = 0 (DEFAULT ON RESET)

TH1 = CRYSTAL FREQUENCY 256___________________

384 X BAUD RATEIf the SMOD IS = 1

CRYSTAL FREQUENCYTH1 = 256--------------------------------------

192 X BAUD RATE

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

1. To use a higher frequency crystal

2. To change a bit in the PCON register

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

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

D7, the SMOD bit. When the 8051 is powered up, D7 (SMOD BIT) OF PCON register is

zero. We can set it to high by software and thereby double the baud rate BAUD RATE

COMPARISION FOR SMOD = 0 AND SMOD =1

TH1 (DECIMAL) HEX SMOD =0 SMOD =1

-3 FD 9600 19200

-6 FA 4800 9600

-12 F4 2400 4800

-24 E8 1200 2400



XTAL = 11.0592 MHZ

IE (INTERRUPT ENABLE REGISTER)

EA IE.7 Disable all interrupts if EA = 0, no interrupts is acknowledged

If EA is 1, each interrupt source is individually enabled or disabled

By sending or clearing its enable bit.

IE.6 NOT implemented

ET2 IE.5 enables or disables timer 2 overflag in 89c52 only

ES IE.4 Enables or disables all serial interrupt

ET1 IE.3 Enables or Disables timer 1 overflow interrupt

EX1 IE.2 Enables or disables external interrupt

ET0 IE.1 Enables or Disables timer 0 interrupt.

EX0 IE.0 Enables or Disables external interrupt 0

INTERRUPT PRIORITY REGISTER

If the bit is 0, the corresponding interrupt has a lower priority and if the bit is 1 the

corresponding interrupt has a higher priority

IP.7 NOT IMPLEMENTED, RESERVED FOR FUTURE USE.

IP.6 NOT IMPLEMENTED, RESERVED FOR FUTURE USE



PT2 IP.5 DEFINE THE TIMER 2 INTERRUPT PRIORITY LELVEL

PS IP.4 DEFINES THE SERIAL PORT INTERRUPT PRIORITY LEVEL

PT1 IP.3 DEFINES THE TIMER 1 INTERRUPT PRIORITY LEVEL

PX1 IP.2 DEFINES EXTERNAL INTERRUPT 1 PRIORITY LEVEL

PT0 IP.1 DEFINES THE TIMER 0 INTERRUPT PRIORITY LEVEL

PX0 IP.0 DEFINES THE EXTERNAL INTERRUPT 0 PRIORITY LEVEL

SCON: SERIAL PORT CONTROL REGISTER, BIT ADDRESSABLE

SCON

SM0 : SCON.7 Serial Port mode specified

SM1 : SCON.6 Serial Port mode specified

SM2 : SCON.5

REN : SCON.4 Set/cleared by the software to Enable/disable reception

TB8 : SCON.3 the 9th bit that will be transmitted in modes 2 and 3, Set/cleared

By software

RB8 : SCON.2 In modes 2 &3, is the 9th data bit that was received. In mode 1,

If SM2 = 0, RB8 is the stop bit that was received. In mode 0

RB8 is not used

T1 : SCON.1 Transmit interrupt flag. Set by hardware at the end of the 8th bit



Time in mode 0, or at the beginning of the stop bit in the other modes. Must be cleared by

software

R1 SCON.0 Receive interrupt flag. Set by hardware at the end of the 8th bit time in mode 0, or

halfway through the stop bit time in the other modes must be cleared by the software.

TCON TIMER COUNTER CONTROL REGISTER

This is a bit addressable

TF1 TCON.7 Timer 1 overflows flag. Set by hardware when the Timer/Counter 1

Overflows. Cleared by hardware as processor

TR1 TCON.6 Timer 1 run control bit. Set/cleared by software to turn Timer

Counter 1 On/off

TF0 TCON.5 Timer 0 overflows flag. Set by hardware when the timer/counter 0

Overflows. Cleared by hardware as processor

TR0 TCON.4 Timer 0 run control bit. Set/cleared by software to turn timer counter 0

on/off.

IE1 TCON.3 External interrupt 1 edge flag

ITI TCON.2 Interrupt 1 type control bit

IE0 TCON.1 External interrupt 0 edge

IT0 TCON.0 Interrupt 0 type control bit.

General Purpose Registers

The 8051 has 4 selectable banks of 8 addressable 8-bit registers, R0 to R7. This means that

there are essentially 32 available general purpose registers, although only 8 (one bank) can be

directly accessed at a time. To access the other banks, we need to change the current bank

number in the flag status register.



A and B Registers

The A register is located in the SFR memory location 0xE0. The A register works in a similar

fashion to the AX register of x86 processors. The A register is called the accumulator, and by

default it receives the result of all arithmetic operations. The B register is used in a similar

manner, except that it can receive the extended answers from the multiply and divide

operations. When not being used for multiplication and Division, the B register is available as

an extra general-purpose register.



ADRESSING MODE:

Definition:

The CPU can access data in various way. The data could be in registers, in memory or could

be provided as an immediate data. The various way of accessing data are called addressing

mode.

Instruction = Mnemonics or opcode + operand

The way by which the address of the operand (source and destination operand) are specified

in the instruction is known as addressing mode

Note: - The various addressing mode of microprocessor are determined when it was designed

and therefore it can not be changed by programmer.

Various addressing mode in 8051

1. Register addressing

2. Direct addressing

3. In direct addressing

4. Register specific addressing

5. Immediate addressing

6. Indexed addressing



1. Register Addressing Mode

In register addressing operands are in registers.

The register addressing modes occur between Register A and R0 to R7. the programmer can

select a register bank by modifying bits 4 and 3 in the PSW.

For example:

MOVA, R0 : copy data from register R0 to register A

ADDA, R1 : Add the content of R1 and A. Store the result in A

ANL A, R2 : AND each bit of A with the same bit of register 2.

2. Direct Addressing Mode

In direct addressing mode the address of operand is specified by an 8-bit address in the

instruction.

