Trackers direct solar panels or modules towards sun. These devices change their orientation throughout the day to follow the sun's path to maximize energy capture.In photovoltaic systems, trackers help minimize the angle of incidence (the angle that a ray of light makes with a line perpendicular to the surface) between the incoming light and the panel, which increases the amount of energy the installation produces. Concentrated solar photovoltaics and concentrated solar thermal have optics that directly accepts sunlight, so solar trackers must be angled correctly to collect energy
Intze Overhead Water Tank Design by Working Stress - IS Method.pdf
Solar Tracking system
1. Solar Tracking System
A project Report
Submitted by
NAVREET SINGH
In partial fulfilment for the award of the degree
of
B.TECH
IN
ELECTRICAL ENGINEERING
At
CT INSTITUTE OF ENGINEERING, MANAGEMENT AND
TECHNOLOGY
JALANDHAR
2. ABSTRACT:-
Trackers direct solar panels or modules toward the sun. These devices change their
orientation throughout the day to follow the sun’s path to maximize energy capture.
In photovoltaic systems, trackers help minimize the angle of incidence (the angle that a
ray of light makes with a line perpendicular to the surface) between the incoming light
and the panel, which increases the amount of energy the installation produces.
Concentrated solar photovoltaics and concentrated solar thermal have optics that directly
accepts sunlight, so solar trackers must be angled correctly to collect energy. All
concentrated solar systems have trackers because the systems do not produce energy
unless directed correctly toward the sun.
Single-axis solar trackers rotate on one axis moving back and forth in a single direction.
Different types of single-axis trackers include horizontal, vertical, tilted, and polar
aligned, which rotate as the names imply. Dual-axis trackers continually face the sun
because they can move in two different directions. Types include tip-tilt and azimuth-
altitude. Dual-axis tracking is typically used to orient a mirror and redirect sunlight
along a fixed axis towards a stationary receiver. Because these trackers follow the sun
vertically and horizontally they help obtain maximum solar energy generation.
2
3. ACKNOWLEDMENT
I would like to express my sincere gratitude to my Supervisors Er.Sonam Jain for their
advices, guidance, continuous encouragement and their generous dedication of precious
time throughout the work of this thesis.
Furthermore, I would like to thank all of my friends for their help and support. Finally I
dedicate the thesis to all the members of my family for their moral support and patience
during this research work.
3
4. TABLE OF CONTENTS
Contents Page
No.
Abstract 2
Acknowledgement 3
Table of Contents 5
List of Figures 5
Chapter 1: INTRODUCTION 6
Chapter 2: LITERATURE REVIEW 7-
39
2.1 Block Diagram 7
2.2 Schematic Diagram 8
2.3 Component’s Description
10
2.3.1 Transformer
10
2.3.2 Specification of Transformer
12
2.3.3 Resistors
12
3. Resistor Colour Code
14
4.Capacitor
15
5.Diode
17
6. Transistor
19
7. Power Supply
22
8.Microcontrollers
4
6. Fig 1.7 Series Diode
18
Fig 1.8 Transistor
19
Fig 1.10 LED
20
Fig 1.11 Voltage Regulator
21
Fig 1.12 Power Supply
22
Fig 1.13 Microcontrollers
24
Fig 1.14 Pin Diagram
26
Fig 1.15 Dc Motor
32
Fig 1.16 Isolators
33
Fig 1.17 H Bridge Circuit
34
Fig 1.18 Op Amp Circuit Working
35
LIST OF TABLES
Table No. Table Description Page
No.
Table 1.1 Resistor Colour Code
15
Table 1.2 Alternate Function
29
1.Introduction
6
7. Solar energy is the radiant light and heat from sun that has been harnessed since ages.
Only a Miniscule of the solar power received by the Earth (174 per watts ) is enough to
meet the present-day energy demand. At the same time, the usage of solar energy today
is only a very tiny fraction of the total energy demand.The sun energy is available in the
form of radiation over visible light and infrared region albeit at a very low intensity.
Most commonly used ways of harvesting the radiant solar energy is using photovoltaic
panels which basically are interconnected assemblies of photovoltaic cells. The
photovoltaic systems receive solar energy mainly in the visible light and near infrared
regions of the spectrum.
