312_DOC

PLEASE NOTE: THE MATTER PRODUCED BELOW IS REFERENCE MATERIAL ONLY FOR PREPARING THE PROJECT REPORT. IT IS NOT THE COMPLETE PROJECT REPORT.

1

A PROJECT REPORT ON

TRANSFORMER HEALTH MONITORING SYSTEM

WIRELESS USING XBEESubmitted in partial fulfillment of the requirements

For the award of the degree

BACHELOR OF ENGINEERING

IN

ELECTRONICS AND COMMUNICATION ENGINEERING

SUBMITTED BY

___________ (_______)

____________ (_______)

____________ (_______)

DEPARTMENT OF ______________ ENGINEERING

________ COLLEGE OF ENGINEERINGAFFILIATED TO ___________ UNIVERSITY

2

CERTIFICATE

This is to certify that the dissertation work entitled TRANSFORMER

HEALTH MONITORING SYSTEM WIRELESS USING XBEE is the work done by

_________________________________________________________ submitted

in partial fulfillment for the award of ‘BACHELOR OF ENGINEERING (B.E)’ in

____________________________ Engineering from ___________ College of

Engineering affiliated to _________ University , Hyderabad .

___________________ _____________

(Head of the department, ECE) (Assistant Professor)

EXTERNAL EXAMINER

3

ACKNOWLEDGEMENT

The satisfaction and euphoria that accompany the successful completion of any

task would be incomplete without the mentioning of the people whose constant

guidance and encouragement made it possible. We take pleasure in presenting

before you, our project, which is result of studied blend of both research and

knowledge.

We express our earnest gratitude to our internal guide, Assistant Professor

___________, Department of ECE, our project guide, for his constant support,

encouragement and guidance. We are grateful for his cooperation and his valuable

suggestions.

4

DECLARATION

We, the undersigned, declare that the project entitled ‘TRANSFORMER

HEALTH MONITORING SYSTEM WIRELESS USING XBEE’,

being submitted in partial fulfillment for the award of Bachelor of Engineering

Degree in Electronics and Communication Engineering, affiliated to __________

University, is the work carried out by us.

___________ ___________ __________

___________ ____________ ___________

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CONTENTS PAGE NO.

1. ABSTRACT 13

2. INTRODUCTION TO EMBEDDED SYSTEMS 13

3. BLOCK DIAGRAM 15

4. HARDWARE REQUIREMENTS

4.1 TRANSFORMERS 17

4.2 VOLTAGE REGULATOR (LM7805) 19

4.3 RECTIFIER

4.4 FILTER

4.5 MICROCONTROLLER (AT89S52/C51) 22

4.6 ADC0808

4.7 MAX232

4.8 ULN2003

4.9 RELAY DRIVER

4.10 DB9 CONNECTOR

4.11 LM35 TEMPERATURE SENSOR

4.12 LED

4.13 IN4007

4.14 RESISTORS

4.15 CAPACITORS

5. SOFTWARE REQUIREMENTS

5.1 IDE 57

5.2 CONCEPT OF COMPILER 57

5.3 CONCEPT OF CROSS COMPILER 58

5.4 KEIL C CROSS COMPILER 59

6

5.5 BUILDING AN APPLICATION IN UVISION2 59

5.6 CREATING YOUR OWN APPLICATION IN UVISION2 59

5.7 DEBUGGING AN APPLICATION IN UVISION2 60

5.8 STARTING UVISION2 & CREATING A PROJECT 61

5.9 WINDOWS_ FILES 61

5.10 BUILDING PROJECTS & CREATING HEX FILES 61

5.11 CPU SIMULATION 62

5.12 DATABASE SELECTION 62

5.13 START DEBUGGING 63

5.14 DISASSEMBLY WINDOW 63

5.15 EMBEDDED C 64

6. SCHEMATIC DIAGRAM 66

6.1 DESCRIPTION 67

7. LAYOUT DIAGRAM 71

8. BILL OF MATERIALS 72

9. CODING 75

9.1 COMPILER 76

9.2 SOURCE CODE 84

10. HARDWARE TESTING 88

10.1 CONTINUITY TEST 88

10.2 POWER ON TEST 89

11. RESULTS 69

12. CONCLUSION 937

13. BIBLIOGRAPHY 94

LIST OF FIGURES PAGE NO.

2(a) EMBEDDED DESIGN CALLS

2(b) V DIAGRAM

3. BLOCK DIAGRAM OF THE PROJECT

4.1 A TYPICAL TRANSFORMER 17

4.2 BLOCK DIAGRAM OF VOLTAGE

REGULATOR 20

4.2(a) PERFORMANCE CHARACTERISTICS

OF VOLTAGE REGULATOR 21

4.5 BLOCK DIAGRAM OF AT89S52 24

4.5(b) PIN DIAGRAM OF AT89S52 25

4.5(c) OSCILLATOR CONNECTIONS 29

4.5(d) EXTERNAL CLOCK DRIVE CONFIG. 30

4.6 ADC0808 31

4.8(a) LOGIC DIAGRAM OF ULN2003 37

4.8(b) SCHEMATIC DIAGRAM OF ULN2003 38

4.8(c) RELAY SHOWING COIL & SWITCH CONTACTS 39

6. SCHEMATIC DIAGRAM OF THE PROJECT 42

7. PROJECT LAYOUT

8

8.1 CONTINUITY TEST 64

8.2 POWER ON TEST 66

ABSTRACTPLEASE REFER CD

9

2. INTRODUCTION TO EMBEDDED SYSTEMS

What is Embedded system?An Embedded System is a combination of computer hardware and software, and perhaps

additional mechanical or other parts, designed to perform a specific function. An embedded

system is a microcontroller-based, software driven, reliable, real-time control system,

autonomous, or human or network interactive, operating on diverse physical variables and in

diverse environments and sold into a competitive and cost conscious market.

An embedded system is not a computer system that is used primarily for processing, not a

software system on PC or UNIX, not a traditional business or scientific application. High-end

embedded & lower end embedded systems. High-end embedded system - Generally 32, 64 Bit

Controllers used with OS. Examples Personal Digital Assistant and Mobile phones etc .Lower

end embedded systems - Generally 8,16 Bit Controllers used with an minimal operating systems 10

and hardware layout designed for the specific purpose. Examples Small controllers and devices

in our everyday life like Washing Machine, Microwave Ovens, where they are embedded in.

SYSTEM DESIGN CALLS:

Figure 2.1(a) Embedded System design calls

EMBEDDED SYSTEM DESIGN CYCLE

Figure 2.1(b): “V Diagram”

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EmbeddedSystemsComputer

Architecture

SoftwareEngineering

Data Communication

ControlEngineering

Electric motorsand actuators

Sensors andmeasurements

AnalogElectronic design

DigitalElectronic design Integrated circuit

design

Embedded system design calls on many disciplines

Operating Systems

BuildDownload

DebugTools

System

Testing

System

Definition

Targeting

Rapid Prototyp

ing

Hardware-in-

the-Loop Testin

g

Characteristics of Embedded System• An embedded system is any computer system hidden inside a product other than a

computer.

• They will encounter a number of difficulties when writing embedded system software in

addition to those we encounter when we write applications.

– Throughput – Our system may need to handle a lot of data in a short period of

time.

– Response–Our system may need to react to events quickly.

– Testability–Setting up equipment to test embedded software can be difficult.

– Debugability–Without a screen or a keyboard, finding out what the software is

doing wrong (other than not working) is a troublesome problem.

– Reliability – embedded systems must be able to handle any situation without

human intervention.

– Memory space – Memory is limited on embedded systems, and you must make

the software and the data fit into whatever memory exists.

– Program installation – you will need special tools to get your software into

embedded systems.

– Power consumption – Portable systems must run on battery power, and the

software in these systems must conserve power.

– Processor hogs – computing that requires large amounts of CPU time can

complicate the response problem.

– Cost – Reducing the cost of the hardware is a concern in many embedded system

projects; software often operates on hardware that is barely adequate for the job.

• Embedded systems have a microprocessor/ microcontroller and a memory. Some have a

serial port or a network connection. They usually do not have keyboards, screens or disk

drives.

APPLICATIONS

1) Military and aerospace embedded software applications

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2) Communicat ion Appl icat ions

3) Indust r ia l automat ion and process control sof tware

4) Mastering the complexity of applications.

5) Reduction of product design time.

6) Real time processing of ever increasing amounts of data.

7) Intelligent, autonomous sensors.

CLASSIFICATION

Real Time Systems.

RTS is one which has to respond to events within a specified deadline.

A right answer after the dead line is a wrong answer

RTS CLASSIFICATION

Hard Real Time Systems

Soft Real Time System

HARD REAL TIME SYSTEM

"Hard" real-time systems have very narrow response time.

Example: Nuclear power system, Cardiac pacemaker.

SOFT REAL TIME SYSTEM

"Soft" real-time systems have reduced constrains on "lateness" but still must operate very

quickly and repeatable.