Using this instruction one can access internal data RAM and SFRs, directly. Internal RAM

uses address from 00H to 7FH to address each byte. The SFR addresses exits from 80Hto

FFH

For example:-

MOVA, 80H : copy data from the port 0 to register A

MOV 80H, A : copy data from register A to port 0

MOV 0F0, 12H: copy data from RAM location 12H to register B

3. Indirect Addressing Mode



In indirect addressing mode instruction specifies a register which holds address of the

operand.

In this mode only register R0 or R1 may be used to hold the address of one of the data

location RAM from address 00H to FFH.

For example:-

MOV A, @ R0 : copy content of memory location, whose address is specified in R0

select bank to accumulator

ADDA, @ R0 : add the content of memory location, whose address is specified in R1

and accumulator .Store the result in A.

ANLA, @ R0 : AND each bit of A with same bit of contents of the address contained in R0.

Store result in A.

4. Register Specific Addressing Mode

In the register specific mode, the operand is specified by certain specific registers such as

accumulator or DPTR.

For example:-

SWAP A : SWAP nibbles within the accumulator.

DAA : Decimal Adjust Accumulator

RR A : Rotate the content of accumulator to the right.

5. Immediate Addressing Mode

In immediate addressing mode the operand is specified within the instruction itself. In this

“DATA” is the part of instruction.

For examples:

MOV A, # 30H : move data 30H immediately to accumulator.



MOV B, #50H : move data 50H immediately to accumulator.

MOV P1, # 00H : move data 00H immediately to port1.

6 .Indexed Addressing Mode

In the indexed addressing mode only the program memory can be accessed. The program

memory can only be read.

This addressing mode can only be preferred for reading looks up tables in the program

memory.

Either the DPTR or PC can be used as INDEX register.

For example:-

MOVC A, @ A+ DPTR : copy the code byte, found at the ROM address formed by adding

A and the DPTR, to A.

MOVC A, @ A +C : copy the code byte, found at the ROM address formed by adding A

and the PC, to A

CODE:

#include <REG2051.H>.

#define stepper P1

void delay();

void main()

while(1)

stepper = 0x0C;

delay();

stepper = 0x06;

delay();

stepper = 0x03;

delay();

stepper = 0x09;



delay();

void delay()

unsigned char i,j,k;

for(i=0;i<6;i++)

for(j=0;j<255;j++)

for(k=0;k<255;k++);

Assembly Programming

CODE:

org 0H

stepper equ P1

main:

mov stepper, #0CH

acall delay

mov stepper, #06H

acall delay

mov stepper, #03H

acall delay

mov stepper, #09H

acall delay

sjmp main

delay:

mov r7,#4



wait2:

mov r6,#0FFH

wait1:

mov r5,#0FFH

wait:

djnz r5,wait

djnz r6,wait1

djnz r7,wait2

ret

end

The working of the above code can be seen in the demo below.



Fig 16: Interfacing of stepper motor with micro-controller

Programming Half step Sequence

C Programming

Just the main routine changes rest everything remains same, we mean same delay routine.

CODE:

void main()

while(1)

stepper = 0x08;

delay();

stepper = 0x0C;

delay();

stepper = 0x04;

delay();

stepper = 0x06;

delay();

stepper = 0x02;

delay();

stepper = 0x03;

delay();

stepper = 0x01;

delay();

stepper = 0x09;

delay();


Here also the main routine changes rest everything remains same.

CODE:



main:

mov stepper, #08H

acall delay

mov stepper, #0CH

acall delay

mov stepper, #04H

acall delay

mov stepper, #06H

acall delay

mov stepper, #02H

acall delay

mov stepper, #03H

acall delay

mov stepper, #01H

acall delay

mov stepper, #09H

acall delay

sjmp main

The working of the above code can be seen in the demo animation below.



Fig 17: Interfacing of unipolar stepper motor with microcontroller

Programming for 2-wire connection of Unipolar Stepper Motor

C Programming

CODE:

void main()

while(1)

stepper = 0x03;

delay();

stepper = 0x01;

delay();

stepper = 0x00;

delay();

stepper = 0x02;

delay();


CODE:

main:

mov stepper, #03H

acall delay

mov stepper, #01H

acall delay

mov stepper, #00H

acall delay

mov stepper, #02H



acall delay

sjmp main

The working of the above code can be seen in the demo animation below.

Fig 18:interfacing of bipolar stepper motor with microcontroller

Programming for Bipolar Stepper Motor

C Programming



CODE:

void main()

while(1)

stepper = 0x08;

delay();

stepper = 0x02;

delay();

stepper = 0x04;

delay();

stepper = 0x01;

delay();


CODE:

main:

mov stepper, #08H

acall delay

mov stepper, #02H

acall delay

mov stepper, #04H

acall delay

mov stepper, #01H

acall delay

sjmp main

4.10 REGULATOR



A voltage regulator is an electrical regulator designed to automatically maintain a constant

voltage level. A voltage regulator may be a simple "feed-forward" design or may include

negative feedback control loops. It may use an electromechanical mechanism, or electronic

components. Depending on the design, it may be used to regulate one or more AC or DC

voltages.

Electronic voltage regulators are found in devices such as computer power supplies where

they stabilize the DC voltages used by the processor and other elements.

In electronics, a linear regulator is a voltage regulator based on an active device (such as a

bipolar junction transistor, field effect transistor or vacuum tube) operating in its "linear

region" (in contrast, a switching regulator is based on a transistor forced to act as an on/off

switch) or passive devices like zener diodes operated in their breakdown region. The

regulating device is made to act like a variable resistor, continuously adjusting a voltage

divider network to maintain a constant output voltage. It is very inefficient compared to a

switched-mode power supply, since it sheds the difference voltage by dissipating heat.