The light power is converted directly into dc electric current. Photovoltaic energy
conversion efficiency in most systems, however, is only in teens. Amount of the
harvested solar energy is critically dependent on the orientation of the solar panel. The
solar energy collection is very inefficient in stationary panels. The efficiency of solar
energy collection in photovoltaic solar panels at any location can be optimized when the
panel a) faces the sun and b) continuously tracks the sun during the day in one or two
axis. This tracking can be controlled in a feed forward or feedback controlled manner.
The later has obvious advantages.
[1] It have used a feedback controlled one-axis mechanism that compares voltages from
two small solar cells mounted on a big solar panel assembly and activates a stepper
motor to adjust the east-west alignment.
[2]It uses an open-loop embedded control system for the solar tracker. This paper
describes a two-axis feedback controlled tracking system which directly uses sun rays as
the feedback signals.
7
10. Fig.1.2
1. (IN4007)
2. Capacitor
3. Voltage Regulator
4. Resistor
Material Used
1. Transformer
2. Diodes
3. Microcontroller
4. Crystal
5. LDR
6. LM358
7. Motor
8. Opto coupler
9. Transistor 8050
10. Transistor 8550
11. Wooden body
12. IC bases
13. Ribbon wire
14. Jumper wire
15. Soldering Iron
16. Soldering Wire
10
11. 17. Multimeter
18. PCB
19. Cutter
20. Screw & Nuts
2.3 Components’ Description
2.3.1 TRANSFORMER
Transformer works on the principle of mutual inductance. We know that if two coils or
windings are placed on the core of iron, and if we pass alternating current in one
winding, back emf or induced voltage is produced in the second winding. We know that
alternating current always changes with the time. So if we apply AC voltage across one
winding, a voltage will be induced in the other winding. Transformer works on this
same principle. It is made of two windings wound around the same core of iron. The
winding to which AC voltage is applied is called primary winding. The other winding is
called as secondary winding. Transformers are of two types Step Up transformer and
Step Down transformer.
11
12. Fig.1.3
Step Up transformer: - These transformers are used to increase the voltage level at the
output means Voltage at secondary winding is more than the primary winding. In this
transformer secondary winding has more number of turns than primary winding. These
types of transformers are generally used in power station.
Step Down transformer: - These transformers are used to decrease the voltage level at
the output winding means voltage of secondary winding is less than the primary
winding. In this transformer secondary winding has less number of turns than primary
winding. These types of transformers have major applications in electronics industry.
Further these are divided into two categories
Simple Transformer
A) Central tapped transformer
12
13. Simple Transformer: - It’s a four wire transformer. These types of transformer have 2
wires on primary winding and 2 wires on secondary output. Symbol of this transformer
is shown below. Voltage rating of these transformer expressed as 6V, 12V, 24V etc.
Central Tapped transformer: - It’s a 5 Wire transformer. This type of transformer has
2 wires on primary winding and 3 wires on secondary. Middle one is known as
Common. Voltage rating of these transformer expressed as 6-0-6 V,12-0-12 V, 24-0-24
V etc.
13
14. Central Tapped transformer
2.3.2 Specification of transformer:-
While purchasing a transformer generally two considerations have to be kept in mind,
first one is voltage rating and second is current rating. Voltage rating depends upon the
circuit’s operating voltage its generally 5 or 12 Volt so 6 or 12 Volt transformers are
generally used. Current rating of transformer depends upon the load of circuit. If our
load current is more than the transformer current then due to loading effects transformer
can burn out. So to protect our transformer, current rating of transformer should be more
than the load current. All transformer comes with different current rating e.g. 6 V
transformer is available in 500m A, 750mA, 1A, 2A so on. One thing should be kept in
mind as the ampear increases cost of transformer also increases. We have to choose best
one according to our circuit requirements.
RESISTORS
The flow of charge (or current) through any material, encounters an opposing force
similar in many respect to mechanical friction. This opposing force is called resistance
of the material. It is measured in ohms. In some electric circuits resistance is
deliberately introduced in the form of the resistor.
Resistors are of following types: Wire wound resistors.
1. Carbon resistors.
14
15. 2. Metal film resistors.
