Hyprid Wind Solar Tracker

8/3/2019 Hyprid Wind Solar Tracker

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INTRODUCTION:

Electricity cannot be seen, felt, tasted, smelled, heard or(safely) touched. Providing Industrial Technology students withvivid, memorable, hands-on learning experiences in the area of

electricity is a challenge for all educators in the Industrial Technology area. The traditional measuring instruments forelectricity (oscilloscopes, voltmeters, ammeters, and powermeters) and traditional signal sources (motors, transformers,resistors, inductors)are fine but have some drawbacks: They have a tendency to become repetitive and boring. They have an artificial, educational non-real-world feel. They may fail to convey the notion of the true complexity and

interrelations of industrial electrical power systems. They may not capture the students attention and motivatelearning. They may not give an intuitive feeling for what electricalquantities reallymean physically.

As the wind does not blow all the time nor does the sun shineall the time,solar and wind power alone are poor power sources. Hybridizing

solar and wind power sources together with storage batteries tocover the periods of time without sun or wind provides arealistic form of power generation.

This variable feature of wind turbine power generation isdifferent from conventional fossil fuel, nuclear , or hydro-basedpower generation. Wind energy has become the leastexpensive renewable energy technology in existence and haspeaked the interest of scientists and educators the world over.A simple relationship exists relating the power generated by a

wind-turbine and the wind parameters:P = 0.5rA Cpv3hg hb (1) where,r = air density (about 1.225 kg/m3 at sea level, less at higherelevations).A = rotor swept area, exposed to the wind (m2).Cp = Coefficient of performance (.59 to .35 depending onturbine).v = wind speed in meters/sechg = generator efficiency

hb = gearbox/bearings efficiency


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A mast-mounted anemometer (wind meter) allows the studentsto directly measure wind speed and to vividly relate this easilyfelt force-of natureto electrical measurements. Photo-Voltaic or PV cells, known

commonly as solar cells, convert the energy from sunlight intoDC electricity. PVs offer added advantages over otherrenewable energy sources in that they give off no noise andrequire practically no maintenance. PV cells are a familiarelement of the scientific calculators owned by many students.

Their operating principles and governing relationships areunfortunately not as pedagogically simple as that of wind-turbines. However, they operate using the same semiconductorprinciples that govern diodes and transistors and the

explanation of their functioning is straightforward and helps tomake more intuitive many of the principles covered insemiconductor electronic classes. Most industrial uses ofelectricity require AC or alternating 60 Hz power. Wind-turbinesand PV cells provide DC power. A semiconductor-based deviceknown as a power inverter is used to convert the DC power toAC power. This device has a relatively simple operation that is avivid illustration of many topics traditionally covered in powerelectronics classes. The inverter also introduces the problem of

power quality. Power quality is an extremely important issue inreal-life industrial electric power systems. Power quality is thecontaminationof the voltage or frequency characteristics of electric power.

The system exhibits many common problems of power qualitysuch as voltage sag (sudden drops in voltage due to overdemand of battery capacity and/or loss of wind or sun),harmonic contamination (errors in the 60 Hz frequency due tononlinear loads such as computers, energy efficient light bulbs,laser printers, scanners), and voltage regulation problems(prolonged drops in voltage due to interactions of systemelements). Power quality is an extremely important problem inindustrial electricity applications and this setup offers uniqueopportunities for the students to study power quality problemsin a real system.

Three major phases of the development and implementation ofthis facility have been completed. First, the set-up itself hasbeen constructed and debugged. Second instruments forhands-on measurement of electrical quantities in the system


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have been acquired and deployed for hands-on lab use. Andthird, numerous simulations have been performed on PSCAD/EMTDC (1996), a well-known power system computersimulation package used by industry and universities. This

software allows the students to make an intuitive link betweenthe physical system present in the hands-on labs and the moreabstract mathematical equations presented in their lecturenotes and texts.

The major components of this system are as follows.

1) LDR (light dependent resistor)2) Microcontroller.3) Output mechanical transducer (stepper motor).4)wind fan

L29

3d


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POWER SUPPLY

TRANSFORMER:A transformer is a device that transfers electrical energy fromone circuit to another through inductively coupled conductors the transformer's coils or "windings". Except for air-coretransformers, the conductors are commonly wound around asingle iron-rich core, or around separate but magnetically-coupled cores. A varying current in the first or "primary"winding creates a varying magnetic field in the core (or cores)


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of the transformer. This varying magnetic field induces avarying electromotive force (EMF) or "voltage" in the"secondary" winding. This effect is called mutual induction.

If a load is connected to the secondary circuit, electric charge

will flow in the secondary winding of the transformer andtransfer energy from the primary circuit to the load connectedin the secondary circuit.

The secondary induced voltage VS, of an ideal transformer, isscaled from the primary VP by a factor equal to the ratio of thenumber of turns of wire in their respective windings:

By appropriate selection of the numbers of turns, a transformerthus allows an alternating voltage to be stepped up bymaking NS more than NP or stepped down, by making it

BASIC PARTS OF A TRANSFORMER

In its most basic form a transformer consists of:

A primary coil or winding. A secondary coil or winding. A core that supports the coils or windings.

Refer to the transformer circuit in figure as you read thefollowing explanation: The primary winding is connected to a60-hertz ac voltage source. The magnetic field (flux) builds up(expands) and collapses (contracts) about the primary winding.

The expanding and contracting magnetic field around theprimary winding cuts the secondary winding and induces analternating voltage into the winding. This voltage causes


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alternating current to flow through the load. The voltage maybe stepped up or down depending on the design of the primaryand secondary windings.

THE COMPONENTS OF A TRANSFORMER

Two coils of wire (called windings) are wound on some type ofcore material. In some cases the coils of wire are wound on acylindrical or rectangular cardboard form. In effect, the corematerial is air and the transformer is called an AIR-CORE

TRANSFORMER. Transformers used at low frequencies, such as60 hertz and 400 hertz, require a core of low-reluctancemagnetic material, usually iron. This type of transformer iscalled an IRON-CORE TRANSFORMER. Most power transformersare of the iron-core type. The principle parts of a transformerand their functions are:

The CORE, which provides a path for the magnetic lines of flux.