Overview of Regulator

The transistor (or other device) is used as one half of a potential divider to control the output

voltage, and a feedback circuit compares the output voltage to a reference voltage in order to

adjust the input to the transistor, thus keeping the output voltage reasonably constant. This is

inefficient: since the transistor is acting like a resistor, it will waste electrical energy by

converting it to heat. In fact, the power loss due to heating in the transistor is the current

times the voltage dropped across the transistor.

Linear regulators exist in two basic forms: series regulators and shunt regulators.

Series regulators are the more common form. The series regulator works by providing

a path from the supply voltage to the load through a variable resistance (the main

transistor is in the "top half" of the voltage divider). The power dissipated by the

regulating device is equal to the power supply output current times the voltage drops

in the regulating device.

The shunt regulator works by providing a path from the supply voltage to ground

through a variable resistance (the main transistor is in the "bottom half" of the voltage

divider). The current through the shunt regulator is diverted away from the load and



http://en.wikipedia.org/wiki/Current_(electricity)

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

http://en.wikipedia.org/wiki/Switched-mode_power_supply



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

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


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

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

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

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

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

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


http://en.wikipedia.org/wiki/Mechanism_(technology)

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

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


http://en.wikipedia.org/wiki/Regulator_(automatic_control)

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


flows uselessly to ground, making this form even less efficient than the series

regulator. It is, however, simpler, sometimes consisting of just a voltage-reference

diode, and is used in very low-powered circuits where the wasted current is too small

to be of concern. This form is very common for voltage reference circuits.

All linear regulators require an input voltage at least some minimum amount higher than the

desired output voltage. That minimum amount is called the dropout voltage. For example, a

common regulator such as the 7805 has an output voltage of 5V, but can only maintain this if

the input voltage remains above about 7V, before the output voltage begins sagging below

the rated output. Its dropout voltage is therefore 7V - 5V = 2V. When the supply voltage is

less than about 2V above the desired output voltage, as is the case in low-voltage

microprocessor power supplies, so-called low dropout regulators (LDOs) must be used.

When one wants an output voltage higher than the available input voltage, no linear regulator

will work (not even an LDO). In this situation, a switching regulator must be used.

Fixed Regulator

"Fixed" three-terminal linear regulators are commonly available to generate fixed voltages of

plus 3 V, and plus or minus 5 V, 6V, 9 V, 12 V, or 15 V when the load is less than 1.5

amperes.

The "78xx" series (7805, 7812, etc.) regulate positive voltages while the "79xx" series (7905,

7912, etc.) regulate negative voltages. Often, the last two digits of the device number are the

output voltage; eg, a 7805 is a +5 V regulator, while a 7915 is a -15 V regulator. There are

variants on the 78xx series ICs, such as 78L and 78S, some of which can supply up to 1.5

Amps.


http://en.wikipedia.org/w/index.php?title=79xx&action=edit&redlink=1

http://en.wikipedia.org/wiki/78xx

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


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

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

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

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

http://en.wikipedia.org/wiki/Low-power_electronics

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


Adjusting fixed regulators:

Several ways are used to make fixed IC regulators adjustable.

A zener diode or resistor is added between the IC's ground terminal and ground. Resistors are

acceptable where ground current is constant, but are ill-suited to regulators with varying

ground current. Switching in different zeners, diodes or resistors can be used to obtain

stepwise adjustment.

A potentiometer can be placed in series with the ground terminal to variably increase the

output voltage. This degrades regulation, and is not suitable for regulators with varying

ground current.

Fig 19: Common IC’s

Operation

For output voltages not provided by standard fixed regulators and load currents of less than 7

amperes, commonly available "adjustable" three-terminal linear regulators may be used. An

adjustable regulator generates a fixed low nominal voltage between its output and its 'adjust'

terminal (equivalent to the ground terminal in a fixed regulator). The "317" series (+1.25V)

regulates positive voltages while the "337" series (-1.25V) regulates negative voltages.

Adjustable voltage regulator circuit showing 'adjust' terminal

The adjustment is performed by constructing a potential divider with its ends between the

regulator output and ground, and its centre-tap connected to the 'adjust' terminal of the

regulator. The ratio of resistances determines the output voltage using the same feedback

mechanisms described earlier.


http://en.wikipedia.org/wiki/LM317

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


Complex power requirements (e.g., op-amp circuits needing matched positive and negative

DC supplies) are more difficult, but single IC dual tracking adjustable regulators are

available. Some even have selectable current limiting as well. An example is the 419x series.

Note that some regulators, like the LM317, require a minimum load.

Component List

7805 regulator IC

1000uF electrolytic capacitor, at least 25V voltage rating

10 uF electrolytic capacitor, at least 6V voltage rating

100 nF ceramic or polyester capacitor

Fig 20: Operation of a regulator



Fig 21: Pin out of the 7805 regulator IC.

1. Unregulated voltage in

2. Ground

3. Regulated voltage out

Protection

Linear IC voltage regulators may include a variety of protection methods:

current limiting

fold back

thermal shutdown

safe area protection

Sometimes external protection is used, such as crowbar protection.

4.11 SWITCH

In electronics, a switch is an electrical component that can break an electrical circuit,

interrupting the current or diverting it from one conductor to another. The most familiar form

of switch is a manually operated electromechanical device with one or more sets of electrical

contacts. Each set of contacts can be in one of two states: either 'closed' meaning the contacts

are touching and electricity can flow between them, or 'open', meaning the contacts are

separated and non conducting.


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

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

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


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

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

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


A switch may be directly manipulated by a human as a control signal to a system, such as a

computer keyboard button, or to control power flow in a circuit.

The simplest type of switch is one where two electrical conductors are brought in contact

with each other by the motion of an actuating mechanism. Other switches are more complex,

containing electronic circuits able to turn on or off depending on some physical stimulus

(such as light or magnetic field) sensed. In any case, the final output of any switch will be (at

least) a pair of wire-connection terminals that will either be connected together by the

switch's internal contact mechanism ("closed"), or not connected together ("open").

