Rsrs Project Work

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WIRELESS ENERGY TRANSMITTER WITH

TARIFF SYSTEM

PROJECT REPORT 2009-2010

N.NAMACHIVAYAM.

R.RAJESH.

J.RAJTHILAK

R.SUNDAR.

A.VENKATASEN

V.SURESH.

UNDER THE GUIDANCE OF

MR.G.KAMALASEKARAN,B.E.,

DEPARTMENT OF E.E.E

IN THE PARTIAL FULFILLMENT OF THE REQUIREMENT OF THE AWARD OF

DIPLOMA IN ELECTRICAL AND ELECTRONICS ENGINEERING

BOARD OF TECHNICAL EDUCATION

GOVERNMENT OF INDIA

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DEPARTMENT OF ELECTRICAL AND ELECTRONICS

ENGINEERING

C.S.I POLYTECHNIC COLLEGE

SALEM-636 007.

DEPARTMENT OF ELECTRICAL AND ELECTRONICS

ENGINEERING

C.S.I POLYTECHNIC COLLEGE

SALEM-636 007

PROJECT REPORT 2009-2010

WIRELESS ENERGY TRANSMITTER WITH TARIFF SYSTEM

Certified that this bonafide record of project work done

by. Register Noin the

final semester ofDIPLOMA IN ELECTRICAL AND

ELECTRONICS ENGINEERINGbranch during the year 2010-

2011.

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Guide Head of the Department

Submitted for board examination held on

Internal examiner External examiner

ACKNOWLEDGEMENT

At this pleasing movement of having successfully completed our project, we

wish to convey our sincere thanks and gratitude to the management of our college

and our beloved chairman RT.REV.BISHOP,

Dr.MANICKAMDURAI,B.A.,B.D.,M.TH.,D.D. who provided all the facilities to us.

We would like to express our sincere thanks to our principal

PROF.M.GEETHA KENNEDI, M.E.,M.B.A.,P.HDfor forwarding us to do our project

and offering adequate duration in completing our project.

We are also grateful to the Electrical And Electronics Engineering Head of

the Department Er.JULIET VANATHI,M.E.,B.E.,M.I.S.T.E.,M.C.S.I., for her

constructive suggestions &encouragement during our project.

With deep sense of gratitude, we extend our earnest &sincere thanks to our

guide Mr.G.KAMALASEKARAN,B.E.,Department of Electrical And Electronics

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Engineering for him kind guidance and encouragement during this project we also

express our indebt thanks to our DEPARTMENT STAFFS.

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WIRE LESS ENERGY TRANSMITTER WITH

TARIFF SYSTEM

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CONTENTS

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1. ABSTRACT

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1. ABSTRACT

1.1 OBJECTIVE:

The objective of this project is to transmit the consumed power unit to EBoffice by using RF technology. This project is very useful to the EB board because

there is no need of employee to take consumed power unit in the every house. It

reduces the man power.

1.2 SCOPE:

This is a type of data transfer through wireless communication by using

RTC (real Time Clock). It is not necessary for the EB people to monitor or to

check the data for each and every independent house regularly. Instead of that, by

using a real time clock we can transmit the electricity bill data to the PC through

wireless communication. These types of system reduce the burden of the

electricity people. Moreover its less time consuming.

1.3 METHODOLOGY:

This type of communication system involves certain components like,

RTC,

IR sensor,

Energy Meter,

Microcontroller,

LCD display,

Keyboard,

RF transmitter and RF receiver,

PC.

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By using the keyboard, we are fixing the corresponding data and time in

RTC. When this data and time is arrived in RTC, the Microcontroller will send the

Corresponding Signal. Before that the IR sensor senses the number of rotation of

energy meter and it gives to signal conditioning circuit.

This Circuit delivers the output in terms of pulses to the Microcontroller.

Number of units consumed is indicated in the display. If the particular data and

time is reached, the microcontroller sends the signal for FSK Modulation. The

Modulated signal is then transmitted to RF transmitter.

The RF receiver receives the transmitted signal and then it is given for FSK

demodulation. The Demodulated original signal is now transferred to PC. This is

wireless type of communication. This system will be useful for the EB people to

transmit the data from the consumer place to EB without going directly to the

consumer place. This particular system will transmit the number of units

consumed by the consumer as well as the amount has to pay for the month.

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2. INTRODUCTION

Present industry is increasingly shifting towards automation. Two principle

components of todays industrial automations are programmable controllers and

robots. In order to aid the tedious work and to serve the mankind, today there is a

general tendency to develop an intelligent operation.

This is a type of data transfer through wireless communication by using

RTC (real Time Clock). It is not necessary for the EB people to monitor or to

check the data for each and every independent house regularly. Instead of that, by

using a real time clock we can transmit the electricity bill data to the PC through

wireless communication. These types of system reduce the burden of the

electricity people. Moreover its less time consuming.

Microcontroller is the heart of the device which handles all the sub devices

connected across it. We have used as microcontroller. It has flash type

reprogrammable memory. It has some peripheral devices to play this project

perform.

It also provides sufficient power to inbuilt peripheral devices. We need not

give individually to all devices. The peripheral devices also activates as low power

operation mode. These are the advantages are appear here.

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3. BLOCK DIAGRAM

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3. BLOCK DIAGRAM

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4. BLOCK DIAGRAM DESCRIPTION

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4. BLOCK DIAGRAM DESCRIPTION

4.1 IR SENSOR:

A InfraRed sensor (IR sensor) is an electronic device that measures

infrared (IR) light radiating from objects in its field of view.Apparent motion is

detected when an infrared source with one temperature, such as a human, passes in

front of an infrared source with another temperature, such as a wall.

All objects emit what is known asblack body radiation. It is usually infrared

radiation that is invisible to the human eye but can be detected by electronic

devices designed for such a purpose.

Infra meaning below our ability to detect it visually, and Red because

this color represents the lowest energy level that our eyes can sense before it

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http://en.wikipedia.org/wiki/Electronic_devicehttp://en.wikipedia.org/wiki/Infraredhttp://en.wikipedia.org/wiki/Temperaturehttp://en.wikipedia.org/wiki/Humanhttp://en.wikipedia.org/wiki/Wallhttp://en.wikipedia.org/wiki/Black_body_radiationhttp://en.wikipedia.org/wiki/Eyehttp://en.wikipedia.org/wiki/Electronic_devicehttp://en.wikipedia.org/wiki/Electronic_devicehttp://en.wikipedia.org/wiki/Infraredhttp://en.wikipedia.org/wiki/Temperaturehttp://en.wikipedia.org/wiki/Humanhttp://en.wikipedia.org/wiki/Wallhttp://en.wikipedia.org/wiki/Black_body_radiationhttp://en.wikipedia.org/wiki/Eyehttp://en.wikipedia.org/wiki/Electronic_devicehttp://en.wikipedia.org/wiki/Electronic_devicehttp://en.wikipedia.org/wiki/Electronic_device


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becomes invisible. Thus, infrared means below the energy level of the color red,

and applies to many sources of invisible energy.

Infrared transmitter is one type of LED which emits infrared rays generally

called as IR Transmitter. Similarly IR Receiver is used to receive the IR rays

transmitted by the IR transmitter. One important point is both IR transmitter and

receiver should be placed straight line to each other.