Wire Wound Resistors:
Wire wound resistors are made from a long (usually Ni-Chromium) wound on a ceramic
core. Longer the length of the wire, higher is the resistance. So depending on the value
of resistor required in a circuit, the wire is cut and wound on a ceramic core. This entire
assembly is coated with a ceramic metal. Such resistors are generally available in power
of 2 watts to several hundred watts and resistance values from 1ohm to 100k ohms. Thus
wire wound resistors are used for high currents.
Carbon Resistors:
Carbon resistors are divided into three types:
Carbon composition resistors are made by mixing carbon grains with binding material
(glue) and moduled in the form of rods. Wire leads are inserted at the two ends. After
this an insulating material seals the resistor. Resistors are available in power ratings of
1/10, 1/8, 1/4 , 1/2 , 1.2 watts and values from 1 ohm to 20 ohms.
a. Carbon film resistors are made by deposition carbon film on a ceramic rod. They are
cheaper than carbon composition resistors.
b. Cement film resistors are made of thin carbon coating fired onto a solid ceramic
substrate. The main purpose is to have more precise resistance values and greater
stability with heat. They are made in a small square with leads.
Fig.1.4
Metal Film Resistors:
15
16. They are also called thin film resistors. They are made of a thin metal coating
deposited on a cylindrical insulating support. The high resistance values are not precise
in value; however, such resistors are free of inductance effect that is common in wire
wound resistors at high frequency.
Variable Resistors:
Potentiometer is a resistor where values can be set depending on the requirement.
Potentiometer is widely used in electronics systems. Examples are volume control, tons
control, brightness and contrast control of radio or T.V. sets.
3. RESISTOR COLOR CODE
Table1.1
Color 1st
band 2nd
band 3rd
band (multiplier) 4th
band (tolerance) Temp. Coefficient
Black 0 0 ×100
Brown 1 1 ×101
±1% (F) 100 ppm
16
17. Red 2 2 ×102
±2% (G) 50 ppm
Orange 3 3 ×103
15 ppm
Yellow 4 4 ×104
25 ppm
Green 5 5 ×105
±0.5% (D)
Blue 6 6 ×106
±0.25% (C)
Violet 7 7 ×107
±0.1% (B)
Gray 8 8 ×108
±0.05% (A)
White 9 9 ×109
Gold ×10−1
±5% (J)
Silver ×10−2
±10% (K)
None ±20% (M)
4. CAPACITORS
A capacitor can store charge, and its capacity to store charge is called capacitance.
Capacitors consist of two conducting plates, separated by an insulating material (known
as dielectric). The two plates are joined with two leads. The dielectric could be air, mica,
paper, ceramic, polyester, polystyrene, etc. This dielectric gives name to the capacitor.
Like paper capacitor, mica capacitor etc.
Types of Capacitors:- Capacitors are of two Types Fixed and variable capacitor.
Fixed types of capacitor are further of two types:-
Polar Capacitor:- Those capacitor have polarity are known as polar capacitor.
Electrolytic capacitor are the example of polar capacitors.
17
18. Non Polar Capacitor:- Those capacitor have no polarity are known as NON- polar
capacitor. Ceramic capacitor are the example of non polar capacitors
Electrolytic Capacitor: Electrolytic capacitors have an electrolyte as a dielectric. When
such an electrolyte is charged, chemical changes takes place in the electrolyte. If its one
plate is charged positively, same plate must be charged positively in future. We call such
capacitors as polarized. Normally we see electrolytic capacitor as polarized capacitors
and the leads are marked with positive or negative on the can. Non-electrolyte capacitors
have dielectric material such as paper, mica or ceramic. Therefore, depending upon the
dielectric, these capacitors are classified.
Ceramic Capacitor: Such capacitors have disc or hollow tabular shaped dielectric
made of ceramic material such as titanium dioxide and barium titanate. Thin coating of
silver compounds is deposited on both sides of dielectric disc, which acts as capacitor
plates. Leads are attached to each sides of the dielectric disc and whole unit is
encapsulated in a moisture proof coating. Disc type capacitors have very high value up
18
19. to 0.001uf. Their working voltages range from 3V to 60000V. These capacitors have
very low leakage current. Breakdown voltage is very high.
5.Diode:-
Diodes are semiconductor devices which might be described as passing current in one
direction only. Diodes have two terminal, an anode and a cathode. The cathode is
always identified by a dot, ring or some other mark. Diode is a unidirectional device. In
this current flows in only one direction.