Any switch designed to be operated by a person is generally called a hand switch, and they

are manufactured in several varieties:

Fig 22: Symbol of toggle switch

The common light switch used in household wiring is an example of a toggle switch. Most

toggle switches will come to rest in any of their lever positions, while others have an internal

spring mechanism returning the lever to a certain normal position, allowing for what is called

"momentary" operation.

Fig 22: Symbol of pushbutton switch

Pushbutton switches are two-position devices actuated with a button that is pressed and

released. Most pushbutton switches have an internal spring mechanism returning the button

to its "out," or "unpressed," position, for momentary operation. Some pushbutton switches

will latch alternately on or off with every push of the button. Other pushbutton switches will

stay in their "in," or "pressed," position until the button is pulled back out. This last type of

pushbutton switches usually has a mushroom-shaped button for easy push-pull action.



Fig 24: Symbol of selector switch

Selector switches are actuated with a rotary knob or lever of some sort to select one of two or

more positions. Like the toggle switch, selector switches can either rest in any of their

positions or contain spring-return mechanisms for momentary operation.

Fig 25: Symbol of joystick switch

A joystick switch is actuated by a lever free to move in more than one axis of motion. One or

more of several switch contact mechanisms are actuated depending on which way the lever is

pushed, and sometimes by how far it is pushed. The circle-and-dot notation on the switch

symbol represents the direction of joystick lever motion required to actuate the contact.

Joystick hand switches are commonly used for crane and robot control.

Some switches are specifically designed to be operated by the motion of a machine rather

than by the hand of a human operator. These motion-operated switches are commonly called

limit switches, because they are often used to limit the motion of a machine by turning off the

actuating power to a component if it moves too far. As with hand switches, limit switches

come in several varieties:

Fig 26: Symbol of lever actuator limit switch

These limit switches closely resemble rugged toggle or selector hand switches fitted with a

lever pushed by the machine part. Often, the levers are tipped with a small roller bearing,

preventing the lever from being worn off by repeated contact with the machine part.



Fig 27: Symbol of proximity switch

Proximity switches sense the approach of a metallic machine part either by a magnetic or

high-frequency electromagnetic field. Simple proximity switches use a permanent magnet to

actuate a sealed switch mechanism whenever the machine part gets close (typically 1 inch or

less). More complex proximity switches work like a metal detector, energizing a coil of wire

with a high-frequency current, and electronically monitoring the magnitude of that current. If

a metallic part (not necessarily magnetic) gets close enough to the coil, the current will

increase, and trip the monitoring circuit. The symbol shown here for the proximity switch is

of the electronic variety, as indicated by the diamond-shaped box surrounding the switch. A

non-electronic proximity switch would use the same symbol as the lever-actuated limit

switch.

Another form of proximity switch is the optical switch, comprised of a light source and

photocell. Machine position is detected by either the interruption or reflection of a light beam.

Optical switches are also useful in safety applications, where beams of light can be used to

detect personnel entry into a dangerous area.

In many industrial processes, it is necessary to monitor various physical quantities with

switches. Such switches can be used to sound alarms, indicating that a process variable has

exceeded normal parameters, or they can be used to shut down processes or equipment if

those variables have reached dangerous or destructive levels. There are many different types

of process switches:

Fig 28: Symbol of speed switch



These switches sense the rotary speed of a shaft either by a centrifugal weight mechanism

mounted on the shaft, or by some kind of non-contact detection of shaft motion such as

optical or magnetic.

Fig 29: Symbol of pressure switch

Gas or liquid pressure can be used to actuate a switch mechanism if that pressure is applied to

a piston, diaphragm, or bellows, which converts pressure to mechanical force.

Fig 30: Symbol of temperature switch

An inexpensive temperature-sensing mechanism is the "bimetallic strip:" a thin strip of two

metals, joined back-to-back, each metal having a different rate of thermal expansion. When

the strip heats or cools, differing rates of thermal expansion between the two metals causes it

to bend. The bending of the strip can then be used to actuate a switch contact mechanism.

Other temperature switches use a brass bulb filled with either a liquid or gas, with a tiny tube

connecting the bulb to a pressure-sensing switch. As the bulb is heated, the gas or liquid

expands, generating a pressure increase which then actuates the switch mechanism.

Fig 31: Symbol of liquid level switch

A floating object can be used to actuate a switch mechanism when the liquid level in an tank

rises past a certain point. If the liquid is electrically conductive, the liquid itself can be used

as a conductor to bridge between two metal probes inserted into the tank at the required



depth. The conductivity technique is usually implemented with a special design of relay

triggered by a small amount of current through the conductive liquid. In most cases it is

impractical and dangerous to switch the full load current of the circuit through a liquid.

Level switches can also be designed to detect the level of solid materials such as wood chips,

grain, coal, or animal feed in a storage silo, bin, or hopper. A common design for this

application is a small paddle wheel, inserted into the bin at the desired height, which is slowly

turned by a small electric motor. When the solid material fills the bin to that height, the

material prevents the paddle wheel from turning. The torque response of the small motor than

trips the switch mechanism. Another design uses a "tuning fork" shaped metal prong, inserted

into the bin from the outside at the desired height. The fork is vibrated at its resonant

frequency by an electronic circuit and magnet/electromagnet coil assembly. When the bin

fills to that height, the solid material dampens the vibration of the fork, the change in

vibration amplitude and/or frequency detected by the electronic circuit.

Fig 32: Symbol of liquid flow switch

Inserted into a pipe, a flow switch will detect any gas or liquid flow rate in excess of a certain

threshold, usually with a small paddle or vane which is pushed by the flow. Other flow

switches are constructed as differential pressure switches, measuring the pressure drop across

a restriction built into the pipe.

Another type of level switch, suitable for liquid or solid material detection, is the nuclear

switch. Composed of a radioactive source material and a radiation detector, the two are

mounted across the diameter of a storage vessel for either solid or liquid material. Any height

of material beyond the level of the source/detector arrangement will attenuate the strength of

radiation reaching the detector. This decrease in radiation at the detector can be used to

trigger a relay mechanism to provide a switch contact for measurement, alarm point, or even

control of the vessel level.