The transmitted signal is given to IR transmitter whenever the signal is high,

the IR transmitter LED is conducting it passes the IR rays to the receiver.

When receiver receives the signal from the transmitter it resistance value is

low.it resistance value become high when the signal was cut. By this sensor sense

the value.

4.2 SIGNAL CONTIONING UNIT:

The signal conditioning unit accepts input signals from the analog sensors

and gives a conditioned output of 0-5V DC corresponding to the entire range of

each parameter. This unit also accepts the digital sensor inputs and gives outputs

in 10 bit binary with a positive logic level of +5V. The calibration voltages* (0,

2.5 and 5V) and the health bits are also generated in this unit.

Microcontrollers are widely used for control in power electronics. They

provide real time control by processing analog signals obtained from the system. A

suitable isolation interface needs to be designed for interaction between the control

circuit and high voltage hardware. A signal conditioning unit which provides

necessary interface between a high power grid inverter and a low voltagecontroller unit.

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4.3 MICROCONTROLLER:

INTRODUCTION:

Microcontrollers are destined to play an increasingly important role in

revolutionizing various industries and influencing our day to day life more

strongly than one can imagine. Since its emergence in the early 1980's the

microcontroller has been recognized as a general purpose building block for

intelligent digital systems. It is finding using diverse area, starting from simple

children's toys to highly complex spacecraft. Because of its versatility and many

advantages, the application domain has spread in all conceivable directions,

making it ubiquitous. As a consequence, it has generate a great deal of interest and

enthusiasm among students, teachers and practicing engineers, creating an acute

education need for imparting the knowledge of microcontroller based system

design and development. It identifies the vital features responsible for their

tremendous impact, the acute educational need created by them and provides a

glimpse of the major application area.

MICROCONTROLLER:

A microcontroller is a complete microprocessor system built on a single IC.

Microcontrollers were developed to meet a need for microprocessors to be put into

low cost products. Building a complete microprocessor system on a single chip

substantially reduces the cost of building simple products, which use the

microprocessor's power to implement their function, because the microprocessor is

a natural way to implement many products. This means the idea of using a

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microprocessor for low cost products comes up often. But the typical 8-bit

microprocessor based system, such as one using a Z80 and 8085 is expensive.

Both 8085 and Z80 system need some additional circuits to make a

microprocessor system. Each part carries costs of money. Even though a product

design may requires only very simple system, the parts needed to make this system

as a low cost product.

To solve this problem microprocessor system is implemented with a single

chip microcontroller. This could be called microcomputer, as all the major parts

are in the IC. Most frequently they are called microcontroller because they are

used they are used to perform control functions.

The microcontroller contains full implementation of a standard

MICROPROCESSOR, ROM, RAM, I/0, CLOCK, TIMERS, and also SERIAL

PORTS. Microcontroller also called "system on a chip" or "single chip

microprocessor system" or "computer on a chip".

A microcontroller is a Computer-On-A-Chip, or, if you prefer, a single-chip

computer. Micro suggests that the device is small, and controller tells you that the

device' might be used to control objects, processes, or events. Another term to

describe a microcontroller is embedded controller, because the microcontroller and

its support circuits are often built into, or embedded in, the devices they control.

Today microcontrollers are very commonly used in wide variety of

intelligent products. For example most personal computers keyboards and

implemented with a microcontroller. It replaces Scanning, Debounce, Matrix

Decoding, and Serial transmission circuits. Many low cost products, such as Toys,

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Electric Drills, Microwave Ovens, VCR and a host of other consumer and

industrial products are based on microcontrollers.

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EVOLUTION OF MICROCONTROROLLER:

Sl.no Manufacture

r

Chip

designation

Year No. Of

pins

No of

i/o

Ram Rom Other features

4 Bit MC

1. Texas

Instruments

TMS 1000 Mid

1970

28 23 64 1K LED Display

2. Hitachi HMCS 40 - 28 10 32 512 10 bit ROM

3. Toshiba TLCS 47 - 42 35 128 2K Serial bit I/O

8 bit MC

1. Intel 8048 1976 40 27 64 1K External Memory 8K

2 Intel 8051 1980 40 32 128 4K External Memory 128 K

3. Motorola 6081 1977 - 31 128 2 K

4. Motorola 68HC11 1985 52 40 256 8K Serial Port, ADC,

5. Zilog Z8 - 40 32 128 2K External Memory 128K,

16 Bit MC

1. Intel 80C196 - 68 40 232 8K External Memory 64K,

Serial Port, ADC, WDT,

PWM

2. Hitachi H8/532 - 84 65 1K 32K External Memory 1M,

Serial Port, ADC, PWM

3. National HPC16164 - 68 52 512 16K External Memory 64K,

ADC, WDT, PWM

32 Bit MC

1. Intel 80960 - 132 20 MHz clock, 32 bit bus, 512 byte instruction cache

APPLICATION:

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A microcontroller is a kind of miniature computer that you can find in all

kinds of Gizmos. Some examples of common, every-day products that have

microcontrollers are built-in. If it has buttons and a digital display, chances are it

also has a programmable microcontroller brain.

Every-Day the devices used by ourselves that contain Microcontrollers. Try

to make a list and counting how many devices and the events with

microcontrollers you use in a typical day. Here are some examples: if your clock

radio goes off, and you hit the snooze button a few times in the morning, the first

thing you do in your day is interact with a microcontroller. Heating up some food

in the microwave oven and making a call on a cell phone also involve operatingmicrocontrollers.

That's just the beginning. Here are a few more examples: Turning on the

Television with a handheld remote, playing a hand held game, Using a calculator,

and Checking your digital wrist watch. All those devices have microcontrollers

inside them, that interact with you. Consumer appliances aren't the only things that

contain microcontrollers. Robots, machinery, aerospace designs and other high-

tech devices are also built with microcontrollers.

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BLOCK DIAGRAM OF MICROCONTROLLER:

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Pin Description:

VCC:

Supply voltage.

GND:

Ground.

Port 0:

Port 0 is an 8-bit open drain bidirectional I/O port. As an 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 and

data memory. In this mode P0 has internal pull-ups. 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 1

Port 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 verification.

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Port 2

Port 2 is an 8-bit bidirectional I/O port with internal pull-ups. The Port 2output 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-bitaddresses (MOVX @ DPTR). In this application it uses strong internal pull-ups

when emitting 1s. During accesses to external data memory that use 8-bit

addresses (MOVX @ RI), Port 2 emits the contents of the P2 Special Function

Register. Port 2 also receives the high-order address bits and some control signals

during Flash programming and verification.

Port 3

Port 3 is an 8-bit bidirectional I/O port with internal pull-ups. The Port 3

output buffers can sink/source four TTL inputs.

When 1s are written to Port 3 pins they are pulled high by the internal pull-

ups and can be used as inputs.

As inputs, Port 3 pins that are externally being pulled low will source

current (IIL) because of the pull-ups.

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Port 3 also serves the functions of various special features of the AT89C51

as listed below:

PORT PIN ALTERNATE FUNCTION

P3.0 RXD (serial input port)

P3.1 TXD(serial output port)

P3.2 INTO (external interrupt 0)

P3.3 INT1 (external interrupt 1)

P3.4 T0(timer 0 external input)

P3.5 T1(timer 1 external input)

P3.6 WR(external data memory write strobe)

P3.7 RD(external data memory write strobe)

Port 3 also receives some control signals for Flash programming and

verification.