The PRIMARY WINDING, which receives energy from the acsource.

The SECONDARY WINDING, which receives energy from theprimary winding and delivers it to the load.


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The ENCLOSURE, which protects the above components fromdirt, moisture, and mechanical damage.

BRIDGE RECTIFIER

A bridge rectifier makes use of four diodes in a bridgearrangement to achieve full-wave rectification. This is a widelyused configuration, both with individual diodes wired as shownand with single component bridges where the diode bridge iswired internally.

Basic operation

According to the conventional model of current flow originallyestablished by Benjamin Franklin and still followed by mostengineers today, current is assumed to flow through electricalconductors from the positive to the negative pole. Inactuality, free electrons in a conductor nearly always flow fromthe negative to the positive pole. In the vast majority ofapplications, however, the actual direction of current flow isirrelevant. Therefore, in the discussion below the conventional

model is retained.

In the diagrams below, when the input connected to the leftcorner of the diamond is positive, and the input connected tothe right corner is negative, current flows from the uppersupply terminal to the right along the red (positive) path to theoutput, and returns to the lower supply terminal via the blue(negative) path.


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When the input connected to the left corner is negative, andthe input connected to the right corner is positive, currentflows from the lower supply terminal to the right along the redpath to the output, and returns to the upper supply terminalvia the blue path.
http://en.wikipedia.org/wiki/Image:Diode_bridge_alt_1.svg


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In each case, the upper right output remains positive and lowerright output negative. Since this is true whether the input is ACor DC, this circuit not only produces a DC output from an ACinput, it can also provide what is sometimes called "reversepolarity protection". That is, it permits normal functioning of

DC-powered equipment when batteries have been installedbackwards, or when the leads (wires) from a DC power sourcehave been reversed, and protects the equipment from potentialdamage caused by reverse polarity.

Prior to availability of integrated electronics, such a bridgerectifier was always constructed from discrete components.Since about 1950, a single four-terminal component containingthe four diodes connected in the bridge configuration became astandard commercial component and is now available withvarious voltage and current ratings.

Output smoothing

For many applications, especially with single phase AC wherethe full-wave bridge serves to convert an AC input into a DCoutput, the addition of a capacitor may be desired because thebridge alone supplies an output of fixed polarity butcontinuously varying or "pulsating" magnitude (see diagram

above).
http://en.wikipedia.org/wiki/Image:Diode_bridge_alt_2.svg


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The function of this capacitor, known as a reservoir capacitor(or smoothing capacitor) is to lessen the variation in (or'smooth') the rectified AC output voltage waveform from thebridge. One explanation of 'smoothing' is that the capacitorprovides a low impedance path to the AC component of theoutput, reducing the AC voltage across, and AC currentthrough, the resistive load. In less technical terms, any drop in

the output voltage and current of the bridge tends to becanceled by loss of charge in the capacitor. This charge flowsout as additional current through the load. Thus the change ofload current and voltage is reduced relative to what wouldoccur without the capacitor. Increases of voltagecorrespondingly store excess charge in the capacitor, thusmoderating the change in output voltage / current.

The simplified circuit shown has a well-deserved reputation forbeing dangerous, because, in some applications, the capacitorcan retain a lethal charge after the AC power source isremoved. If supplying a dangerous voltage, a practical circuitshould include a reliable way to safely discharge the capacitor.If the normal load cannot be guaranteed to perform thisfunction, perhaps because it can be disconnected, the circuitshould include a bleeder resistor connected as close aspractical across the capacitor. This resistor should consume acurrent large enough to discharge the capacitor in a reasonabletime, but small enough to minimize unnecessary power waste.
http://en.wikipedia.org/wiki/File:Diode_bridge_smoothing.svg


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Because a bleeder sets a minimum current drain, the regulationof the circuit, defined as percentage voltage change fromminimum to maximum load, is improved. However in manycases the improvement is of insignificant magnitude.

capacitor and the load resistance have a typical time constant = RC where C and R are the capacitance and load resistancerespectively. As long as the load resistor is large enough so thatthis time constant is much longer than the time of one ripplecycle, the above configuration will produce a smoothed DCvoltage across the load.

In some designs, a series resistor at the load side of thecapacitor is added. The smoothing can then be improved byadding additional stages of capacitorresistor pairs, often doneonly for sub-supplies to critical high-gain circuits that tend to besensitive to supply voltage noise.

The idealized waveforms shown above are seen for bothvoltage and current when the load on the bridge is resistive.When the load includes a smoothing capacitor, both the voltageand the current waveforms will be greatly changed. While thevoltage is smoothed, as described above, current will flow

through the bridge only during the time when the input voltageis greater than the capacitor voltage. For example, if the loaddraws an average current of n Amps, and the diodes conductfor 10% of the time, the average diode current duringconduction must be 10n Amps. This non-sinusoidal currentleads to harmonic distortion and a poor power factor in the ACsupply.

In a practical circuit, when a capacitor is directly connected to

theoutput of a bridge, the bridge diodes must be sized towithstand the current surge that occurs when the power isturned on at the peak of the AC voltage and the capacitor isfully discharged. Sometimes a small series resistor is includedbefore the capacitor to limit this current, though in mostapplications the power supply transformer's resistance isalready sufficient.

Output can also be smoothed using a choke and second

capacitor. The choke tends to keep the current (rather than thevoltage) more constant. Due to the relatively high cost of an


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effective choke compared to a resistor and capacitor this is notemployed in modern equipment.

Some early console radios created the speaker's constant field

with the current from the high voltage ("B +") power supply,which was then routed to the consuming circuits, (permanentmagnets were then too weak for good performance) to createthe speaker's constant magnetic field. The speaker field coilthus performed 2 jobs in one: it acted as a choke, filtering thepower supply, and it produced the magnetic field to operate thespeaker.

REGULATOR IC (7805)

It is a three pin IC used as a voltage regulator. It convertsunregulated DC current into regulated DC current.


