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CHAPTER I

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1.1 Introduction

Cellular telephone technology became commercially available in the 1980

Since then, it has been like a snowball rolling downhill, ever increasing in the number

of users and the speed at which the technology advances. When the cellular phone

was first implemented, it was enormous in size by today standards. This reason is

two-fold; the battery had to be large, and the circuits themselves were large. The

circuits of that time used in electronic devices were made from off the shelf integrated

circuits (IC), meaning that usually every part of the circuit had its own package. These

packages were also very large These large circuit boards required large amounts of

power, which meant bigger batteries. This reliance on power was a major contributorto the reason these phones were so big.

Through the years, technology has allowed the cellular phone to shrink not

only the size of the ICs, but also the batteries. New combinations of materials have

made possible the ability to produce batteries that not only are smaller and last longer,

but also can be recharged easily. However, as technology has advanced and made our

phones smaller and easier to use, we still have one of the original problems: we mustplug the phone into the wall in order to recharge the battery. Most people accept this

as something that will never change, so they might as well accept it and carry around

either extra batteries with them or a charger. Either way, just something extra to

weigh a person down. There has been research done in the area of shrinking the

charger in order to make it easier to carry with the phone. One study in particular

went on to find the lower limit of charger size [1]. But as small as the charger

becomes, it still needs to be plugged in to a wall outlet.

Now, think about this; what if it have to be that way? Most people realize

that there is an abundance of energy all around us at all times. We are being

bombarded with energy waves every second of the day. Radio and television towers,

satellites orbiting earth, and even the cellular phone antennas are constantly

transmitting energy. What if there was a way we could harvest the energy that is being

transmitted and use it as a source of power? If it could be possible to gather the

energy and store it, we could potentially use it to power other circuits. In the case of

the cellular phone, this power could be used to recharge a battery that is constantly

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being depleted. The potential exists for cellular phones, and even more complicated

devices - i.e. pocket organizers, person digital assistants (PDAs), and even notebook

computers to become completely wireless. Of course, right now this is all theoretical.

There are many complications to be dealt with. The first major obstacle is that it is not

a trivial problem to capture energy from the air. We will use a concept called energy

harvesting. Energy harvesting is the idea of gathering transmitted energy and either

using it to power a circuit or storing it for later use. The concept needs an efficient

antenna along with a circuit capable of converting alternating-current (AC) voltage to

direct-current (DC) voltage. The efficiency of an antenna, as being discussed here, is

related to the shape and impedance of the antenna and the impedance of the circuit. If

the two impedances matched then there is reflection of the power back into the

antenna meaning that the circuit was unable to receive.

A chip for inductive batterycharging is presented, which needs no external

components except an antenna to capture the energy from an electromagnetic

field. The integrated system blocks are a front-end to limit and rectify the

induced alternating voltage and a charge regulator with three control loops for

the current, the voltage and the temperature.

The external antenna forms a resonance circuit with the on-chip capacitor. The

resonance frequency of the front end is 13.56 MHz, so it is compatible to the

well known smart-card standard. In the electromagnetic field of commercial

reader systems the chip produces an output current to charge a lithium battery

with the mandatory constant-current-constant voltage (cccv) charge profile

This architecture is implemented to charge lithium cells at a current of 4 mA

up to a cell voltage of 4.2 volts. The target application are high-end smart-

cards with secondary batteries.

The chip, fabricated in a 0.8 m BICMOS-technology , includes two contacts

for the antenna and two for the battery. The operating current of the IC is

approximately 1 mA.

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1.2 Transmitter

In electronics and telecommunications or radio transmitter is an electronic device

which, with the aid of an antenna, produces radio waves. The transmitter itself

generates a radio frequency alternating current, which is applied to the antenna. When

excited by this alternating current, the antenna radiates radio waves. In addition to

their use in broadcasting, transmitters are necessary component parts of many

electronic devices that communicate by radio, such as cell phones, Wifi and Bluetooth

enabled devices, garage door openers, two-way radios in aircraft, ships, and

spacecraft, radar sets, and navigational beacons. The term transmitter is usually

limited to equipment that generates radio waves for communication purposes; or

radiolocation, such as radar and navigational transmitters. Generators of radio waves

for heating or industrial purposes, such as microwave ovens or diathermy equipment,

are not usually called transmitters even though they often have similar circuits. The

term is popularly used more specifically to refer to transmitting equipment used for

broadcasting, as in radio transmitter or television transmitter. This usage usually

includes both the transmitter proper as described above, and the antenna, and often the

building it is housed in.

An unrelated use of the term is in industrial process control, where a "transmitter" is a

device which converts measurements from a sensor into a signal, and sends it, us. The

4

CodeGeneratorVoice

ElectricalSignal

Digital /AnalogConversion

Voltage/FrequencyConversion

Amplifier

Crystal Module

Antena

Figure -1


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antenna plays a very important role. To charge a battery, a high DC power signal is

needed. The wireless battery charger circuit must keep the power loss to the minimal.

Therefore, there are many considerations to choose the correct parts for the design.

The considerations of choosing the appropriate antenna are: 1. Impedance of the

antenna 2. Gain of the antenna

The most basic transmitter setup consists of a piece of equipment that generates a

signal whose output is then fed into an amplifier that is finally output through a

radiating antenna the air interface. A condition must be met where the antenna

operates optimally at the desired frequency output from the signal generator. In the

current case, an antenna was connected through an amplifier to a radio-frequency

(RF) source. The RF source is a circuit that outputs a signal at a user-specified

frequency and voltage. The range of frequencies of the signal generator resides in the

radio frequency band, 3 mega-hertz (MHz) to 3 giga-hertz (GHz). The output power

of this device is limited. For this reason, an amplifier is required on the output. The

transmitting antenna is called a patch antenna and is fabricated from copper plating

that is soldered to a feed wire and has a ground plane.

The frequency of 915MHz was chosen for this project because it is one at which our

team has experience, and it falls in one of the Industrial-Scientific-Medical (ISM) RF

bands made available by the Federal Communications Commission for low power,

short distance experimentation. This frequency was chosen mostly for simplicity in

using the available equipment. It is not used for mass communication or anything else

on a major scale, and therefore is not going to be interfered with, or interfere with

other devices at low power levels. This also means that transmitters for short distances

are readily available. In fact, 915MHz is a very common frequency used in RF

research. This makes a transmitter system easy to construct and manage. The source is

nothing more than a signal generator, capable of outputting a low-noise AC signal at

915MHz. This setup results in the antenna beaming approximately 6mW of power per

square meter. This was the limit of the gain of the amplifier.

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1.3 Receiver

The receiver main purpose is to charge a battery. A simple battery charging theory is

to run current through the battery, and apply a voltage difference between the

terminals of the battery to reverse the chemical process. By doing so, it recharges thebattery. There are other efficient and faster ways to charge the battery, but it requires

a large amount of energy which the wireless battery charger cannot obtain, yet.

Therefore, in our design, we use a straight forward method to charge the battery.

Microwave signal is an AC signal with a frequency range of 1 GHz 1000 GHz. 915

MHz is in between the RF/ Microwave range. No matter how high the frequency is,

AC signal is still AC signal. Therefore, the signal can also be treated as a low

frequency AC signal. In order to get a DC signal out of the AC signal, a rectifier

circuit is needed. At the output of the rectifier, the signal is not a fully DC signal yet.

Thus, by adding a capacitor and a resistor can smooth out the output to become DC

signal

6

Antena

Filter

Demodule

SeperatorFilter

Frequency/Voltageconversion

Crystal

Reset

Analog /DigitalConversion

Input/Outputinterface

- P Outputinterface

Batterycharger

Speaker

Figure -2


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The receiver in information theory is the receiving end of a communication channel. It

receives decoded messages/information from the sender, who first encoded them.