Example: Railway reservation system – takes a few extra seconds the data remains valid.

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3. BLOCK DIAGRAM

PLEASE REFER CD

14

4. HARDWARE REQUIREMENTS

HARDWARE COMPONENTS:

1. TRANSFORMER (230 – 12 V AC)

2. VOLTAGE REGULATOR (LM 7805)

3. FILTER

4. RECTIFIER

5. MICROCONTROLLER (AT89S52/AT89C51)

6. ADC0808

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7. MAX232

8. RELAYS

9. DB9 CONNECTOR

10. LM35 TEMPERATURE SENSOR

11. ULN2003

12. LED

13. IN4007

14. RESISTORS

15. CAPACITORS

4.1 TRANSFORMER

Transformers convert AC electricity from one voltage to another with a little loss of power.

Step-up transformers increase voltage, step-down transformers reduce voltage. Most power

supplies use a step-down transformer to reduce the dangerously high voltage to a safer low

voltage.

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FIG 4.1: A TYPICAL TRANSFORMER

The input coil is called the primary and the output coil is called the secondary. There is

no electrical connection between the two coils; instead they are linked by an alternating magnetic

field created in the soft-iron core of the transformer. The two lines in the middle of the circuit

symbol represent the core. Transformers waste very little power so the power out is (almost)

equal to the power in. Note that as voltage is stepped down and current is stepped up.

The ratio of the number of turns on each coil, called the turn’s ratio, determines the ratio

of the voltages. A step-down transformer has a large number of turns on its primary (input) coil

which is connected to the high voltage mains supply, and a small number of turns on its

secondary (output) coil to give a low output voltage.

TURNS RATIO = (Vp / Vs) = ( Np / Ns )

Where,

Vp = primary (input) voltage.

Vs = secondary (output) voltage

Np = number of turns on primary coil

Ns = number of turns on secondary coil

Ip = primary (input) current

Is = secondary (output) current.

Ideal power equation

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The ideal transformer as a circuit element

If the secondary coil is attached to a load that allows current to flow, electrical power is

transmitted from the primary circuit to the secondary circuit. Ideally, the transformer is perfectly

efficient; all the incoming energy is transformed from the primary circuit to the magnetic field

and into the secondary circuit. If this condition is met, the incoming electric power must equal

the outgoing power:

giving the ideal transformer equation

Transformers normally have high efficiency, so this formula is a reasonable approximation.

If the voltage is increased, then the current is decreased by the same factor. The impedance in

one circuit is transformed by the square of the turns ratio. For example, if an impedance Zs is

attached across the terminals of the secondary coil, it appears to the primary circuit to have an

impedance of (Np/Ns)2Zs. This relationship is reciprocal, so that the impedance Zp of the primary

circuit appears to the secondary to be (Ns/Np)2Zp.

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4.2 VOLTAGE REGULATOR 7805

Features

• Output Current up to 1A.

• Output Voltages of 5, 6, 8, 9, 10, 12, 15, 18, 24V.

• Thermal Overload Protection.

• Short Circuit Protection.

• Output Transistor Safe Operating Area Protection.

Description

The LM78XX/LM78XXA series of three-terminal positive regulators are available in the

TO-220/D-PAK package and with several fixed output voltages, making them useful in a Wide

range of applications. Each type employs internal current limiting, thermal shutdown and safe

operating area protection, making it essentially indestructible. If adequate heat sinking is

provided, they can deliver over 1A output Current. Although designed primarily as fixed voltage

regulators, these devices can be used with external components to obtain adjustable voltages and

currents.

Internal Block Diagram

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FIG 4.2(a): BLOCK DIAGRAM OF VOLTAGE REGULATOR

Absolute Maximum Ratings

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TABLE 4.2(b): RATINGS OF THE VOLTAGE REGULATOR

4.3 RECTIFIER

A rectifier is an electrical device that converts alternating current (AC), which

periodically reverses direction, to direct current (DC), current that flows in only one direction, a

process known as rectification. Rectifiers have many uses including as components of power

supplies and as detectors of radio signals. Rectifiers may be made of solid state diodes, vacuum

tube diodes, mercury arc valves, and other components. The output from the transformer is fed to

the rectifier. It converts A.C. into pulsating D.C. The rectifier may be a half wave or a full wave

rectifier. In this project, a bridge rectifier is used because of its merits like good stability and full

wave rectification. In positive half cycle only two diodes( 1 set of parallel diodes) will conduct,

in negative half cycle remaining two diodes will conduct and they will conduct only in forward

bias only.

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4.4 FILTER

Capacitive filter is used in this project. It removes the ripples from the output of rectifier

and smoothens the D.C. Output received from this filter is constant until the mains voltage and

load is maintained constant. However, if either of the two is varied, D.C. voltage received at this

point changes. Therefore a regulator is applied at the output stage.

The simple capacitor filter is the most basic type of power supply filter. The use of this

filter is very limited. It is sometimes used on extremely high-voltage, low-current power supplies

for cathode-ray and similar electron tubes that require very little load current from the supply.

This filter is also used in circuits where the power-supply ripple frequency is not critical and can

be relatively high. Below figure can show how the capacitor charges and discharges.

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4.5 MICROCONTROLLER AT89S52 The AT89S52 is a low-power, high-performance CMOS 8-bit microcontroller with 8K

bytes 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

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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:• Compatible with MCS®-51 Products

• 8K Bytes of In-System Programmable (ISP) Flash Memory

– Endurance: 10,000 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)

• Green (Pb/Halide-free) Packaging Option

24

Block Diagram of AT89S52:

FIG 4.5: BLOCK DIAGRAM OF AT89S52

Pin Configurations of AT89S52

25

FIG 4.2.5(b): PIN DIAGRAM OF AT89S52

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 can 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

26

low will source current (IIL) because of the internal pull-ups. In addition, P1.0 and P1.1 can be

configured to be the timer/counter 2 external count input (P1.0/T2) and the timer/counter 2

trigger input (P1.1/T2EX).

Port 2:

Port 2 is an 8-bit bidirectional I/O port with internal pull-ups. The Port 2 output buffers

can sink/source four TTL inputs. When 1s are written to Port 2 pins, they are pulled high by the

internal pull-ups and can be used as inputs. As inputs, Port 2 pins that are externally being pulled

low will source current (IIL) because of the internal pull-ups. Port 2 emits the high-order address

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

that use 16-bit addresses (MOVX @ DPTR). In this application, Port 2 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 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.

RST:

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

resets the device. This pin drives high for 98 oscillator periods after the Watchdog times out. The

DISRTO bit in SFR AUXR (address 8EH) can be used to disable this feature. In the default state

of bit DISRTO, the RESET HIGH out feature is enabled.

ALE/PROG:

Address Latch Enable (ALE) is an 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 each access to external data memory.

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PSEN:

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

AT89S52 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.

XTAL1:

Input to the inverting oscillator amplifier and input to the internal clock operating circuit.

XTAL2:

Output from the inverting oscillator amplifier

Oscillator Characteristics:

XTAL1 and XTAL2 are the input and output, respectively, of an inverting amplifier

which can be configured for use as an on-chip oscillator, as shown in Figure 1. Either a quartz

crystal or ceramic resonator may be used. To drive the device from an external clock source,

XTAL2 should be left unconnected while XTAL1 is driven as shown in Figure 6.2. There are no

requirements on the duty cycle of the external clock signal, since the input to the internal

clocking circuitry is through a divide-by-two flip-flop, but minimum and maximum voltage high

and low time specifications must be observed.

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FIG 4.5(c): Oscillator Connections

FIG 4.5(d): External Clock Drive Configuration

Idle Mode

In idle mode, the CPU puts itself to sleep while all the on chip peripherals remain active.

The mode is invoked by software. The content of the on-chip RAM and all the special functions

registers remain unchanged during this mode. The idle mode can be terminated by any enabled

interrupt or by a hardware reset.

Power down Mode

In the power down mode the oscillator is stopped, and the instruction that invokes power

down is the last instruction executed. The on-chip RAM and Special Function Registers retain

their values until the power down mode is terminated. The only exit from power down is a

hardware reset. Reset redefines the SFRs but does not change the on-chip RAM. The reset

should not be activated before VCC is restored to its normal operating level and must be held

active long enough to allow the oscillator to restart and stabilize.

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LIQUID CRYSTAL DISPLAY(LCD)

Description:

This is the example for the Parallel Port. This example doesn't use the Bi-directional

feature found on newer ports, thus it should work with most, if not all Parallel Ports. It however

doesn't show the use of the Status Port as an input for a 16 Character x 2 Line LCD Module to

the Parallel Port. These LCD Modules are very common these days, and are quite simple to work

with, as all the logic required running them is on board.