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Normally we get fixed output by connecting the voltageregulator at the output of the filtered DC (see in abovediagram). It can also be used in circuits to get a low DC

voltage from a high DC voltage (for example we use7805 to get 5V from 12V). There are two types ofvoltage regulators 1. fixed voltage regulators (78xx,79xx) 2. variable voltage regulators (LM317) In fixedvoltage regulators there is another classification 1. +vevoltage regulators 2. -ve voltage regulators POSITIVEVOLTAGE REGULATORS This include 78xx voltageregulators. The most commonly used ones are 7805 and7812. 7805 gives fixed 5V DC voltage if input voltage is

in (7.5V, 20V).

The Capacitor Filter

The simple capacitor filter is the most basic type of powersupply filter. The application of the simple capacitor filter is

very limited. It is sometimes used on extremely high-voltage,low-current power supplies for cathode ray and similar electrontubes, which require very little load current from the supply.

The capacitor filter is also used where the power-supply ripplefrequency is not critical; this frequency can be relatively high.

The capacitor (C1) shown in figure 4-15 is a simple filterconnected across the output of the rectifier in parallel with theload.

Full-wave rectifier with a capacitor filter.

When this filter is used, the RC charge time of the filtercapacitor (C1) must be short and the RC discharge time must


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be long to eliminate ripple action. In other words, the capacitormust charge up fast, preferably with no discharge at all. Betterfiltering also results when the input frequency is high;therefore, the full-wave rectifier output is easier to filter than

that of the half-wave rectifier because of its higher frequency.

For you to have a better understanding of the effect thatfiltering has on Eavg, a comparison of a rectifier circuit with afilter and one without a filter is illustrated in views A and B offigure 4-16. The output waveforms in figure 4-16 represent theunfiltered and filtered outputs of the half-wave rectifier circuit.Current pulses flow through the load resistance (RL) each time adiode conducts. The dashed line indicates the average value of

output voltage. For the half-wave rectifier, Eavg is less than half(or approximately 0.318) of the peak output voltage. This valueis still much less than that of the applied voltage. With nocapacitor connected across the output of the rectifier circuit,the waveform in view A has a large pulsating component(ripple) compared with the average or dc component. When acapacitor is connected across the output (view B), the averagevalue of output voltage (Eavg) is increased due to the filteringaction of capacitor C1.

UNFILTERED


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Half-wave rectifier with andwithout filtering.

FILTERED

The value of the capacitor is fairly large (several microfarads),thus it presents a relatively low reactance to the pulsatingcurrent and it stores a substantial charge.

The rate of charge for the capacitor is limited only by theresistance of the conducting diode, which is relatively low.Therefore, the RC charge time of the circuit is relatively short.As a result, when the pulsating voltage is first applied to thecircuit, the capacitor charges rapidly and almost reaches thepeak value of the rectified voltage within the first few cycles.

The capacitor attempts to charge to the peak value of therectified voltage anytime a diode is conducting, and tends toretain its charge when the rectifier output falls to zero. (The

capacitor cannot discharge immediately.) The capacitor slowly


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discharges through the load resistance (RL) during the time therectifier is non-conducting.

The rate of discharge of the capacitor is determined by the

value of capacitance and the value of the load resistance. If thecapacitance and load-resistance values are large, the RCdischarge time for the circuit is relatively long.

A comparison of the waveforms shown in figure 4-16 (view Aand view B) illustrates that the addition of C1 to the circuitresults in an increase in the average of the output voltage (Eavg)and a reduction in the amplitude of the ripple component (Er),which is normally present across the load resistance.

Now, let's consider a complete cycle of operation using a half-wave rectifier, a capacitive filter (C1), and a load resistor (RL).As shown in view A of figure 4-17, the capacitive filter (C1) isassumed to be large enough to ensure a small reactance to thepulsating rectified current. The resistance of RL is assumed tobe much greater than the reactance of C1 at the inputfrequency. When the circuit is energized, the diode conducts onthe positive half cycle and current flows through the circuit,allowing C1 to charge. C1 will charge to approximately the peak

value of the input voltage. (The charge is less than the peakvalue because of the voltage drop across the diode (D1)). Inview A of the figure, the heavy solid line on the waveformindicates the charge on C1. As illustrated in view B, the diodecannot conduct on the negative half cycle because the anodeof D1 is negative with respect to the cathode. During thisinterval, C1 discharges through the load resistor (RL). Thedischarge of C1 produces the downward slope as indicated bythe solid line on the waveform in view B. In contrast to the

abrupt fall of the applied ac voltage from peak value to zero,the voltage across C1 (and thus across RL) during the dischargeperiod gradually decreases until the time of the next half cycleof rectifier operation. Keep in mind that for good filtering, thefilter capacitor should charge up as fast as possible anddischarge as little as possible.

Figure. - Capacitor filter circuit (positive and negative halfcycles). POSITIVE HALF-CYCLE


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Figure. - Capacitor filter circuit (positive and negative halfcycles). NEGATIVE HALF-CYCLE

Since practical values of C1 and RL ensure a more or lessgradual decrease of the discharge voltage, a substantial chargeremains on the capacitor at the time of the next half cycle ofoperation. As a result, no current can flow through the diodeuntil the rising ac input voltage at the anode of the diodeexceeds the voltage on the charge remaining on C1. Thecharge on C1 is the cathode potential of the diode. When thepotential on the anode exceeds the potential on the cathode(the charge on C1), the diode again conducts, and C1 begins tocharge to approximately the peak value of the applied voltage.

After the capacitor has charged to its peak value, the diode willcut off and the capacitor will start to discharge. Since the fall ofthe ac input voltage on the anode is considerably more rapid

than the decrease on the capacitor voltage, the cathode quickly


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become more positive than the anode, and the diode ceases toconduct.

Operation of the simple capacitor filter using a full-wave

rectifier is basically the same as that discussed for the half-wave rectifier. Referring to figure, you should notice thatbecause one of the diodes is always conducting on alternation,the filter capacitor charges and discharges during each halfcycle. (Note that each diode conducts only for that portion oftime when the peak secondary voltage is greater than thecharge across the capacitor.)

Figure - Full-wave rectifier (with capacitor filter).

