adaptive light system

7/31/2019 Adaptive Light System

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HBeonLabs

Off. No. 46, 1st Floor, Kadamba Complex

Gamma-I, Greater Noida (India) - 201308

Contact us:

+91-120-4298000+91-9212314779

[email protected]

[email protected]

m

www.

hbeonlabs.com


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TABLE OF CONTENTS

CHAPTER ONE:

INTRODUCTION

1.1Introduction1.2 CIRCUITDIAGRAM

CHAPTER TWO: DESIGN AND

CONSTRUCTION

2.1 ComponentList

2.2 Power supply

2.2.1

Transformer2.2.2Diode

2.2.3Regulator

2.2.4 Capacitorfilter

2.2.5 Circuit diagram powersupply

2.3LDR

2.4LED

2.5Registers

2.6Capacitors

CHAPTERTHREE: SERIAL COMMUNICATION, PROGRAMMER,

SIMULATOR,BURNE

R

3.1 Ser ia lCommunication

3.1.1 DTE andDCE

3.1.1 RS-232


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3.1.3 RTS/CTSHandshaking

3.1.4 Specifying Baud Rate, Parity &Stop bits

3.1.5 DCE BaudRates

3.1.6 Testing a DB-9 RS-232 serial port inHyperTerminal

3.1.7 Making aloopback

3.1.8Initializations

3.1.9 Serial transfer using TI and RIflags

3.2Programmer

3.3Simulator

3.4Burner

CHAPTER FOUR: RECOMMENDATION AND

CONCLUSION

4.

1

Conclusion

4.2 ProblemsEncountered

REFERENCE

S

APP EN DI X C: P ROG RAM

FLOWCODE


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CHAPTER ONE:

PRINCIPLE OF OPERATION

The circuit is powered by a 12V automatic power supply which changes overautomatically to a

backup power source when there is power outage on the main A.C. supply. The circuituses a

popular timer I C LM358 which is connected as a comparator with pin-6connected with

positive rail; the output goes high (1) when the trigger pin 3 is lower than voltagelevel at pin

no 2. Conversely the output goes low (0) when it is above pin no 2 level. So a smallchange in

the voltage of pin-2 is enough to change the level of output (pin-1) from 1 to 0 and0 to 1.

This change in the output level of the I.C. LM 358 is due to the sensing ability ofthe light

dependent resistor which senses the presence of light. The output has only two stateshigh and

low and cannot remain in any intermediate stage. The comparator goes high (1)when it

becomes dark and the microcontroller sends a switching signal to the relay and thesecurity

lights are turned ON. In the event of power outage in the A.C. mains an automaticchangeover

to the backup power source occurs immediately. After a period of delay themicrocontroller

sends an alarm signal to the buzzer and at the restoration of power supply thealarm stops.

The

approach used in the design of this project is the modular approach where the overalldesign

was broken into functional block diagrams and each block in the diagram represents asection of

the circuit that carries out a specific function and these functions are laid out by thesystem flow

chart. The system was designed using five functional blocks, as shown in thediagram below.


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POWER SUPPLY

CONTROL UNIT SWITCHING UNIT LOAD

Figure 1.1 System block diagram

.

Circuit Diagram of the Project:


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CHAPTER TWO: CONSTRUCTION AND

DESIGN2.1 COMPONENT

LIST:


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2.2 POWER

SUPPLY:

Power supply is a reference to a source of electrical power. A device or system thatsupplieselectrical or other types of energy to an output load or group of loads is

called apower supply

uni

t

or PSU . The term is most commonly applied to electrical energy supplies, lessoften tomechanical ones, and rarely to

others.

Here in our application we need a 5v DC power supply for all electronicsinvolved in theproject. This requires step down transformer, rectifier, voltage regulator, and filtercircuit forgeneration of 5v DC power. Here a brief description of all the components are given asfollows:

2.2.1

TRANSFORMER:

A transformer is a device that transfers electrical energy from one circuit to anotherthroughinductively coupled conductors the transformer's coils or "windings". Except for

air-coretransformers, the conductors are commonly wound around a single iron-rich core, oraroundseparate but magnetically-coupled cores. A varying current in the first or "primary"windingcreates a varying magnetic field in the core (or cores) of the transformer. This varyingmagneticfield induces a varying electromotive force (EMF) or "voltage" in the "secondary"winding. Thiseffect is called mutualinduction.


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A primary coi l or winding.

A secondary coil orwinding.

A core that supports the coils orwindings.


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A diode is a semiconductor device which allows current to flow through it in only one direction.Although a transistor is also a semiconductor device, it does not operate the way a diodedoes. Adiode is specifically made to allow current to flow through it in only one direction. Someways inwhich the diode can be used are listedhere.


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A diode can be used as a rectifier that converts AC (Alternating Current) to DC(Direct

diode can be used as a rectifier that converts AC (Alternating Current) to DC (Directdiode can be used as a rectifier that converts AC (Alternating Current) to DC (Direct

Current) for a power supply device.Current) for a power supply device.

Diodes can be used to separate thesignal fro

Diodes can be used to separate the signal from radiofrequencies.

Diodes can be used as an on/off switch that controlscurrent.