Switch Contact Design



A switch can be constructed with any mechanism bringing two conductors into contact with

each other in a controlled manner. This can be as simple as allowing two copper wires to

touch each other by the motion of a lever, or by directly pushing two metal strips into contact.

However, a good switch design must be rugged and reliable, and avoid presenting the

operator with the possibility of electric shock. Therefore, industrial switch designs are rarely

this crude.

The conductive parts in a switch used to make and break the electrical connection are called

contacts. Contacts are typically made of silver or silver-cadmium alloy, whose conductive

properties are not significantly compromised by surface corrosion or oxidation. Gold contacts

exhibit the best corrosion resistance, but are limited in current-carrying capacity and may

"cold weld" if brought together with high mechanical force. Whatever the choice of metal,

the switch contacts are guided by a mechanism ensuring square and even contact, for

maximum reliability and minimum resistance.

Contacts such as these can be constructed to handle extremely large amounts of electric

current, up to thousands of amps in some cases. The limiting factors for switch contact

ampacity are as follows:

Heat generated by current through metal contacts (while closed).

Sparking caused when contacts are opened or closed.

The voltage across open switch contacts (potential of current jumping across the gap).

One major disadvantage of standard switch contacts is the exposure of the contacts to the

surrounding atmosphere. In a nice, clean, control-room environment, this is generally not a

problem. However, most industrial environments are not this benign. The presence of

corrosive chemicals in the air can cause contacts to deteriorate and fail prematurely. Even

more troublesome is the possibility of regular contact sparking causing flammable or

explosive chemicals to ignite.

When such environmental concerns exist, other types of contacts can be considered for small

switches. These other types of contacts are sealed from contact with the outside air, and

therefore do not suffer the same exposure problems that standard contacts do.

A common type of sealed-contact switch is the mercury switch. Mercury is a metallic

element, liquid at room temperature. Being a metal, it possesses excellent conductive



properties. Being a liquid, it can be brought into contact with metal probes (to close a circuit)

inside of a sealed chamber simply by tilting the chamber so that the probes are on the bottom.

Many industrial switches use small glass tubes containing mercury which are tilted one way

to close the contact, and tilted another way to open. Aside from the problems of tube

breakage and spilling mercury (which is a toxic material), and susceptibility to vibration,

these devices are an excellent alternative to open-air switch contacts wherever environmental

exposure problems are a concerm.

Push Button Switches

A push-button (also spelled pushbutton) (press-button in the UK) or simply button is a simple

switch mechanism for controlling some aspect of a machine or a process. Buttons are

typically made out of hard material, usually plastic or metal. The surface is usually flat or

shaped to accommodate the human finger or hand, so as to be easily depressed or pushed.

Buttons are most often biased switches, though even many un-biased buttons (due to their

physical nature) require a spring to return to their un-pushed state. Different people use

different terms for the "pushing" of the button, such as press, depress, mash, and punch.

Fig 32: Contact (Normal) State & Make/Break Sequence

Any kind of switch contact can be designed so that the contacts "close" (establish continuity)

when actuated, or "open" (interrupt continuity) when actuated. For switches that have a

spring-return mechanism in them, the direction that the spring returns it to with no applied

force is called the normal position. Therefore, contacts that are open in this position are called

normally open and contacts that are closed in this position are called normally closed.


http://en.wikipedia.org/wiki/Spring_(device)

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

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

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

http://en.wikipedia.org/wiki/Process_(engineering)

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

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


For process switches, the normal position, or state, is that which the switch is in when there is

no process influence on it. An easy way to figure out the normal condition of a process switch

is to consider the state of the switch as it sits on a storage shelf, uninstalled. Here are some

examples of "normal" process switch conditions:

Speed switch: Shaft not turning

Pressure switch: Zero applied pressure

Temperature switch: Ambient (room) temperature

Level switch: Empty tank or bin

Flow switch: Zero liquid flow

It is important to differentiate between a switch's "normal" condition and its "normal" use in

an operating process. Consider the example of a liquid flow switch that serves as a low-flow

alarm in a cooling water system. The normal, or properly-operating, condition of the cooling

water system is to have fairly constant coolant flow going through this pipe. If we want the

flow switch's contact to close in the event of a loss of coolant flow (to complete an electric

circuit which activates an alarm siren, for example), we would want to use a flow switch with

normally-closed rather than normally-open contacts. When there's adequate flow through the

pipe, the switch's contacts are forced open; when the flow rate drops to an abnormally low

level, the contacts return to their normal (closed) state. This is confusing if you think of

"normal" as being the regular state of the process, so be sure to always think of a switch's

"normal" state as that which it's in as it sits on a shelf.

The schematic symbology for switches vary according to the switch's purpose and actuation.

A normally-open switch contact is drawn in such a way as to signify an open connection,

ready to close when actuated. Conversely, a normally-closed switch is drawn as a closed

connection which will be opened when actuated. Note the following symbols:



Fig 33: Push button switch in open and closed situation

Uses

The "push-button" has been utilized in calculators, push-button telephones, kitchen

appliances, and various other mechanical and electronic devices, home and commercial.

In industrial and commercial applications, push buttons can be linked together by a

mechanical linkage so that the act of pushing one button causes the other button to be

released. In this way, a stop button can "force" a start button to be released. This method of

linkage is used in simple manual operations in which the machine or process have no

electrical circuits for control.

Pushbuttons are often color-coded to associate them with their function so that the operator

will not push the wrong button in error. Commonly used colors are red for stopping the

machine or process and green for starting the machine or process.