Pros:

Very compact and light

Low power consumption

No geometric distortion

Little or no flicker depending on backlight technology

Not affected by screen burn-in

No high voltage or other hazards present during repair/service

Can be made in almost any size or shape

No theoretical resolution limit

LCD Background:

Frequently, an 8051 program must interact with the outside world using input and output

devices that communicate directly with a human being. One of the most common devices

attached to an 8051 is an LCD display. Some of the most common LCDs connected to the 8051

are 16x2 and 20x2 displays. This means 16 characters per line by 2 lines and 20 characters per

line by 2 lines, respectively.

Fortunately, a very popular standard exists which allows us to communicate with the vast

majority of LCDs regardless of their manufacturer. The standard is referred to as HD44780U,

which refers to the controller chip which receives data from an external source (in this case, the

8051) and communicates directly with the LCD.

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FIG 4.10: LCD

44780 LCD BACKGROUND

The 44780 standard requires 3 control lines as well as either 4 or 8 I/O lines for the data

bus. The user may select whether the LCD is to operate with a 4-bit data bus or an 8-bit data bus.

If a 4-bit data bus is used the LCD will require a total of 7 data lines (3 control lines plus the 4

lines for the data bus). If an 8-bit data bus is used the LCD will require a total of 11 data lines (3

control lines plus the 8 lines for the data bus).

The three control lines are referred to as EN, RS, and RW.

The EN line is called "Enable." This control line is used to tell the LCD that you are

sending it data. To send data to the LCD, your program should make sure this line is low (0) and 31

then set the other two control lines and/or put data on the data bus. When the other lines are

completely ready, bring EN high (1) and wait for the minimum amount of time required by the

LCD datasheet (this varies from LCD to LCD), and end by bringing it low (0) again.

The RS line is the "Register Select" line. When RS is low (0), the data is to be treated as a

command or special instruction (such as clear screen, position cursor, etc.). When RS is high (1),

the data being sent is text data which should be displayed on the screen. For example, to display

the letter "T" on the screen you would set RS high.

The RW line is the "Read/Write" control line. When RW is low (0), the information on

the data bus is being written to the LCD. When RW is high (1), the program is effectively

querying (or reading) the LCD. Only one instruction ("Get LCD status") is a read command. All

others are write commands--so RW will almost always be low .Finally, the data bus consists of 4

or 8 lines (depending on the mode of operation selected by the user). In the case of an 8-bit data

bus, the lines are referred to as DB0, DB1, DB2, DB3, DB4, DB5, DB6, and DB7.

4.6 ADC0808Features

Easy interface to all microprocessors

Operates ratio metrically or with 5 VDC or analog span adjusted voltage reference

No zero or full-scale adjust required

8-channel multiplexer with address logic

0V to 5V input range with single 5V power supply

Outputs meet TTL voltage level specifications

Standard hermetic or molded 28-pin DIP package

28-pin molded chip carrier package

ADC0808 equivalent to MM74C949

ADC0809 equivalent to MM74C949-1

32

FIG: ADC0808 PIN CONFIGURATION

Key Specifications

Resolution 8 Bits

Total Unadjusted Error ±1⁄2 LSB and ±1 LSB

Single Supply 5 VDC

Low Power 15 mW

Conversion Time 100 μs

The ADC0808, ADC0809 data acquisition component is a monolithic CMOS device with

an 8-bit analog-to-digital converter, 8-channel multiplexer and microprocessor compatible

control logic. The 8-bit A/D converter uses successive approximation as the conversion 33

technique. The converter features a high impedance chopper stabilized comparator, a 256R

voltage divider with analog switch tree and a successive approximation register.

Fig 4.6 ADC0808

The 8-channel multiplexer can directly access any of 8-single-ended analog signals. The

device eliminates the need for external zero and full-scale adjustments. Easy interfacing to

microprocessors is provided by the latched and decoded multiplexer address inputs and latched

TTL TRI-STATE outputs. The design of the ADC0808, ADC0809 has been optimized by

incorporating the most desirable aspects of several A/D conversion techniques. The ADC0808,

ADC0809 offers high speed, high accuracy, minimal temperature dependence, excellent long-

term accuracy and repeatability, and consumes minimal power. These features make this device

ideally suited to applications from process and machine control to consumer and automotive

applications.

The ADC0808/ADC0809 Data Acquisition Devices (DAD) implement on a single chip

most the elements of the standard data acquisition system. They contain an 8-bit A/D Converter,

8-channel multiplexer with an address input latch, and associated control logic. These devices

provide most of the logic to interface to a variety of microcontrollers with the addition of a

minimum number of parts.

34

These circuits are implemented using a standard metal-gate CMOS process. This process

is particularly suitable to applications. Where both analog and digital functions must be

implemented on the same chip. These two converters, the ADC0808 and ADC0809, are

functionally identical except that the ADC0808 has a total unadjusted error of ±1⁄2 LSB and the

ADC0809 has an unadjusted error of ±1 LSB. All these converters will typically do a conversion

in100 μs when using a 640 kHz clock, but can convert a single input in as little as 50 μs.

4.6(b): FUNCTIONAL BLOCK DIAGRAM OF ADC0808/ADC0809

Functional Description

The ADC0808/ADC0809, shown in the above figure, can be functionally divided into 2

basic sub circuits. These two sub circuits are an analog multiplexer and an A/D converter. The

multiplexer uses 8 standard CMOS analog switches to provide for up to 8 analog inputs. The

switches are selectively turned on, depending on the data latched into a 3-bit multiplexer address

register. The second function block, the successive approximation A/D converter, transforms the

analog output of the multiplexer to an 8-bit digital word. The output of the multiplexer goes to

one of two comparator inputs. The other input is derived from a 256R resistor ladder, which is

tapped by a MOSFET transistor switch tree. The converter control logic controls the switch tree,

funneling a particular tap voltage to the comparator. Based on the result of this comparison, the

control logic and the successive approximation register (SAR) will decide whether the next tap to

35

be selected should be higher or lower than the present tap on the resistor ladder. This algorithm is

executed 8 times per conversion, once every 8 clock periods, yielding a total conversion time of

64 clock periods.

When the conversion cycle is complete the resulting data is loaded into the TRI-STATE

output latch. The data in the output latch can then be read by the host system any time before the

end of the next conversion. The TRI-STATE capability of the latch allows easy interface to bus

oriented systems. The operation of these converters by a microprocessor or some control logic is

very simple. The controlling device first selects the desired input channel. To do this, a 3-bit

channel address is placed on the A, B, C input pins; and the ALE input is pulsed positively,

clocking the address into the multiplexer address register. To begin the conversion, the START

pin is pulsed. On the rising edge of this pulse the internal registers are cleared and on the falling

edge the start conversion initiated. There are 8 clock periods per approximation. Even though

there is no conversion in progress the ADC0808/ADC0809 is still internally cycling through

these 8 clock periods. A start pulse can occur any time during this cycle but the conversion will

not actually begin until the converter internally cycles to the beginning of the next 8 clock period

sequence.

As long as the start pin is held high no conversion begins, but when the start pin is taken

low the conversion will start within 8 clock periods. The EOC output is triggered on the rising

edge of the start pulse. It, too, is controlled by the 8 clock period cycle, so it will go low within 8

clock periods of the rising edge of the start pulse. One can see that it is entirely possible for EOC

to go low before the conversion starts internally, but this is not important, since the positive

transition of EOC, which occurs at the end of a conversion, is what the control logic is looking

for. Once EOC does go high this signals the interface logic that the data resulting from the

conversion is ready to be read. The output enable (OE) is then raised high. This enables the TRI-

STATE outputs, allowing the data to be read.

36

2.4 GHZ RF MODULE

RF 2.4HGhz Serial Link module is an embedded solutions providing wireless end-

point connectivity to devices. These modules use a simple proprietary networking

protocol for fast point-to-multipoint or peer-to-peer networking. They are designed

for high-throughput applications requiring low latency and predictable

communication timing. It should be connected to any TTL/CMOS logic serial

RXD and TXD lines and can support baud-rate of 9600bps, 19200bps, 38400bps

and 57600bps. It also supports 4 unique RF channel selections to reduce

congestions on the same channel during peer-to-peer communication.