Diodes can be used as an on/off switch that controlscurrent.

Fig. 2.26 DiodeSymbol

This symbol is used to indicate a diode in a circuit diagram. The meaning of thesymbol is

s used to indicate a diode in a circuit diagram. The meaning of the symbol iss used to indicate a diode in a circuit diagram. The meaning of the symbol is

(Anode)(Cathode).

Current flows from the anode side to the cathodeside.

anode side to the cathodeside.

lthough all diodes operate with the same general principle, there are different types suited tolthough all diodes operate with the same general principle, there are different types suited tolthough all diodes operate with the same general principle, there are different types suited todifferent applications. For example, the following devices are best used for the applications

different applications. For example, the following devices are best used for the applicationsdifferent applications. For example, the following devices are best used for the applicationsnote

d.

Voltage regulation diode(Zener Diode)

(Zener Diode)The circuit symbol is.

It is used to regulate voltage, by taking advantage of the fact that Zener diodes tend to stabilize atIt is used to regulate voltage, by taking advantage of the fact that Zener diodes tend to stabilize atIt is used to regulate voltage, by taking advantage of the fact that Zener diodes tend to stabilize ata certain voltage when that voltage is applied in the opposite direction.a certain voltage when that voltage is applied in the opposite direction.

Light emitting

diode

The circuit symbol is.

This type of diode emits light when current flows through it in the forward direction. (ForwardThis type of diode emits light when current flows through it in the forward direction. (ForwardThis type of diode emits light when current flows through it in the forward direction. (Forwardbiase

d)


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Characteristics of Diode

The graph above shows the electrical characteristics of a typical diode. When a smallvoltage isapplied to the diode in the forward direction, current flows easily. Because thediode has acertain amount of resistance, the voltage will drop slightly as current flows through thediode. Atypical diode causes a voltage drop of about 0.6 -1V (V

) (In the case of silicon diode,almost

F

0.6V)

This voltage drop needs to be taken into consideration in a circuit which uses manydiodes inseries. Also, the amount of current passing through the diodes must beconsidered.

When voltage is applied in the reverse direction through a diode, the diode willhave a greatresistance to current flow. Different diodes have different characteristics whenreverse-biased. Agiven diode should be selected depending on how it will be used in the circuit. Thecurrent thatwill flow through a diode biased in the reverse direction will vary from several mA tojust A,which i s verysmall.


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The limiting voltages and currents permissible must be considered on a case by case basis. ForThe limiting voltages and currents permissible must be considered on a case by case basis. ForThe limiting voltages and currents permissible must be considered on a case by case basis. Forexample, when using diodes for rectification, part of the timexample, when using diodes for rectification, part of the time they will be required to withstand a

e they will be required towithstand a

everse voltage. If the diodes are not chosen carefully, they will break down.everse voltage. If the diodes are not chosen carefully, they will break down.everse voltage. If the diodes are not chosen carefully, they will break down.

2.2.3 REGULATOR IC

(78XX

.2.3 REGULATOR IC

(78XX

)

It is a three pin IC used as a voltage regulator. It converts unregulated DC current intoregulated

IC used as a voltage regulator. It converts unregulated DC current into regulatedIC used as a voltage regulator. It converts unregulated DC current into regulated

DC current.


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Normally we get fixed output by connecting the voltage regulator at the output of thefiltered

DC (see in above diagram). It can also be used in circuits to get a low DC voltagefrom a high

DC voltage (for example we use 7805 to get 5V from 12V). There are two types ofvoltage

regulators 1. fixed voltage regulators (78xx, 79xx) 2. variable voltage regulators(LM317) In

fixed voltage regulators there is another classification 1. +ve voltage regulators 2.-ve voltage

regulators POSITIVE VOLTAGE REGULATORS This include 78xx voltageregulators. The

most commonly used ones are 7805 and 7812. 7805 gives fixed 5V DC voltage ifinput voltage

is in (7.5V,20V).


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3.2.5

CIRCUIT DIAGRAM OF POWER

SUPPLY

2.3 LDR

A photoresistor or light dependent resistor (LDR) is

a

resistor whose resistance decreases

with increasing incident light intensity; in other words, it exhibits photoconductivity . It can also

bereferred to as

aphotoconductor or CdS device, from "cadmium sulfide," which is the material

from which the device is made and that actually exhibits the variation in resistance with light

level. Note that CdS is not a semiconductor in the usual sense of the word (not doped

silicon).A photoresistor is made of a high resistance semiconductor . If light f alling on the device isofhigh enough frequency , photons absorbed by the semiconductor give

bound

elect rons enough

energy to jump into the conduction band . The resulting f ree electron (andits

hole partner)

conduct electricity, thereby lowering resistance .