Sometimes the receiver is modeled so as to include the decoder. Real-world receivers

like radio receivers or telephones can not be expected to receive as much information

as predicted by the noise receiver operating characteristic (ROC), or simply ROC

curve, is a graphical plot of the sensitivity, or true positive rate, vs. false positive rate

(1 specificity or 1 true negative rate), for a binary classifier system as its

discrimination threshold is varied. The ROC can also be represented equivalently by

plotting the fraction of true positives out of the positives (TPR = true positive rate) vs.

the fraction of false positives out of the negatives (FPR = false positive rate). Also

known as a Relative Operating

Characteristic curve, because it is a comparison of two operating

characteristics (TPR & FPR) as the criterion changes.ROC analysis provides tools to

select possibly optimal models and to discard suboptimal ones independently from

(and prior to specifying) the cost context or the class distribution. ROC analysis is

related in a direct and natural way to cost/benefit analysis of diagnostic decision

making. The ROC curve was first developed by electrical engineers and radar

engineers during World War II for detecting enemy objects in battle fields, also

known as the signal detection theory, and was soon introduced in psychology to

account for perceptual detection of stimuli. ROC analysis since then has been used in

medicine, radiology, and other areas for many decades, and it has been introduced

relatively recently in other areas like machine learning and data mining

1.3.1 The Antenna

The most straightforward option for the receiving antenna is to use an existing

antenna that can be obtained commercially. This idea was explored along with

fabricating a new antenna. As can be seen from Figures 3.1 and 3.2, there is a coaxial

connector to connect to the antenna. For the initial research, a quarter-wave whip

antenna was used for all the testing purposes. This antenna is similar to that used on

car radios. It is called a quarter-wave antenna because it is designed so that its length

is approximately one quarter of the wavelength of the signal. This means that for a

915MHz signal, with a wavelength equal 32cm, a quarter-wave antenna would have

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an 8cm length. The main dilemma in using this type of an antenna is that it requires a

rather large ground plane in order to work properly. This is fine for car radios that can

be grounded to the frame of the car. But, for this project, the ground plane needed to

receive enough of a signal to power the charging circuit is larger than the form factors

of the charging stands chosen to house the circuits. A picture of the quarter-wave

whip antenna The largecopper plate is the ground plane. The antenna is attached to

the copper, with an SMA connector on the under side of the ground plane. This type

of connector uses a simple screw mechanism allowing for easy connectivity with

other circuits and test equipment. The cord is connected on the other side to the BNC

connector of the board. As you can see, this ground plane is rather large, too large to

be used inside the stand for a cellular phone. It covers almost 50% more area than the

stands that were selected for this research. With this in mind, a different type of

antenna needs to be researched and tested. Other types of antennas to consider are

patches, microstrips, dipoles, and monopoles. The patch antenna has two major

problems when being used with a research project like this. The first is that it also

needs to be relatively large, on the order of the ground plane for the quarter-wave

whip antenna. The second reason is that it is highly directional, meaning that it only

radiates, and accepts radiation, in one direction, i.e., it does not have a good coverage

area. These reasons rule out this option. A microstrip antenna can be any type of

antenna discussed previously, but what makes it unique is that it is painted on to a

surface so that it is in the same plane as the printed circuit board. This type of antenna

is used mostly on small surfaces such as silicon die to be used by the circuit on the

same die. By painted on, what is meant is that on a silicon die it is etched onto the

surface, or on a printed circuit board, it is part of a conductive layer. This means that

it can be patch, a dipole, or a quarter-wave whip, as long as all the metal is in the

same plane. The main problems with this antenna are its gain and its directionality.

These types of antennas are appropriate to be used in RFID, but for this project they

would be a hindrance. It is possibly an option to explore in future research.

The last two types of antennas, dipole and monopole, are similar in characteristics and

structure. The difference is that a monopole has one connection point to the circuit,

while a

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1.4 Charging system

At this point, it is necessary to explain what exactly a charge pump is, and how it

works. A charge pump is a circuit that when given an input in AC is able to output a

DC voltage typically larger than a simple rectifier would generate. It can be thoughtof as a AC to DC converter that both rectifies the AC signal and elevates the DC

level. It is the foundation of power converters such as the ones that are used for many

electronic devices today. These circuits typically are much more complex than the

charge pumps used in this thesis. Power converter circuits have a lot of protective

circuitry along with circuitry to reduce noise. In fact, it is a safety regulation that any

power-conversion circuits use a transformer to isolate the input from the output. This

prevents overload of the circuit and user injury by isolating the components from any

spikes on the input line. For this thesis, however, such a low power level is being used

that a circuit this complex would require more power than is available, and it would

therefore be very inefficient and possibly not function. In that case, it is necessary to

use a simple design.

The simplest design that can be used is a peak detector or half wave peak rectifier.

This circuit requires only a capacitor and a diode to function. The schematic is shown

in Figure 3.1. The explanation of how this circuit works is quite simple. The AC wave

has two halves, one positive and one negative. On the positive half, the diode turns on

and current flows, charging the capacitor. On the negative half of the wave, the diode

is off such that no current is flowing in either direction. Now, the capacitor has

voltage built up which is equal to the peak of the AC signal, hence the name. Without

the load on the circuit, the voltage would hold indefinitely on the capacitor and look

like a DC signal, assuming ideal components. With the load, however, the output

voltage decreases during the negative cycle of the AC input, shown in Figure 3.2.

This figure shows the voltage decreases exponentially. This is due to the RC time

constant. The voltage decreases in relation to the inverse of the resistance of the load,

R, multiplied by the capacitance C. This circuit produces a lot of ripple, or noise, on

the output DC of the signal. With more circuitry, that ripple can be reduced.

The next topology presented in Figure 3.3 is a full-wave rectifier. Whereas the

previous circuit only captures the positive cycle of the signal, here both halves of the

input are captured in the capacitor. From this figure, we see that in the positive half of

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the cycle, D1 is on, D2 is off and charge is stored on the capacitor. But, during the

negative half, the diodes are reversed, D2 is on and D1 is off. The capacitor doesnt

discharge nearly as much as in the previous circuit, so the output has much less noise,

as shown in Figure 3.4. It produces a cleaner DC signal than the half-wave rectifier,

but the circuit itself is much more complicated with the introduction of a transformer.

This essentially rules this topology out for this research because of the space needed

to implement it.

There are other topologies for charge pumps but they will not be covered here. The

others are more complex and all involve transformers, like the full-wave rectifier, and

therefore take up more room than there is real estate for in this project. Instead, the

circuit that was chosen to be used will now be presented. The charge pump circuit is

made of stages of voltage doublers. This circuit is called a voltage doubler because in

theory, the voltage that is received on the output is twice that at the input. The

schematic in Figure 3.5 represents one stage of the circuit. The RF wave is rectified

by D2 and C2 in the positive half of the cycle, and then by D1 and C1 in the negative

cycle. But, during the positive half-cycle, the voltage stored on C1 from the negative

half-cycle is transferred to C2. Thus, the voltage on C2 is roughly two times the peak

voltage of the RF source minus the turn-on voltage of the diode, hence the name

voltage doubler.

The most interesting feature of this circuit is that by connecting these stages in series,

we can essentially stack them, like stacking batteries to get more voltage at the output.

One might ask, after the first stage, how can this circuit get more voltage with more

stages because the output of the stage is DC? Well, the answer is that the output is not

exactly DC. It is essentially

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Charging System

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Figure - 3


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1.5 Charging Profile

12

Working of project with circuit diagram

Figure -4


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1.6 Description

1.6.1 The Phone

The design aspect of this project is focused on the receiving side. For this stage of

research, of which the goal is to prove that the wireless battery charger idea isfeasible, it was decided to incorporate the energy harvesting circuitry and antenna in

some sort of base station or charging stand. It is necessary to hide the components for

demonstration purposes. This being the case, two phones were chosen that have

accessories currently available to use as our charging stands. The Nokia 3570 was the

first phone that was received for the research. This phone comes standard with a

battery and an AC/DC travel charger. The battery included with the phone has a

voltage range from 3.2V - when the phone shuts off - to 3.9V when fully charged.

This battery only takes about 2 hours to charge when plugged into the wall through

the travel charger supplied with the phone. This charger has an unloaded, unregulated

direct current (DC) output voltage of 9.2V. When connected to the phone, the

charging voltage goes to the battery voltage, approximately 3.6V, and then slowly

increases until it saturates at 3.9V. This charger regulates the current to around

350mA.

The other phone that was chosen is the Motorola V60i. This phone has many of the

same features as the Nokia above, and it also comes standard with its own battery and

travel charger. The battery for this phone is a 3.6V battery like the Nokia battery. The

travel charger shown is quite different from its Nokia counterpart. First of all, there

are 3 pins going to the phone, not just the 2 needed for power and ground. Two of

these pins are at a ground potential, and the other one is 6.09V higher than the other

two. This is very close to the regulated voltage of 5.9V seen by the phone during

charging. It runs at 400mA, a little higher than the Nokia charger.