Red pushbuttons can also have large heads (called mushroom heads) for easy operation and

to facilitate the stopping of a machine. These pushbuttons are called emergency stop buttons

and are mandated by the electrical code in many jurisdictions for increased safety. This large

mushroom shape can also be found in buttons for use with operators who need to wear gloves

for their work and could not actuate a regular flush-mounted push button. As an aid for

operators and users in industrial or commercial applications, a pilot light is commonly added

to draw the attention of the user and to provide feedback if the button is pushed. Typically

this light is included into the center of the pushbutton and a lens replaces the pushbutton hard

center disk. The source of the energy to illuminate the light is not directly tied to the contacts

on the back of the pushbutton but to the action the pushbutton controls. In this way a start

button when pushed will cause the process or machine operation to be started and a


http://en.wikipedia.org/wiki/Lens_(optics)

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

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

http://en.wikipedia.org/wiki/End-user

http://en.wikipedia.org/w/index.php?title=Flush-mount&action=edit&redlink=1

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

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

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

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

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

http://en.wikipedia.org/wiki/Color-coding

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

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

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

http://en.wikipedia.org/wiki/Push-button_telephone

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


secondary contact designed into the operation or process will close to turn on the pilot light

and signify the action of pushing the button caused the resultant process or action to start.

In popular culture, the phrase "the button" (sometimes capitalized) refers to a (usually

fictional) button that a military or government leader could press to launch nuclear weapons.

4.12 CRYSTALS

Pin no 18 and 19 is connected to external crystal oscillator to provide a clock to the circuit.

Whenever ever we are using crystals we need to put the capacitor behind it to make it free

from noises. It is good to go for a 33pf capacitor.

Fig 34: A Crystal

We can also resonators instead of costly crystal which are low cost and external capacitor can

be avoided. But the frequency of the resonators varies a lot. And it is strictly not advised

when used for communications projects.

4.13 DIODE

In electronics, a diode is a two-terminal electronic component that conducts electric current in

only one direction. The term usually refers to a semiconductor diode, the most common type

today. This is a crystalline piece of semiconductor material connected to two electrical

terminals. A vacuum tube diode (now little used except in some high-power technologies) is

a vacuum tube with two electrodes: a plate and a cathode.

The most common function of a diode is to allow an electric current to pass in one direction

(called the diode's forward direction), while blocking current in the opposite direction (the

reverse direction). Thus, the diode can be thought of as an electronic version of a check


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

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

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

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

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

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


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

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

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

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

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


valve. This unidirectional behavior is called rectification, and is used to convert alternating

current to direct current, and to extract modulation from radio signals in radio receivers.

However, diodes can have more complicated behavior than this simple on-off action. This is

due to their complex non-linear electrical characteristics, which can be tailored by varying the

construction of their P-N junction. These are exploited in special purpose diodes that perform

many different functions. For example, specialized diodes are used to regulate voltage (Zener

diodes), to electronically tune radio and TV receivers (varactor diodes), to generate radio

frequency oscillations (tunnel diodes), and to produce light (light emitting diodes). Tunnel

diodes exhibit negative resistance, which makes them useful in some types of circuits.

Diodes were the first semiconductor electronic devices. The discovery of crystals' rectifying

abilities was made by German physicist Ferdinand Braun in 1874. The first semiconductor

diodes, called cat's whisker diodes, developed around 1906, were made of mineral crystals

such as galena. Today most diodes are made of silicon, but other semiconductors such as

germanium are sometimes used.

Semiconductor diodes

Figure 35: A typical packages in same alignment as diode symbol. Thin bar depicts the

cathode.

A modern semiconductor diode is made of a crystal of semiconductor like silicon that has

impurities added to it to create a region on one side that contains negative charge carriers

(electrons), called n-type semiconductor, and a region on the other side that contains positive

charge carriers (holes), called p-type semiconductor. The diode's terminals are attached to

each of these regions. The boundary within the crystal between these two regions, called a

PN junction, is where the action of the diode takes place. The crystal conducts a current of

electrons in a direction from the N-type side (called the cathode) to the P-type side (called the

anode), but not in the opposite direction; that is, a conventional current flows from anode to

cathode (opposite to the electron flow, since electrons have negative charge).


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


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

http://en.wikipedia.org/wiki/P-type_semiconductor

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

http://en.wikipedia.org/wiki/N-type_semiconductor

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



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


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

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

http://en.wikipedia.org/wiki/Cat's_whisker_diode

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

http://en.wikipedia.org/wiki/Rectification_(electricity)

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

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

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

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

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

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

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

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



http://en.wikipedia.org/wiki/P-N_junction

http://en.wikipedia.org/wiki/Non-linear

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

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



http://en.wikipedia.org/wiki/Rectification_(electricity)

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

http://en.wikipedia.org/wiki/File:Diode_pinout_en_fr.svg


Another type of semiconductor diode, the Schottky diode, is formed from the contact

between a metal and a semiconductor rather than by a p-n junction.

Current–voltage characteristic

A semiconductor diode’s behavior in a circuit is given by its current–voltage characteristic, or

I–V graph (see graph below). The shape of the curve is determined by the transport of charge

carriers through the so-called depletion layer or depletion region that exists at the p-n

junction between differing semiconductors. When a p-n junction is first created, conduction

band (mobile) electrons from the N-doped region diffuse into the P-doped region where there

is a large population of holes (vacant places for electrons) with which the electrons

“recombine”. When a mobile electron recombines with a hole, both hole and electron vanish,

leaving behind an immobile positively charged donor (dopant) on the N-side and negatively

charged acceptor (dopant) on the P-side. The region around the p-n junction becomes

depleted of charge carriers and thus behaves as an insulator.

However, the width of the depletion region (called the depletion width) cannot grow without

limit. For each electron-hole pair that recombines, a positively charged dopant ion is left

behind in the N-doped region, and a negatively charged dopant ion is left behind in the P-

doped region. As recombination proceeds more ions are created, an increasing electric field

develops through the depletion zone which acts to slow and then finally stop recombination.

At this point, there is a “built-in” potential across the depletion zone.