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The symbol for a photoresisto A light dependent resistorThe symbol for a photoresisto A light dependent resistorThe symbol for a photoresisto A light dependent resistor

photoelectric device can be eit her intrinsic or extrinsic. An intrinsic semiconductor has its

photoelectric device can be eit her intrinsic or extrinsic. An intrinsic semiconductor has itsphotoelectric device can be eit her intrinsic or extrinsic. An intrinsic semiconductor has its

own charge carriers and is not an efficient semiconductor, e.g. silicon. In intrinsic devicesthe

and is not an efficient semiconductor, e.g. silicon. In intrinsic devices theand is not an efficient semiconductor, e.g. silicon. I n intrinsic devices theonly available electrons are in theonly available electrons are in the

valenceband

, and hence the photon must have enough, and hence the photon must have enoughenergy to excite the electron across the entire

energy to excite the electron across the entire

bandga

p

. Extrinsic devices have impurit ies, also

. Extrinsic devices have impurities, alsocalled dopants, added whose ground state energy is closer to the conduction band; since the

, added whose ground state energy is closer to the conduction band; since the, added whose ground state energy is closer to the conduction band; since theelectrons do not have as far to jump, lower energy photons (i.e., longer wavelengt hs and lowerelectrons do not have as far to jum p, lower energy photons (i.e., longer wavelengt hs and lower

electrons do not have as far to jum p, lower energy photons (i.e., longer wavelengths and lowerfrequencies) are sufficient to trigger the device. If

frequencies) are sufficient to trigger the device. If a sample of silicon has some of its atoms

a sample of silicon has some of its atoms

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



conduction. This is an example of an extrinsic semiconductor. Photoresistors are basicallyconduction. This is an example of an extrinsic semiconductor. Photoresistors are basically

conduction. This is an example of an extrinsic semiconductor. Photoresistors are basicallyphotocells

Application

sPhotoresistors come in many diff erent types. InexpensivePhotoresistors come in many diff erent types. Inexpensivecadmium sulphidecadmium sulphide

cells can be found

n many consumer items such as camera light m eters, street light s, clock radios,n many consumer items such as camera light m eters, street lights, clock radios,

n many consumer items such as camera light meters, street lights, clock radios,

alarm devices ,

and outdoor clocks.

They are also used in somedynamic compressordynamic compressors

together with a smallncandescentncandescent lam p or light emitting diode to control gainto control gain reduction.

Lead

sulphide

(PbS)

and

ndium antimonide

ndium antimonide

(InSb) LDRs (light dependent resistor)

are

(InSb) LDRs (light dependent resistor) are used

for

the mid infrared spectral region.the mid infrared spectral region.

Ge :Cuphotoconductors are among the best farphotoconductors are among the best far-

, and are used for, and are used for

infraredastronomy

and

nfrarednfrared

infrared det ectors

availablespectroscopy


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LDRs or Light Dependent Resistors are ver y useful especially in light/dark sensor circuits.LDRs or Light Dependent Resistors are ver y useful especially in light/dark sensor circuits.LDRs or Light Dependent Resistors are ver y useful especially in light/dark sensor circuits.ormally the resistance of an LDR is very high, sometimes as high as 1000 000 ohms,

ormally the resistance of an LDR is very high, sometimes as high as 1000 000 ohms,ormally the resistance of an LDR is very high, sometimes as high as 1000 000 ohms, but when

they are illuminated with light resistance drops dramaticallythey are illuminated with light resistance drops dramatically

Light Dependent

Resistor


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2.4

LED

1 Watt LEDFull intensity 350mA, Maximum current500mA

2.8V Vol t drop @350mA

3 Watt LEDFull intensity 700mA, Maximum current1A


5 Watt LED (multi-die package)Full intensity 700mA, Maximumcurrent 1A


5 Watt LED (single-die)Full intensity1.5A

Forward Voltage (VF) drop across LEDDiodes are currentdriven!


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Wavelength variationsCrystal and junction growthdefects

Brightness variationsCrystal defects resulting formation of phonons andnon-radiation energy

transfer

Temperature Junction temperatureof the device affects each of theparametersabov

e

2.5 Resistors

The resistor's function is to reduce the flow of electric current. There are two classes ofresistors;fixed resistors and the variable resistors. They are also classified according to thematerial fromwhich they are made. The typical resistor is made of either carbon film or metal film.There areother types as well, but these are the most common. The resistance value of the resistor isnot theonly thing to consider when selecting a resistor for use in a circuit. The "tolerance"and theelectric power ratings of t he resistor are also important. The tolerance of a resistordenotes howclose it is to the actual rated resistence value. For example, a 5% tolerance wouldindicate aresistor that is within 5% of the specified resistancevalue.

Fixed Resistors

A fixed resistor is one in which the value of its r esistance cannotchange.

Carbon film

resistors


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This is the most general purpose, cheap resistor. Usually the tolerance of the resiThis is the most general purpose, cheap resistor. Usually the tolerance of the resiThis is the most general purpose, cheap resistor. Usually the tolerance of the resistance value is5%. Power ratings of 1/8W, 1/4W and 1/2W are frequently used.5%. Power ratings of 1/8W, 1/4W and 1/2W are frequently used.5%. Power ratings of 1/8W, 1/4W and 1/2W are frequently used.Carbon film resistors have a disadvantage; they tend to be electrically noisy. Metal film resistorsCarbon film resistors have a disadvantage; they tend to be electrically noisy. Metal film resistorsCarbon film resistors have a disadvantage; they tend to be electrically noisy. Metal film resistorsare recommended for use in analog circuits. However, I have never experiencedare recommended for use in analog circuits. However, I have never experiencedare recommended for use in analog circuits. However, I have never experienced any problemsith this noise. The physical size of the different resistors is as follows.

ith this noise. The physical size of the different resistors is as follows.