Fig.1.5
Diodes can be used as voltage regulators, tuning devices in rf tuned circuits, frequency
multiplying devices in rf circuits, mixing devices in rf circuits, switching applications or
can be used to make logic decisions in digital circuits. There are also diodes which emit
"light", of course these are known as light-emitting-diodes or LED's.
A rectifying diode of the 1N4001-07 ( 1A) type or even one of the high power, high
current stud mounting types. You will notice the straight bar end has the letter "k", this
denotes the "cathode" while the "a" denotes anode. Current can only flow from anode to
cathode and not in the reverse direction, hence the "arrow" appearance. This is one very
important property of diodes.
The principal early application of diodes was in rectifying 50 / 60 Hz AC mains to raw
DC which was later smoothed by choke transformers and / or capacitors. This procedure
19
20. is still carried out today and a number of rectifying schemes for diodes have evolved,
half wave, full wave and bridge, full wave and bridge rectifiers.
Fig.1.6
As examples in these applications the half wave rectifier passes only the positive half of
successive cycles to the output filter through D1. During the negative part of the cycle
D1 does not conduct and no current flows to the load. In the full wave application it
essentially is two half wave rectifiers combined and because the transformer secondary
is centre tapped, D1 conducts on the positive half of the cycle while D2 conducts on the
negative part of the cycle. Both add together. This is more efficient. The full wave
bridge rectifier operates essentially the same as the full wave rectifier but does not
require a centre tapped transformer. Further discussion may be seen on the topic power
supplies
1N400X series Diode:-
Features
• Diffused Junction
• High Current Capability and Low Forward Voltage Drop
• Low Reverse Leakage Current
20
21. Fig.1.7
6. Transistor:-
The schematic representation of a transistor is shown. Note the arrow pointing down
towards the emitter. This signifies it's an NPN transistor a transistor is basically a
current amplifier. Say we let 1mA flow into the base. We may get 100mA flowing into
the collector. Note: The currents flowing into the base and collector exit through the
emitter (sum off all currents entering or leaving a node must equal zero). The gain of the
transistor will be listed in the datasheet as either βDC or Hfe. The gain won't be identical
even in transistors with the same part number. The gain also varies with the collector
current and temperature.
Fig.1.8
21
22. Fig.1.9
LED: - LED means light emitting diode. Its function is similar to the diode. But these
are not made up from silicon or germanium. These are generally used as an indicating
device. There are variety of LEDs are available in market depending upon their size and
colour.
22
23. Fig.1.10
Polarity of LED: - LED have polarity. We can judge its polarity by watching flags in
its structure. Bigger flag is known as cathode and smaller flag is known as anode as
shown below.
Voltage Regulator The LM78XX 3-terminal positive voltage regulators employ
internal current-limiting, thermal shutdown and safe-area compensation, making them
essentially indestructible. Heat sinking is provided; they can deliver over 1.0A output
current. They are intended as fixed voltage regulators in a wide range of applications
including local (on-card) regulation for elimination of noise and distribution problems
associated with single-point regulation. In addition to use as fixed voltage regulators.
23
24. Fig.1.11
Features
■ Output current up to 1 A
■ Output voltages of 5; 6; 8; 9; 12; 15; 18; 24 V
■ Thermal overload protection
■ Short circuit protection
Crystal: - It’s a 2 terminal component. This component has no polarity. Its basic
function to generate a Square Wave of some fixes frequency. Its value is measure in
MHz
7.Power supply: -
24
25. Power supply is the essential part of any device or project. We are using
microcontroller and LED. These components needs +5V DC supply. So we need a
power supply circuit of +5V DC. Power supply circuit includes step down transformer,
rectifier circuit, filter circuit and regulator circuit. An indicating component is also
attached with the power supply to indicate the power ON condition of power supply
unit.