If an external voltage is placed across the diode with the same polarity as the built-in

potential, the depletion zone continues to act as an insulator, preventing any significant

electric current flow (unless electron/hole pairs are actively being created in the junction by,

for instance, light. see photodiode). This is the reverse bias phenomenon. However, if the

polarity of the external voltage opposes the built-in potential, recombination can once again

proceed, resulting in substantial electric current through the p-n junction (i.e. substantial

numbers of electrons and holes recombine at the junction). For silicon diodes, the built-in

potential is approximately 0.7 V (0.3 V for Germanium and 0.2 V for Schottky). Thus, if an

external current is passed through the diode, about 0.7 V will be developed across the diode

such that the P-doped region is positive with respect to the N-doped region and the diode is

said to be “turned on” as it has a forward bias.

A diode’s 'I–V characteristic' can be approximated by four regions of operation.


http://en.wikipedia.org/wiki/P-n_junction


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

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

http://en.wikipedia.org/wiki/Electron-hole_pair

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

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

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





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

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

http://en.wikipedia.org/wiki/Current%E2%80%93voltage_characteristic

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


Figure 36: I–V characteristics of a P-N junction diode (not to scale).

At very large reverse bias, beyond the peak inverse voltage or PIV, a process called reverse

breakdown occurs which causes a large increase in current (i.e. a large number of electrons

and holes are created at, and move away from the pn junction) that usually damages the

device permanently. The avalanche diode is deliberately designed for use in the avalanche

region. In the zener diode, the concept of PIV is not applicable. A zener diode contains a

heavily doped p-n junction allowing electrons to tunnel from the valence band of the p-type

material to the conduction band of the n-type material, such that the reverse voltage is

“clamped” to a known value (called the zener voltage), and avalanche does not occur. Both

devices, however, do have a limit to the maximum current and power in the clamped reverse

voltage region. Also, following the end of forward conduction in any diode, there is reverse

current for a short time. The device does not attain its full blocking capability until the

reverse current ceases.

The second region, at reverse biases more positive than the PIV, has only a very small reverse

saturation current. In the reverse bias region for a normal P-N rectifier diode, the current

through the device is very low (in the µA range). However, this is temperature dependent,

and at sufficiently high temperatures, a substantial amount of reverse current can be observed

(mA or more).

The third region is forward but small bias, where only a small forward current is conducted.



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

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

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

http://en.wikipedia.org/wiki/File:Diode-IV-Curve.svg


As the potential difference is increased above an arbitrarily defined “cut-in voltage” or “on-

voltage” or “diode forward voltage drop (Vd), the diode current becomes appreciable (the

level of current considered “appreciable” and the value of cut-in voltage depends on the

application), and the diode presents a very low resistance. The current–voltage curve is

exponential. In a normal silicon diode at rated currents, the arbitrary “cut-in” voltage is

defined as 0.6 to 0.7 volts. The value is different for other diode types — Schottky diodes can

be rated as low as 0.2 V, Germanium diodes 0.25 to 0.3 V, and red or blue light-emitting

diodes (LEDs) can have values of 1.4 V and 4.0 V respectively.

At higher currents the forward voltage drop of the diode increases. A drop of 1 V to 1.5 V is

typical at full rated current for power diodes.


http://en.wikipedia.org/wiki/Light-emitting_diode

http://en.wikipedia.org/wiki/Light-emitting_diode

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


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


Shockley diode equation

The Shockley ideal diode equation or the diode law (named after transistor co-inventor

William Bradford Shockley, not to be confused with tetrode inventor Walter H. Schottky)

gives the I–V characteristic of an ideal diode in either forward or reverse bias (or no bias).

The equation is:

where

I is the diode current,

IS is the reverse bias saturation current (or scale current),

VD is the voltage across the diode,

VT is the thermal voltage, and

n is the ideality factor, also known as the quality factor or sometimes emission coefficient.

The ideality factor n varies from 1 to 2 depending on the fabrication process and

semiconductor material and in many cases is assumed to be approximately equal to 1 (thus

the notation n is omitted).

The thermal voltage VT is approximately 25.85 mV at 300 K, a temperature close to “room

temperature” commonly used in device simulation software. At any temperature it is a known

constant defined by:

where k is the Boltzmann constant, T is the absolute temperature of the p-n junction, and q is

the magnitude of charge on an electron (the elementary charge).

The Shockley ideal diode equation or the diode law is derived with the assumption that the

only processes giving rise to the current in the diode are drift (due to electrical field),

diffusion, and thermal recombination-generation. It also assumes that the recombination-

generation (R-G) current in the depletion region is insignificant. This means that the

Shockley equation doesn’t account for the processes involved in reverse breakdown and


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

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

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

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

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

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

http://en.wikipedia.org/wiki/Walter_H._Schottky

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

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

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


photon-assisted R-G. Additionally, it doesn’t describe the “leveling off” of the I–V curve at

high forward bias due to internal resistance.

Under reverse bias voltages (see Figure 5) the exponential in the diode equation is negligible,

and the current is a constant (negative) reverse current value of −IS. The reverse breakdown

region is not modeled by the Shockley diode equation.

For even rather small forward bias voltages the exponential is very large because the thermal

voltage is very small, so the subtracted ‘1’ in the diode equation is negligible and the forward

diode current is often approximated as

The use of the diode equation in circuit problems is illustrated in the article on diode

modeling.

Small-signal behavior

For circuit design, a small-signal model of the diode behavior often proves useful. A specific

example of diode modeling is discussed in the article on small-signal circuits.

Reverse-recovery effect

Following the end of forward conduction in a PN type diode, a reverse current flows for a

short time. The device does not attain its full blocking capability until the reverse current

ceases.

The effect can be significant when switching large currents very quickly (di/dt on the order of

100 A/µs or more). A certain amount of "reverse recovery time" t r (on the order of tens of

nanoseconds) may be required to remove the "reverse recovery charge" Q r (on the order of

tens of nanocoulombs) from the diode. During this recovery time, the diode can actually

conduct in the reverse direction. In certain real-world cases it can be important to consider the

losses incurred by this non-ideal diode effect. However, when the slew rate of the current is

not so severe (di/dt on the order of 10 A/µs or less), the effect can be safely ignored . For most

applications, the effect is also negligible for Schottky diodes.