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1.6.2 Stand

Before starting the design of the circuitry for charging the phones, it is beneficial toknow the space available for the board. The Nokia DCV-15 desktop stand and

Motorola SYN8610 hands free speakerphone have commercially available

accessories for holding the phones. The Nokia stand, Figure 2.1, is used

additionally for synchronization purposes between the phone and a personal

computer. It does incorporate a circuit board that connects to the phone for

charging. This board is simply a bridge from the phone to the PC, using a

switch. The power supply plugs into the back of the stand underneath, and itsjack is also located on the printed circuit board. Since there is a lot of wasted

space inside that can be used for the energy harvesting board and antenna, all

that is needed to do is to tap into this existing board to supply the power for

the phone. This facilitates replacing the existing board with a newly designed

printed circuit board. This would be difficult because the jack the phone plugs

into, on the existing board, is difficult to replace. It appears to be a proprietary

device available only from Nokia. Thankfully, there is enough room in the

stand for both boards to exist, along with the antenna. For the Motorola

phone, there is a similar product available, but it is not really a stand. The

Motorola SYN8610, Figure 2.8, is a hands-free speakerphone that

accommodates the phone. This device also allows the user to charge the phone

while the phone is in the stand. It is similar to the Nokia stand in that there is a

printed circuit board that connects the power from the wall to the phone

through the stand itself. This allows for the same option as the Nokia stand to

just tap into the existing board to power the phone from our printed circuit

board. However, because there is not as much space in this stand as in the

Nokia stand, to use this accessory, it was necessary to hollow out the inside to

make room for the energy harvesting circuitry. This meant removing the

speakerphone functionality. Whereas the Nokia phones desktop stand

could still be used to connect to the PC, this item will no longer perform its

original function

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1.7 Antenna

The most straightforward option for the receiving antenna is to use an existing

antenna that can be obtained commercially. This idea was explored along withfabricating a new antenna. As can be seen from Figures 3.1 and 3.2, there is a

coaxial connector to connect to the antenna. For the initial research, a quarter-

wave whip antenna was used for all the testing purposes. This antenna is

similar to that used on car radios. It is called a quarter-wave antenna because it

is designed so that its length is approximately one quarter of the wavelength of

the signal. This means that for a 915MHz signal, with a wavelength equal

32cm, a quarter-wave antenna would have an 8cm length. The main dilemmain using this type of an antenna is that it requires a rather large ground plane in

order to work properly. This is fine for car radios that can be grounded to the

frame of the car. But, for this project, the ground plane needed to receive

enough of a signal to power the charging circuit is larger than the form factors

of the charging stands chosen to house the circuits. A picture of the quarter-

wave whip antenna The largecopper plate is the ground plane. The antenna is

attached to the copper, with an SMA connector on the under side of the

ground plane. This type of connector uses a simple screw mechanism allowing

for easy connectivity with other circuits and test equipment. The cord is

connected on the other side to the BNC connector of the board. As you can

see, this ground plane is rather large, too large to be used inside the stand for a

cellular phone.

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It covers almost 50% more area than the stands that were selected for this research.

With this in mind, a different type of antenna needs to be researched and

tested. Other types of antennas to consider are patches, microstrips, dipoles,

and monopoles. The patch antenna has two major problems when being used

with a research project like this. The first is that it also needs to be relatively

large, on the order of the ground plane for the quarter-wave whip antenna. The

second reason is that it is highly directional, meaning that it only radiates, and

accepts radiation, in one direction, i.e., it does not have a good coverage area.

These reasons rule out this option. A microstrip antenna can be any type of

antenna discussed previously, but what makes it unique is that it is painted on

to a surface so that it is in the same plane as the printed circuit board. This

type of antenna is used mostly on small surfaces such as silicon die to be used

by the circuit on the same die. By painted on, what is meant is that on a silicon

die it is etched onto the surface, or on a printed circuit board, it is part of a

conductive layer. This means that it can be patch, a dipole, or a quarter-wave

whip, as long as all the metal is in the same plane. The main problems with

this antenna are its gain and its directionality. These types of antennas are

appropriate to be used in RFID, but for this project they would be a hindrance.

It is possibly an option to explore in future research.

The last two types of antennas, dipole and monopole, are similar in

characteristics and structure. The difference is that a monopole has one

connection point to the circuit, while a

1.7.1 Voltage limiter.

Integrated circuits work only in a limited voltage range, so special protection circuits

are used. For commercial ICs this range is e. g. 4.5V the voltage is regulated by an

NMOS transistor, controlled by an amplifier. This transistor regulates the maximum

voltage indirectly by shortening the current.

1.7.2 Current regulation:

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The current is measured indirectly by the voltage drop over a small resistor called

RSENSER .The voltage drop depends on the current ILOAD and the value of the

resistor.

1.7.3 Voltage regulation:

A circuit to limit the output voltage, which is called regulator, is used here. At first,

the battery voltage must be divided by an voltage divider which is build of two

resistors. This voltage is compared with a stable dc-voltage and the difference is

amplified by a loop amplifier

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CHAPTER - II

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2.1 Circuit Description

2.1.1 Resistor:These are current resisting devices.These are made of carbon, metallic wire

wound etc. These are read through this acronym BBROYGBVGW. This stands for,

Black, Brown, Red, Orange, Yellow, Green, Blue, Violet, Gray and, White

respectively. These colors are printed as lines on the resistor the first and second

colors lines indicate the number corresponding to color. The numbers indicated by the

colors are shown in table below. The third line indicate the number of zeros, the

fourth line indicate the percentage of tolerance of the resistor.

BLACK 0 YELLOW 4 GRAY 8BROWN 1 GREEN 5 WHITE 9

RED 2 BLUE 6 Gold 5%ORANGE 3 VIOLET 7 Silver 10%

E.g. Red, Red, Black Gold = 22 +/-5%; Red, Red, Brown

= 220 ; Red, Red, Red = 2200 ; Red, Red, Orange = 22K ; Red,

Red, Yellow = 220K ; Red, Red, Green = 2.2M; Red, Red, Yellow

= 22 M

These are available in various wattages like 1/4W, 1/2 W,

1W, 2W, 5W, 10W, 20W, 50W, 100W, 200W. In e lect ron ics mos t

common use are up to 5Watt.Higher the wattages bigger the sizes. The

value and wattage of resisters are to be selected as per the applications.

The tolerance in variation of the rated value is also selected as per the

applications. The resisters are fabricated directly on the IC itself.

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2.1.2 Diodes:

These devices allow to flow current in only one direction.

These devices are a lso called unidirect ional devices . Earl ier thesedev ices were made o f vacuum tubes , now a days the se a re s emi

conductor solid-state devices. These are PN junction devices .The PN

means doping of the semi conductor with posit ive and negative

electronic valence atoms. The silicon diodes have knee voltage drop

of 0.7 volts i.e. forward biased voltage drop whereas germanium diodes

have 0 .3 vol tage drop . The d if feren t d iodes a re used for d if feren t

purposes. The diodes work in forward biased condition or reverse

biased conditions.

These are available with different current rating, voltage

rating, power rating and are used for different applications. The diodes

of higher wattages are of bigger s izes . The Symbol of Diode and the

ideal curves of diodes are shown below.

Current

Voltage

Diode Symbol ideal curve

Current

Forward Region

Break Down Voltage

Voltage

Knee Voltage =0.7V

Reverse Region

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Figure -3


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2.1.3 Diode Characteristics :

Diodes are of different types l ike Photodiode, Varactor

diode, Schotkey Diode, PIN diode, Zener Diode etc.

2.1.4 Zener Diode:

Small signal and rectifier diodes are never operated in the

break down region because this may damage them. The zener diode is

made to operate in breakdown region, sometimes called breakdown

diode. The zener diode is the back bone of voltage regulators, circuits

that hold the load voltage almost constant despite large changes in the

line voltage and load resistance.

Symbol of Zener Diode

2.1.5 Light Emitting Diode:

In a forward biased diode, free electrons cross the junctionand fa l l in to holes . As these e lectrons fa l l from a higher to a lower

energy level, they radiate energy. In ordinary diodes this energy goes

off in the form of hea t . But in the l igh t emit t ing d iode (LED) the

energy radia tes as l ight . LEDs that radia te red, green, yellow, blue,

orange or infrared are manufactured by using e lements l ike gall ium,

arsenic, and phosphorous. LEDs that produce visible radia t ions are

usefu l wi th ins t ruments , calculators e tc . The in fra red LED f inds

appl icat ion in burg la r sys tems and o ther a reas requir ing invis ib le

radiations. The seven segment displays uses 7 LEDs.