Rough size

Rating powerThickness

Thickness

Lengt

h(W)(mm)

(mm)

(mm

)From the top of the photographFrom the top of the photograph 1/8

23

1/8W1/4W

1/4 2 6

1/2W

1/2 3 9

The physical size of the different

resistors

The physical size of the different

resistors

Variable Resistors

There are two general ways in which variable resistors are used. One is the variable resistor

There are two general ways in which variable resistors are used. One is the variable resistorThere are two general ways in which variable resistors are used. One is the variable resistorhich value is easily changed, like the volume adjustment of Radio. The other is semi

hich value is easily changed, like the volume adjustment of Radio. The other is semihich value is easily changed, like the volume adjustment of Radio. The other is semi-fixedresistor that is not meant to be adjusted by anyone but a technician. It is used to

adjust the

stor that is not meant to be adjusted by anyone but a technician. It is used to adjust thestor that is not meant to be adjusted by anyone but a technician. It is used to adjust theoperating condition of the circuit by the technician. Semioperating condition of the circuit by the technician. Semi-fixed resistors are used to compensate

fixed resistors are used tocompensate

for the inaccuracies of the resistors, and to finefor the inaccuracies of the resistors, and to fine-tune a circuit. The rotation angle of the variable

The rotation angle of thevariable


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resistor is usually about 300 degrees. Some variable resistors must be turned manytimes to usethe whole range of resistance they offer. This allows for very precise adjustments oftheir value.

These are called "Potentiometers" or "TrimmerPotentiometers."

Variable Resistors

In the photograph to the left, the variable r esistor typically used for volume controls cane seenon the far right. Its value is very easy to adjust. The four resistors at the center of thephotographare the semi-fixed type. These ones are mounted on the printed circuit board. The tworesistorson the lef t a re the t rimmer potentiometers.


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Resistance value Vs. Rotation Angle

There are three ways in which a variable resistor's value canThere are three ways in which a variable resistor's value can change according to the rotation

angle of itsaxis.

second half of its axis, it changes very quickly. The "A" type variable resistor is typically usedsecond half of its axis, it changes very quickly. The "A" type variable resistor is typically usedsecond half of its axis, it changes very quickly. The "A" type variable resistor is typically usedume control of a radio, for example. It is well suited to adjust a low sound subtly. Itume control of a radio, for example. It is well suited to adjust a low sound subtly. It

small changes in loud sounds. A larger change is needed as the vosmall changes in loud sounds. A larger change is needed as the volume is increased. These "A"type variable resistors are sometimes called "audio taper" potentiometers.type variable resistors are sometimes called "audio taper" potentiometers.

elated. The rate of change is the same, or linear, througelated. The rate of change is the same, or linear, throughout the sweep of the axis. This type

suits a resistance value adjustment in a circuit, a balance circuit and so on.suits a resistance value adjustment in a circuit, a balance circuit and so on.

ay to type "A". In the early stages of theay to type "A". In the early stages of the rotation of the axis, the resistance value changes

apidly, and in the second half, the change occurs more slowly. This type isn't too much used. Itapidly, and in the second half, the change occurs more slowly. This type isn't too much used. Itapidly, and in the second half, the change occurs more slowly. This type isn't too much used. It


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Color Value Multiplier

Tolerance (%)

Black 0 0-

Brown 1 1 1Example1(Brown=1),(Black=0),(Orange=3) Red 2 2 210 x 10 = 10k ohm3

Tolerance(Gold) =5% Orange 3 3

0.05

Yello

w

4 4-

Green 5 50.5

Blue 6 60.25

Viole

t

7 70.1

8 8-

Gray

9 9-

Whit

eExample2(Yellow=4),(Violet=7),(Black=0),(Red=2) - -1

5Gold

470 x 10 = 47k ohm2

Tolerance(Brown) =1% Silver - -2

10

Non

e- -20


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Resistor color code

2.6 Capacitors

The capacitor's function is to store electricity, or electrical energy. The capacitor alsofunctionsas a filter, passing alternating current (AC), and blocking direct current (DC). Thissymbol F isused to indicate a capacitor in a circuit diagram. The capacitor is constructed with twoelectrodeplates facing each other, but separated by an insulator. When DC voltage isapplied to thecapacitor,

an electric charge is stored on each electrode. While the capacitor ischarging up,

current flows. The current will stop flowing when the capacitor has fullycharged.

Types of Capacitor

Types of Capacitor


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Breakdown voltage

when using a capacitor, we must pay attention to the maximum voltage which can beused. Thisis the "breakdown voltage." The breakdown voltage depends on the kind of capacitorbeing used.We must be especially careful with electrolytic capacitors because the breakdownvoltage iscomparatively low. The breakdown voltage of electrolytic capacitors is displayed asWorkingVoltage. The breakdown voltage is the voltage that when exceeded will cause thedielectric(insulator) inside the capacitor to break down and conduct. When this happens, thefailure can becatastrophic.