37

Pin-out Info

Pin 1- GroundPin 2- VCC (4.25V to 12.0V regulated power)Pin 3- Transmit Serial Data Output from Module (3.3V TTL)Pin 4- Receive Serial Data Input from External Device (3.3V to 5V TTL)Baud Jumper Info

Default No Baud Jumper – 9600bpsBaud 1 Jumper – 19200bpsBaud 2 Jumper – 38400bpsBaud 1 & Baud 2 Jumper – 57600bpsFreq Jumper Info

Default No Freq Jumper – 2433MHzFreq 1 Jumper – 2438MHzFreq 2 Jumper – 2443MHzFreq 1 & Freq 2 Jumper – 2450MHzLED InfoPWR LED – power supply presentTX LED – RF transmission of dataRX LED – RF reception of dataFeatures

• No configuration needed for out-of-the-box RF communications• Standard Serial Communication Socket for easy integration• Fast 250 kbps RF air-data rate to the end node• 2.4 GHz for worldwide deployment• Baud-rate selection and channel frequency selection• Up to 100meters outdoor open air node-to-node rangeApplications

• Wireless telemetry for transmitting sensor data• Remote control applications with fast response requirements• Wireless Home Networking applications• Point-to-point and point-to-multipoint network topologies• Wireless mouse, wireless keyboard and other wireless user interface devices• Wireless data logging applications

38

• Audience response systems• UAV communication and control• Swarm Robotics• Wireless Audio transmission applications

4.10 RELAYA relay is an electrically operated switch. Many relays use an electromagnet to operate a

switching mechanism mechanically, but other operating principles are also used. Relays are used

where it is necessary to control a circuit by a low-power signal (with complete electrical isolation

between control and controlled circuits), or where several circuits must be controlled by one

signal.

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 most have double throw (changeover)

switch contacts as shown in the diagram.

39

Fig 4.8 Relay showing coil and switch contacts

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 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.

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. For further

information about switch contacts and the terms used to describe them please see the page on

switches.

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 supplier's catalogue should show you the relay's connections. The coil will be

obvious and it may be connected either way round. Relay coils produce brief high voltage

'spikes' when they are switched off and this can destroy transistors and ICs in the circuit. To

prevent damage you must connect a protection diode across the relay coil.

The figure shows a 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.

40

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 labelled 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.

41

Applications of relays

Relays are used to and for:

Control a high-voltage circuit with a low-voltage signal, as in some types of modems or

audio amplifiers.

Control a high-current circuit with a low-current signal, as in the starter solenoid of an

automobile.

Detect and isolate faults on transmission and distribution lines by opening and closing

circuit breakers.

Time delay functions. Relays can be modified to delay opening or delay closing a set of

contacts. A very short (a fraction of a second) delay would use a copper disk between the

armature and moving blade assembly. Current flowing in the disk maintains magnetic

field for a short time, lengthening release time. For a slightly longer (up to a minute)

delay, a dashpot is used. A dashpot is a piston filled with fluid that is allowed to escape

slowly. The time period can be varied by increasing or decreasing the flow rate. For longer

time periods, a mechanical clockwork timer is installed.

4.11 TEMPERATURE SENSOR(LM35)

Features

n Calibrated directly in ˚ Celsius (Centigrade)

n Linear + 10.0 mV/˚C scale factor

n 0.5˚C accuracy guarantee able (at +25˚C)

n Rated for full −55˚ to +150˚C range

n Suitable for remote applications

n Low cost due to wafer-level trimming

n Operates from 4 to 30 volts

n Less than 60 µA current drain

n Low self-heating, 0.08˚C in still air

42

n Nonlinearity only ±1⁄4˚C typical

n Low impedance output, 0.1 for 1 mA load

The LM35 series are precision integrated-circuit temperature sensors, whose output

voltage is linearly proportional to the Celsius (Centigrade) temperature. The LM35 thus has

an advantage over linear temperature sensors calibrated in Kelvin, as the user is not

required to subtract a large constant voltage from its output to obtain convenient

Centigrade scaling. The LM35 does not require any external calibration or trimming to

provide typical accuracies of ±1⁄4˚C at room temperature and ±3⁄4˚C over a full −55 to

+150˚C temperature range. Low cost is assured by trimming and calibration at the wafer level.

The LM35’s low output impedance, linear output, and precise inherent calibration make interfacing to

readout or control circuitry especially easy. It can be used with single power supplies, or

with plus and minus supplies. As it draws only 60 µA from its supply, it has very low self-

heating, less than 0.1˚C in still air. The LM35 is rated to operate over a −55˚ to +150˚C

temperature range, while the LM35C is rated for a −40˚ to +110˚C range (−10˚ with

improved accuracy). The LM35 series is available packaged in hermetic TO-46 transistor

packages, while the LM35C, LM35CA, and LM35D are also available in the plastic

TO-92 transistor package. The LM35D is also avail- able in an 8-lead surface mount small

outline package and a plastic TO-220 package.

Fig 4.10: Basic Centigrade Temperature Sensor (+2˚C to +150˚C)

Applications:

• The LM35 can be applied easily in the same way as other integrated circuit

temperature sensors. It can be glued or cemented to a surface and its

temperature will be within about 0.01˚C of the surface temperature.

43

• This presumes that the ambient air temperature is almost the same as the surface

temperature; if the air temperature were much higher or lower than the surface

temperature, the actual temperature of the LM35 die would be at an intermediate

temperature between the surface temperature and the air temperature. This is

especially true for the TO-92 plastic package, where the copper leads are the

principal thermal path to carry heat into the device, so its temperature might be

closer to the air temperature than to the surface temperature.

• To minimize this problem, be sure that the wiring to the LM35, as it leaves

the device, is held at the same temperature as the surface of interest. The easiest

way to do this is to cover up these wires with a bead of epoxy which will

insure that the leads and wires are all at the same temperature as the surface, and

that the LM35 die’s temperature will not be affected by the air temperature.

4.12 LED

A light-emitting diode (LED) is a semiconductor light source. LEDs are used as indicator

lamps in many devices, and are increasingly used for lighting. When a light-emitting diode is

forward biased (switched on), electrons are able to recombine with holes within the device,

releasing energy in the form of photons.

This effect is called electroluminescence and the color of the light (corresponding to the

energy of the photon) is determined by the energy gap of the semiconductor. An LED is often

small in area (less than 1 mm2), and integrated optical components may be used to shape its

radiation pattern. LEDs present many advantages over incandescent light sources including

lower energy consumption, longer lifetime, improved robustness, smaller size, faster switching,

and greater durability and reliability.

44

Types of LED’S

Fig 4.12(a): Types of LED

Light-emitting diodes are used in applications as diverse as replacements for aviation lighting,

automotive lighting as well as in traffic signals. The compact size, the possibility of narrow

bandwidth, switching speed, and extreme reliability of LEDs has allowed new text and video

displays and sensors to be developed, while their high switching rates are also useful in advanced

communications technology.

Electronic Symbol:

Fig 4.12(b): symbol of LED

Colors and materials of LED’S

Conventional LEDs are made from a variety of inorganic semiconductor materials, the

following table shows the available colors with wavelength range, voltage drop and material.

White LED’S

Light Emitting Diodes (LED) have recently become available that are both white and

bright, so bright that they seriously compete with incandescent lamps in lighting applications.

They are still pretty expensive as compared to a GOW lamp but draw much less current and

project a fairly well focused beam.

45

When run within their ratings, they are more reliable than lamps as well. Red LEDs are

now being used in automotive and truck tail lights and in red traffic signal lights. You will be

able to detect them because they look like an array of point sources and they go on and off

instantly as compared to

conventional

incandescent

lamps.

Fig 4.12(c): White LED spectrum

LEDs are monochromatic (one color) devices. The color is determined by the band gap of

the semiconductor used to make them. Red, green, yellow and blue LEDs are fairly common.

White light contains all colors and cannot be directly created by a single LED. The most

common form of "white" LED really isn't white. It is a Gallium Nitride blue LED coated with a

phosphor that, when excited by the blue LED light, emits a broad range spectrum that in addition

to the blue emission, makes a fairly white light.

There is a claim that these white LED's have a limited life. After 1000 hours or so of

operation, they tend to yellow and dim to some extent. Running the LEDs at more than their

rated current will certainly accelerate this process.

There are two primary ways of producing high intensity white-light using LEDs. One is

to use individual LEDs that emit three primary colours—red, green, and blue—and then mix all

the colours to form white light. The other is to use a phosphor material to convert

monochromatic light from a blue or UV LED to broad-spectrum white light, much in the same

46

way a fluorescent light bulb works. Due to metamerism, it is possible to have quite different

spectra that appear white.

4.13 IN4007

Diodes are used to convert AC into DC these are used as half wave rectifier or full wave

rectifier. Three points must he kept in mind while using any type of diode.

1. Maximum forward current capacity

2. Maximum reverse voltage capacity

3. Maximum forward voltage capacity

Fig: IN4007 diodesThe number and voltage capacity of some of the important diodes available in the market are as

follows:

Diodes of number IN4001, IN4002, IN4003, IN4004, IN4005, IN4006 and IN4007 have

maximum reverse bias voltage capacity of 50V and maximum forward current capacity

of 1 Amp.

Diode of same capacities can be used in place of one another. Besides this diode of more

capacity can be used in place of diode of low capacity but diode of low capacity cannot

be used in place of diode of high capacity. For example, in place of IN4002; IN4001 or

IN4007 can be used but IN4001 or IN4002 cannot be used in place of IN4007.The diode

BY125made by company BEL is equivalent of diode from IN4001 to IN4003. BY 126 is

equivalent to diodes IN4004 to 4006 and BY 127 is equivalent to diode IN4007.