Fig.1.12
Now the aim is to design the power supply section which converts 230V AC in to 5V
DC. Since 230V is too high to reduce it to directly 5V DC, therefore we need a step
down transformer that reduces the line voltage to certain voltage that will help us to
convert it in to a 5V DC. Considering the efficiency factor of the full wave, we came to
a conclusion to choose a transformer, whose secondary voltage is 3-4 higher than the
required voltage. Thus a step down transformer of 9 V and 500 mA is used to step down
the AC power supply. This transformer can provide current up to 750 mA. Our circuit
load is below 750 mA. So there will not be any loading effect on transformer. Output of
transformer is given to the rectifier circuit. We are using a central tapped full wave
rectifier. In this rectifier we are using 1N4007 pn diode to rectify AC voltage. Output of
this rectifier is not purely DC. Output of rectifier is rippled DC. So we need some
filtering section to rectify these ripples. Output voltage of rectifier can be calculated by:-
Vout = (Vin * √2)- (Forward voltage drop of diode)
1N4007 is a silicon semiconductor material based diode. So in this case forward Voltage
drop is .7 V. Final output of this rectifier be:-
Vout= (12*√2)- .7
Vout= 16.1 V
25
26. Rectifier circuit is build of capacitor. A capacitor of 1000uF,25V is used to filter the
ripples. Output of capacitor is almost pure DC. But its voltage is 16V and we need +5V
DC. So we are using a voltage regulator to get the desired +5V DC. A 7805 voltage
regulator is a suitable component for this purpose. Output of 7805 regulator is +5V DC.
A capacitor of 470uf, 10V is used to further filter out the critical ripples. A LED is used
as an indicating device. Most of LED operates at 1.5 to 2.5V voltage range with 8-10
mA. LED used here is of 5mm size. We consider that LED operating at 1.6V with 8mA
current. We can calculate the value of resistor using the KVC law.
Total Voltage= Voltage across resistor+ Voltage across LED
LED and resistor are connected in series so same current will flow. Means 8mA current
will flow through the resistor.
Now Total Voltage is =5V
Voltage across resistor is =1.6v
Current is = 10mA
So our equation will be
5V= (10mA * resistance) + 1.6V
3.4V=10mA * resistance
Resistance =3.4/10mA
= 340 ohm
Thus we can calculate the any series resistor for any input voltage and LED.
8. MICROCONTROLLERS (MCU)
Figure shows the block diagram of a typical microcontroller, which is a true computer
on a chip. The design incorporates all of the features found in micro-processor CPU,
ALU, PC, SP, and registers. It also added the other features needed to make a complete
computer: ROM, RAM, I/O,timer & counters,and clock circuit.
26
27. Fig.1.13
Structure of microprocessor and microcontroller
DIFFERENCE BETWEEN MICROCONTROLLER & MICROPROCESSOR
It is very clear from figure that in microprocessor we have to interface additional
circuitry for providing the function of memory and ports, for example we have to
interface external RAM for data storage, ROM for program storage, programmable
peripheral interface (PPI) 8255 for the Input Output ports, 8253 for timers, USART for
serial port. While in the microcontroller RAM, ROM, I/O ports, timers and serial
communication ports are in built. Because of this it is called as “system on chip”. So in
micro-controller there is no necessity of additional circuitry which is interfaced in the
microprocessor because memory and input output ports are inbuilt in the
microcontroller. Microcontroller gives the satisfactory performance for small
applications. But for large applications the memory requirement is limited because only
64 KB memory is available for program storage. So for large applications we prefer
microprocessor than microcontroller due to its high processing speed.
8.1 8051 MICROCONTROLLER
Description:-
27
28. The AT89S52 is a low-power, high-performance CMOS 8-bit microcontroller with
8Kbytes of in-system programmable Flash memory. The device is manufactured using
Atmel’s high-density non-volatile memory technology and is compatible with the
industry-standard 80C51 instruction set and pin out. The on-chip Flash allows the
program memory to be reprogrammed in-system or by a conventional non-volatile
memory programmer. By combining a versatile 8-bit CPU with in-system
programmable Flash on a monolithic chip, the Atmel AT89S52 is a powerful
microcontroller which provides a highly-flexible and cost-effective solution to many
embedded control applications. The AT89S52 provides the following standard features:
8K bytes of Flash, 256 bytes of RAM, 32 I/O lines, Watchdog timer, two data pointers,
three 16-bit timer/counters, a six-vector two-level interrupt architecture, a full duplex
serial port, on-chip oscillator, and clock circuitry. In addition, the AT89S52 is designed
with static logic for operation down to zero frequency and supports two software
selectable power saving modes. The Idle Mode 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 but freezes the oscillator, disabling all other chip
functions until the next interrupt
or hardware reset.