Electrolytic Capacitors (Electrochemical type

capacitors)

Aluminum is used for the electrodes by using a thin oxidizationmembrane.Large values of capacitance can be obtained in comparison with the size of thecapacitor,because the dielectric used is very thin. The most important characteristic ofelectrolyticcapacitors is that they have polarity. They have a positive and a negative electrode.[Polarised]This means that it is very important which way round they are connected. If thecapacitor issubjected to voltage exceeding its working voltage, or if it is connected with incorrectpolarity, itmay burst. It is extremely dangerous, because it can quite literally explode. Makeabsolutely nomistakes. Generally, in the circuit diagram, the positive side is indicated by a "+"(plus) symbol.Electrolytic capacitors range in value from about 1 F to thousands of F. Mainly thistype ofcapacitor is used as a ripple filter in a power supply circuit, or as a filter to bypass lowfrequencysignals, etc. Because this type of capacitor is comparatively similar to the nature of acoil inconstruction, it isn't possible to use for high-frequency circuits. (It is said that thefrequencycharacteristic isbad.)The photograph on the left is an example of the different values of electrolytic

capacitors inwhich the capacitance and voltagediffer.


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Electrolytic Capacitors

From the left toright:

1 F (50V) [diameter 5 mm, high 12mm]


100F (25V) [diameter 5 mm, high 11mm]

220F (25V) [diameter 8 mm, high 12mm]


The size of the capacitor sometimes depends on the manufacturer. So the sizes shownhere onthis page are jus texamples.

Ceramic Capacitors

Ceramic capacitors are constructed with materials such as titanium acid barium usedas thedielectric. Internally, these capacitors are not constructed as a coil, so they can be usedin highfrequency applications. Typically, they are used in circuits which bypass high frequencysignals

to ground. These capacitors have the shape of a disk. Their capacitance iscomparatively small.The capacitor on the left is a 100pF capacitor with a diameter of about 3 mm. Thecapacitor onthe right side is printed with 103, so 10 x10

pF becomes 0.01 F. The diameter of thedisk is

3


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about 6 mm. Ceramic capacitors have no polarity. Ceramic capacitors should not beused foranalog circuits, because they can distort thesignal.

Ceramic Capacitors

Variable Capacitors

Variable capacitors are used for adjustment etc. of frequency mainly. On theleft in thephotograph is a "trimmer," which uses ceramic as the dielectric. Next to it on the right isone thatuses polyester film for the dielectric. The pictured components are meant to bemounted on aprinted circuitboard.

Variable Capacitors


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When adjusting the value of a variable capacitor, it is advisable to be careful.One of thecomponent's leads is connected to the adjustment screw of the capacitor. This meansthat thevalue of the capacitor can be affected by the capacitance of the screwdriver in yourhand. It isbetter to use a special screwdriver to adjust thesecomponents.

Relay

A relay is an electrically operated switch . Many relays use an 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. The first relays were used in long distance telegraph circuits, repeating the

signalcoming in from one circuit and re-transmitting it to another. Relays were used extensively in

telephone exchanges and early computers to perform logical operations.

A type of relay that can handle t he high power required to directly control an electric motor or

other loads is calleda

contactor . Solid-staterelays

control power circuits with no moving parts ,

instead using a semiconductor device to perform switching. Relays with calibrated operating

characteristics and sometimes multiple operating coils are used to protect electrical circuits from

overload or faults; in modern electric power systems these functions are performed by digital

instruments still called " protective relays "

Basic design and operation


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Simple elect romechanical relay.

Small "cradle" relay often used in electronics. The "cradle" term refers to the shape of the

relay'sarmat ure.

A simple electromagnetic relay consists of a coil of wire wrapped around a soft iron core , an ironyoke which provides a low reluctance path for magnetic flux, a movable iron armature , and one

or more sets of contacts (there are two in the relay pictured). The armature is hinged to the yoke

and mechanically linked to one or more sets of moving contacts. It is held in place by

energized there is an air gap in the magnetic

circuit.a spring so t hat when the relay is

de-


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In this condition, one of the two sets of contacts in the relay pictured isclosed, andthe other set is open. Other relays may have more or fewer sets of

contactsdepending on their function. The relay in the picture also has a wireconnecting thearmature to the yoke. This ensures continuity of the circuit between themovingcontacts on the armature, and the circuit track on

the

printed circuit

board

(PCB)

viathe yoke, which is soldered to thePCB.Whenan

electriccurrent

is passed through the coil itgenerates a

magneticfield

that

activates the armature, and the consequent movement of the movablecontact(s)either makes or breaks (depending upon construction) a connection with a

fixedcontact. If the set of contacts was closed when the relay was de-energized,

then themovement opens the contacts and breaks the connection, and viceversa if thecontacts were open. When the current to the coil is switched off, the

armature isreturned by a force, approximately half as strong as the magnetic force,to itsrelaxed position. Usually this force is provided by a spring, but gravity is

also usedcommonly in industrial motor starters. Most relays are manufactured to

operatequickly. In a low-voltage application this reduces noise; in a high voltage orcurrentapplica tion i treduces

arcing .