The symbol of LED

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Figure -4


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2.2 Transformer:

This are the devices which converts the pr imary ac voltage

to different secondary ac voltages .If the secondary voltage is highert he n p ri ma ry vo lt ag e t he n t he t ra ns fo rm er i s c al le d step up

transformer , i f the secondary is less then primary voltage then i t is

called step down transformer , if secondary is same as primary voltage

then it is called unity transformer. This unity transformer is also used

as isolation transformer. These devices a re h igh ly e ff icien t unto

99.9%, i.e. very low power loss.

The transformers are required for making dc supply, tuning

c ircui t e tc . The curren t ra ting of p r imary and secondary winding

determines the SWG gauge of the copper wire.

2.2.1 Power supplier:

The Power is given to the transformer, which steps down the

input voltage to 10 times less i.e. 20 V.

78M05

Transformer Rectifier Filter Regulator

Regulated Power Supply

T hi s l ow v ol tag e i s f ed t o b ri dg e r ec ti fi er t hat r ec ti fi es t he ac

waveform to dc waveform with some ripples. These ripples are filtered

through capacitance filter and is fed to linear regulator .The output of

regulator is further filtered to produce clean DC VOLTAGE.

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Figure -5


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2.2.2 Capacitor:

This are the s torage devices but has in buil t Resis tance

thats why the storage voltage does not last for longer period. The use

of capacitor is for tuning the c ircuit , f i l tering the noise to ground,c rea t ing the t iming pulse as in our case . The capac i tors cannot be

fabricated on ICs because of the technical difficulty.

The different values of capacitor that are available are 1pf,

2pf, 2.2pf, 100pf, 200pf, 1000pf, 0.001uf, and 0.01uf, 0.1uf, 2uf, 10uf,

22uf , 33uf , 47uf , 56uf , 68uf , 82uf , 100uf , 220uf , 330uf e tc . The

capacitors are selected based on capacitance and voltage rating. Higher

the voltage higher the s ize of the capacitor . These are available in

following types.

2.2.3 Electrolytic Capacitor :

These capacitors have electrolyte as the dielectric between the two

plates. These are available with polarity + and -.These are available

with vertical mount or horizontal mount configuration.

2.2.4 Paper Capacitor :

These capacitors are available in low range of capacitance. The paper

is used as dielectrics media between the two plates.

2.2.5 Mica Capacitor :

These capacitors are a lso available in low range of capacitance. The

mica is used as dielectrics media between the two plates.

Disc Capacitor : These are available from 1pF to 1ooooUF.

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2.3 Relay:

These are electromagnetic devices which make or break

the contac t as per the contro l vo l tage . There a re so l id s ta te re layswhich do no t consume much power for the i r opera t ion , bu t a re no t

available in higher current rating. Relays are being substituted by SCRs

also cal led thyris ter for on/off control The firs t Tracking and Data

Relay Satellite was launched in 1983 on the Space Shuttle Challenger's

first flight, STS-6. The Boeing-built Inertial Upper Stage that was to

take the satellite from Challenger's orbit to its ultimate geosynchronous

orbit suffered a fa i lure that caused i t not to deliver the TDRS to the

correct orbit. As a result, i t was necessary to command the satellite to

use its onboard rocket thrusters to move it into its correct orbit. This

expendi ture of fuel reduced i t s capabi li ty to remain in an unt i lted

geosynchronous orbit, and this TDRS, in orbit for a long time, has been

re-assigned to the part-time mission of supporting communications to

Antarctic scientific stations.

Th e s ec on d T ra ck in g a nd D at a R el ay S at el li te w as

destroyed in the Space Shutte Challenger's 10th launch when the entire

Challenger was destroyed shortly after takeoff in the STS-51-L flight

in January 1986. The next f ive TRW-buil t TDRSS satel l ites were

successfully launched on other Space Shuttles. Then, three follow-on

Boeing-buil t sa te l l i tes were launched by Atlas rockets in 2000 and

2002. A NASA Press Release[4] summarized the capabil i t ies of the

system as a whole A Tracking and Data Relay Satellite (TDRS) is type

of communications satellite, that forms part of the Tracking and Data

Relay Satellite System (TDRSS) used by NASA and other United States

government agencies for communications to and from independent

"User P la tforms" such a s s atel li te s, bal loons, a ircraf t, and the

International Space Station. This system was designed to replace a pre-

existing worldwide network of ground stations that had supported all of

NASA's manned flight missions and unmanned satellites in low-Earth

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orbits . The primary system design goal was to increase the amount of

time that these spacecraft were in communication with the ground and

improve the amount of data that could be transferred. These TDRSS

satellites are all designed and built to be launched to and function in

geosynchronous orbit, 22,300 miles above the surf ace of the Earth.

Relay

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Figure -6


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CHAPTER - III

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3.1 Introduction To MCS-51 Series

Before the e ra of microprocessor , c ircui t were const ruc ted using

desecrate log ic l ike var ious gates , counters , f l ip -f lops, decoders ,

monostables and regis ters . Circuit diagram was designed as per the

r eq ui rem en t p ro to ty pe P CB i s m ad e i nt er co nn ect in g t he l og ic

components as per the design. Testing and debugging was done in the

lab. During the tes t ing some modificat ion were required. When the

product was tested on the field, some changes are required this requires

new design of PCB.To overcome this difficulties scientist and engineer were

working on a machine, which could read the set of instruction to do a

particular job called PROGRAM, stored in a memory and executes it.

The ins truction would be s imple l ike ADD, SUBTRACT, AND, OR,

INVERT, ROTATE and MOVE. If such a machine could made then,

making changes in the design means, making changes in the program,

which is comparatively easy. The birth of computer is also a result ofsuch thinking. Because of the advancement in the silicon technology, it

was poss ib le to des ign such a dev ice cal led microprocessor . The

microprocessor will read the instruction stored in Rom, the read only

memory , and execute in PROM programmers were used to put the

desired program inside the ROM. This process called the programming

the ROM, also called burning the program inside the ROM Intel come

out f irs t with 8080 microprocessor. This was fol lowed by the 8085,

which become vary popula r and accepted by indus try a ll over the

world. The use of 8085, always follows the use of external ROM like

2764, external RAM 6264, 8bit latch 74LS373, address decoding logic

74LS138, I/O device such as 8155/8255. Serial interface

8251,timers/counters 8253,or discrete logic again the effort were made

to put all the standard hardware logic in one chip. As a result of such

an effort , Inte l comes out with MCS-51 series . I t has a l l the above

features, i .e . ROM. RAM, I/O, serial interface. Timers/counters logic

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built- in chip or embedded in it. Plus enhanced instruction set. This

includes bit manipulation instruction, and instruction to multiply and

divide 8 bit hexadecimal number. It also has code protection features.

When Intel introduced MCS-51 series there were basically

three ICs in the ser ies , namely 8031,8051 and8751. 8031 needs

external ROM like 2764. 8051 has internal but one time programmable

or OTP ROM 8751 has on chip UV erasable ROM 8031 was suitable for

production, it is not possible to reprogram 8751 has UV erasable on

c hi p R OM , w hi ch r eq ui re s 2 0 m in ut es t o e ras e a nd i t w as q ui t

expensive. Atmel made a break through and developed flash version of

8051, called the 89C51 which has built in Flash Rom .in flash version

applying proper logic levels a t controls pin and jus t one push a t the

erase pin can erase program. The process is called flash erasing. With

this technique existing program can be erased quickly and new program

can be burn. The price of the flash version was also affordable. 89C51

ICs become very popular. It is Hardware and Software compatible with

MCS-51 series IC 8051.

Quick look at 8085 IC revels that, it has 16 bit for addressing the

memory, which can address 64K memory of which some part can be ROM and

remaining can be RAM. But total of RAM and ROM can not exceed 64K. MCS-51

series can address 64K ROM, 64K RAM & 256 byte internal RAM. Out of the 64K

ROM. Not all the ROM resides on the chip 89C59 has 4k of on chip ROM and rest of

the must be physically out side the chip. The 64K RAM is always out side the chip

and is called external RAM. Apart from the 64K external RAM, there is 256 byte

internal RAM which is always in side the chip & is called internal RAM. Industrial

application with moderate complexity can be fitted inside the 4K of ROM. The 256

byte internal RAM is divided into two equal parts of 128 byte each. The upper half,

from location 128 to 256 is reserved for special purpose registers & is called SFR

area. If program demands extra ROM, one can use higher version, the 89C52 which

has on chip 8K ROM. Next higher version is also available. Next higher version is

also available. The 89C55 has 20K of on chip ROM. If the program is written in

assembly language, 4K ROM of 89C 51 is more then sufficient for most of the

application. The AT89C51 is a low-power, high-performance CMOS 8-bitmicrocomputer with 4

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Kbytes of Flash Programmable and Erasable Read Only Memory (PEROM). The

device is manufactured using Atmels high density nonvolatile memory technology

and is compatible with the industry standard MCS-51 instruction set and pinout.