47

Fig:PN Junction diode

PN JUNCTION OPERATION

Now that you are familiar with P- and N-type materials, how these materials are joined

together to form a diode, and the function of the diode, let us continue our discussion with the

operation of the PN junction. But before we can understand how the PN junction works, we

must first consider current flow in the materials that make up the junction and what happens

initially within the junction when these two materials are joined together.

Current Flow in the N-Type Material

Conduction in the N-type semiconductor, or crystal, is similar to conduction in a copper

wire. That is, with voltage applied across the material, electrons will move through the crystal

just as current would flow in a copper wire. This is shown in figure 1-15. The positive

potential of the battery will attract the free electrons in the crystal. These electrons will leave

the crystal and flow into the positive terminal of the battery. As an electron leaves the crystal,

an electron from the negative terminal of the battery will enter the crystal, thus completing the

current path. Therefore, the majority current carriers in the N-type material (electrons) are

48

repelled by the negative side of the battery and move through the crystal toward the positive

side of the battery.

Current Flow in the P-Type Material

Current flow through the P-type material is illustrated. Conduction in the P material is by

positive holes, instead of negative electrons. A hole moves from the positive terminal of the P

material to the negative terminal. Electrons from the external circuit enter the negative

terminal of the material and fill holes in the vicinity of this terminal. At the positive terminal,

electrons are removed from the covalent bonds, thus creating new holes. This process

continues as the steady stream of holes (hole current) moves toward the negative terminal.

4.14 RESISTORS

A resistor is a two-terminal electronic component designed to oppose an electric current by

producing a voltage drop between its terminals in proportion to the current, that is, in accordance

with Ohm's law:

V = IR

Resistors are used as part of electrical networks and electronic circuits. They are extremely

commonplace in most electronic equipment. Practical resistors can be made of various

compounds and films, as well as resistance wire (wire made of a high-resistivity alloy, such as

nickel/chrome).

The primary characteristics of resistors are their resistance and the power they can

dissipate. Other characteristics include temperature coefficient, noise, and inductance. Less well-

known is critical resistance, the value below which power dissipation limits the maximum

permitted current flow, and above which the limit is applied voltage. Critical resistance depends

upon the materials constituting the resistor as well as its physical dimensions; it's determined by

design.

Resistors can be integrated into hybrid and printed circuits, as well as integrated

circuits. Size, and position of leads (or terminals) are relevant to equipment designers; resistors

must be physically large enough not to overheat when dissipating their power.49

A resistor is a two-terminal passive electronic component which implements electrical

resistance as a circuit element. When a voltage V is applied across the terminals of a resistor, a

current I will flow through the resistor in direct proportion to that voltage. The reciprocal of the

constant of proportionality is known as the resistance R, since, with a given voltage V, a larger

value of R further "resists" the flow of current I as given by Ohm's law:

Resistors are common elements of electrical networks and electronic circuits and are

ubiquitous in most electronic equipment. Practical resistors can be made of various compounds

and films, as well as resistance wire (wire made of a high-resistivity alloy, such as nickel-

chrome). Resistors are also implemented within integrated circuits, particularly analog devices,

and can also be integrated into hybrid and printed circuits.

The electrical functionality of a resistor is specified by its resistance: common

commercial resistors are manufactured over a range of more than 9 orders of magnitude. When

specifying that resistance in an electronic design, the required precision of the resistance may

require attention to the manufacturing tolerance of the chosen resistor, according to its specific

application. The temperature coefficient of the resistance may also be of concern in some

precision applications. Practical resistors are also specified as having a maximum power rating

which must exceed the anticipated power dissipation of that resistor in a particular circuit: this is

mainly of concern in power electronics applications. Resistors with higher power ratings are

physically larger and may require heat sinking. In a high voltage circuit, attention must

sometimes be paid to the rated maximum working voltage of the resistor.

The series inductance of a practical resistor causes its behavior to depart from ohms law;

this specification can be important in some high-frequency applications for smaller values of

50

resistance. In a low-noise amplifier or pre-amp the noise characteristics of a resistor may be an

issue. The unwanted inductance, excess noise, and temperature coefficient are mainly dependent

on the technology used in manufacturing the resistor. They are not normally specified

individually for a particular family of resistors manufactured using a particular technology. A

family of discrete resistors is also characterized according to its form factor, that is, the size of

the device and position of its leads (or terminals) which is relevant in the practical manufacturing

of circuits using them.

Units

The ohm (symbol: Ω) is the SI unit of electrical resistance, named after Georg Simon

Ohm. An ohm is equivalent to a volt per ampere. Since resistors are specified and manufactured

over a very large range of values, the derived units of milliohm (1 mΩ = 10−3 Ω), kilohm (1 kΩ =

103 Ω), and megohm (1 MΩ = 106 Ω) are also in common usage.

The reciprocal of resistance R is called conductance G = 1/R and is measured in Siemens

(SI unit), sometimes referred to as a mho. Thus a Siemens is the reciprocal of an ohm: S = Ω − 1.

Although the concept of conductance is often used in circuit analysis, practical resistors are

always specified in terms of their resistance (ohms) rather than conductance.

VARIABLE RESISTORSAdjustable resistors

A resistor may have one or more fixed tapping points so that the resistance can be

changed by moving the connecting wires to different terminals. Some wire wound power

resistors have a tapping point that can slide along the resistance element, allowing a larger or

smaller part of the resistance to be used.

Where continuous adjustment of the resistance value during operation of equipment is

required, the sliding resistance tap can be connected to a knob accessible to an operator. Such a

device is called a rheostat and has two terminals.

Potentiometer

A potentiometer is a manually adjustable resistor. The way this device works is relatively simple.

One terminal of the potentiometer is connected to a power source. Another is hooked up to ground (a

point with no voltage or resistance and which serves as a neutral reference point), while the third

51

terminal runs across a strip of resistive material. This resistive strip generally has a low resistance at

one end; its resistance gradually increases to a maximum resistance at the other end. The third terminal

serves as the connection between the power source and ground, and is usually interfaced to the user by

means of a knob or lever. The user can adjust the position of the third terminal along the resistive strip

in order to manually increase or decrease resistance. By controlling resistance, a potentiometer can

determine how much current flow through a circuit. When used to regulate current, the potentiometer

is limited by the maximum resistivity of the strip.

The power of this simple device is not to be underestimated. In most analog devices, a

potentiometer is what establishes the levels of output. In a loud speaker, for example, a potentiometer

directly adjusts volume; in a television monitor, it controls brightness.

A potentiometer can also be used to control the potential difference, or voltage, across a circuit.

The setup involved in utilizing a potentiometer for this purpose is a little bit more complicated. It

involves two circuits: the first circuit consists of a cell and a resistor. At one end, the cell is connected

in series to the second circuit, and at the other end it is connected to a potentiometer in parallel with

the second circuit. The potentiometer in this arrangement drops the voltage by an amount equal to the

ratio between the resistance allowed by the position of the third terminal and the highest possible

resistivity of the strip. In other words, if the knob controlling the resistance is positioned at the exact

halfway point on the resistive strip, then the output voltage will drop by exactly fifty percent, no

matter how high the potentiometer's input voltage. Unlike with current regulation, voltage regulation is

not limited by the maximum resistivity of the strip

4.15 CAPACITORS

52

A capacitor or condenser is a passive electronic component consisting of a pair of conductors

separated by a dielectric. When a voltage potential difference exists between the conductors, an

electric field is present in the dielectric. This field stores energy and produces a mechanical force

between the plates. The effect is greatest between wide, flat, parallel, narrowly separated

conductors.

An ideal capacitor is characterized by a single constant value, capacitance, which is

measured in farads. This is the ratio of the electric charge on each conductor to the potential

difference between them. In practice, the dielectric between the plates passes a small amount of

leakage current. The conductors and leads introduce an equivalent series resistance and the

dielectric has an electric field strength limit resulting in a breakdown voltage.

The properties of capacitors in a circuit may determine the resonant frequency and

quality factor of a resonant circuit, power dissipation and operating frequency in a digital logic

circuit, energy capacity in a high-power system, and many other important aspects.

A capacitor (formerly known as condenser) is a device for storing electric charge. The

forms of practical capacitors vary widely, but all contain at least two conductors separated by a

non-conductor. Capacitors used as parts of electrical systems, for example, consist of metal foils

separated by a layer of insulating film.

Capacitors are widely used in electronic circuits for blocking direct current while

allowing alternating current to pass, in filter networks, for smoothing the output of power

supplies, in the resonant circuits that tune radios to particular frequencies and for many other

purposes.

53

A capacitor is a passive electronic component consisting of a pair of conductors separated

by a dielectric (insulator). When there is a potential difference (voltage) across the conductors, a

static electric field develops in the dielectric that stores energy and produces a mechanical force

between the conductors. An ideal capacitor is characterized by a single constant value,

capacitance, measured in farads. This is the ratio of the electric charge on each conductor to the

potential difference between them.