When the coil is energizedwith

directcurrent

, a diode is often placed across thecoilto dissipate the energy from the collapsing magnetic field at

deactivation, whichwould otherwise

generate a

voltage

spike

dangerous

to

semiconductor circuit

components. Some automotive relays include a diode inside the relay

case.Alternatively, a contact protection network consisting of a capacitor andresistor inseries

(

snubber circuit) may absorb the surge. If the coil is designed to be

energizedwith

alternatingcurrent

(AC), a small copper "shading ring" can be crimped tothe

end of the solenoid, creating a small out-of-phase current whichincreases theminimum pull on the armature during the ACcycle.

[1]

A solid-state relay uses

a

thyristo

r

or other solid-state switching device,

activated bythe control signal, to switch the controlled load, instead of a

solenoid.Anoptocouple

r(a light-emitting

diode(LED) coupled witha

phototransistor

) can be

used to isolate control and controlled

circuits


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3.1 Serial Communication

3.1.1 DTE and

DCE

The terms DTE and DCE are very common in the data communications market. DTE isshort for

Data Terminal Equipment and DCE stands for Data Communications Equipment. Asthe full

DTE name indicates this is a piece of device that ends a communication line, whereasthe DCE

provides a path for communication. Let's say I have a computer on which wants tocommunicate

with the Internet through a modem and a dial-up connection. To get to the Internet Itell my

modem to dial the number of my provider. After my modem has dialed the number, themodem

of the provider will answer my call and I will hear a lot of noise. Then it becomes quietand I see

my login prompt or my dialing program tells me the connection is established. Now Ihave a

connection with the server from my provider and I can surf the Internet[13].

3.1.1 RS-

232

In telecommunications, RS-232 is a standard for serial binary data signals connectingbetween a

DTE (Data terminal equipment)and a

DCE (Data Circuit-terminating Equipment)[14].It is

commonly used in computer serialports

. In RS-232, data is sent as a time-series of bits.Both

synchronous and asynchronous transmissions are supported by the standard. Inaddition to the

data circuits, the standard defines a number of control circuits used to manage theconnection

between the DTE and DCE [14]. Each data or control circuit only operates in onedirection that

is, signaling f rom a DTE to the attached DCE or the reverse. Since transmit data andreceive data

are separate circuits, the interface can operate in a full duplex manner, supportingconcurrent

data flow in both directions [15]. The standard does not define character framingwithin the data

stream, or characterencoding.


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Female 9 pinplug

3.1.3 RTS/CTS

Handshaking

The standard RS-232 use of the RTS and CTS lines is asymmetrical. The DTE assertsRTS to

indicate a desire to transmit and the DCE asserts CTS in response to grantpermission. This

allows for half-duplex modems that disable their transmitters when not required,and must

transmit a synchronization preamble to the receiver when they are re enabled [16].There is no

way for the DTE to indicate that it is unable to accept data from the DCE. A non-standard

symmetrical alternative is widely used: CTS indicates permission from the DCE for theDTE to

transmit, and RTS indicates permission from the DTE for the DCE to transmit [17]. The"request

to transmit" is implicit and continuous. The standard defines RTS/CTS as the signalingprotocol

for flow control for data transmitted from DTE to DCE. The standard has no provisionfor flow

control in the other direction. In practice, most hardware seems to have repurposedthe RTS

signal for this function [18]. A minimal 3-wire RS-232 connection consisting only oftransmits

data, receives data and ground, and is commonly used when the full facilities of RS-232 are not

required. When only flow control is required, the RTS and CTS lines are added ina 5-wire

version.

3.1.4 Specifying Baud Rate, Parity & Stop

bits


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Serial communication using RS-232 requires four parameters: the baud rate of thetransmission,

the number of data bits encoding a character, the sense of the optionalparity bit

, and thenumber

of stop bits. Each transmitted character is packaged in a character frame that consists ofa single

start bit followed by the data bits, the optional parity bit, and the stop bit or bits.A typical

character frame encoding the letter "m" is shownhere.

I specified the parameters as baud rate 9600 bps, 8 data bits, no parity, and1 stop bit

(9600-

8

N-

1).

This was set in pre-operational phase while setting up the modem through thehyper

terminal, as per the serial transmission standards in 8051microcontroller [19].

3.1.5 DCE Baud Rates

110,300,1200,2400,

480

0

,9600,19200,38400,57600,

115200 ,230400,460800,921600(Possible

Baud Rates) Baud Rate Used Power ondefault rate

3.1.6

Testing a DB-9 RS-232 ser ia l port in

HyperTerminal

This procedure explains how to troubleshoot a COM card using HyperTerminal. Beforetesting

my serial ports, I first hook up a loopback. A loopback connects the output signal (TXD)to the

input signal (RXD) in a single serial port connector to make it seem like there aretwo ports

connectedtogether.

3.1.7

Making a loopback


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Steps

V Turn off thecomputer.

VConnect RXD (pin 2) and TXD (pin 3) of the serialport.

Use a loop-back connector if

available, or any kind of conductive wire, even a paper clip[21].