The on-chip Flash allows the program memory to be reprogrammed in-system or by

a conventional nonvolatile memory programmer. By combining a versatile 8-bit CPU

with Flash on a monolithic chip, the Atmel AT89C51 is a powerful microcomputer

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

control applications.

The AT89C51 provides the following standard features: 4Kbytes of Flash, 128 bytes

of RAM, 32 I/O lines, two 16-bittimer/counters, a five vector two-level interrupt

architecture,a full duplex serial port, on-chip oscillator and clockcircuitry. In addition,

the AT89C51 is designed with staticlogic for operation down to zero frequency and

supportstwo software selectable power saving modes. The IdleMode stops the CPU

while allowing the RAM, timer/counters,serial port and interrupt system to continue

functioning.The Power Down Mode saves the RAM contents butfreezes the oscillator

disabling all other chip functions untilthe next hardware reset.

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Overview of 89C51

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Figure -7


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3.2 Pin configuration

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

the pins can be used as high-impedance inputs. Port 0 may also be configured to be

the multiplexed low order address/data bus during accesses to external program anddata memory. In this mode P0 has internal pull up. Port 0 also receives the code bytes

during Flash programming, and outputs the code bytes during program verification.

External pull ups are required during program verification.

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

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

pulled high by the internal pull ups and can be used as inputs. As inputs, Port 1 pins

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

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

and program verification. Port Port 2 is an 8-bit bidirectional I/O port with internal

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

written to Port 2 pins they are pulled high by the internal pull-ups and can be used as

inputs. As inputs, Port 2 pins that are externally being pulled low will source current

(IIL) because of the internal pull-ups. Port 2 emits the high-order address byte during

fetches from external program memory and during accesses to external data memory

that use 16-bit addresses (MOVX)

89C51 is a 40 pin device. Two pins are used for power supply, and require

+5V. It has on chip oscillator circuitry to which requires use of external crystal.

Normally crystal frequency is around 12MHz. This oscillator is further divided by 12

by internally and considered as clock for machine cycle. Most of the instruction takes

one or two machine cycle to execute. For 12MHz crystal, most of the instruction will

get executed in one or two microsecond it has one pin called ALE. When program

execution is going on. ALE pin will pulse at one sixth of clock frequency. So for

12MHz crystal, ALE pin will pulse at 2MHz.it has one pin called Reset. And it

requires active high pulse. Please note that 8085 requires active low reset. After reset

program counter becomes 0000 and program execution starts from 0000. It has one

pin called PSEN. If external ROM is used then PSEN pin is connected to RD/ of

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ROM. So we will leave them unconnected in our design. It has one more pin called

EA and has to be connected to Vcc, so that 89C51 will start using internal ROM.

It has four 8 bit ports port 0, port 1, port 2 and port 3. All the

ports pin can be used as input or output with out predefining. Port1, port2 and port3

are internally pulled up through FET. But port0 requires external pull up resister.

After reset all the port pins are high. Each port has a place in internal RAM and has a

specific address. The address of the port0 is 80 hex, address of the port1 is 90 hex,

address for port2 is A0 hex and address for port3is B0 hex. Anything that is written to

port 0, reading location A0 hex is same as reading port 2. The port pins are also

labeled in dot notation for convenience. Port 0 pins will labeled as port0.0, port0.1,

port0.2 and so on. Similarly other port pins will be labeled.

BIT ADDRESS BIT ADDRESS40 VCC

90 H P 1.0 1 P39 P0.0 80H91 H P1.1 2 P O 38 P0.1 81H92 H P1.2 3 0 (80n) R 37 P0.2 82 H93 H P1.3 4 R (90n) T 36 P0.3 83 H94 H P1.4 5 T 35 P0.4 84 H

95 H P1.5 6 03 P0.5 85H96 H P1.6 7 1 33 P0.6 86H97 H P1.7 8 32 P0.7 87HRESET9

31 EA/VP VCC

BOH P3.0 10 RXD P 30 ALEB1H P3.1 11 TXD 0 29 PSEN RDOF

ROYB2H P3.2 12 INTO R 28 P2.7 A7HB3H P3.3 13 INT1 P 27 P2.6 A6HB5H P3.4 14 TOT 0 26 P2.3 A5H

B6 H P3.5 15 T1 R 25 P2.4 A4HB7 H P3.6 16 WR T 24 P2.3 A3H

P.37 17 RD 2 22 P2.1 A1HXTL1 18 21 P2.0 A0HXTL2 19GND 20

Table -1

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All the port pins are said to be Bit addressable. The bit addressable RAM is a new

concept. If the RAM location is bit addressable then its in individual bit has unique

bit address. Refer to fig. 2 for pin configuration and bit addressable concepts. Bits in

the bit addressable RAM can be addressed by their bit address or in the dot notation.

The bit address for pin, port 0.0 is 80 hex, port 0.1 is 81 hex, port 0.2 is 82 hex and so

on. The bit address for pin port1.0 is 90 hex, port 1.1 is 91hex,port 1.2 is 92hex and

so on. Please note bit address and port address are different 80 hex bit address means

port P0.0 and 80 hex internal RAM address means port 0 as a complete. There are

separate instruction for addressing bit and byte it is the instruction which decides

weather bit is addressed or byte is addressed 89C51 has instruction to clear the bit ,set

the bit, compliment the bit OR the bit ,AND the bit and conditional jump instructiondepending on , the bit is set or clear.

The pins of the port 3 have alternate use. 89C51 has built in serial interface

two pins are used for this purpose. Serial data will be always received on port pin

P3.0, so the port 3.0 is labeled as RXD and serial data will be transmitted on port pin

P3.1,so the port 3.1 is labeled as TXD. External interrupt if used will be connected to

port pin P3.2 and P3.3. So these pins are labeled as INT0 and INT1 89C51 has two

timer/ counter module they can count pulses appearing a port pin P3.4 and P3.5 these

pins are labeled T0 and T1 respectively

If external ROM or RAM has to be interfaced then port 0 is used as 8 bit

multiplexed AD bus. AD0 TO AD7. And port 2 is used as higher order Addressed

Bus A8 to A15. the function of pin ALE is same as in 8085, to generate strobe for

latching lower order address byte. Port pin P3.6 and P6.7 are connected to WR and

RD/ for external RAM.

From the practical point of view, we can say that 89C51 has 4K on chip

Flash ROM and 256 byte of on chip RAM called internal RAM plus it has two timer/

counter module, serial interface, four 8-bit ports, interrupt handling logic as standard

feature. It can also address 64K external RAM , and /or remaining 60K of external

ROM. But as many as 80 pins are used to interfacing external memory. As so many

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pin are lost in interfacing, design using these external memory are not preferred if

one needs more RAM one can use serial EEROM , which are more economical, and

used 3 lines for interfacing.

89C51 has wonderful features it has multiprocessing mode in this mode, there is one

master 89C51 and nos of other slave 89C51 master can communicate with the slave

89C51,sharing the common serial bus, without disturbing other 89C51 even though

they are connected to common serial bus. This feature is quite advanced. We just

mention that chips in the MCS-51 have multiprocessing capability and is not advised

to go into details of it unless person gathers basic skill in programming.

3.3 Interrupts:

We have seen earlier that many times, processor has to respond to event happening

real time world. The event may take place at any time. Interrupts handling logic is

incorporated inside the chip, for this purpose. In such a case, Processor will suspend

current execution of the program, & branch to interrupt service routine. After

finishing, it will resume the suspended work.

The situation can be seen very frequently, in our every day life. Suppose a person is

busy in doing some work, say writing a letter and all of a sudden telephone ring. Then

the person will stop writing the book, ans. the telephone, & resume the writing the

book. Some time there are 4,5 telephone lines are available. In that case he may have

to decide about to priority, in answering the phone. Some times he himself is very

busy in imp. meeting,& does not want to get disturbed by the phone calls. All this

types of situations exist in microprocessor world also.