Another thing to keep in mind is that the ripple component (E r)of the output voltage is an ac voltage and the average outputvoltage (Eavg) is the dc component of the output. Since the filtercapacitor offers relatively low impedance to ac, the majority of

the ac component flows through the filter capacitor. The accomponent is therefore bypassed (shunted) around the loadresistance, and the entire dc component (or Eavg) flows throughthe load resistance. This statement can be clarified by usingthe formula for XC in a half-wave and full-wave rectifier. First,you must establish some values for the circuit.

As you can see from the calculations, by doubling thefrequency of the rectifier, you reduce the impedance of thecapacitor by one-half. This allows the ac component to passthrough the capacitor more easily. As a result, a full-wave


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rectifier output is much easier to filter than that of a half-waverectifier. Remember, the smaller the XC of the filter capacitorwith respects to the load resistance, the better the filteringaction. Since

the largest possible capacitor will provide the best filtering.

Remember, also, that the load resistance is an importantconsideration. If load resistance is made small, the load currentincreases, and the average value of output voltage (Eavg)

decreases. The RC discharge time constant is a direct functionof the value of the load resistance; therefore, the rate ofcapacitor voltage discharge is a direct function of the currentthrough the load. The greater the load current, the more rapidthe discharge of the capacitor, and the lower the average valueof output voltage. For this reason, the simple capacitive filter isseldom used with rectifier circuits that must supply a relativelylarge load current. Using the simple capacitive filter inconjunction with a full-wave or bridge rectifier provides

improved filtering because the increased ripple frequencydecreases the capacitive reactance of the filter capacitor.

APPENDIX

1. Software used in the projectcodevisionavrcodevisionavr software to provide you with software

development tools for avr based microcontrollers. With the thistools, you can generate embedded applications for virtuallyevery avr derivative. The supported microcontrollers are listedin the codeVisionDevice Database. The codevision Software avr developmenttools are designed for the professional software developer, butany level of programmer can use them to get the most out ofthe avr microcontroller architecture.Codevision software burn the C-codes in avr directly.


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Datasheets

A BRIEF INTRODUCTION TO ATMEGA32

MICROCONTROLLER-:

When we have to learn about a new computer we haveto familiarize about the machine capability we are using, andwe can do it by studying the internal hardware design (devicesarchitecture), and also to know about the size, number and thesize of the registers.


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A microcontroller is a single chip that contains theprocessor (the CPU), non-volatile memory for the program(ROM or flash), volatile memory for input and output (RAM), aclock and an I/O control unit. Also called a "computer on a

chip," billions of microcontroller units (MCUs) are embeddedeach year in a myriad of products from toys to appliances toautomobiles. For example, a single vehicle can use 70 or moremicrocontrollers. The following picture describes a generalblock diagram of microcontroller.

ATMEGA32: The ATMEGA32 is a low-power, high-performance advance RISC 8-bit microcontroller with 32K bytesof in-system programmable Flash memory. The on-chip Flash

allows the program memory to be reprogrammed in-system orby a conventional nonvolatile memory pro-grammer. Bycombining a versatile 8-bit CPU with in-system programmableFlash on a monolithic chip, the Atmel ATMEGA32 is a powerfulmicrocontroller, which provides a highly flexible and cost-effective solution to many, embedded control applications. TheATMEGA32 provides the following standard features: 32Kbytes of Flash, 1024 byte of EEPROM & 2KB INTERNAL S RAM ,32 I/O lines, Watchdog timer, two data pointers, two 16-bittimer/counters, a six-vector two-level interrupt architecture, afull duplex serial port, on-chip oscillator,8-channel 10 bit ADCand clock circuitry. In addition, the ATMEGA32 is designedwith static logic for operation down to zero frequency andsupports two software selectable power saving modes. The IdleMode stops the CPU while allowing the RAM, timer/counters,serial port, and interrupt system to continue functioning. ThePower-down mode saves the RAM con-tents but freezes theoscillator, disabling all other chip functions until the nextinterrupt

4L. LCD DISPLAY2.LCD

The liquid - crystal display (LCD) consist of a liquid crystalmaterial (normally organic for LCDs) that will flow like a


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liquid but whose molecular structure has some propertiesnormally associated with solids.

The LCD does not generate its own light but depends on anexternal or internal source.

Under dark conditions, it would be necessary for the unit tohave its own internal light source either behind or to theside of the LCD.

During the day, or in the lighted areas, a reflector can beput behind the LCD to reflect the light back through thedisplay for maximum intensity.

The LCD has the distinct advantage of having the lower powerrequirement than the LED. It is typical in the order of

microwatts for the display, as compared to the same order ofmilliwatts for LEDs. LCD is limited to a temperature range ofabout 0 to 60 C. Lifetime is an area of concern because LCDscan chemically degrade.

LCDs can add a lot to out applications in terms of providing anuseful interface for the user, debugging an application or justgiving it a "professional" look. The most common type of LCDcontroller is the Hitatchi 44780 which provides a relatively

simple interface between a processor and an LCD. Besides thisthere are several other reasons for LCDs replacing LEDs(sevensegment LEDs or other multisegment LEDs).This is due thefollowing reasons :-

The declining prices of LCDs. The ability to display numbers, characters and graphics.

This is in contrast to LEDs , which are limited to numbersand a few characters.

In corporation of a refreshing controller into the LCD ,

thereby relieving the CPU of the task of refreshing the LCDin contrast, the LED must be refreshed by the CPU (or insome other way) to keep displaying the data.

Ease of programming for characters and graphics.


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LCD PIN DESCRIPTIONS

Fig 1. Shows the pin diagram of a 14 pin LCD.

The LCD used here has 14 pins. The functions of each pin aregiven below:VCC, VSS, and VEE :While Vcc and Vss provide +5V and ground, respectively, VEE isused for controlling LCD contrast.RS, register select:

There are two very important registers inside the LCD. The RSpin is used for their selection as follows .If RS = 0 , theninstruction command code register is selected , allowing the

user to send the command such as clear display, cursor athome, etc. If RS = 1 the data register is selected, allowing theuser to send data to be displayed on the LCD.R/W, read/write:R/W input allows the user to write information to the LCD orread information from it.R/W =1 when reading ; R/W = 0 when writing.E, enable:

The enable pin is used by the LCD to latch information

presented to its data pins. When data is supplied to data pins, ahigh to low pulse must be applied to this pin in order for the


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LCD to latch in the data present at the data pins. This pulsemust be a minimum of 450 ns wide.D0 D7:

The 8 bit data pins , D0 D7, are used to send information to

the LCD or read the contents of the LCD's internal registers.To display letters and numbers, we send ASCII codes for theletters A- Z, a-z, and 0-9 to these pins while making RS = 1.