V Turn on thecomputer.

I am now ready to test theport.

DB9interface

RunningHyperTerminal

Step Pr ocedureDescription

VLaunch HyperTerminal. In Windows, select Programs/Accessories/

Communications/HyperTerminal.

V Cr ea te a n ewsession.

When prompted, give the session any name Iwish.

VSelect the COM # associated with thecomputer,

I am now set up to test theport.

VWith the session open, type any text. If the text I type is echoed on the screen, theport is

functioningproperly.

V Close thesession.

VRepeat all above steps to test additional you will first need to connect the

Loopback Ports[22]. On the other ports using the stepsabove.

3.1.8

Initializations


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The baud rate of the modem was set to be 9600 bps using the HyperTerminal, TheECHO from

the modem was turned off using the command ATE0 at the HyperTerminal. Forserial

transmission and reception to be possible both the DTE and DCE should have sameoperational

baud rates. Hence to set the microcontroller at a baud rate of 9600bps, I set terminalcount of

Timer 1 at 0FFh (clock frequency = 1.8432). The TCON and SCON registerswere set

accordingly.

3.1.9 Serial transfer using TI and RI flags

After setting the baud rates of the two devices both the devices are now ready totransmit and

receive data in form of characters. Transmission is done when TI flag is set andsimilarly data is

known to be received when the Rx flag is set. The microcontroller then sends an ATcommand to

the modem in form of string of characters serially just when the TI flag is set. Afterreception of

a character in the SBUF register of the microcontroller (response of MODEM withthe read

message in its default format or ERROR message or OK message), the RI flag is setand the

received character is moved into the physical memory of the microcontroller[22].

3. 2 Programmer

When we have to learn about a new computer we have to familiarize about themachinecapability we are using, and we can do it by studying the internal hardware design

(devicesarchitecture), and also to know about the size, number and the size of theregisters.

A microcontroller is a single chip that contains the processor (the CPU), non-volatilememory forthe program (ROM or flash), volatile memory for input and output (RAM), a clock andan I/Ocontrol unit. Also called a "computer on a chip," billions of microcontroller units(MCUs) are


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embedded each year in a myriad of products from toys to appliances toautomobiles. Forexample, a single vehicle can use 70 or more microcontrollers. The following picturedescribes age ne ra l b loc k d ia gr am of microcontroller.

89S52: The AT89S52 is a low-power, high-performance CMOS 8-bit microcontrollerwith 8Kbytes of in-system programmable Flash memory. The device is manufactured using

Atmelshigh-density nonvolatile memory technology and is compatible with the industry-standard 80C51instruction set and pin out. The on-chip Flash allows the program memory to bereprogrammedin-system or by a conventional nonvolatile memory pro-grammar. By combining aversatile 8-bitCPU with in-system programmable Flash on a monolithic chip, the AtmelAT89S52 is apowerful microcontroller, which provides a highly flexible and cost-effective solution tomany,embedded control applications. The AT89S52 provides the following standardfeatures: 8K bytesof Flash, 256 bytes of RAM, 32 I/O lines, Watchdog timer, two data pointers,three 16-bittimer/counters, a six-vector two-level interrupt architecture, a full duplex serial port,on-chiposcillator, and clock circuitr y. In addition, the AT89S52 is designed with staticlogic foroperation down to zero frequency and supports two software selectable power savingmodes. TheIdle Mode stops the CPU while allowing the RAM, timer/counters, serial port, andinterruptsystem to continue functioning. The Power-down mode saves the RAM con-tents butfreezes theoscillator, disabling all other chip functions until the nextinterrupt


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The hardware is driven by a set of program instructions, or software. Oncefamiliar with

ardware is driven by a set of program instructions, or software. Once familiar withardware is driven by a set of program instructions, or software. Once familiar withardware and software, the user can then apply the microcontroller to the problems easily.ardware and software, the user can then apply the microcontroller to the problems easily.ardware and software, the user can then apply the microcontroller to the problems easily.

The pin diagram of the 8051 shows all of the input/output pins unique to microcoThe pin diagram of the 8051 shows all of the input/output pins unique to microcoThe pin diagram of the 8051 shows all of the input/output pins unique to microcontrollers:


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The following are some of the capabilities of 8051microcontroller.

VInternal ROM andRAMVI/O ports with programmablepinsV Timers andcountersV Serial datacommunication

The 8051 architecture consists of these specificfeatures:

16 bit PC &data pointer(DPTR)8 bit program status word(PSW)8 bit stack pointer(SP)Internal ROM4kInternal RAM of 128bytes. 4 register banks, each containing 8registers80 bits of general purpose data

memory 32 input/output pins arranged as four 8 bit ports:P0-P3 Two 16 bit timer/counters: T0-T1 Two external and three internal interrupt sourcesOscillator and clock

circuits.

3.3

Simulator

KEIL Micro Vision is an integrated development environment used to create softwareto be runon embedded systems (like a microcontroller). It allows for such software to be writteneither inassembly or C programming languages and for that software to be simulated on acomputerbefore being loaded onto the microcontroller. The software used is cprogramming


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Keil Vision3 is an IDE (Integrated Development Environment) that helpswrite,

compile, and debug embedded programs. It encapsulates the followingcomponents:

A projectmanager.