RST

Reset input. A high on this pin for two machine cycles while the oscillator is

running resets the device.

ALE/PROG

Address Latch Enable output pulse for latching the low byte of the address

during accesses to external memory. This pin is also the program pulse input

(PROG) during Flash programming. In normal operation ALE is emitted at a

constant rate of 1/6 the oscillator frequency, and may be used for external timing

or clocking purposes. Note, however, that one ALE pulse is skipped during eachaccess to external Data Memory.

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If desired, ALE operation can be disabled by setting bit 0 of SFR location

8EH. With the bit set, ALE is active only during a MOVX or MOVC instruction.

Otherwise, the pin is weakly pulled high. Setting the ALE-disable bit has no effect

if the microcontroller is in external execution mode.

PSEN

Program Store Enable is the read strobe to external program memory. When

the AT89C51 is executing code from external program memory, PSEN is

activated twice each machine cycle, except that two PSEN activations are skipped

during each access to external data memory.

EA/VPP

External Access Enable(EA) must be strapped to GND in order to enable

the device to fetch code from external program memory locations starting at

0000H up to FFFFH. Note, however, that if lock bit 1 is programmed, EA will be

internally latched on reset. EA should be strapped to VCC for internal program

executions.

This pin also receives the 12-volt programming enable voltage (VPP) during

Flash programming, for parts that require 12-volt VPP.

XTAL1

Input to the inverting oscillator amplifier and input to the internal clock

operating circuit.

XTAL2

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Output from the inverting oscillator amplifier. It should be noted that when

idle is terminated by a hard ware reset, the device normally resumes program

execution, from where it left off, up to two machine cycles before the internal reset

algorithm takes control. On-chip hardware inhibits access to internal RAM in this

event, but access to the port pins is not inhibited.

To eliminate the possibility of an unexpected write to a port pin when Idle is

terminated by reset, the instruction following the one that invokes Idle should not

be one that writes to a port pin or to external memory.

Applications of Microcontrollers:

Microcontrollers are designed for use in sophisticated real time applications

such as

1. Industrial Control

2. Instrumentation and

3. Intelligent computer peripherals

They are used in industrial applications to control,

Motor.

Robotics.

Discrete and continuous process control.

In missile guidance and control.

In medical instrumentation.

Oscilloscopes.

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Telecommunication.

Automobiles.

For Scanning a keyboard.

Driving an LCD.

For Frequency measurements.

4.4 LCD DISPLAY

INTRODUCTION:

Liquid crystal displays (LCDs) have materials which combine the properties

of both liquids and crystals. Rather than having a melting point, they have a

temperature range within which the molecules are almost as mobile as they would

be in a liquid, but are grouped together in an ordered form similar to a crystal.

An LCD consists of two glass panels, with the liquid crystal material sand

witched in between them. The inner surface of the glass plates are coated with

transparent electrodes which define the character, symbols or patterns to be

displayed polymeric layers are present in between the electrodes and the liquidcrystal, which makes the liquid crystal molecules to maintain a defined orientation

angle.

One each polarisers are pasted outside the two glass panels. These polarisers

would rotate the light rays passing through them to a definite angle, in a particular

direction

When the LCD is in the off state, light rays are rotated by the two polarisers

and the liquid crystal, such that the light rays come out of the LCD without any

orientation, and hence the LCD appears transparent.

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When sufficient voltage is applied to the electrodes, the liquid crystal

molecules would be aligned in a specific direction. The light rays passing through

the LCD would be rotated by the polarisers, which would result in activating /

highlighting the desired characters.

The LCDs are lightweight with only a few millimeters thickness. Since the

LCDs consume less power, they are compatible with low power electronic

circuits, and can be powered for long durations.

The LCDs dont generate light and so light is needed to read the display.

By using backlighting, reading is possible in the dark. The LCDs have long life

and a wide operating temperature range.

Changing the display size or the layout size is relatively simple which

makes the LCDs more customer friendly.

The LCDs used exclusively in watches, calculators and measuring

instruments are the simple seven-segment displays, having a limited amount of

numeric data. The recent advances in technology have resulted in better legibility,

more information displaying capability and a wider temperature range. These have

resulted in the LCDs being extensively used in telecommunications and

entertainment electronics. The LCDs have even started replacing the cathode ray

tubes (CRTs) used for the display of text and graphics, and also in small TV

applications.

POWER SUPPLY:

The power supply should be of +5V, with maximum allowable transients of

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10mv. To achieve a better / suitable contrast for the display, the voltage (VL) at

pin 3 should be adjusted properly.

A module should not be inserted or removed from a live circuit. The ground

terminal of the power supply must be isolated properly so that no voltage is

induced in it. The module should be isolated from the other circuits, so that stray

voltages are not induced, which could cause a flickering display.

HARDWARE:

Develop a uniquely decoded E strobe pulse, active high, to accompany

each module transaction. Address or control lines can be assigned to drive the RS

and R/W inputs.

Utilize the Hosts extended timing mode, if available, when transacting with

the module. Use instructions, which prolong the Read and Write or other

appropriate data strobes, so as to realize the interface timing requirements.

If a parallel port is used to drive the RS, R/W and E control lines, setting

the E bit simultaneously with RS and R/W would violate the modules set uptime. A separate instruction should be used to achieve proper interfacing timing

requirements.

MOUNTING:

Cover the display surface with a transparent protective plate, to protect the

polarizer.

Dont touch the display surface with bare hands or any hard materials. This

will stain the display area and degrade the insulation between terminals.

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Do not use organic solvents to clean the display panel as these may

adversely affect tape or with absorbant cotton and petroleum benzene.

The processing or even a slight deformation of the claws of the metal frame

will have effect on the connection of the output signal and cause an abnormal

display.

Do not damage or modify the pattern wiring, or drill attachment holes in the

PCB.

When assembling the module into another equipment, the space between the

module and the fitting plate should have enough height, to avoid causing stress to

the module surface.

Make sure that there is enough space behind the module, to dissipate the

heat generated by the ICs while functioning for longer durations.

When an electrically powered screwdriver is used to install the module,

ground it properly.

While cleaning by a vacuum cleaner, do not bring the sucking mouth near

the module. Static electricity of the electrically powered driver or the vacuum

cleaner may destroy the module.

INTERFACING THE MICROPROCESSOR / CONTROLLER:

The module, interfaced to the system, can be treated as RAM input/output,

expanded or parallel I/O.

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Since there is no conventional chip select signal, developing a strobe signal

for the enable signal (E) and applying appropriate signals to the register select

(RS) and read/write (R/W) signals are important.

The module is selected by gating a decoded module address with the

host processors read/write strobe. The resultant signal, applied to the LCDs

enable (E) input, clocks in the data.

The E signal must be a positive going digital strobe, which is active while

data and control information are stable and true. The falling edge of the enable

signal enables the data / instruction register of the controller.

All module timings are referenced to specific edges of the E signal. The

E signal is applied only when a specific module transaction is desired.

The read and write strobes of the host, which provides the E signals,

should not be linked to the modules R/W line. An address bit which sets up

earlier in the hosts machine cycle can be used as R/W.