Those of you who are familiar with 8085 will recall that 8085 can handle 5 different

interrupts. 89C51 can also respond to 5 different interrupting lines, equivalent of

having 5 telephone lines. Two are external interrupts they are called INT0, INT1 at

port pin P3.2 & P3.3 respectively. If these interrupts are activated & enable in

software the program will branch to location 0003 & 0013 hex of program memory

(ROM). 89C51 have two timers/counter modules. These counters are UPCOUNTERS

only. When counting starts, during the course of counting whenever they overflow

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from FFFF to 0000, timer overflow flag, TF0, TF1 is set, & interrupts are generated.

If the interrupts are enable in software then the will branch to location 0000bB hex.

and 0001B hex respectively. 89C51 has built in serial interface.

Bit RI is set and whenever data is fully shifted out Transmit Interrupt bit TI

is set. The RI & TI together generate one interrupt, called serial interrupt. If this

interrupt is enabled in software then the program will branch to location 0023 hex. In

ROM memory. The interrupt handling logic of 89C51 can be explained with the help

of following figure -

The external INT0 and INT1 can be defined as either negative edge

triggered or level triggered this means if interrupt is defined as negative edge

triggered interrupt will be generated whenever negative edge is detected on INT0 or

INT1 line or if interrupt is defined as level triggered then interrupt is active as long as

INT0 or INT1 is held low. The bits IT0 interrupt type zero and IT1 interrupt type one

will decide whether the interrupt is defined as edge triggered or level triggered. If the

byte 0 then corresponding interrupt is level triggered and if the bit is 1 then it is edge

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Figure 8


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triggered. These bits are found in TCON register in the SFR area of the internal RAM

and its address is 88hex.

EA ----- ET2 ES ET1 EX1 ET0 EX0

Table -2

Interrupt Enable Register

There is interrupt enable register IE. The bits in the register IE will

decide which interrupts are active or in built. The MSB it of the IE register is the

global enable bit labeled as EA. If this bit is 1 mean interrupt are enabled and if is 0

then all interrupts are disabled. Other bits in the IE register will enable if they are 1 or

disable if they are 0, the individual interrupts. The interrupt enable register IE has a

place in SFR area and its address is A8 hex. It is a bit addressable register. A level-

triggered interrupt is a class of interrupts where the presence of an unserviced

interrupt is indicated by a high level (1), or low level (0), of the interrupt request line.

A device wishing to signal an interrupt drives line to its active level, and then holds it

at that level until serviced. It ceases asserting the line when the CPU commands it toor otherwise handles the condition that caused it to signal the interrupt.

Typically, the processor samples the interrupt input at predefined times during each

bus cycle such as state T2 for the Z80 microprocessor. If the interrupt isn't active

when the processor samples it, the CPU doesn't see it. One possible use for this type

of interrupt is to minimize spurious signals from a noisy interrupt line: a spurious

pulse will often be so short that it is not noticed.

Multiple devices may share a level-triggered interrupt line if they are designed to. The

interrupt line must have a pull-down or pull-up resistor so that when not actively

driven it settles to its inactive state. Devices actively assert the line to indicate an

outstanding interrupt, but let the line float (do not actively drive it) when not signaling

an interrupt. The line is then in its asserted state when any (one or more than one) of

the sharing devices is signaling an outstanding interrupt.

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There is a provision to decide the priority of the interrupt either high

or low. The priority can be defined in the register IP, interrupt priority register the

address of the register is B8 hex in the SFR area. It is a bit addressable register if

lower priority interrupt work is in progress and higher priority interrupt arrives. Then

lower priority interrupt work will be suspended processor will branch to higher

priority service routine after finishing higher priority work he will resume the

execution lower priority interrupt. And after finishing execution of lower priority

interrupt the procession will go back to start the execution of main program. If higher

priority interrupt is in progress and lower priority interrupt arrive then lower priority

interrupt will be Capt. pending till execution of higher priority interrupts ends. After

finishing higher priority interrupt processor will start the execution of lower priority

interrupt after finishing the same processor will go back to main program.

----- PT2 PS PT1 PX1 PT0 PX0Table -3

Interrupt Priority Register

As was mentioned earlier INT0 or INT1 pins will activate the interrupt

in two ways. Interrupt can be defined as edge triggered or level triggered. IE0 and IE1or the two bits which actually cases the interrupts. If interrupts are defined as level

triggered then bits IE0 and IE1 will remain set as long as pins INT0 or INT1 are low.

If they are defined as level triggered and activated then program will branch the

respective vector address in ROM and will start the execution of the service routine.

It is then hardwires and /or programs responsibility to see that pin INT0or INT1 who

has cased the interrupt goes high so that bit IE0 or IE1 will be cleared if INT0or INT1

is not cleared then program will again enter into the same service routine. Mostly thisinterrupt are defined as edge triggered mode only. If they are defined as edge

triggered then the bit IE0 or IE1 will set whenever negative edge is detected and the

bits will automatically get cleared when program branches to respective interrupt

service vector.

Timer over flow bit TF0 or TF1 will set, whenever counter over flow

from FFFF hex to 0000. They will automatically get cleared when program branches

to respective interrupt service vector.

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The bits RI and TI in the serial interface logic will be ORed and will

generate one common interrupt. If this interrupt are enabled then program will start

execution at ROM address 0023 hex. These bits will not get cleared automatically.

Program will find out who has cased the interrupt then will take the appropriate action

and program will clear the bit the bits TI and RI are found in serial control resister

SCON. The register SCON is found at address 98hex in the SFR area.

3.4 Timers And Counters

89C51 has 2 on chip, timer/counter modules. They are called TIMER0 AND

TIMER1. They are UP counter only. Both the modules are identical in nature. Let us

consider TIMER0 as shown in the following figure. This figure will illustrate the

working of module clearly.

Figure -9

The two register TL0 &TH0 will form 16 bit counter.TL0 & TH0 are

the registers & have place in the SFR area. Their location is 8A hex. & 8C hex.

respectively. They are not bit addressable. The counters are used in UP counter mode

only. While counting UP, whenever it will overflow from FFFF hex. to 0000, the bit

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TF0 will set. The switch in the small box will pass the pulses to the counter. Pulses

will be passed to counter if out of the AND gate is high. The AND gate has to input,

one is bit TR0 & another is connected to the output of the OR gate. The OR gate has

again 2 input. One is Inverted GATE0 bit &other is connected to PORT3 Pin P3.2, the

INTO. The counter can count the pulses coming from internal oscillator after division

by 12 pulses appearing at Port 3 Pin P3.4, the T0.The bit C/T0 will decide this.

The bits GATE0, C/T0 of TIMER0 & corresponding bits of TIMER1

the GATE1 & C/T1 are found in register TMOD located at address 89 in the SFR

area. This TMOD register is not bit addressable. The bits TR0, TF0 of TIMER0 &

corresponding bit TR1 & TF1 of TIMER1 are found in the register TCON locate at

address 88 hex. in SFR area. It is a bit addressable register .

Table -4

When the pulses will be passed to counter, will depending on the status

of bit, GATE0. if the GATE0 bit is cleared i.e. zero then bit TR0 will purely control

the counting. Counting will on as long bit TR0 is SET. So if GATE bit is zero, then

counting will be purely controlled by software. If GATE bit SET, then counting will

be on when Bit TR0 is SET plus port pin P3.2, the INT0 is high. Thus if GATE bit is

zero then counting will be purely controlled by software &if GATE bit is one then

counting will be controlled by software plus hardware.

If we want the bit TF0 to set after counting 2000 pulses. As the counter is counting

up only, we must set registers TH0, TL0, initially to a value equal to the hexadecimal

F830 hex. Which is equivalent of decimal no. 65536 -2000? So that bit TF0 will set

exactly after counting 2000 pluses. If we want the bit to set regularly after setting

2000 pluses, then we must reload the register TH0, TL0 to value equal to the

hexadecimal equivalent of no. 65536-2000, WHENEVER THEY BECOME 0000.

Usually this is the 1st job of the interrupt service routine to reload TH0, TL0. The

above mode is called 16 bit counter mode. This mode is called MODE1.

39

GATE C/T M1 M0 GATE C/T M1 M0 89HTF1 TR1 TF0 TR0 IE1 IT1 IE0 IT0 88H


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There is one more mode called MODE2, the 8-Bit Auto Reload Mode,

which is also used very commonly. In this mode counting is done in register TL0, so

it is 8 bit counter mode. After overflow from FF hex. to 00, the TF0 bit is SET. At the

same time data in the register TH1 will be automatically get copied or reloaded in to

register

TL0.The register TH0 set to holds the auto reload count. This will ensure that

interrupt will arrive exactly after same time interval. All other logic will remain same.