There are also instruction commands codes that can be send tothe LCD to clear the display or force to cursor to the homeposition or blink the cursor.We also use RS=0 to check the busy flag bit to see if the LCD isready to receive information. The busy flag is D7 and can beread when R/W=1.RS=0, as follows: if R/W=1 and RS=0.When

D7=1 (busy flag=1), the LCD is busy taking care of internaloperations and will not accept any new information. When D7= 0, the LCD is ready to receive new information.

PIN DESCRIPTION FOR LCD

Pin

Symbol

I/O Description

1 Vss -- Ground2 Vcc -- +5V power supply3 VEE -- Power supply to control contrast4 RS I RS=0 for command register, RS=1 for

data register5 R/W I R/W+0 for write, R/W+1 for read6 E I/O Enable7 DB0 I/O The 8-bit data bus8 DB1 I/O The 8-bit data bus9 DB2 I/O The 8-bit data bus10 DB3 I/O The 8-bit data bus


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11 DB4 I/O The 8-bit data bus12 DB5 I/O The 8-bit data bus13 DB6 I/O The 8-bit data bus14 DB7 I/O The 8-bit data bus

LCD Command Codes

Code (Hex) Command to LCD InstructionRegister

1 Clear display screen2 Return home4 Decrement cursor(shift cursor to

left)6 Increment cursor(shift cursor to

right)5 Shift display left

7 Shift display left8 Display off, cursor off A Display off, cursor onC Display on, cursor off E Display onF Display on, cursor blinking10 Shift cursor position to left14 Shift cursor position to right18 Shift the entire display to the left

1C Shift the entire display to the right80 Force cursor to beginning of first

lineC0 Force cursor to beginning of second

line38 2 lines and 5x7 matrix

WORKING:


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The interface used by LCD is a parallel bus, allowing simple andfast reading/writing of data to and from the LCD.

.

This waveform will write an ASCII Byte out to the LCD's screen.The ASCII code to be displayed is eight bits long and is sent to

the LCD either four or eight bits at a time. If four bit mode isused, two "nibbles" of data (Sent high four bits and then lowfour bits with an "Enable" Clock pulse with each nibble) are sentto make up a full eight bit transfer. The "Enable" Clock is usedto initiate the data transfer within the LCD.

Sending parallel data as either four or eight bits are the twoprimary modes of operation. While there are secondaryconsiderations and modes, deciding how to send the data to

the LCD is most critical decision to be made for an LCDinterface application.

Eight bit mode is best used when speed is required in anapplication and at least ten I/O pins are available. Four bitmode requires a minimum of six bits. To wire a microcontrollerto an LCD in four bit mode, just the top four bits (DB4-7) arewritten to.

The "RS" bit is used to select whether data or an instruction is

being transferred between the microcontroller and the LCD. If


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the Bit is set, then the byte at the current LCD "Cursor" Positioncan be read or written. When the Bit is reset, either aninstruction is being sent to the LCD or the execution status ofthe last instruction is read back (whether or not it has

completed).

Reading Data back is best used in applications which requireddata to be moved back and forth on the LCD (such as inapplications which scroll data between lines).In our Project wehave permanently grounded R/W pin which means we are notretrieving any data from LCD.

The LCD can be thought of as a "Teletype" display because innormal operation, after a character has been sent to the LCD,the internal "Cursor" is moved one character to the right. The"Clear Display" and "Return Cursor and LCD to Home Position"instructions are used to reset the Cursor's position to the topright character on the display.

To move the Cursor, the "Move Cursor to Display" instruction isused. For this instruction, bit 7 of the instruction byte is set withthe remaining seven bits used as the address of the characteron the LCD the cursor is to move to. These seven bits provide

128 addresses, which matches the maximum number of LCDcharacter addresses available.

Eight programmable characters are available and use codes0x000 to 0x007. They are programmed by pointing the LCD's

"Cursor" to the Character Generator RAM


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The last aspect of the LCD to discuss is how to specify acontrast voltage to the Display. I typically use a potentiometerwired as a voltage divider. This will provide an easily variablevoltage between Ground and Vcc, which will be used to specify

the contrast (or "darkness") of the characters on the LCDscreen. You may find that different LCDs work differently withlower voltages providing darker characters in some and highervoltages do the same thing in others

L293D


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The L293 and L293D are quadruple high-current half-H drivers.The L293 is designed to provide bidirectional drive currents of

up to 1 A at voltages from 4.5 V to 36 V. The L293D is designedto provide bidirectional drive currents of up to 600-mA atvoltages from 4.5 V to 36 V. Both devices are designed to driveinductive loads such as relays, solenoids, dc and bipolarstepping motors, as well as other high-current/high-voltageloads in positive-supply applications.All inputs are TTL compatible. Each output is a complete totem-pole drive circuit, with a Darlington transistor sink and apseudo-Darlington source. Drivers are enabled in pairs, with

drivers 1 and 2 enabled by 1,2EN anddrivers 3 and 4 enabled by 3,4EN. When an enable input ishigh, the associated drivers are enabled and their outputs areactive and in phase with their inputs. When the enable input islow, those drivers are disabled and their outputs are off and inthe high-impedance state. With the proper data inputs, eachpair of drivers forms a full-H (or bridge) reversible drive suitablefor solenoid or motor applications.On the L293, external high-speed output clamp diodes should

be used for inductive transient suppression. A VCC1 terminal,


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separate from VCC2, is provided for the logic inputs to minimizedevice power dissipation.

Stepper motor

A stepper motor (or step motor) is a brushless, synchronouselectric motor that can divide a full rotation into a large numberof steps. The motor's position can be controlled precisely,without any feedback mechanism (see Open-loop controller).Stepper motors are similar to switched reluctance motors(which are very large stepping motors with a reduced polecount, and generally are closed-loop commutated.)