When the host processor is so fast that the strobes are too narrow to serve as

the E pulse

a. Prolong these pulses by using the hosts Ready input

b. Prolong the host by adding wait states

c. Decrease the Hosts Crystal frequency.

In spite of doing the above mentioned, if the problem continues, latch both the

data and control information and then activate the E signal

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When the controller is performing an internal operation he busy flag (BF) will

set and will not accept any instruction. The user should check the busy flag or

should provide a delay of approximately 2ms after each instruction.

The module presents no difficulties while interfacing slower MPUs.

The liquid crystal display module can be interfaced, either to 4-bit or 8-bit

MPUs.

For 4-bit data interface, the bus lines DB4 to DB7 are used for data transfer,

while DB0 to DB3 lines are disabled. The data transfer is complete when the 4-bit

data has been transferred twice.

The busy flag must be checked after the 4-bit data has been transferred twice.

Two more 4-bit operations then transfer the busy flag and address counter data.

4.5 REAL TIME CLOCK:

DESCRIPTION:

The DS12887 real-time clock (RTC) plus ram is designed to be a direct

replacement for the ds1287.the ds12887 is identical in form, fit, and function to

the ds1287, and has an additional 64 bytes of general-purpose ram. The logic level

presented on ad6 during the address portion of an access cycle determines access

to this additional ram space. A lithium energy source, quartz crystal, and write-

protection circuitry are contained within a 24-pin dual in-line package. As such,

the ds12887 is a complete subsystem replacing 16 components in a typical

application. The functions include a nonvolatile time-of-day clock, an alarm, a

100-year calendar, programmable interrupt, square-wave generator, and 114 bytes

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of NV SRAM. The RTC is unique in that time-of-day and memory are maintained

even in the absence of power.

FEATURES:

Drop-in replacement for IBM AT computer clock/calendar

Pin-compatible with the MC146818B and DS1287

Totally nonvolatile with over 10 years of operation in the absence of power

Self-contained subsystem includes lithium, quartz, and support circuitry

Counts seconds, minutes, hours, days, day of the week, date, month, and year

with leap-year compensation valid up to 2100

Binary or BCD representation of time, calendar, and alarm

12-hour or 24-hour clock with AM and PM in 12-hour mode

Daylight Savings Time option

Selectable between Motorola and Intel bus timing

Multiplex bus for pin efficiency

Interfaced with software as 128 RAM locations

14 bytes of clock and control registers

114 bytes of general-purpose RAM

Programmable square-wave output signal

Bus-compatible interrupt signals (IRQ)

Three interrupts are separately software-maskable and testable

Time-of-day alarm once/second to once/day

Periodic rates from 122ms to 500ms

End-of-clock update cycle

Underwriters Laboratory (UL) recognized

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RELAY:

A relay is an electrically operated switch. Current flowing through the coil

of the relay creates a magnetic field which attracts a lever and changes the switch

contacts. The coil current can be on or off so relays have two switch positions and

they are doublethrow (changeover) switches. Relays allow one circuit to switch a

second circuit which can be completely separate from the first. For example a low

voltage battery circuit can use a relay to switch a 230V AC mains circuit. There is

no electrical connection inside the relay between the two circuits; the link is

magnetic and mechanical.

The coil of a relay passes a relatively large current, typically 30mA for a12V relay, but it can be as much as 100mA for relays designed to operate from

lower voltages.

Most ICs (chips) cannot provide this current and a transistor is usually used

to amplify the small IC current to the larger value required for the relay coil.

The maximum output current for the popular 555 timer IC is 200mA so

these devices can supply relay coils directly without amplification.

Relays are usually SPDT or DPDT but they can have many more sets ofswitch contacts, for example relays with 4 sets of changeover contacts are readily

available. Most relays are designed for PCB mounting but you can solder wires

directly to the pins providing you take care to avoid melting the plastic case of the

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relay. The animated picture shows a working relay with its coil and switch

contacts.

You can see a lever on the left being attracted by magnetism when the coil

is switched on. This lever moves the switch contacts. There is one set of contacts

(SPDT) in the foreground and another behind them, making the relay DPDT.

The relay's switch connections are usually labeled COM, NC and NO:

COM = Common, always connect to this, it is the moving part of the

switch.

NC = Normally Closed, COM is connected to this when the relay coil is off.

NO = Normally Open, COM is connected to this when the relay coil is on.

RS232-SETUP

Interfacing the hard ware with the PC has the following advantages:

Storing and retrieval of data becomes easier.

Networking can be done and hence the entire system can be

monitored online.

Access can be user friendly.

Interfacing the hard ware with the PC is done using MAX232 (rs232)

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The MAX220MAX249 family of line drivers/receivers is intended for all

EIA/TIA-232E and V.28/V.24 communications interfaces, particularly

applications where 12V is not available. These parts are especially useful in

battery-powered systems, since their low-power shutdown mode reduces power

dissipation to less than 5W.

The MAX225, MAX233, MAX235, and MAX245/MAX246/MAX247 use

no external components and are recommended for applications where printed

circuit board space is critical.

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FEATURES:

Operate from Single +5V Power Supply (+5V and +12V

MAX231/MAX239)

Low-Power Receive Mode in Shutdown (MAX223/MAX242)

Meet All EIA/TIA-232E and V.28 Specifications

Multiple Drivers and Receivers

3-State Driver and Receiver Outputs

Open-Line Detection (MAX243)

4.6 KEYPAD

A numeric keypad, or numpad for short, is the small, palm-sized, seventeen

key section of a computer keyboard, usually on the very far right. The numeric

keypad features digits 0 to 9, addition (+), subtraction (-), multiplication (*) and

division (/) symbols, a decimal point (.) and Num Lock and Enter keys. Laptop

keyboards often do not have a numpad, but may provide numpad input by holdinga modifier key (typically lapelled "Fn") and operating keys on the standard

keyboard.

Particularly large laptops (typically those with a 17 inch screen or larger)

may have space for a real numpad, and many companies sell separate numpads

which connect to the host laptop by a USB connection.

Numeric keypads usually operate in two modes: when Num Lock is off,

keys 8, 6, 2, 4 act like an arrow keys and 7, 9, 3, 1 act like Home, PgUp, PgDn and

End; when Num Lock is on, digits keys produce corresponding digits.

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These, however, differ from the numeric keys at the top of the keyboard in

that, when combined with the Alt key on a PC, they are used to enter characters

which may not be otherwise available: for example, Alt-0169 produces the

copyright symbol. These are referred to as Alt codes.

On Apple Computer Macintosh computers, which lack a Num Lock key, the

numeric keypad always produces only numbers. The num lock key is replaced by

the clear key.

Numeric keypads usually operate in two modes: when Num Lock is off,

keys 8, 6, 2, 4 act like an arrow keys and 7, 9, 3, 1 act like Home, PgUp, PgDn and

End; when Num Lock is on, digits keys produce corresponding digits. These,

however, differ from the numeric keys at the top of the keyboard in that, when

combined with the Alt key on a PC, they are used to enter characters which may

not be otherwise available: for example, Alt-0169 produces the copyright symbol.

These are referred to as Alt codes.