The bits M0 & M1 in the TMOD register will set the mode. If both the bits are 0

then MODE0 is selected. If exactly same as MODE1, except counting is done 13 bit

instead of 16 bit. If the bits are 0 1 then MODE 1, the 16 bit counter mode is selected.

This mode we have seen above. If the bits are 1 0 then MODE2, the 8-Bit

AUTORELOAD mode is selected. If this bits are 1 then MODE3, special mode is

selected. In this mode TIMER1 is temporally halted. TL0 & TH0 are used as separate

8 bit counters. Counting logic for TL0 is same as in case of MODE2. But all control

bits of TIMER1 are now diverted for counting of 8- Bit into TH0. This mode is not

used in practice very much because of the involved complexity.

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Figure -10


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3.5 Circuit description

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

single integrated circuit containing a processor core, memory, and programmableinput/output peripherals. Program memory in the form of NOR flash or OTP ROM is

also often included on chip, as well as a typically small amount of RAM.

Microcontrollers are designed for embedded applications, in contrast to the

microprocessors used in personal computers or other general purpose applications.

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

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

office machines, appliances, power tools, and toys. By reducing the size and cost

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

devices, microcontrollers make it economical to digitally control even more devices

and processes. Mixed signal microcontrollers are common, integrating analog

components needed to control non-digital electronic systems.

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

as low as 4 kHz, for low power consumption (milliwatts or microwatts). They will

generally have the ability to retain functionality while waiting for an event such as a

button press or other interrupt; power consumption while sleeping (CPU clock and

most peripherals off) may be just nanowatts, making many of them well suited for

long lasting battery applications. Other microcontrollers may serve performance-

critical roles, where they may need to act more like a digital signal processor (DSP),

with higher clock speeds and power consumption.

In microcontroller used is 89C51 whose ports are configured as I/P and output ports.

The pins of input and output ports and both indicator assemble. The ports P1 is

configured as input port and P0 as output port. P1 is from pin 1 and pin8 of ICR. Pin

18 and 19 are connected to crystal pin 40 and pin 20 are connected +5V and ground

respectively pin9 is connected to reset switch though R and C combination and +5V.

Port P0 is having pin 39 to pin32 as P0.0 to P0.7 in sequence order.

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The interface IC1 and IC3 are connected to ports P1 and P0 respectively. The I/P of

IC1 i.e. pin 2 and pin 9 to which sensors can be connected. The pins of IC3 i.e. pin 18

to pin11 are output pins. The output from P0.1 is fed to relay driver which sends the

command to delay the stored number to communication system. The output from P0.2

is fed to relay which remove the connection from cradle. The command is also fed to

the circuit which starts the play of recorded message. Microcontroller programs must

fit in the available on-chip program memory, since it would be costly to provide a

system with external, expandable, memory. Compilers and assemblers are used to

convert high-level language and assembler language codes into a compact machine

code for storage in the microcontroller's memory. Depending on the device, the

program memory may be permanent, read-only memory that can only be programmed

at the factory, or program memory may be field-alterable flash or erasable read-only

memory.

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BLOCK DIAGRAM OF 89C51S

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CHAPTER IV

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4.1 Pcb layout

Front side

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Figure 13


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REAR SIDE

Figure 14

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4.2 Preparation Of The PCB

4.2.1 Schematic Preparation

Schematic is a circuit that is drawn either with the help of software or by

manually on paper with standard symbols. If the circuit is big and complicated

then multi layer schematic is made otherwise single layer schematic is made . The

schematic is drawn with colored pen to indicate the different layers , power lines

, signal lines and ground lines.

4.2.2 Artwork Preparation

After making the schematic on a paper, same is duplicated on transparent acrylic

plastic sheet . This circuit is called artwork . The artwork is made either bigger

or smaller or same size of the desired PCB .The artwork is drawn with different

color tapes to identify the signal lines, power lines and ground lines . The artwork

should be proper without leaving any connection or making any excessconnection or shorts .

4.2.3 Film Making

The artwork is reduced or enlarged or made of same size of the PCB on the

film through the camera . The camera produces both the positive and negative

films . These films are used to made PCB .

4.2.4 Etching of copper cladded board

The films are put on copper cladded board and the board is exposed to light. The

time of exposure depends on many factors. After the exposure of the board it is

rinsed in the etching solution. During this etching operation the exposed copper

gets dissolved in the solution whereas unexposed copper remains intact with the

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board .This unexposed copper in turn makes the pattern what we see on PCB.

The board is then washed in water with gentle brush .

4.2.5 Drilling of holes

The PCB is now ready for drilling operation .The holes are now drilled at all

places wherever the components are to be put .The size of the drills should not be

either more then the required or less then the required . If the hole is large the it will

be difficult to solder and lot of lead will be consumed. If the hole is small then

component will not be inserted easily.

4.2.6 Tinning of pcb

The PCB is tinned after putting the mask on PCB .This is done to insulate the

patterns and avoid any short. The mask covers the areas where the soldering is to

be done.

4.3 PCB Testing

With a PCB and antenna in each stand, testing was done to show that the phones

were able to be turned on by power provided by the energy harvesting circuit. Thetwo phones placed in their stands for testing are shown in Figure 7.5. Tests were also

performed to get the unconnected voltage reading. The previous board, using the

quarter-wave whip, was able to produce ~90V DC unloaded, but this board with the

monopole antenna can only produce about ~45V DC. This confirms the point brought

up in the previous sections about the antenna not being able to perform as well as the

off-the-shelf counterpart. However, considering this voltage is about half of the

original voltage, the phone is still able to turn itself on to show that the power is beingsupplied. And in tests that were performed with direct connections to the battery

terminals, this board and antenna combo performed almost as well as with the quarter-

wave whip antenna. Previously, the board was able to charge at about 5-6 mV per

second, resulting in about 2 hour charging time from 3.2 V to 3.9 V. Here it was about

4 mV per second, resulting in about 3 hour charging time. In previous research, the

battery charged at about 2 mV per second. That is almost 6 hours charging time, so

we have almost cut the charging time in half

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PCB is checked for all interconnections through multimeter , whether

the tracks are broken or short at any place , thereby correction is done

th rou gh so ld er in g. With a PCB and antenna in each stand, testing was done to

show that the phones were able to be turned on by power provided by the energy

harvesting circuit. The two phones placed in their stands for testing are shown in

Figure 7.5. Tests were also performed to get the unconnectedvoltage reading.

The previous board, using the quarter-wave whip, was able to produce ~90V DC

unloaded, but this board with the monopole antenna can only produce about ~45V

DC. This confirms the point brought up in the previous sections about the antenna not

being able to perform as well as the off-the-shelf counterpart. However, considering

this voltage is about half of the original voltage, the phone is still able to turn itself on

to show that the power is being supplied. And in tests that were performed with direct

connections to the battery terminals, this board and antenna combo performed almost

as well as with the quarter-wave whip antenna. Previously, the board was able to

charge at about 5-6 mV per second, resulting in about 2 hour charging time from 3.2

V to 3.9 V. Here it was about 4 mV per second, resulting in about 3 hour charging

time. In previous research, the battery charged at about 2 mV per second. That is

almost 6 hours charging time, so we have almost cut the charging time in half

4.3.1 Assembling Of The Unit

Components are assembled in proper direction and

avoid the touching of the components to one another. Heat sink is to

be put wherever required with a heat sink compound After

assembling the components , they are soldered and thereafter cleaned

with CTC liquid.

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Seperator.