Features:-
• 8K Bytes of In-System Programmable (ISP) Flash Memory
– Endurance: 1000 Write/Erase Cycles
• 4.0V to 5.5V Operating Range
• Fully Static Operation: 0 Hz to 33 MHz
• Three-level Program Memory Lock
• 256 x 8-bit Internal RAM
• 32 Programmable I/O Lines
• Three 16-bit Timer/Counters
• Eight Interrupt Sources
• Full Duplex UART Serial Channel
• Low-power Idle and Power-down Modes
• Interrupt Recovery from Power-down Mode
• Watchdog Timer
• Dual Data Pointer
• Power-off Flag
• Fast Programming Time
• Flexible ISP Programming (Byte and Page Mode)
8.2 PIN CONFIGURATION OF 8051 MICROCONTROLLER
28
29. Although 8051 family members come in different packages such DIP(dual in line
package),QFP(Quad flat package), and LLC(leadless chi0p carrier),they all have 40 pins
that are dedicated to various functions such as I/O,RD,WR, address, data and interrupts.
VCC:
Pin 40 provides supply voltage to the chip. The voltage source is +5 Volts.
GND:
Pin 20 is the ground.
Fig.1.14
FIG 28: PIN
DIAGRAM OF THE P89C51
XTAL1 and XTAL2:
The 8051 has an on chip oscillator but requires an external clock to run it. Most often a
quartz crystal oscillator is connected to inputs XTAL1 (pin 19) and XTAL2 (pin 18).
The quartz crystal oscillator connected to XTAL1 and X
TAL2 also needs two capacitors of 27 pf value. One side of each capacitor is connected
to the ground. Speed refers to the maximum oscillator frequency connected to XTAL
.When the 8051 is connected to a crystal oscillator is powered up we can observe the
frequency on the XTAL2 pin using the oscilloscope.
29
30. RST:
Pin 9 is the RESET pin. It is an input and is active high. Upon applying a high pulse to
this pin the microcontroller well reset and terminate all activities. This is often referred
to as a power on reset .Activating a power on reset will cause all values the registers to
be lost. It will set program counter to all 0s.
In order for the RESET input to be effective it must have a minimum duration of two
machine cycles. In other words the high pulse must be high for a minimum of two
machine cycles before it is allowed to go low.
EA:
The 8051 family members such as the 8751/52, 89C51/52 or DS89C4*0 all come with
on chip ROM to store programs. In such cases the EA pin is connected to Vcc. For
30
31. family members such as the 8031 and 8032 in which there is no on chip ROM, code is
stored on an external ROM and is fetched by 8031/32. Therefore for the 8031 the EA
pin must be connected to GND to indicate that the code is stored externally. EA which
stands for “external access” is pin number 31 in the DIP packages. It is an input pin and
must be connected to either Vcc or GND. In other words it cannot be unconnected.
PSEN:
This is an output pin. PSEN stands for “program store enable”. In an 8031 based system
in which an external ROM holds the program code, this pin is connected to the OE pin
of the ROM.
ALE: ALE stands for “address latch enable. It is an output pin and is active high. When
connecting an 8031 to external memory, port 0 provides both address and data. In other
words the 8031 multiplexes address and data through port 0 to save pins. The ALE pin
is used for de-multiplexing the address and data by connecting to G pin of the 74LS373
chip.
PORTS 0,1,2,3:
All the ports upon RESET are configured as input, since P0-P3 have value FFH on
them. The following is a summary of features of P0-P3.
PORT 0:
Port 0 is also designated as AD0-AD7 allowing it to be used for both address and data.
When connecting an 8051/31 to an external memory, port 0 provides both address and
data. The 8051 multiplexes address and data through port 0 to save pins. ALE indicates
if p0 has address A0-A7.in the 8051 based systems where there is no external memory
connection the pins of P0 must be connected externally to 10k-ohm pull-up resistor.
This is due to the fact that P0 is an open drain, unlike P1, P2 and P3. Open drain is a
term used for MOS chips in the same way that open collector is used for TTL chips. In
many systems using the 8751, 89c51 or DS89c4*0 chips we normally connect P0 to pull
up resistors.