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4.7 FSK (Frequency Shift Keying)

Frequency-shift keying (FSK) is a frequency modulation scheme in which

digital information is transmitted through discrete frequency changes of a carrier

wave. The simplest FSK isbinary FSK(BFSK). BFSK literally implies using a

pair of discrete frequencies to transmit binary (0s and 1s) information. With this

scheme, the "1" is called the mark frequency and the "0" is called the space

frequency. The time domain of an FSK modulated carrier is illustrated in the

figures to the right.

OTHER FORMS OF FSK

1. Minimum-shift keying

Minimum frequency-shift keying or minimum-shift keying (MSK) is a

particularly spectrally efficient form of coherent FSK. In MSK the difference

between the higher and lower frequency is identical to half the bit rate.

Consequently, the waveforms used to represent a 0 and a 1 bit differ by exactly

half a carrier period. This is the smallest FSKmodulation index that can be chosen

such that the waveforms for 0 and 1 are orthogonal. A variant of MSK

calledGMSKis used in the GSMmobile phone standard.

FSK is commonly used in Caller ID and remote metering applications:

see FSK standards for use in Caller ID and remote metering for more details.

2. Audio FSK

Audio frequency-shift keying (AFSK) is a modulation technique by

which digitaldata is represented by changes in the frequency (pitch) of

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an audio tone, yielding an encoded signal suitable for transmission

via radio ortelephone.

Normally, the transmitted audio alternates between two tones: one, the

"mark", represents abinary one; the other, the "space", represents a binary zero.

AFSK differs from regularfrequency-shift keying in performing the

modulation atbaseband frequencies. In radio applications, the AFSK-modulated

signal normally is being used to modulate an RFcarrier(using a conventional

technique, such as AM orFM) for transmission.

AFSK is not always used for high-speed data communications, since it is far

less efficient in both power and bandwidth than most other modulation modes. In

addition to its simplicity, however, AFSK has the advantage that encoded signals

will pass through AC-coupled links, including most equipment originally designed

to carry music or speech.

Most early telephone-line modems used audio frequency-shift keying to

send and receive data, up to rates of about 300 bits per second. The common Bell

103 modem used this technique, for example. Even today, North American callerID uses 1200 baud AFSK in the form of theBell 202 standard. Some

early microcomputers used a specific form of AFSK modulation, theKansas City

standard, to store data on audio cassettes. AFSK is still widely used in amateur

radio, as it allows data transmission through unmodified voiceband

equipment. Radio controlgear uses FSK, but calls it FM and PPM instead.

AFSK is also used in the United States' Emergency Alert System to transmit

warning information. It is used at higherbitrates forWeathercopyused

on Weatheradio byNOAA in the U.S., and more extensively by Environment

Canada.

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The CHUshortwave radio station in Ottawa, Canada broadcasts an

exclusive digital time signal encoded using AFSK modulation

4.8 RF TRANSMITTER RECEIVER

Radio frequency (RF) radiation is a subset of electromagnetic radiation

with a wavelength of 100km to 1mm, which is a frequency of 3 KHz to 300 GHz,

[1] respectively. This range of electromagnetic radiation constitutes the radio

spectrum and corresponds to the frequency ofalternating currentelectrical signals

used to produce and detect radio waves. RF can refer to electromagnetic

oscillations in either electrical circuits or radiation through air and space. Like

other subsets of electromagnetic radiation, RF travels at the speed of light.

RADIO COMMUNICATION

In order to receive radio signals, for instance from AM/FM radio stations, a

radio antenna must be used. However, since the antenna will pick up thousands of

radio signals at a time, a radio tuner is necessary to tune in to a particular

frequency (or frequency range).[2] This is typically done via a resonator (in its

simplest form, a circuit with a capacitor and an inductor). The resonator is

configured to resonate at a particular frequency (or frequency band), thus

amplifying sine waves at that radio frequency, while ignoring other sine waves.

Usually, either the inductor or the capacitor of the resonator is adjustable, allowing

the user to change the frequency at which it resonates.[3]

SPECIAL PROPERTIES OF RF ELECTRICAL SIGNALS

Electrical currents that oscillate at RF have special properties not shared by

direct current signals. One such property is the ease with which they can ionize air

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to create a conductive path through air. This property is exploited by 'high

frequency' units used in electric arc welding, although strictly speaking these

machines do not typically employ frequencies within the HF band.

Another special property is an electromagnetic force that drives the RF

current to the surface of conductors, known as the skin effect. Another property is

the ability to appear to flow through paths that contain insulating material, like the

dielectric insulator of a capacitor. The degree of effect of these properties depends

on the frequency of the signals.

RADIO SPECTRUM:

Radio spectrum refers to the part of the electromagnetic spectrum

corresponding to radio frequencies that is, frequencies lower than around

300 GHz (or, equivalently, wavelengths longer than about 1 mm).

Different parts of the radio spectrum are used for different radio

transmission technologies and applications. Radio spectrum is typically

government regulated in developed countries, and in some cases is sold or licensed

to operators of private radio transmission systems (for example, cellular telephoneoperators or broadcast television stations). Ranges of allocated frequencies are

often referred to by their provisioned use (for example, cellular spectrum or

television spectrum)

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BAND:

BAND NAME ABBR ITU

BAND

FREQUENCY &

WAVE LENGTH IN

AIR

EXAMPLE USES

subHertz subHz 0 < 3 Hz

> 100,000 km

Natural and man-made electromagnetic waves (millihertz,

microhertz, nanohertz) from earth, ionosphere, sun,

planets, etc [citation needed]

Extremely

low frequency

ELF 1 330 Hz

100000 km 10000km

Communication with submarines

Super low

frequency

SLF 2 30300 Hz

10,000 km 1000 km

Communication with submarines

Ultra low

frequency

ULF 3 3003000 Hz

1000 km 100 km

Communication within mines

Very low

frequency

VLF 4 330 kHz

100 km 10 km

Submarine communication, avalanche beacons, wireless

heart rate monitors, geophysics

Low

frequency

LF 5 30300 kHz

10 km 1 km

Navigation, time signals, AM longwave broadcasting,

RFID

Medium

frequency

MF 6 3003000 kHz

1 km 100 m

AM (medium-wave) broadcasts

High

frequency

HF 7 330 MHz

100 m 10 m

Shortwavebroadcasts, amateur radio and over-the-horizon

aviation communications, RFID

Veryhigh

frequency

VHF 8 30300 MHz

10 m 1 m

FM, television broadcasts and line-of-sight ground-to-

aircraft and aircraft-to-aircraft communications. Land

Mobile and Maritime Mobile communications

Ultra high

frequency

UHF 9 3003000 MHz

1 m 100 mm

Television broadcasts, microwave ovens, mobile phones,

wireless LAN, Bluetooth, GPS and two-way radios such

as Land Mobile, FRS and GMRS radios

Super high SHF 10 330 GHz Microwave devices, wireless LAN, most modern radars

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tp://en.wikipedia.org/wiki/Megahertzhttp://en.wikipedia.org/wiki/Millimeterhttp://en.wikipedia.org/wiki/Televisionhttp://en.wikipedia.org/wiki/Microwavehttp://en.wikipedia.org/wiki/Mobile_phonehttp://en.wikipedia.org/wiki/Wireless_LANhttp://en.wikipedia.org/wiki/Bluetoothhttp://en.wikipedia.org/wiki/GPShttp://en.wikipedia.org/wiki/Super_high_frequencyhttp://en.wikipedia.org/wiki/Gigahertzhttp://en.wikipedia.org/wiki/Microwavehttp://en.wikipedia.org/wiki/Wireless_LANhttp://en.wikipedia.org/wiki/Radar


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frequency 100 mm 10 mm

Extremely

highfrequency

EHF 11 30300 GHz

10 mm 1 mm

Radio astronomy, high-frequency microwave radio relay

Terahertz THz 12 3003,000 GHz

1 mm 100 m

Terahertz imaging a potential replacement for X-rays in

some medical applications, ultrafast molecular dynamics,

condensed-matter physics, terahertz time-domain

spectroscopy, terahertz computing/communications

Notes

Above 300 GHz, the absorption of electromagnetic radiation by Earth's

atmosphere is so great that the atmosphere is effectively opaque, until it

becomes transparent again in the infrared and optical window frequency

ranges.