The capacitance is greatest when there is a narrow separation between large areas of

conductor, hence capacitor conductors are often called "plates", referring to an early means of

construction. In practice the dielectric between the plates passes a small amount of leakage

current and also has an electric field strength limit, resulting in a breakdown voltage, while the

conductors and leads introduce an undesired inductance and resistance.

Theory of operation

Capacitance

Charge separation in a parallel-plate capacitor causes an internal electric field. A dielectric

(orange) reduces the field and increases the capacitance.

54

A simple demonstration of a parallel-plate capacitor

A capacitor consists of two conductors separated by a non-conductive region. The non-

conductive region is called the dielectric or sometimes the dielectric medium. In simpler terms,

the dielectric is just an electrical insulator. Examples of dielectric mediums are glass, air, paper,

vacuum, and even a semiconductor depletion region chemically identical to the conductors. A

capacitor is assumed to be self-contained and isolated, with no net electric charge and no

influence from any external electric field. The conductors thus hold equal and opposite charges

on their facing surfaces, and the dielectric develops an electric field. In SI units, a capacitance of

one farad means that one coulomb of charge on each conductor causes a voltage of one volt

across the device.

The capacitor is a reasonably general model for electric fields within electric circuits. An ideal

capacitor is wholly characterized by a constant capacitance C, defined as the ratio of charge ±Q

on each conductor to the voltage V between them:

Sometimes charge build-up affects the capacitor mechanically, causing its capacitance to vary. In

this case, capacitance is defined in terms of incremental changes:

Energy storage

Work must be done by an external influence to "move" charge between the conductors in a

capacitor. When the external influence is removed the charge separation persists in the electric

field and energy is stored to be released when the charge is allowed to return to its equilibrium

position. The work done in establishing the electric field, and hence the amount of energy stored,

is given by:

Current-voltage relation

The current i(t) through any component in an electric circuit is defined as the rate of flow of a

charge q(t) passing through it, but actual charges, electrons, cannot pass through the dielectric

55

layer of a capacitor, rather an electron accumulates on the negative plate for each one that leaves

the positive plate, resulting in an electron depletion and consequent positive charge on one

electrode that is equal and opposite to the accumulated negative charge on the other. Thus the

charge on the electrodes is equal to the integral of the current as well as proportional to the

voltage as discussed above. As with any ant derivative, a constant of integration is added to

represent the initial voltage v (t0). This is the integral form of the capacitor equation,

.

Taking the derivative of this, and multiplying by C, yields the derivative form,

.

The dual of the capacitor is the inductor, which stores energy in the magnetic field rather than the

electric field. Its current-voltage relation is obtained by exchanging current and voltage in the

capacitor equations and replacing C with the inductance L.

DC circuits

RC circuit

A simple resistor-capacitor circuit demonstrates charging of a capacitor.

A series circuit containing only a resistor, a capacitor, a switch and a constant DC source of

voltage V0 is known as a charging circuit. If the capacitor is initially uncharged while the switch

is open, and the switch is closed at t = 0, it follows from Kirchhoff's voltage law that

Taking the derivative and multiplying by C, gives a first-order differential equation,

56

At t = 0, the voltage across the capacitor is zero and the voltage across the resistor is V0. The

initial current is then i (0) =V0 /R. With this assumption, the differential equation yields

where τ0 = RC is the time constant of the system.

As the capacitor reaches equilibrium with the source voltage, the voltage across the resistor and

the current through the entire circuit decay exponentially. The case of discharging a charged

capacitor likewise demonstrates exponential decay, but with the initial capacitor voltage

replacing V0 and the final voltage being zero.

AC circuits

See also: reactance (electronics) and electrical impedance deriving the device specific

impedances

Impedance, the vector sum of reactance and resistance, describes the phase difference and the

ratio of amplitudes between sinusoidally varying voltage and sinusoidally varying current at a

given frequency. Fourier analysis allows any signal to be constructed from a spectrum of

frequencies, whence the circuit's reaction to the various frequencies may be found. The reactance

and impedance of a capacitor are respectively

where j is the imaginary unit and ω is the angular velocity of the sinusoidal signal. The - j phase

indicates that the AC voltage V = Z I lags the AC current by 90°: the positive current phase

corresponds to increasing voltage as the capacitor charges; zero current corresponds to

instantaneous constant voltage, etc.

Note that impedance decreases with increasing capacitance and increasing frequency. This

implies that a higher-frequency signal or a larger capacitor results in a lower voltage amplitude

per current amplitude—an AC "short circuit" or AC coupling. Conversely, for very low

57

frequencies, the reactance will be high, so that a capacitor is nearly an open circuit in AC

analysis—those frequencies have been "filtered out".

Capacitors are different from resistors and inductors in that the impedance is inversely

proportional to the defining characteristic, i.e. capacitance.

Parallel plate model

Dielectric is placed between two conducting plates, each of area A and with a separation of d.

The simplest capacitor consists of two parallel conductive plates separated by a dielectric with

permittivity ε (such as air). The model may also be used to make qualitative predictions for other

device geometries. The plates are considered to extend uniformly over an area A and a charge

density ±ρ = ±Q/A exists on their surface. Assuming that the width of the plates is much greater

than their separation d, the electric field near the centre of the device will be uniform with the

magnitude E = ρ/ε. The voltage is defined as the line integral of the electric field between the

plates

Solving this for C = Q/V reveals that capacitance increases with area and decreases with

separation

.

The capacitance is therefore greatest in devices made from materials with a high permittivity.

58

Several capacitors in parallel.

Networks

See also: Series and parallel circuits

For capacitors in parallel

Capacitors in a parallel configuration each have the same applied voltage. Their

capacitances add up. Charge is apportioned among them by size. Using the schematic

diagram to visualize parallel plates, it is apparent that each capacitor contributes to the

total surface area.

For capacitors in series

Several capacitors in series.

Connected in series, the schematic diagram reveals that the separation distance, not the

plate area, adds up. The capacitors each store instantaneous charge build-up equal to that

of every other capacitor in the series. The total voltage difference from end to end is

apportioned to each capacitor according to the inverse of its capacitance. The entire series

acts as a capacitor smaller than any of its components.

Capacitors are combined in series to achieve a higher working voltage, for example for

smoothing a high voltage power supply. The voltage ratings, which are based on plate

separation, add up. In such an application, several series connections may in turn be

59

connected in parallel, forming a matrix. The goal is to maximize the energy storage utility

of each capacitor without overloading it.

Series connection is also used to adapt electrolytic capacitors for AC use.

Non-ideal behaviour

Capacitors deviate from the ideal capacitor equation in a number of ways. Some of these, such as

leakage current and parasitic effects are linear, or can be assumed to be linear, and can be dealt

with by adding virtual components to the equivalent circuit of the capacitor. The usual methods

of network analysis can then be applied. In other cases, such as with breakdown voltage, the

effect is non-linear and normal (i.e., linear) network analysis cannot be used, the effect must be

dealt with separately. There is yet another group, which may be linear but invalidate the

assumption in the analysis that capacitance is a constant. Such an example is temperature

dependence.

Breakdown voltage

Main article: Breakdown voltage

Above a particular electric field, known as the dielectric strength Eds, the dielectric in a capacitor

becomes conductive. The voltage at which this occurs is called the breakdown voltage of the

device, and is given by the product of the dielectric strength and the separation between the

conductors, Vbd = Edsd

The maximum energy that can be stored safely in a capacitor is limited by the breakdown

voltage. Due to the scaling of capacitance and breakdown voltage with dielectric thickness, all

capacitors made with a particular dielectric have approximately equal maximum energy density,

to the extent that the dielectric dominates their volume.

For air dielectric capacitors the breakdown field strength is of the order 2 to 5 MV/m; for mica

the breakdown is 100 to 300 MV/m, for oil 15 to 25 MV/m, and can be much less when other

materials are used for the dielectric. The dielectric is used in very thin layers and so absolute

breakdown voltage of capacitors is limited. Typical ratings for capacitors used for general

electronics applications range from a few volts to 100V or so. As the voltage increases, the

dielectric must be thicker, making high-voltage capacitors larger than those rated for lower

voltages. The breakdown voltage is critically affected by factors such as the geometry of the

capacitor conductive parts; sharp edges or points increase the electric field strength at that point

and can lead to a local breakdown. Once this starts to happen, the breakdown will quickly "track"

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through the dielectric till it reaches the opposite plate and cause a short circuit. The usual

breakdown route is that the field strength becomes large enough to pull electrons in the dielectric

from their atoms thus causing conduction. Other scenarios are possible, such as impurities in the

dielectric, and, if the dielectric is of a crystalline nature, imperfections in the crystal structure can

result in an avalanche breakdown as seen in semi-conductor devices. Breakdown voltage is also

affected by pressure, humidity and temperature.