PORT 1, PORT 2:
In 8051 based systems with no external memory connection both P1 and P2 are used as
simple I/O. however in 8031/51 based systems with external memory connections P2
must be used along with P0 to provide the 16-bit address for the external memory. P2 is
also designated as A8-A15 indicating its dual function. Since an 8031/51 is capable of
accessing 64k bytes of external memory it needs a path for the 16 bits of address. While
P0 provides the lower 8 bits via A0-a7 it is the job P2 to provide bits A8-A15 of the
address. In other words when the 8031/51 is connected to external memory P2 is used
for the upper 8 bits of the 16 bit address and it cannot be used for I/O.
PORT 3:
Port 3 occupies a total of 8 pins 10 through 17. It can be used as input or output. P3 does
not need any pull-up resistors the same as P1 and P2 did not. Although port 3 is
31
32. configured as input port upon reset this is not the way it is most commonly used. Port 3
has the additional function of providing some extremely important signals such as
interrupts.
Port 3 Alternate functions:
Table1.2
P3 Bit Function Pin
P3.0 RxD 10
P3.1 TxD 11
P3.2 INT0 12
P3.3 INT1 13
P3.4 T0 14
P3.5 T1 15
P3.6 WR 16
P3.7 RD 17
Difference between RAM and ROM
• RAM is used for data storage while ROM is used for program storage.
• Data of RAM can be changed during processing while data of ROM can’t
be changed during processing.
• We can take an example of calculator. If we want to perform addition of
two numbers then we type the two numbers in calculator, this is saved in
the RAM, but the Algorithms by which the calculation is performed is saved
in the ROM. Data which is given by us to calculator can be changed but the
algorithm or program by which calculation is performed can’t be changed.
32
33. PROGRAMMING MODEL
In programming model of 8051 we have different types of registers are available and
te4hse registers are used to store temporarily data is then the information could be a byte
of data to be processed or an address pointing to the data to be fetched the majority of
registers is 8051 are 8-bikt registers.
a) ACCUMULATOR (REGISTER A):
Accumulator is a mathematical register where all the arithmetic and logical operations
are done is this register and after execution of instructions the outpour data is stored in
the register is bit addressable near. We can access any of the single bit of this register.
b) B REGISTER:
B register is same as that of accumulator of. It is also an 8 bit register and every bit of
this is accessible. This is also a mathematical register B which is used mostly for
multiplication and division.
c) PSW (PROGRAM STATUS WORD) Register:
Program status word register is an 8 bit register. It is also referred to as the flag register.
Although the PSW register is 8 bits wide, only 6 bits of it are used by the 8051. The
unused bits are user-definable flags. Four of the flags are called conditional flags,
meaning that they indicate some conditions that result after an instruction is executed.
These four are CY (carry), AC (auxiliary carry), P (parity) and OV (overflow).
Table.1.3
CY PSW.7 Carry Flag
AC PSW.6 Auxiliary
Carry Flag
F0 PSW.5 Available to
the user for
General
Purpose
RS1 PSW.4 Register
33
34. Bank
Selector Bit 1
RS0 PSW.3 Register
Bank
Selector Bit 0
OV PSW.2 Overflow
Flag
-- PSW.1 User
Definable Bit
P PSW.0 Parity Flag.
c) SP (STACK POINTER, ADDRESS 81H):
This is the stack pointer of the microcontroller. This SFR indicates where the next value
to be taken from the stack will be read from in Internal RAM. If you push a value onto
the stack, the value will be written to the address of SP + 1. That is to say, if SP holds
the value 07h, a PUSH instruction will push the value onto the stack at address 08h. This
SFR is modified by all instructions, which modify
The stack, such as PUSH, POP, LCALL, RET, RETI, and whenever interrupts are
provoked by the microcontroller.
d) DPL/DPH (DATA POINTER LOW/HIGH, ADDRESSES 82H/83H):
The SFRs DPL and DPH work together to represent a 16-bit value called the Data
Pointer. The data pointer is used in operations regarding external RAM and some
instructions involving code memory. Since it is an unsigned two-byte integer value, it
can represent values from 0000h to FFFFh (0 through 65,535 decimal).
Two instructions which are used to start and terminate program.
• ORG → this instruction indicate the origin of program ORG 3000H
→ means program starts from 3000H loc
→ this instruction hasn’t take any memory space. It is used to show the
starting address of program.