The ELF, SLF, ULF, and VLF bands overlap the AF (audio frequency)

spectrum, which is approximately 2020,000 Hz. However, sounds are

transmitted by atmospheric compression and expansion, and not by

electromagnetic energy.

The SHF and EHF bands are sometimes not considered to be a part of the radio

spectrum, forming their own microwave spectrum.

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5.OVERALL CIRCUIT DIAGRAM

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5.OVERALL CIRCUIT DIAGRAM

Pg. 48


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Receiver

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6. OVERALL CIRCUIT DIAGRAM DESCRIPTION

Pg. 50


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6. OVERALL CIRCUIT DIAGRAM DESCRIPTION

6.1 POWERSUPPLY

1.Block diagram:

The ac voltage, typically 220V rms, is connected to a transformer, which

steps that ac voltage down to the level of the desired dc output. A diode rectifier

then provides a full-wave rectified voltage that is initially filtered by a simple

capacitor filter to produce a dc voltage. This resulting dc voltage usually has some

ripple or ac voltage variation.

A regulator circuit removes the ripples and also remains the same dc value

even if the input dc voltage varies, or the load connected to the output dc voltage

changes. This voltage regulation is usually obtained using one of the popular

voltage regulator IC units.

Block diagram (Power supply)

2.Working principle

Transformer

The potential transformer will step down the power supply voltage (0-230V)

to (0-6V) level. Then the secondary of the potential transformer will be connected

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to the precision rectifier, which is constructed with the help of opamp. The

advantages of using precision rectifier are it will give peak voltage output as DC,

rest of the circuits will give only RMS output.

Bridge rectifier

When four diodes are connected as shown in figure, the circuit is called as

bridge rectifier. The input to the circuit is applied to the diagonally opposite

corners of the network, and the output is taken from the remaining two corners.

Let us assume that the transformer is working properly and there is a

positive potential, at point A and a negative potential at point B. the positive

potential at point A will forward bias D3 and reverse bias D4.

The negative potential at point B will forward bias D1 and reverse D2. At

this time D3 and D1 are forward biased and will allow current flow to pass

through them; D4 and D2 are reverse biased and will block current flow.

The path for current flow is from point B through D1, up through RL,

through D3, through the secondary of the transformer back to point B. this path is

indicated by the solid arrows. Waveforms (1) and (2) can be observed across D1

and D3.

One-half cycle later the polarity across the secondary of the transformer

reverse, forward biasing D2 and D4 and reverse biasing D1 and D3. Current flow

will now be from point A through D4, up through RL, through D2, through the

secondary of T1, and back to point A. This path is indicated by the broken arrows.

Waveforms (3) and (4) can be observed across D2 and D4. The current flow

through RL is always in the same direction. In flowing through RL this current

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develops a voltage corresponding to that shown waveform (5). Since current flows

through the load (RL) during both half cycles of the applied voltage, this bridge

rectifier is a full-wave rectifier.

One advantage of a bridge rectifier over a conventional full-wave rectifier is

that with a given transformer the bridge rectifier produces a voltage output that is

nearly twice that of the conventional full-wave circuit.

This may be shown by assigning values to some of the components shown

in views A and B. assume that the same transformer is used in both circuits. The

peak voltage developed between points X and y is 1000 volts in both circuits. In

the conventional full-wave circuit shownin view A, the peak voltage from the

center tap to either X or Y is 500 volts. Since only one diode can conduct at any

instant, the maximum voltage that can be rectified at any instant is 500 volts.

The maximum voltage that appears across the load resistor is nearly-but

never exceeds-500 v0lts, as result of the small voltage drop across the diode. In the

bridge rectifier shown in view B, the maximum voltage that can be rectified is the

full secondary voltage, which is 1000 volts. Therefore, the peak output voltageacross the load resistor is nearly 1000 volts. With both circuits using the same

transformer, the bridge rectifier circuit produces a higher output voltage than the

conventional full-wave rectifier circuit.

IC voltage regulators

Voltage regulators comprise a class of widely used ICs. Regulator IC

units contain the circuitry for reference source, comparator amplifier, controldevice, and overload protection all in a single IC. IC units provide regulation of

either a fixed positive voltage, a fixed negative voltage, or an adjustably set

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voltage. The regulators can be selected for operation with load currents from

hundreds of milli amperes to tens of amperes, corresponding to power ratings from

milli watts to tens of watts.

Circuit diagram (Power supply)

A fixed three-terminal voltage regulator has an unregulated dc input

voltage, Vi, applied to one input terminal, a regulated dc output voltage, Vo, from

a second terminal, with the third terminal connected to ground.

The series 78 regulators provide fixed positive regulated voltages from 5 to

24 volts. Similarly, the series 79 regulators provide fixed negative regulated

voltages from 5 to 24 volts.

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For ICs, microcontroller, LCD --------- 5 volts

For alarm circuit, op-amp, relay circuits ---------- 12 volts

6.2 IR SENSING CIRCUIT

Infrared transmitter is one type of LED which emits infrared rays generally

called as IR Transmitter. Similarly IR Receiver is used to receive the IR rays

transmitted by the IR transmitter. One important point is both IR transmitter and

receiver should be placed straight line to each other.

The transmitted signal is given to IR transmitter whenever the signal is high,

the IR transmitter LED is conducting it passes the IR rays to the receiver. The IRreceiver is connected with comparator. The comparator is constructed with LM

358 operational amplifier. In the comparator circuit the reference voltage is given

to inverting input terminal. The non inverting input terminal is connected IR

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receiver. When interrupt the IR rays between the IR transmitter and receiver, the

IR receiver is not conducting. So the comparator non inverting input terminal

voltage is higher then inverting input. Now the comparator output is in the range

of +5V. This voltage is given to microcontroller or PC and led so led will glow.

When IR transmitter passes the rays to receiver, the IR receiver is

conducting due to that non inverting input voltage is lower than inverting input.

Now the comparator output is GND so the output is given to microcontroller or

PC. This circuit is mainly used to for counting application, intruder detector etc.

6.3 LCD WITH MICROCONTROLLER

AT89CS1 is the 40 pins, 8 bit Microcontroller manufactured by Atmel

group. It is the flash type reprogrammable memory. Advantage of this flash

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memory is we can erase the program with in few minutes. It has 4kb on chip ROM

and 128 bytes internal RAM and 32 I/O pin as arranged as port 0 to port 3 each

has 8 bit bin .Port 0 contain 8 data line(D0-D7) as well as low order address

line(AO-A7).