_

+ _+

_+

_+

+ 5 4 7 o h m7 8 0 5

7 9 0 5

1 N 4 1 4 8

L A S E R

I / P

4 7 p F1 0 0 K

1 0 K8 2 0 K 8 2 0 K

1 0 K

1 0 4

3 9 K 2 2 K

4 7 p F

4 7 K 1 0 21 0 2

1 0 K

+ 5

- 5

L M 3 8 6

1

83

2 5

6 = + 5 V

4 =

+

s p k1 0 o h m

3 9 K2 2 K

4 7 K

1 0 K

1 0 4

4 7 3

+ -

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Figure 15


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Mixer

1 6

2

1

3

4

5

7 1 3

6

1 5

1 2

1 0

2 0

1 0 P 3 . 0

P 1 . 0

1 1 P 3 . 1

P 1 . 1

1 8

1 9

4 0 3 1 9

+ 5 V

1 0 K1 0 K

1 u f

1 u f

1 u f

1 u f

P I N 2

P I N 3

3 3 p f

1 2 M H Z

3 3 p f

+ 5 V

1 0 u f

1 0 K

R e l a y s

2 1

2 6

1 6

2

1

3

4

5

7 1 3

6

1 5

1 2

1 0

1 u f

1 u f

1 u f

1 u f

P I N 2

P I N 3

+ 5 V

1 k

+ 5 V

m o b i l e f r o n t

v i e w

U

5 4 85 4 8

Figure -16

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CHAPTER V

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5.1 Functional Components

COMPONENT LIST

SN COMPONENT TYPE QUANTITY

1 IC Base 40 PIN 12 IC Base 20 PIN 23 IC1 89C51 14 IC2 & IC3 74245 25 Crystal 11.0592 MHz 16 Relay 12v D.C. 57 Regulator IC 7805 18 Regulator IC 7812 19 Transistor BC547 5

10 Resistor 10k,1/4W 204.7k,1/4W 51k,1/4W 1

11 Capacitor 33pf 21

7000 microF/25v 147 microF/50v 1

100 microF/25v 1012 LED Red 513 Switch Micro 1

14 Diode 1N4007 15

18 Transformer 6-0-6/750mA 16-0-6/250mA 1

19 Lead Wire 1Table - 5

The approximate costing in the purchasing of all the related ICs and related circuitry

equipment which is used in the total project is about theRs 6000 in our cost because

there are we need to purchase each and every thing and also the related programming

cost .

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CHAPTER VI

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6.1 Implementation Future Enhancement:

The Wireless Transmission of Electrical Energy Using Schumann ResonanceIt has

been proven that electrical energy can be propagated around the world

between the surface of the Earth and the ionosphere at extreme low

frequencies in what is known as the Schumann Cavity. The Schumann cavity

surrounds the Earth between ground level and extends upward to a maximum

80 kilometers. Experiments to date have shown that electromagnetic waves of

extreme low frequencies in the range of 8 Hz, the fundamental Schumann

Resonance frequency, propagate with little attenuation around the planet

within the Schumann Cavity.

6.1.1 Background

Although it was not until 1954-1959 when experimental measurements were made of

the frequency that is propagated in the resonant cavity surrounding the Earth, recent

analysis shows that it was Nikola Tesla who, in 1899, first noticed the existence of

stationary waves in the Schumann cavity. Tesla's experimental measurements of the

wave length and frequency involved closely match Schumann's theoretical

calculations. Some of these observations were made in 1899 while Tesla was

monitoring the electromagnetic radiations due to lightning discharges in a

thunderstorm which passed over his Colorado Springs laboratory and then moved

more than 200 miles eastward across the plains. In his Colorado Springs Notes, Tesla

noted that these stationary waves "... can be produced with an oscillator," and added

in parenthesis, "This is of immense importance."6 The importance of his observations

is due to the support they lend to the prime objective of the Colorado Springs

laboratory. The intent of the experiments and the laboratory Tesla had constructed

was to prove that wireless transmission of electrical power was possible.

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6.2 Advantages:

Inductive charging carries a far lower risk of electrical shock, when compared with

conductive charging, because there are no exposed conductors. The ability to fully

enclose the charging connection also makes the approach attractive where water

impermeability is required; for instance, inductive charging is used for implanted

medical devices that require periodic or even constant external power, and for electric

hygiene devices, such as toothbrushes and shavers, that are frequently used near or

even in water. Inductive charging makes charging mobile devices more convenient;

rather than having to connect a power cable, the device can be placed on a charge

Its provide more battery backup

Power theft protection.

It provide emergency power

Less infrastructure cost

6.3 Disadvantage:

One disadvantage of inductive charging is its lower efficiency and increased ohmic

(resistive) heating in comparison to direct contact. Implementations using lower

frequencies or older drive technologies charge more slowly and generate heat for most

portable electronics the technology is nonetheless commonly used in some electric

toothbrushes and wet/dry electric shavers, partly for the advantage that the battery

contacts can be completely sealed to prevent exposure to water. Inductive charging

also requires drive electronics and coils that increase manufacturing complexity and

cost

The goal of this thesis is to determine if is possible to capture enough power in a

cellular phone in order to charge the battery. The requirements for the system to be

presented are that it be incorporated into a base station and the operating frequency is

set. The design of the board and choice of antenna for the stand are the focal point of

the experiments that are to be performed. In order to prove the concept, power needs

to be supplied to the energy harvesting circuit by an external transmitter. This

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transmitter will send a signal at the set frequency. Our test system will then receive

this signal through the energy harvesting circuit. This circuit is the fundamental

design problem of this thesis. This circuit will convert the received signal into DC

voltage to charge the battery. The RF transmitter, the analysis of the cellular phones to

be used, and the modification of cellular phone stands to accommodate the circuitry to

be designed are elements of the research covered in this section. A set of experiments

will be conducted to demonstrate the feasibility of wirelessly charging a cellular

phone battery.

6.4 Application:

This research project is primarily empirical. There are many variables in the system

that can change the voltage that is developed. The stage capacitors need to be

optimized. The number of stages needs to be determined that, combined with the

capacitor values for each stage, will result in a sufficiently high voltage level to turn

on the phone and charge the phones battery. Also, a capacitor can be used across

the output as a filter to provide a flat DC signal and store charge. The value of that

capacitance also needs to be determined. There really are no fixed parameters for any

of these values. The only specified value for any element in this research is thefrequency that is being transmitted to the station. This frequency is to be 915MHz.

As discussed in the previous chapter, there have been projects completed to lay the

foundation for this research. One of these projects involved the charging of a cellular

phone battery directly from a charge pump. The results of this experiment were

sufficient to provide a starting point. The previous project used the same charge pump

we have chosen, i.e., stages of voltage doublers.

Wireless mobile charging Electrical and Electronic device can charge wireless

We can use in ruler area

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Conclusions:

An fully integrated inductive charging system was presented in this paper. There are

no external components required except the antenna for charging. The charge current

for the battery was 4 mA. For the reader and the antenna standard components has

been used Implementing this charging system in smart-cards high performance

devices with various applications become possible. By the use of rechargeable

accumulators, the lifetime of the card is not limited to the capacity of the battery as it

was with active cards and primary batteries. The most important result is that Isuccessfully proved that the concept of charging a cellular phone battery while in a

phone using wireless RF energy harvesting is feasible. We were able to get enough

power to turn the phone on.

This is an important result because it shows that the circuit that was designed,

simulated, and tested throughout this research can be used to accomplish our ultimate

goal. Because of this result, future work in this area can be expected. It is probable

that with more focus placed on the antenna, and, as energy harvesting technology

becomes more advanced, this work will be successful at achieving a commercial

product. The ultimate goal, of course, is to get everything in the phone and use

ambient RF energy to charge the battery. In this thesis, we have laid the foundation

for this work to continue by accomplishing the following goals:

We were able to charge the battery directly faster than had been done previously; we

were able to power the phone using an RF signal transmitted to the phone and stand;

we provided simulated and empirical data that can be used as a reference for future

work in the area; and we were able to condense the circuitry down to a sufficiently

small size to conceal the charging circuitry and antenna within a commercially

available stand. Involved in achieving these goals were the modeling of the circuit in

a program suitable for simulating high frequency circuits, the design of a testing board

and procedure for verifying the simulation results, and finally creation of a board and

antenna combination that would be small enough to be contained within a

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commercially available stand, yet be able to show that indeed we are able to power

the phone.

Reference:

Sabate, J. A., Kustera, D. and Sridhar, S., Cell-Phone Battery ChargerMiniaturization. IEEE Journal 2000.

Mi, Minhong, Personal Interview. 2003

http://www.seas.upenn.edu/~jan/spice/spi...rview.html

http://we.home.agilent.com/cgibin/bvpub/agilent/Product/cp_ProductCompariso

http://www.seas.upenn.edu/~jan/spice/spic e.overview.html

Wireless battery charging system using radio frequency energy harvesting by

Daniel W. Harrist, BS, University of Pittsburgh

www.electronicstoday.com

www.ecoupled.com

www.fultoninnovation.com

Ftom wikipidea

Different site www.pcb.desinging.in/www.refrence.wirelessbaterry.in

Through wireless communication book transmitter and receiver block study

from different ref book

Data sheet related to 89C51 through site on google search

From the book of Millman halkias

Dr.Simon haykin

Shedra and smith

Boylestad
http://www.seas.upenn.edu

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