Equivalent circuit

Two different circuit models of a real capacitor

An ideal capacitor only stores and releases electrical energy, without dissipating any. In reality,

all capacitors have imperfections within the capacitor's material that create resistance. This is

specified as the equivalent series resistance or ESR of a component. This adds a real component

to the impedance:

As frequency approaches infinity, the capacitive impedance (or reactance) approaches zero and

the ESR becomes significant. As the reactance becomes negligible, power dissipation approaches

PRMS = VRMS² /RESR.

Similarly to ESR, the capacitor's leads add equivalent series inductance or ESL to the

component. This is usually significant only at relatively high frequencies. As inductive reactance

is positive and increases with frequency, above a certain frequency capacitance will be canceled

by inductance. High-frequency engineering involves accounting for the inductance of all

connections and components.

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If the conductors are separated by a material with a small conductivity rather than a perfect

dielectric, then a small leakage current flows directly between them. The capacitor therefore has

a finite parallel resistance, and slowly discharges over time (time may vary greatly depending on

the capacitor material and quality).

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5. SOFTWARE REQUIREMENTS

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5.1 INTRODUCTION TO KEIL MICRO VISION (IDE) Keil an ARM Company makes C compilers, macro assemblers, real-time kernels,

debuggers, simulators, integrated environments, evaluation boards, and emulators for

ARM7/ARM9/Cortex-M3, XC16x/C16x/ST10, 251, and 8051 MCU families.

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. When starting a new project, simply select the microcontroller

you use from the Device Database and the µVision IDE sets all compiler, assembler, linker, and

memory options for you.

Keil is a cross compiler. So first we have to understand the concept of compilers and

cross compilers. After then we shall learn how to work with keil.

5.2 CONCEPT OF COMPILER Compilers are programs used to convert a High Level Language to object code. Desktop

compilers produce an output object code for the underlying microprocessor, but not for other

microprocessors. I.E the programs written in one of the HLL like ‘C’ will compile the code to

run on the system for a particular processor like x86 (underlying microprocessor in the

computer). For example compilers for Dos platform is different from the Compilers for Unix

platform So if one wants to define a compiler then compiler is a program that translates source

code into object code.

The compiler derives its name from the way it works, looking at the entire piece of

source code and collecting and reorganizing the instruction. See there is a bit little difference

between compiler and an interpreter. Interpreter just interprets whole program at a time while

compiler analyses and execute each line of source code in succession, without looking at the

entire program.

The advantage of interpreters is that they can execute a program immediately. Secondly

programs produced by compilers run much faster than the same programs executed by an

interpreter. However compilers require some time before an executable program emerges. Now

as compilers translate source code into object code, which is unique for each type of computer,

many compilers are available for the same language.

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5.3 CONCEPT OF CROSS COMPILER A cross compiler is similar to the compilers but we write a program for the target

processor (like 8051 and its derivatives) on the host processors (like computer of x86). It means

being in one environment you are writing a code for another environment is called cross

development. And the compiler used for cross development is called cross compiler. So the

definition of cross compiler is a compiler that runs on one computer but produces object code for

a different type of computer.

5.4 KEIL C CROSS COMPILER Keil is a German based Software development company.It provides several development

tools like

• IDE (Integrated Development environment)

• Project Manager

• Simulator

• Debugger

• C Cross Compiler, Cross Assembler, Locator/Linker

The Keil ARM tool kit includes three main tools, assembler, compiler and linker. An

assembler is used to assemble the ARM assembly program. A compiler is used to compile the C

source code into an object file. A linker is used to create an absolute object module suitable for

our in-circuit emulator.

5.5 Building an Application in µVision2To build (compile, assemble, and link) an application in µVision2, you must:

1. Select Project -(forexample,166\EXAMPLES\HELLO\HELLO.UV2).

2. Select Project - Rebuild all target files or Build target.µVision2 compiles, assembles, and

links the files in your project.

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5.6 Creating Your Own Application in µVision2 To create a new project in µVision2, you must:

1. Select Project - New Project.

2. Select a directory and enter the name of the project file.

3. Select Project - Select Device and select an 8051, 251, or C16x/ST10 device from the

Device Database™.

4. Create source files to add to the project.

5. Select Project - Targets, Groups, Files. Add/Files, select Source Group1, and add the

source files to the project.

6. Select Project - Options and set the tool options. Note when you select the target device

from the Device Database™ all special options are set automatically. You typically only

need to configure the memory map of your target hardware. Default memory model

settings are optimal for most applications.

7. Select Project - Rebuild all target files or Build target.

5.7 Debugging an Application in µVision2To debug an application created using µVision2, you must:

1. Select Debug - Start/Stop Debug Session.

2. Use the Step toolbar buttons to single-step through your program. You may enter G, main

in the Output Window to execute to the main C function.

3. Open the Serial Window using the Serial #1 button on the toolbar.

Debug your program using standard options like Step, Go, Break, and so on.

5.8 Starting µVision2 and Creating a ProjectµVision2 is a standard Windows application and started by clicking on the program icon.

To create a new project file select from the µVision2 menu Project – New Project…. This opens

a standard Windows dialog that asks you for the new project file name. We suggest that you use

a separate folder for each project. You can simply use the icon Create New Folder in this dialog

to get a new empty folder. Then select this folder and enter the file name for the new project, i.e.

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Project1. µVision2 creates a new project file with the name PROJECT1.UV2 which contains a

default target and file group name. You can see these names in the Project.

5.9 Window – Files.Now use from the menu Project – Select Device for Target and select a CPU for your

project. The Select Device dialog box shows the µVision2 device data base. Just select the

microcontroller you use. We are using for our examples the Philips 80C51RD+ CPU. This

selection sets necessary tool Options for the 80C51RD+ device and simplifies in this way the

tool Configuration.

5.10 Building Projects and Creating a HEX FilesTypical, the tool settings under Options – Target are all you need to start a new

application. You may translate all source files and line the application with a click on the Build

Target toolbar icon. When you build an application with syntax errors, µVision2 will display

errors and warning messages in the Output Window – Build page. A double click on a message

line opens the source file on the correct location in a µVision2 editor window. Once you have

successfully generated your application you can start debugging.

After you have tested your application, it is required to create an Intel HEX file to

download the software into an EPROM programmer or simulator. µVision2 creates HEX files

with each build process when Create HEX files under Options for Target – Output is enabled.

You may start your PROM programming utility after the make process when you specify the

program under the option Run User Program #1.

5.11 CPU SimulationµVision2 simulates up to 16 Mbytes of memory from which areas can be mapped for

read, write, or code execution access. The µVision2 simulator traps

and reports illegal memory accesses. In addition to memory mapping, the simulator also provides

support for the integrated peripherals of the various 8051 derivatives. The on-chip peripherals of

the CPU you have selected are configured from the Device.

5.12 Database selection67

You have made when you create your project target. Refer to page 58 for more

Information about selecting a device. You may select and display the on-chip peripheral

components using the Debug menu. You can also change the aspects of each peripheral using the

controls in the dialog boxes.

5.13 Start DebuggingYou start the debug mode of µVision2 with the Debug – Start/Stop Debug

Session Command. Depending on the Options for Target – Debug Configuration, µVision2 will

load the application program and run the startup code µVision2 saves the editor screen layout

and restores the screen layout of the last debug session. If the program execution stops, µVision2

opens an editor window with the source text or shows CPU instructions in the disassembly

window. The next executable statement is marked with a yellow arrow. During debugging, most

editor features are still available.

For example, you can use the find command or correct program errors. Program source

text of your application is shown in the same windows. The µVision2 debug mode differs from

the edit mode in the following aspects:

_ The “Debug Menu and Debug Commands” described on page 28 are available. The additional

debug windows are discussed in the following.

_ The project structure or tool parameters cannot be modified. All build commands are disabled.

5.14 Disassembly WindowThe Disassembly window shows your target program as mixed source and assembly

program or just assembly code. A trace history of previously executed instructions may be

displayed with Debug – View Trace Records. To enable the trace history, set Debug –

Enable/Disable Trace Recording.

If you select the Disassembly Window as the active window all program step commands

work on CPU instruction level rather than program source lines. You can select a text line and

set or modify code breakpoints using toolbar buttons or the context menu commands.

You may use the dialog Debug – Inline Assembly… to modify the CPU instructions.

That allows you to correct mistakes or to make temporary changes to the target program you are

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

popular embedded 8051 devices.

The Keil µVision Debugger accurately simulates on-chip peripherals (I²C, CAN, UART,

SPI, Interrupts, I/O Ports, A/D Converter, D/A Converter, and PWM Modules) of your 8051

device. Simulation helps you understand hardware configurations and avoids time wasted on

setup problems. Additionally, with simulation, you can write and test applications before target

hardware is available.

5.15 EMBEDDED C Use of embedded processors in passenger cars, mobile phones, medical equipment,

aerospace systems and defense systems is widespread, and even everyday domestic appliances

such as dish washers, televisions, washing machines and video recorders now include at least one

such device.