Fundamentals of Operation

Stepper motors operate differently from DC brush motors,which rotate when voltage is applied to their terminals. Steppermotors, on the other hand, effectively have multiple "toothed"electromagnets arranged around a central gear-shaped pieceof iron. An external control circuit, such as a microcontroller,energizes the electromagnets. To make the motor shaft turn,first one electromagnet is given power, which makes the gear'steeth magnetically attracted to the electromagnet's teeth.When the gear's teeth are thus aligned to the firstelectromagnet, they are slightly offset from the next

electromagnet. So when the next electromagnet is turned onand the first is turned off, the gear rotates slightly to align withthe next one, and from there the process is repeated. Each ofthose slight rotations is called a "step," with an integer numberof steps making a full rotation. In that way, the motor can beturned by a precise angle.


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Stepper motor characteristics

1. Stepper motors are constant power devices.2. As motor speed increases, torque decreases.3. The torque curve may be extended by using current limitingdrivers and increasing the driving voltage.4. Steppers exhibit more vibration than other motor types, asthe discrete step tends to snap the rotor from one position toanother.5. This vibration can become very bad at some speeds and cancause the motor to lose torque.

6. The effect can be mitigated by accelerating quickly throughthe problem speeds range, physically damping the system, orusing a micro-stepping driver.7. Motors with a greater number of phases also exhibitsmoother operation than those with fewer phases.

Open-loop versus closed-loop commutation

Steppers are generally commutated open loop, ie. the driver

has no feedback on where the rotor actually is. Stepper motorsystems must thus generally be over engineered, especially ifthe load inertia is high, or there is widely varying load, so thatthere is no possibility that the motor will lose steps. This hasoften caused the system designer to consider the trade-offsbetween a closely sized but expensive servomechanism systemand an oversized but relatively cheap stepper.

A new development in stepper control is to incorporate a rotorposition feedback (eg. an encoder or resolver), so that thecommutation can be made optimal for torque generation


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according to actual rotor position. This turns the stepper motorinto a high pole count brushless servo motor, with exceptionallow speed torque and position resolution. An advance on thistechnique is to normally run the motor in open loop mode, and

only enter closed loop mode if the rotor position error becomestoo large -- this will allow the system to avoid hunting oroscillating, a common servo problem.

There are three main types of stepper motors:

Permanent Magnet StepperHybrid Synchronous StepperVariable Reluctance Stepper

Permanent magnet motors use a permanent magnet (PM) inthe rotor and operate on the attraction or repulsion betweenthe rotor PM and the stator electromagnets. Variable reluctance(VR) motors have a plain iron rotor and operate based on theprinciple of that minimum reluctance occurs with minimumgap, hence the rotor points are attracted toward the statormagnet poles. Hybrid stepper motors are named because theyuse use a combination of PM and VR techniques to achieve

maximum power in a small package size.

Two-phase stepper motors

There are two basic winding arrangements for theelectromagnetic coils in a two phase stepper motor: bipolar andunipolar.

Unipolar motors

A unipolar stepper motor has two windings per phase, one foreach direction of magnetic field. Since in this arrangement amagnetic pole can be reversed without switching the directionof current, the commutation circuit can be made very simple(eg. a single transistor) for each winding. Typically, given aphase, one end of each winding is made common: giving threeleads per phase and six leads for a typical two phase motor.Often, these two phase commons are internally joined, so the

motor has only five leads.


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A microcontroller or stepper motor controller can be used toactivate the drive transistors in the right order, and this ease ofoperation makes unipolar motors popular with hobbyists; they

are probably the cheapest way to get precise angularmovements.

Unipolar stepper motor coils

(For the experimenter, one way to distinguish common wirefrom a coil-end wire is by measuring the resistance. Resistancebetween common wire and coil-end wire is always half of whatit is between coil-end and coil-end wires. This is due to the factthat there is actually twice the length of coil between the endsand only half from center (common wire) to the end.) A quickway to determine if the stepper motor is working is to shortcircuit every two pairs and try turning the shaft, whenever ahigher than normal resistance is felt, it indicates that the circuitto the particular winding is closed and that the phase isworking.

Bipolar motor

Bipolar motors have a single winding per phase. The current ina winding needs to be reversed in order to reverse a magneticpole, so the driving circuit must be more complicated, typicallywith an H-bridge arrangement. There are two leads per phase,none are common.

Static friction effects using an H-bridge have been observedwith certain drive topologies Because windings are betterutilised, they are more powerful than a unipolar motor of thesame weight.

8-lead stepper

An 8 lead stepper is wound like a unipolar stepper, but the

leads are not joined to common internally to the motor. Thiskind of motor can be wired in several configurations:
http://en.wikipedia.org/wiki/File:Unipolar-stepper-motor-windings.png


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Unipolar.

Bipolar with series windings. This gives higher inductance butlower current per winding.

Bipolar with parallel windings. This requires higher current butcan perform better as the winding inductance is reduced.Bipolar with a single winding per phase. This method will runthe motor on only half the available windings, which will reducethe available low speed torque but require less current.Higher-phase count stepper motors

Multi-phase stepper motors with many phases tend to havemuch lower levels of vibration, although the cost of

manufacture is higher.

Stepper motor drive circuits

Stepper motor performance is strongly dependent on the drivecircuit. Torque curves may be extended to greater speeds if thestator poles can be reversed more quickly, the limiting factor

being the winding inductance. To overcome the inductance andswitch the windings quickly, one must increase the drivevoltage. This leads further to the necessity of limiting thecurrent that these high voltages may otherwise induce.

L/R drive circuits

L/R drive circuits are also referred to as constant voltage drivesbecause a constant positive or negative voltage is applied to

each winding to set the step positions. However, it is windingcurrent, not voltage that applies torque to the stepper motorshaft. The current I in each winding is related to the appliedvoltage V by the winding inductance L and the windingresistance R. The resistance R determines the maximumcurrent according to Ohm's law I=V/R. The inductance Ldetermines the maximum rate of change of the current in thewinding according to the formula for an Inductor dI/dt = V/L.

Thus when controlled by an L/R drive, the maximum speed of a

stepper motor is limited by its inductance since at some speed,


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the voltage V will be changing faster than the current I cankeep up.