The reverse current ceases abruptly when the stored charge is depleted, which is exploited in

step recovery diodes for generation of extremely short pulses.


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

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

http://en.wikipedia.org/wiki/Small-signal_model

http://en.wikipedia.org/wiki/Diode_modelling#Shockley_diode_model

http://en.wikipedia.org/wiki/Diode_modelling#Shockley_diode_model


In this project we use IN 4007 diode as a rectifier. IN 4007 is special diode to convert the AC

into DC.

In this project we use two diode as a rectifier. Here we use full wave rectifier. Output of

rectifier is pulsating DC. To convert the pulsating dc into smooth dc we use Electrolytic

capacitor as a main filter. Capacitor converts the pulsating dc into smooth dc and this DC is

connected to the Regulator circuit for Regulated 5 volt DC.

4.14 RESET CIRCUITRY

Pin no 9 of the controller is connected to the reset circuit. On the circuit we connect one

resistor and capacitor circuit to provide a reset option when power is ON.

As soon as you give the power supply the 8051 doesn’t start. You need to restart for the

microcontroller to start. Restarting the microcontroller is nothing but giving a Logic 1 to the

reset pin at least for the 2 clock pulses. So it is good to go for a small circuit which can

provide the 2 clock pulses as soon as the microcontroller is powered.

ADVANTAGES

PIR sensors have several important advantages such as:

1. PIR sensors are able to detect infrared light from between several feet and several yards away, depending on how the device is calibrated. PIR sensors are generally compact and can be fitted into virtually any electronic device.

2. PIR sensors also do not need an external power source as they generate electricity as they absorb infrared light.

3. It can accommodate new devices at any time.

4. It is flexible to go through physical partitions.

5. It can be accessed through a centralized monitor.

DISADVANTAGES

Although PIR sensors can be advantageous, they also have several disadvantages:



1. PIR sensors are only capable of receiving infrared light and cannot emit it like other types of infrared sensors. PIR sensors can also be expensive not only to purchase, but to install and calibrate as well.

2. It is easy for hackers to hack it as we can’t control propagation of waves.

3. Comparatively low speed of communication.

4. Gets distracted by various elements like Blue-tooth.

5. Still Costly at large.

DESIGN CONSIDERATION

Reliability

Energy :There are four way in which node consume energy

1. Sensing

2. Computation

3. Storing

4. Communicating

APPLICATIONSPIR sensors are used for a wide variety of applications:

1. PIR sensors are used on television sets and television accessory devices, such as

VCRs and DVD players, to receive infrared light coming from a television remote.

2. PIR sensors are also used as motion detectors for most public doorways in grocery

stores, hospitals, and libraries.

3. PIR sensors can also be used for military applications in the form of laser range

finding, night vision, and heat-seeking missiles.



4. On a global scale, WINS will permit monitoring of land, water, and air resources for

environmental monitoring.

5. On a national scale, transportation systems, and borders will be monitored for

efficiency, safety, and security.

6. On a local, enterprise scale, WINS will create a manufacturing information service for

cost and quality control



CHAPTER- 5

PROBLEM DESCRIPTION



PROBLEM DESCRIPTION

Security systems use many different inputs to alert the owners, but can do very little as far as

actively deterring intruders and determining their identities. Also, many systems use low

quality video cameras to capture movement but cannot capture descriptive features of the

intruder. This project seeks to create a system that can both act as a physical deterrent and

capture hi-resolution images of the intruder.

We experienced several failure as a result of undetectable, incorrectly download program and

depleted energy level etc.

For example: node will detect false event when sensor board is overheated.



CHAPTER- 6

CONCLUSION



CONCLUSIONThus, we can conclude that wireless integrated network sensor is:

1. Densely distributed sensor networks.

2. Application specific networking architectures

3. Development platforms are now available.

4. The network is self-monitoring and secure.

5. Now it is possible to secure the border with an invisible wall of thousands or even millions

of tiny interconnected sensors.



CHAPTER- 7

FUTURE ADVANCEMENT



FUTURE ADVANCEMENT

1. PC interface with the circuit for future processes.

2. Updating and displaying the number of bullets fired.

3. Using image processing for targeting the gun with the hatch in closed position.

4. Use of advanced motors for a better control of position.

5. Use of real time cameras for tracking the movement of the air defense gun.

6. Since sensors have only limited range up to 10 km’s. So our task is to design such a

system which has a wide range. This may be achieved by using satellite systems as we

are now using in our borders.

7. We have to find the alternatives for the jammers.

8. And a sensor that can sense explosive material such as RDX.

9. On finalization of the hardware the same will be procured for testing and assembly.

Necessary software also to be generated for the mechanism to function



CHAPTER- 8

REFERENCES



REFERENCES

1. http://www.cctc.demon.co.uk/stepper.htm

2. http://www.embedded.com/guess.htm

3. http://www.hut.fi/Misc/Electronics/index.html

4. http://www.seminarprojects.com/Thread-air-defense-gun

5. http://www.seminarprojects.com/Thread-interfacing-pir-sensor-with-microcontroller#ixzz1Le0zFw6U

6. http://en.wikipedia.org/wiki/Camera#cite_ref-Alhazen_3-0


http://en.wikipedia.org/wiki/Camera#cite_ref-Alhazen_3-0

http://www.seminarprojects.com/Thread-interfacing-pir-sensor-with-microcontroller#ixzz1Le0zFw6U

http://www.seminarprojects.com/Thread-interfacing-pir-sensor-with-microcontroller#ixzz1Le0zFw6U

http://www.seminarprojects.com/Thread-air-defense-gun

http://www.hut.fi/Misc/Electronics/index.html

http://www.embedded.com/guess.htm

http://www.cctc.demon.co.uk/stepper.htm

Documents

complet finalised