Because most embedded projects have severe cost constraints, they tend to use low-cost

processors like the 8051 family of devices considered in this book. These popular chips have

very limited resources available most such devices have around 256 bytes (not megabytes!) of

RAM, and the available processor power is around 1000 times less than that of a desktop

processor. As a result, developing embedded software presents significant new challenges, even

for experienced desktop programmers. If you have some programming experience - in C, C++

or Java - then this book and its accompanying CD will help make your move to the embedded

world as quick and painless as possible.

6. SCHEMATIC DIAGRAM

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FOR SCHEMATIC DIAGRAM REFER CD

6.1 SCHEMATIC EXPLANATIONPOWER SUPPLY

The circuit uses standard power supply comprising of a step-down transformer from

230Vto 12V and 4 diodes forming a bridge rectifier that delivers pulsating dc which is then

filtered by an electrolytic capacitor of about 470µF to 1000µF. The filtered dc being

unregulated, IC LM7805 is used to get 5V DC constant at its pin no 3 irrespective of input DC

varying from 7V to 15V. The input dc shall be varying in the event of input ac at 230volts

section varies from 160V to 270V in the ratio of the transformer primary voltage V1 to

secondary voltage V2 governed by the formula V1/V2=N1/N2. As N1/N2 i.e. no. of turns in the

primary to the no. of turns in the secondary remains unchanged V2 is directly proportional to

V1.Thus if the transformer delivers 12V at 220V input it will give 8.72V at 160V.Similarly at

270V it will give 14.72V.Thus the dc voltage at the input of the regulator changes from about

8V to 15V because of A.C voltage variation from 160V to 270V the regulator output will remain

constant at 5V.

The regulated 5V DC is further filtered by a small electrolytic capacitor of 10µF for any

noise so generated by the circuit. One LED is connected of this 5V point in series with a current

limiting resistor of 330Ω to the ground i.e., negative voltage to indicate 5V power supply

availability. The unregulated 12V point is used for other applications as and when required.

STANDARD CONNECTIONS TO 8051 SERIES MICRO CONTROLLER

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ATMEL series of 8051 family of micro controllers need certain standard connections.

The actual number of the Microcontroller could be “89C51” , “89C52”, “89S51”, “89S52”, and

as regards to 20 pin configuration a number of “89C2051”. The 4 set of I/O ports are used based

on the project requirement. Every microcontroller requires a timing reference for its internal

program execution therefore an oscillator needs to be functional with a desired frequency to

obtain the timing reference as t =1/f.

A crystal ranging from 2 to 20 MHz is required to be used at its pin number 18 and 19 for

the internal oscillator. It may be noted here the crystal is not to be understood as crystal oscillator

It is just a crystal, while connected to the appropriate pin of the microcontroller it results in

oscillator function inside the microcontroller. Typically 11.0592 MHz crystal is used in general

for most of the circuits using 8051 series microcontroller. Two small value ceramic capacitors of

33pF each is used as a standard connection for the crystal as shown in the circuit diagram.

RESET

Pin no 9 is provided with an resset arrangement by a combination of an electrolytic

capacitor and a register forming RC time constant. At the time of switch on, the capacitor gets

charged, and it behaves as a full short circuit from the positive to the pin number 9. After the

capacitor gets fully charged the current stops flowing and pin number 9 goes low which is pulled

down by a 10k resistor to the ground. This arrangement of reset at pin 9 going high initially and

then to logic 0 i.e., low helps the program execution to start from the beginning. In absence of

this the program execution could have taken place arbitrarily anywhere from the program cycle.

A pushbutton switch is connected across the capacitor so that at any given time as desired it can

be pressed such that it discharges the capacitor and while released the capacitor starts charging

again and then pin number 9 goes to high and then back to low, to enable the program execution

from the beginning. This operation of high to low of the reset pin takes place in fraction of a

second as decided by the time constant R and C.

For example: A 10µF capacitor and a 10kΩ resistor would render a 100ms time to pin number 9

from logic high to low, there after the pin number 9 remains low.

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External Access(EA):

Pin no 31 of 40 pin 8051 microcontroller termed as EA¯ is required to be connected to 5V for

accessing the program form the on-chip program memory. If it is connected to ground then the

controller accesses the program from external memory. However as we are using the internal

memory it is always connected to +5V.

BRIEF DESCRIPTION OF WORKING OF 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 most have double throw (changeover)

switch contacts. 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.

8. BILL OF MATERIALS

PLEASE REFER CD

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9. CODING

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9.1 SOURCE CODE

1. Click on the Keil Vision Icon on Desktop

2. The following fig will appear

3. Click on the Project menu from the title bar

4. Then Click on New Project

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5. Save the Project by typing suitable project name with no extension in u r own folder sited in either C:\ or D:\

6. Then Click on save button above.

7. Select the component for u r project. i.e. Atmel……

8. Click on the + Symbol beside of Atmel

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9. Select AT89C51 as shown below

10. Then Click on “OK”

11. The Following fig will appear

12. Then Click either YES or NO………mostly “NO”.76

13. Now your project is ready to USE.

14. Now double click on the Target1, you would get another option “Source group 1” as

shown in next page.

15. Click on the file option from menu bar and select “new”.

16. The next screen will be as shown in next page, and just maximize it by double

clicking on its blue boarder.

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17. Now start writing program in either in “EMBEDDED C” or “ASM”.

18. For a program written in Assembly, then save it with extension “. asm” and for

“EMBEDDED C” based program save it with extension “ .C”

19. Now right click on Source group 1 and click on “Add files to Group Source”.

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20. Now you will get another window, on which by default “EMBEDDED C” files will

appear.

21. Now select as per your file extension given while saving the file

22. Click only one time on option “ADD”.

23. Now Press function key F7 to compile. Any error will appear if so happen.

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24. If the file contains no error, then press Control+F5 simultaneously.

25. The new window is as follows

26. Then Click “OK”.

27. Now click on the Peripherals from menu bar, and check your required port as shown

in fig below.

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28. Drag the port a side and click in the program file.

29. Now keep Pressing function key “F11” slowly and observe.

30. You are running your program successfully.

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10 .HARDWARE TESTING

10.1 CONTINUITY TEST:

In electronics, a continuity test is the checking of an electric circuit to see if current flows

(that it is in fact a complete circuit). A continuity test is performed by placing a small voltage

(wired in series with an LED or noise-producing component such as a piezoelectric speaker)

across the chosen path. If electron flow is inhibited by broken conductors, damaged components,

or excessive resistance, the circuit is "open".

Devices that can be used to perform continuity tests include multi meters which measure

current and specialized continuity testers which are cheaper, more basic devices, generally with a

simple light bulb that lights up when current flows.

An important application is the continuity test of a bundle of wires so as to find the two ends

belonging to a particular one of these wires; there will be a negligible resistance between the

"right" ends, and only between the "right" ends.

This test is the performed just after the hardware soldering and configuration has been

completed. This test aims at finding any electrical open paths in the circuit after the soldering.

Many a times, the electrical continuity in the circuit is lost due to improper soldering, wrong and

rough handling of the PCB, improper usage of the soldering iron, component failures and

presence of bugs in the circuit diagram. We use a multi meter to perform this test. We keep the

multi meter in buzzer mode and connect the ground terminal of the multi meter to the ground.

We connect both the terminals across the path that needs to be checked. If there is continuation

then you will hear the beep sound.

10.2 POWER ON TEST:This test is performed to check whether the voltage at different terminals is according to

the requirement or not. We take a multi meter and put it in voltage mode. Remember that this test

is performed without microcontroller. Firstly, we check the output of the transformer, whether

we get the required 12 v AC voltage.

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Then we apply this voltage to the power supply circuit. Note that we do this test without

microcontroller because if there is any excessive voltage, this may lead to damaging the

controller. We check for the input to the voltage regulator i.e., are we getting an input of 12v and

an output of 5v. This 5v output is given to the microcontrollers’ 40 th pin. Hence we check for the

voltage level at 40th pin. Similarly, we check for the other terminals for the required voltage. In

this way we can assure that the voltage at all the terminals is as per the requirement.

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84

11. RESULTS

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12 .CONCLUSION

Hence this project has been designed and data from different analog loads has been

acquisited and digitally displayed on an LCD. Several loads have been monitored in real time.

Infrastructure processes may be public or private, and include water treatment and

distribution, wastewater collection and treatment, oil and gas pipelines, electrical power

transmission and distribution, civil defense siren systems, and large communication systems.

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13. BIBLIOGRAPHY

TEXT BOOKS REFERED:

1. “The 8051 Microcontroller and Embedded systems” by Muhammad Ali Mazidi and Janice

Gillispie Mazidi , Pearson Education.

2. ATMEL 89S52 Data Sheets.

WEBSITES

www.atmel.com

www.beyondlogic.org

www.wikipedia.org

www.howstuffworks.com

www.alldatasheets.com

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