34
35. • END → this instruction show the END of program or it is used to terminate
the program.
9. DC MOTOR
Fig.1.15
PRINCIPLE OF OPERATION
In any electric motor, operation is based on simple electromagnetism. A current-
carrying conductor generates a magnetic field; when this is then placed in an external
magnetic field, it will experience a force proportional to the current in the conductor,
and to the strength of the external magnetic field. As you are well aware of from playing
with magnets as a kid, opposite (North and South) polarities attract, while like polarities
(North and North, South and South) repel. The internal configuration of a DC motor is
designed to harness the magnetic interaction between a current-carrying conductor and
an external magnetic field to generate rotational motion.
10. ISOLATORS
Opto coupler (PC-817)
An isolator device to electrically insulate and isolate a separate component in a circuit
board arrangement to allow for relatively fast and convenient diagnostic inspection of a
circuit to locate failed components
In electronics, an opto-isolator, also called an optocoupler, photocoupler, or optical
isolator, is "an electronic device designed to transfer electrical signals by utilizing light
waves to provide coupling with electrical isolation between its input and output. The
main purpose of an opto-isolator is "to prevent high voltages or rapidly changing
voltages on one side of the circuit from damaging components or distorting
transmissions on the other side
35
36. An opto-isolator contains a source (emitter) of light, almost always a near infrared light-
emitting diode (LED), that converts electrical input signal into light, a closed optical
channel (also called dielectrical channel[5]
), and a photo sensor, which detects incoming
light and either generates electric energy directly, or modulates electric current flowing
from an external power supply. The sensor can be a photoresistor, a photodiode, a
phototransistor. Pin diagram of PC 817 is shown below.
Fig.1.16
Working: - PC 817 is a 4 pin opto coupler as shown above. A series resistance of 470
ohm is used to limit the voltage across the diode. +5V power supply is connected to the
36
37. first pin of IC, which is the anode pin diode. 2nd
pin is connected to the port of
microcontroller. When the second pin is low then we get low output, when the input to
2nd
pin high we get high voltage the output. Thus we isolate the voltage having the same
logic level.
H-BRIDGE CIRCUIT
Fig.1.17
Working: - An H bridge is an electronic circuit which enables a voltage to be applied
across a load in either direction. These circuits are often used in robotics and other
applications to allow DC motors to run forwards and backwards.
The term H Bridge is derived from the typical graphical representation of such a circuit.
An H bridge is built with four switches (solid-state or mechanical).
37
38. When the switches S1 and S4 are closed (and S2 and S3 are open) a positive voltage
will be applied across the motor. By opening S1 and S4 switches and closing S2 and S3
switches, this voltage is reversed, allowing reverse operation of the motor.
Using the nomenclature above, the switches S1 and S2 should never be closed at the
same time, as this would cause a short circuit on the input voltage source. The same
applies to the switches S3 and S4. This condition is known as shoot-through.
The two basic states of an H bridge
The H-bridge arrangement is generally used to reverse the polarity of the motor, but can
also be used to 'brake' the motor, where the motor comes to a sudden stop, as the motor's
terminals are shorted, or to let the motor 'free run' to a stop, as the motor is effectively
disconnected from the circuit.
OP-AMP Comparator Circuit Working
A comparator circuit compares two voltages and outputs either a 1 (the voltage at the
plus side; VDD in the illustration) or a 0 (the voltage at the negative side) to indicate
which is larger. Comparators are often used, for example, to check whether an input has
reached some predetermined value. In most cases a comparator is implemented using a
dedicated comparator IC, but op-amps may be used as an alternative. Comparator
diagrams and op-amp diagrams use the same symbols.
Figure 4 shows a comparator circuit. Note first that the circuit does not use feedback.
The circuit amplifies the voltage difference between Vin and VREF, and outputs the
result at Vout. If Vin is greater than VREF, then voltage at Vout will rise to its positive
saturation level; that is, to the voltage at the positive side. If Vin is lower than VREF,
then Vout, will fall to its negative saturation level, equal to the voltage at the negative
side.
38
39. In practice, this circuit can be improved by incorporating a hysteresis voltage range to
reduce its sensitivity to noise. The circuit shown in Fig. 5, for example, will provide
stable operation even when the Vin signal is somewhat noisy.
Fig.1.18
39