Port ` contain higher order address line (A8-A15). Port 3 contains special

purpose register such as serial input receiver register SBUF, interrupt INT0,INT1

and timers T0 , T1 many of the pins have multi functions which can be used as

general purpose I/P pins (or) Special purpose function can be decided by the

programmer itself.

CRYSTAL

The heart of the micro controller is the circuitries which generate the clock

pulse. Then micro controller provides the two pins. XTAL 1, XTAL 2 to correct

the external crystal resonator along with capacitor. The crystal frequency is the

basic clock frequency of the microcontroller.

RESET

The memory location for 89C51 0000H to 0FFFH. Whenever switch on the

supply the memory location starts from 0000H.The 89C51 micro controller

provide 9th pin for Reset Function.

Here the reset circuitry consists of 10Mf capacitor in series with 10K

resister. When switch on the supply the capacitor is changed and discharged gives

high low pulse to the 9th

pin through the 7414 inverter.

Here we interface LCD display to microcontroller via port 0 and port 2.

LCD control lines are connected in port 2 and Data lines are connected in port 0.

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6.4 FSK MODULATION WITH RF TRANSMITTER

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Frequency-shift keying (FSK) is a form of frequency modulation in which

the modulating signal shifts the output frequency between predetermined values.

Usually, the instantaneous frequency is shifted between two discrete values termed

the mark frequency and the space frequency. Continuous phase forms of FSK exist

in which there is no phase discontinuity in the modulated signal. The example

shown at right is of such a form. Other names for FSK are frequency-shift

modulation and frequency-shift signaling.

Circuit Description:

The digital data communication and computer peripheral, binary data is

transmitted by means of a carrier frequency which is shifted between two preset

frequencies. This type of data transmission is called frequency shift keying

technique. Frequency keying is a form of frequency modulation in which the

carrier switches abruptly from one frequency to another on receipt of a commandor keying signal. Most oscillator circuit can be subjected to FSK by simply

designing them so that an alternative frequency determining component or

parameter is selected on receipt of the key signal. The key signal or input signal

may be delivered electro- mechanically via a switch, electronically via transistor

gate or via PC etc.

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The XR 2206 is the waveform generator specifically allocated for FSK

use.

This IC has two alternative timing resistor pins such as pins 7 and 8. Either

pin can be selected by applying a suitable bias signal to pin 9 of the IC.

When the pin 9 FSK input terminal is open circuit or externally biased

above 2v with respect to negative supply, the pin 7 timing resistor is automatically

selected and the circuit operates at a frequency determined by R1 and C1. When

pin 9 is shorted to the negative supply or biased below 1V with reference to the

negative supply, the pin 8 timing resistor is selected and the circuit operates at a

frequency determined by R2 and C1. The XR-2206 IC can thus be frequency shift

keyed by simply applying a suitable keying or pulse signal between pin 9 and the

negative supply.

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In this circuit the data signal to be modulated is out from PC through serial

port.

9 pin D type connector is used to interface the PC and FSK circuit in

which 3 pin is transmitting pin. This pin is connected to base of the Q1 transistor.

When high pulse is coming Q1 is conducting so collector and emitter is short 0V is

given to input of the two serious inverter so -12V is given to 9 th pin of XR-2206.

When low pulse from PC Q1 transistor is in the cut off region so +12V is given to

9th pin of XR-2206 vice versa.

Depending on the pulse on 9th pin the timing resistor R1 and R2 is selected from

the pin 7 and 8 respectively. Here the capacitor C1 is kept constant. So XR-2206

generating two set of frequency 1200 Hz and 1400 Hz named as F1 and F2

respectively on the 11th pin. Then the frequency shifted output is given to RF

transmitter.

FSK DEMODULATION WITH RF RECEIVER

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The binary data or code is transmitted by means of a carrier frequency that

is shifted between two preset frequencies. Since a carrier frequency is shifted

between two preset frequencies, the data transmission is said to use a frequency

shift keying technique.

RF Receiver:

The RF receiver is used to receive the data which is transmitted by the RF

transmitter. Then the received data is given to transistor which acts as amplifier.

Then the amplified signal is given to carrier demodulator section in which

transistor Q1 is turn on and turn off conducting depends on the signal. Due to this

the capacitor C14 is charged and discharged so carrier signal is removed and saw

tooth signal is appears across the capacitor. Then this saw tooth signal is given to

comparator.

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The comparator circuit is constructed by LM568. The comparator is used to

convert the saw tooth signal to exact square pulse. Then the square pulse is further

amplified by LM741. After the amplification the amplified signal is given to FSK

demodulator section.

FSK Demodulator:

The FSK demodulator is constructed by LM 565 phase locked loop. In the

565 PLL the frequency shift is usually accomplished by driving a VCO with the

binary data signal so that the two resulting frequencies correspond to logic 0 and

logic 1 state are commonly called the mark and space frequencies.

The input frequencies are applied to pin 2 and output is taken from pin 7. In

addition to the low pass filter, a three-stage RC filter is connected to pin 7 to

remove the carrier from the output. The output pin 7 and reference pin 6 are

connected to a comparator, which provide the output pulse. The free running

frequency is set by VR1. Here we set the free running frequency is 1300Hz. It is

also called as centre frequency. The input frequencies are 1200Hz and 1400Hz.

When the input frequency is 1400Hz, the output 7th pin is higher then reference pin

6th the comparator provides the pulse at the output. When the input frequency is

1200Hz, the output 7th pin is lower than reference 6th pin the comparator provides

the zero at the output. Now we are getting exact pulse as we transmit from

transmitting side PC. The output pulse is given to receiver side PC or to the

microcontroller. When output is given to microcontroller, the pulse is converted

into 0 to 5v pulse with the help of transistor.

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RS232 COMMUNICATION

RS232:

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

interconnection between a DTE (Data terminal equipment) and a DCE (Data

Circuit-terminating Equipment). It is commonly used in computer serial ports.

SCOPE OF THE STANDARD:

The Electronic Industries Alliance (EIA) standard RS-232-C [3] as of 1969

defines:

Electrical signal characteristics such as voltage levels, signaling rate, timing

and slew-rate of signals, voltage withstand level, short-circuit behavior,

maximum stray capacitance and cable length Interface mechanical characteristics, pluggable connectors and pin

identification

Functions of each circuit in the interface connector

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Standard subsets of interface circuits for selected telecom applications

The standard does not define such elements as character encoding (for

example, ASCII, Baudot or EBCDIC), or the framing of characters in the data

stream (bits per character, start/stop bits, parity). The standard does not define

protocols for error detection or algorithms for data compression.

The standard does not define bit rates for transmission, although the standard

says it is intended for bit rates lower than 20,000 bits per second. Many modern

devices can exceed this speed (38,400 and 57,600 bit/s being common, and

115,200 and 230,400 bit/s making occasional appearances) while still using RS-

232 compatible signal levels.

Details of character format and transmission bit rate are controlled by the serial

port hardware, often a single integrated circuit called a UART that converts data

from parallel to serial form. A typical serial port includes specialized driver and

receiver integrated circuits to convert between internal logic levels and RS-232

compatible signal levels.