A makefacility.

Toolconfiguration.

Editor.

A powerfuldebugger.

To create a RFID BASED ANIMAL IDENTIFICATION SYSTEM FOR DAIRYFORMS

project in

uVision3:

1. Select Project - NewProject.

2. Select a directory and enter the name of theproject file.

3. Select Project Select Device and select a device from DeviceDatabase.

4. Create source files to add to theproject

5. Select Project - Targets, Groups, and Files. Add/Files, select Source Group1,and add the

Source files to theproject.

6. Select Project - Options and set the tool options. Note that when the targetdevice is

selected from the Device Database all-special options are set automatically.Defaultmemory model settings are optimal for mostapplications.

7. Select Project - Rebuild all target files or Buildtarget.

To create a new project, simply start micro vision and select Project=>NewProject

from the pulldown menus. In the file dialog that appears, a filename anddirectory waschosen for the project. It is recommended that a new directory be created for eachproject, as

several files will be generated. Once the project has been named, the dialogshown in thefigure below will appear, prompting the user to select a target device. The chipbeing used isthe AT89S52, which is listed under the headingAtmel.


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Next, Micro Vision was instructed to generate a HEX file upon programcompilation. A

HEX file is a standard file format for storing executable code that is to be loadedonto themicrocontroller. In the Project Workspace pane at the left, rightclick on Target 1 andselectOptions for Target 1 .Under the Output tab of the resulting options dialog, ensurethat boththe Create Executable and Create HEX File options are checked. Then clickOK.

Next, a file must be added to the project that will contain the project code. Todo this,

expand the Target 1 heading, rightclick on the Source Group 1 folder, andselect Addfiles Create a new blank file (the file name should end in .c), select it, and clickAdd. Thenew file should now appear in the Project Workspace pane under the Source Group 1folder.Double-click on the newly created file to open it in the editor. To compile the program,first saveall source files by clicking on the Save All button, and then click on the Rebuild AllTargetFiles to compile the program as shown in the figure below. If any errors or warningsoccurduring compilation, they will be displayed in the output window at the bottom of thescreen. Allerrors and warnings will reference the line and column number in which they occur alongwith adescription of the problem so that they can be easilylocated [23].

When the program has been successfully compiled, it can be simulatedusing the

integrated debugger in Keil Micro Vision. To start the debugger, selectDebug=>Start/StopDebug Session from the pulldownmenus.

At the left side of the debugger window, a table is displayed containingseveral key

parameters about the simulated microcontroller, most notably the elapsed time (circledin thefigure below). Just above that, there are several buttons that control code execution.The Runbutton will cause the program to run continuously until a breakpoint is reached,whereas theStep Into button will execute the next line of code and then pause (the currentposition in theprogram is indicated by a yellow arrow to the left of thecode).

3.4 PRO51 BURNER

SOFTWARE

PRO51 BURNER provides you with software burning tools for 8051 basedMicrocontrollers intheir Flash memory. The 51 BURNER tools, you can burn AT89C/SXXXX series ofATMEL


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microcontrollers .

A vie w o f PRO 5 1


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4.1

Conclusion

The circuit is powered by a 12V automatic power supply which changes overautomatically to abackup power source when there is power outage on the main A.C. supply. The circuituses apopular timer I C LM358 which is connected as a comparator with pin-6 connected withpositiverail; the output goes high (1) when the trigger pin 3 is lower than voltage level atpin no 2.Conversely the output goes low (0) when it is above pin no 2 level. So a smallchange in thevoltage of pin-2 is enough to change the level of output (pin-1) from 1 to 0 and 0 to1. Thischange in the output level of the I.C. LM 358 is due to the sensing ability of the lightdependentresistor which senses the presence of light. The output has only two states high andlow andcannot remain in an y intermediate stage. The comparator goes high (1) when itbecomes darkand the microcontroller sends a switching signal to the relay and the security lights areturnedON. In the event of power outage in t he A.C. mains an automatic changeover to the

backuppower source occurs immediately. After a period of delay the microcontroller sends analarmsignal to the buzzer and at the restoration of power supply thealarm stops

4. 2 P robl em

Encountered

During soldering, many of the connection become short cktd. So wedesolder theconnection and did soldering

again. A leg of the crystal oscillator was broken during mounting. So it has to bereplaced. LED`s get damaged when we switched ON the supply so we replace it by thenew one. Care should be taken while soldering. There should be no shortingof joints. Proper power supply shouldmaintain.

4.3

References:

1. 8051 and embedded system by Mazidi and

Mazidi

2. All datasheets from www.datasheetcatalog.com

3. About AT89s8252 from

www.atmel.com


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4. And

www.triindia.co.in

5. About D S1820 f rom

www.dallas.com

APPENDIX

A

APPENDIX

A

PROGRAM

FLOW

#include

sbit

s1=P3^2;

sbit

RELAY=P1^0;

void

main()

{

while(0

)

{

If(s1==1

)

{

RELAY=1

;


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}

else

{

RELAY=0

;

}

}

}


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adaptive light system

Documents