With an L/R drive it is possible to control a low voltage resistive

motor with a higher voltage drive simply by adding an externalresistor in series with each winding. This will waste power in theresistors, and generate heat. It is therefore considered a lowperforming option, albeit simple and cheap.

Chopper drive circuits

Chopper drive circuits are also referred to as constant currentdrives because they generate a somewhat constant current in

each winding rather than applying a constant voltage. On eachnew step, a very high voltage is applied to the winding initially.This causes the current in the winding to rise quickly since dI/dt= V/L where V is very large. The current in each winding ismonitored by the controller, usually by measuring the voltageacross a small sense resistor in series with each winding. Whenthe current exceeds a specified current limit, the voltage isturned off or "chopped", typically using power transistors.When the winding current drops below the specified limit, the

voltage is turned on again. In this way, the current is heldrelatively constant for a particular step position. This requiresadditional electronics to sense winding currents, and controlthe switching, but it allows stepper motors to be driven withhigher torque at higher speeds than L/R drives. Integratedelectronics for this purpose are widely available.Phase current waveforms

A stepper motor is a polyphase AC synchronous motor (seeTheory below), and it is ideally driven by sinusoidal current. Afull step waveform is a gross approximation of a sinusoid, andis the reason why the motor exhibits so much vibration. Variousdrive techniques have been developed to better approximate asinusoidal drive waveform: these are half stepping andmicrostepping.Full step drive (two phases on)

This is the usual method for full step driving the motor. Bothphases are always on. The motor will have full rated torque.


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Wave drive

In this drive method only a single phase is activated at a time.It has the same number of steps as the full step drive, but the

motor will have significantly less than rated torque. It is rarelyused.

Half stepping

When half stepping, the drive alternates between two phaseson and a single phase on. This increases the angular resolution,but the motor also has less torque at the half step position(where only a single phase is on). This may be mitigated by

increasing the current in the active winding to compensate. Theadvantage of half stepping is that the drive electronics neednot change to support it.

Microstepping

What is commonly referred to as microstepping is actual "sinecosine microstepping" in which the winding currentapproximates a sinusoidal AC waveform. Sine cosinemicrostepping is the most common form, but other waveformsare used. Regardless of the waveform used, as the microstepsbecome smaller, motor operation becomes more smooth,thereby greatly reducing resonance in any parts the motor maybe connected to, as well as the motor itself. It should be notedthat while microstepping appears to make running at very highresolution possible, this resolution is rarely achievable inpractice regardless of the controller, due to mechanical stictionand other sources of error between the specified and actualpositions. In professional equipment gearheads are thepreferred way to increase angular resolution.

Step size repeatability is an important step motor feature and afundamental reason for their use in positioning. Example: manymodern hybrid step motors are rated such that the travel ofevery Full step (example 1.8 Degrees per Full step or 200 Fullsteps per revolution) will be within 3% or 5% of the travel ofevery other Full step; as long as the motor is operated with inits specified operating ranges. Several manufacturers show that

their motors can easily maintain the 3% or 5% equality of step


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travel size as step size is reduced from Full stepping down to1/10th stepping. Then, as the microstepping divisor numbergrows, step size repeatability degrades. At large step sizereductions it is possible to issue many microstep commands

before any motion occurs at all and then the motion can be a"jump" to a new position.

Theory

A step motor can be viewed as a synchronous AC motor withthe number of poles (on both rotor and stator) increased, takingcare that they have no common denominator. Additionally, softmagnetic material with many teeth on the rotor and stator

cheaply multiplies the number of poles (reluctance motor).Modern steppers are of hybrid design, having both permanentmagnets and soft iron cores.

To achieve full rated torque, the coils in a stepper motor mustreach their full rated current during each step. Windinginductance and reverse EMF generated by a moving rotor tendto resist changes in drive current, so that as the motor speedsup, less and less time is spent at full current -- thus reducing

motor torque. As speeds further increase, the current will notreach the rated value, and eventually the motor will cease toproduce torque.

Pull-in torque

This is the measure of the torque produced by a stepper motorwhen it is operated without an acceleration state. At low speedsthe stepper motor can synchronise itself with an applied stepfrequency, and this Pull-In torque must overcome friction andinertia.

Pull-out torque

The stepper motor pull-out torque is measured by acceleratingthe motor to the desired speed and then increasing the torqueloading until the motor stalls or "pulls out of synchronism" withthe step frequency. This measurement is taken across a widerange of speeds and the results are used to generate thestepper motor's dynamic performance curve. As noted below


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this curve is affected by drive voltage, drive current andcurrent switching techniques. It is normally recommended touse a safety factor of between 50% and 100% when comparingyour desired torque output to the published "pull-Out" torque

performance curve of a step motor.

Detent torque

Synchronous electric motors using permanent magnets have aremnant position holding torque (called detent torque, and

sometimes included in the specifications) when not drivenelectrically. Soft iron reluctance cores do not exhibit thisbehavior.

Stepper motor ratings and specifications

Stepper motors nameplates typically give only the windingcurrent and occasionally the voltage and winding resistance.

The rated voltage will produce the rated winding current at DC:but this is mostly a meaningless rating, as all modern driversare current limiting and the drive voltages greatly exceed themotor rated voltage.

A stepper's low speed torque will vary directly with current.How quickly the torque falls off at faster speeds depends on thewinding inductance and the drive circuitry it is attached to,especially the driving voltage.

Steppers should be sized according to published torque curve,which is specified by the manufacturer at particular drivevoltages and/or using their own drive circuitry. It is notguaranteed that you will achieve the same performance givendifferent drive circuitry, so the pair should be chosen with greatcare.

Applications


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Computer-controlled stepper motors are one of the mostversatile forms of positioning systems. They are typicallydigitally controlled as part of an open loop system, and aresimpler and more rugged than closed loop servo systems.

Industrial applications are in high speed pick and placeequipment and multi-axis machine CNC machines often directlydriving lead screws or ballscrews. In the field of lasers andoptics they are frequently used in precision positioningequipment such as linear actuators, linear stages, rotationstages, goniometers, and mirror mounts. Other uses are inpackaging machinery, and positioning of valve pilot stages forfluid control systems.