CIRCUIT WORKING DESCRIPTION:

In this circuit the MAX 232 IC used as level logic converter. The MAX232

is a dual driver/receiver that includes a capacive voltage generator to supply EIA

232 voltage levels from a single 5v supply. Each receiver converts EIA-232 to 5v

TTL/CMOS levels. Each driver converts TLL/CMOS input levels into EIA-232

levels.

FUNCTION TABLES:

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LOGIC DIAGRAM (POSITIVE LOGIC):

In this circuit the microcontroller transmitter pin is connected in the MAX232

T2IN pin which converts input 5v TTL/CMOS level to RS232 level. Then T2OUT

pin is connected to reviver pin of 9 pin D type serial connector which is directly

connected to PC.

In PC the transmitting data is given to R2IN of MAX232 through

transmitting pin of 9 pin D type connector which converts the RS232 level to 5v

TTL/CMOS level. The R2OUT pin is connected to receiver pin of the

microcontroller. Likewise the data is transmitted and received between the

microcontroller and PC or other device vice versa.

RELAY CIRCUIT - SPST

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Relay:

A relay is an electrically operated switch. Current flowing through the coil

of the relay creates a magnetic field which attracts a lever and changes the switch

contacts. The coil current can be on or off so relays have two switch positions and

they are doublethrow (changeover) switches. Relays allow one circuit to switch a

second circuit which can be completely separate from the first. For example a low

voltage battery circuit can use a relay to switch a 230V AC mains circuit. There isno electrical connection inside the relay between the two circuits; the link is

magnetic and mechanical.

The coil of a relay passes a relatively large current, typically 30mA for a

12V relay, but it can be as much as 100mA for relays designed to operate from

lower voltages. Most ICs (chips) cannot provide this current and a transistor is

usually used to amplify the small IC current to the larger value required for the

relay coil. The maximum output current for the popular 555 timer IC is 200mA so

these devices can supply relay coils directly without amplification.

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Relays are usually SPDT or DPDT but they can have many more sets of

switch contacts, for example relays with 4 sets of changeover contacts are readily

available. Most relays are designed for PCB mounting but you can solder wires

directly to the pins providing you take care to avoid melting the plastic case of the

relay.

The animated picture shows a working relay with its coil and switch

contacts. You can see a lever on the left being attracted by magnetism when the

coil is switched on. This lever moves the switch contacts. There is one set of

contacts (SPDT) in the foreground and another behind them, making the relay

DPDT.

The relay's switch connections are usually labeled COM, NC and NO:

COM = Common, always connect to this, it is the moving part of the

switch.

NC = Normally Closed, COM is connected to this when the relay coil is off.

NO = Normally Open, COM is connected to this when the relay coil is on.

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Circuit description:

This circuit is designed to control the load. The load may be motor or any

other load. The load is turned ON and OFF through relay. The relay ON and OFF

is controlled by the pair of switching transistors (BC 547). The relay is connected

in the Q2 transistor collector terminal. A Relay is nothing but electromagnetic

switching device which consists of three pins. They are Common, Normally close

(NC) and Normally open (NO).

The relay common pin is connected to supply voltage. The normally open

(NO) pin connected to load.

When high pulse signal is given to base of the Q1 transistors, the transistor is

conducting and shorts the collector and emitter terminal and zero signals is given

to base of the Q2 transistor. So the relay is turned OFF state.

When low pulse is given to base of transistor Q1 transistor, the

transistor is turned OFF. Now 12v is given to base of Q2 transistor so the

transistor is conducting and relay is turned ON. Hence the common terminal and

NO terminal of relay are shorted. Now load gets the supply voltage through relay.

Voltage signal from

microcontroller or

pc

Transistor Q1 Transistor Q2 Relay

1 ON OFF OFF

0 OFF ON ON

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7. PCB DESIGNING

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7. PCB DESIGNING

Design and Fabrication of Printed circuit boards

7.1 INTRODUCTION:

Printed circuit boards, or PCBs, form the core of electronic equipment

domestic and industrial. Some of the areas where PCBs are intensively used are

computers, process control, telecommunications and instrumentation.

7.2 MANUFATCURING:

The manufacturing process consists of two methods; print and etch, and

print, plate and etch. The single sided PCBs are usually made using the print and

etch method. The double sided plate through hole (PTH) boards are made by the

print plate and etch method.

The production of multi layer boards uses both the methods. The inner

layers are printed and etch while the outer layers are produced by print, plate and

etch after pressing the inner layers.

7.3 SOFTWARE:

The software used in our project to obtain the schematic layout is

MICROSIM.

7.4 PANELISATION:

Here the schematic transformed in to the working positive/negative films.

The circuit is repeated conveniently to accommodate economically as many

circuits as possible in a panel, which can be operated in every sequence of

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subsequent steps in the pcb process. This is called penalization. For the pth boards,

the next operation is drilling.

7.5 DRILLING:

PCB drilling is a state of the art operation. Very small holes are drilled with

high speed CNC drilling machines, giving a wall finish with less or no smear or

epoxy, required for void free through hole plating.

7.6 PLATING:

The heart of the PCB manufacturing process. The holes drilled in the board

are treated both mechanically and chemically before depositing the copper by the

electro less copper platting process.

7.7 ETCHING:

Once a multiplayer board is drilled and electro less copper deposited, the

image available in the form of a film is transferred on to the out side by photo

printing using a dry film printing process. The boards are then electrolytic plated

on to the circuit pattern with copper and tin. The tin-plated deposit serves an etch

resist when copper in the unwanted area is removed by the conveyors spray

etching machines with chemical etch ants. The etching machines are attached to an

automatic dosing equipment, which analyses and controls etch ants concentrations

7.8 SOLDERMASK:

Since a PCB design may call for very close spacing between conductors, asolder mask has to be applied on the both sides of the circuitry to avoid the

bridging of conductors. The solder mask ink is applied by screening. The ink is

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dried, exposed to UV, developed in a mild alkaline solution and finally cured by

both UV and thermal energy.

HOT AIR LEVELLING:

After applying the solder mask, the circuit pads are soldered using the hot

air leveling process. The bare bodies fluxed and dipped in to a molten solder bath.

While removing the board from the solder bath, hot air is blown on both sides of

the board through air knives in the machines, leaving the board soldered and

leveled. This is one of the common finishes given to the boards. Thus the double

sided plated through whole printed circuit board is manufactured and is now ready

for the components to be soldered.

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8.SOFTWARE TOOLS

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8.SOFTWARE TOOLS

8.1 KEIL C COMPILER:

Keil development tools for the 8051 Microcontroller Architecture support

every level of software developer from the professional applications engineer to

the student just learning about embedded software development.

The industry-standard Keil C Compilers, Macro Assemblers, Debuggers,

Real-time Kernels, Single-board Computers, and Emulators support all 8051

derivatives and help you get your projects completed on schedule.

THE KEIL 8051 DEVELOPMENT TOOLS ARE DESIGNED TO SOLVE THE

COMPLEX PROBLEMS FACING EMBEDDED SOFTWARE DEVELOPERS.

When starting a new project, simply select the microcontroller you use from

the Device Database and the Vision IDE sets all compiler, assembler,

linker, and memory options for you.

Numerous example programs are included to help you get started with the

most popular embedded 80

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