Upload
nikhil-mallviya
View
224
Download
0
Embed Size (px)
Citation preview
7/27/2019 projecr major2
1/60
CHAPTER I
1
7/27/2019 projecr major2
2/60
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
2
7/27/2019 projecr major2
3/60
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.
3
7/27/2019 projecr major2
4/60
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
7/27/2019 projecr major2
5/60
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.
5
7/27/2019 projecr major2
6/60
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
7/27/2019 projecr major2
7/60
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
7
7/27/2019 projecr major2
8/60
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
8
7/27/2019 projecr major2
9/60
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
9
7/27/2019 projecr major2
10/60
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
10
7/27/2019 projecr major2
11/60
Charging System
11
Figure - 3
7/27/2019 projecr major2
12/60
1.5 Charging Profile
12
Working of project with circuit diagram
Figure -4
7/27/2019 projecr major2
13/60
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.
13
7/27/2019 projecr major2
14/60
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
14
7/27/2019 projecr major2
15/60
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.
15
7/27/2019 projecr major2
16/60
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:
16
7/27/2019 projecr major2
17/60
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
17
7/27/2019 projecr major2
18/60
CHAPTER - II
18
7/27/2019 projecr major2
19/60
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.
19
7/27/2019 projecr major2
20/60
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
20
Figure -3
7/27/2019 projecr major2
21/60
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
21
Figure -4
7/27/2019 projecr major2
22/60
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.
22
Figure -5
7/27/2019 projecr major2
23/60
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.
23
7/27/2019 projecr major2
24/60
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
24
7/27/2019 projecr major2
25/60
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
25
Figure -6
7/27/2019 projecr major2
26/60
CHAPTER - III
26
7/27/2019 projecr major2
27/60
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
27
7/27/2019 projecr major2
28/60
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
28
7/27/2019 projecr major2
29/60
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.
29
7/27/2019 projecr major2
30/60
Overview of 89C51
30
Figure -7
7/27/2019 projecr major2
31/60
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
31
7/27/2019 projecr major2
32/60
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
32
7/27/2019 projecr major2
33/60
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
33
7/27/2019 projecr major2
34/60
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
34
7/27/2019 projecr major2
35/60
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
35
Figure 8
7/27/2019 projecr major2
36/60
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.
36
7/27/2019 projecr major2
37/60
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.
37
7/27/2019 projecr major2
38/60
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
38
7/27/2019 projecr major2
39/60
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
7/27/2019 projecr major2
40/60
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.
40
Figure -10
7/27/2019 projecr major2
41/60
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.
41
7/27/2019 projecr major2
42/60
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.
42
Figure 11
7/27/2019 projecr major2
43/60
BLOCK DIAGRAM OF 89C51S
43
Figure -12
7/27/2019 projecr major2
44/60
CHAPTER IV
44
7/27/2019 projecr major2
45/60
4.1 Pcb layout
Front side
45
Figure 13
7/27/2019 projecr major2
46/60
REAR SIDE
Figure 14
46
7/27/2019 projecr major2
47/60
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
47
7/27/2019 projecr major2
48/60
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
48
7/27/2019 projecr major2
49/60
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.
49
7/27/2019 projecr major2
50/60
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
+ -
50
Figure 15
7/27/2019 projecr major2
51/60
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
51
7/27/2019 projecr major2
52/60
CHAPTER V
52
7/27/2019 projecr major2
53/60
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 .
53
7/27/2019 projecr major2
54/60
54
7/27/2019 projecr major2
55/60
CHAPTER VI
55
7/27/2019 projecr major2
56/60
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.
56
7/27/2019 projecr major2
57/60
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
57
7/27/2019 projecr major2
58/60
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
58
7/27/2019 projecr major2
59/60
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
59
7/27/2019 projecr major2
60/60
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