Commercially, stepper motors are used in floppy disk drives,flatbed scanners, computer printers, plotters, slot machines,and many more devices.

TROUBLESHOOTCare should be taken while soldering. There should be no

shorting of joints.Proper power supply should maintain.

Project should be handled with care since IC are delicateComponent change and check again circuit

Introduction to matlab-:A graphical user interface (GUI) is a pictorial interface to aprogram. A good GUI can make programs easier to use byproviding them with a consistent appearance and with intuitivecontrols like pushbuttons, list boxes, sliders, menus, and soforth. The GUI should behave in an understandable andpredictable manner, so that a user knows what to expect whenhe or she performs an action. For example, when a mouse clickoccurs on a pushbutton, the GUI should initiate the actiondescribed on the label of the button. This


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chapter introduces the basic elements of the MATLAB GUIs. Thechapter does not contain a complete description of componentsor GUI features, but it does provide the basics required tocreate functional GUIs for your programs

1.1 How a Graphical User Interface WorksA graphical user interface provides the user with a familiarenvironment in which to work. This environment containspushbuttons, toggle buttons, lists, menus, text boxes, and soforth, all of which are already familiar to the user, so that he orshe can concentrate on using the application rather than on themechanics involved in doing things. However, GUIs are harderfor the programmer because a GUI-based program must be

prepared for mouse clicks (or possibly keyboard input) for anyGUI element at any time. Such inputs are known as events, anda program that responds to events is said to be event driven.

The three principal elements required to create a MATLABGraphicalUser Interface are1. Components. Each item on a MATLAB GUI (pushbuttons,labels, edit boxes, etc.) is a component. The types ofcomponents include graphical controls (pushbuttons,

edit boxes, lists, sliders, etc.), static elements (frames and textstrings), menus, and axes. Graphical controls and staticelements are created by the function uicontrol, and menus arecreated by the functions uimenu and uicontextmenu. Axes,which are used to display graphical data, are created by thefunction axes.

2. The components of a GUI must be arranged within a figure,which is a window on the computer screen. In the past, figureshave been created automatically whenever we have plotteddata. However, empty figures can be created with the functionfigure and can be used to hold any combination of components.3. Callbacks. Finally, there must be some way to perform anaction if a user clicks a mouse on a button or types informationon a keyboard. A mouse click or a key press is an event, andthe MATLAB program must respond to each event if theprogram is to perform its function. For example, if a user clickson a button, that event must cause the MATLAB code thatimplements the function of the button to be executed. The codeexecuted in response to an event is known as a call back. There


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must be a callback to implement the function of each graphicalcomponent on the GUI. The basic GUIelements. We will be studying examples of these elements andthen build working GUIs from them.

1.2 Creating and Displaying a Graphical User InterfaceMATLAB GUIs are created using a tool called guide, the GUIDevelopmentEnvironment. This tool allows a programmer to layout the GUI,selecting and aligning the GUI components to be placed in it.Once the components are in place, the programmer can edittheir properties: name, color, size, font, text to display, and soforth. When guide saves the GUI, it creates working program

including skeleton functions that the programmer can modifyto implement the behavior of the GUI. When guide is executed,it creates the Layout Editor, shown in Figure 1.2. The largewhite area with grid lines is the layout area, where aprogrammer can layout the GUI. The Layout Editor window hasa palate of GUI components along the left side of the layoutarea. A user cancreate any number of GUI components by first clicking on thedesired component, and then dragging its outline in the layout

area. The top of the window has a toolbar with a series of usefultools that allow the user to distribute and align GUIcomponents, modify the properties of GUI components, addmenus to GUIs, and so on. The basic stepsrequired to create a MATLAB GUI are:1. Decide what elements are required for the GUI and what thefunction of each element will be. Make a rough layout of thecomponents by hand on a piece of paper.


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Figure 1.1 A Figure Window showing examples of MA TLAB GUIelements. From top to bottom and left to right, the elementsare: (1) a pushbutton; (2) a toggle button in the 'on' state; (3)two radio buttons surrounded by a frame; (4) a check box; (5) atext field and an edit box; (6) a slider; (7) a set of axes; and (8)a list box.2. Use a MATLAB tool called guide (GUI DevelopmentEnvironment) to layout the Components on a figure. The size ofthe figure and the alignment and spacing of components on the

figure can be adjusted using the tools built into guide.3. Use a MATLAB tool called the Property Inspector (built intoguide) to give each component a name (a "tag") and to set thecharacteristics of each component, such as its color, the text itdisplays, and so on.4. Save the figure to a file. When the figure is saved, two fileswill be created on disk with the same name but differentextents. The fig file contains the actual GUI that you havecreated, and the M-file contains the code to load the figure and

skeleton call backs for each GUI element.


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5. Write code to implement the behavior associated with eachcallback function.


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Circuit diagram


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WORKING-:

The solar and wind energy systems both have theirbenefits and disadvantages, so it is possible to build ahybrid system that combines the 2 of them. Theadvantage with this combination system is that it willstill function in the event that there is no wind or sunenergy.

This hybrid system is good for helping to even out thepeaks and valleys in levels of power produced by the 2

systems. The solar panels can only generate electricity


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when they are exposed to sunlight, and becomeuseless in cloudy day and at night. This also applies toa wind power system when there is a lack of wind. Acombination system has a much lower chance of failingto produce power in any time of the day.

It is very important that you do careful planning beforedeciding on the type of home energy system that youwant to build. This planning phase includes calculatingthe total power that your home requires, how muchpower you plan to produce with the system and howmuch reserve power your home will need.

Thousands of people have already eliminated their ownhome electricity bills with the free energy system thatthey learned how to build with a step-by-step guideonline. You can find out more about how to build thishomemade power system at the website link below


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REFERENCES

Introduction to Microcontroller by MAZIDI AND

MAZIDI.

Microprocessors & Microcontroller by U.S.SHAH.

WEBSITES

www.atmel.com

www.seimens.com

www.philipsemiconductors.com

www.howstuffworks.com

www.alldatasheets.com

www.efyprojects.com

www.thomson.com/learning

www google com

Documents

Hyprid Wind Solar Tracker