PREPAID ENERGY METER WITH TARIFF INDICATOR

A PROJECT REPORT

Submitted byG.VIJAYA KRISHNA

M.DURGA PRASAD

J.VISHNU VARDHAN REDDY

K.VINEELA CHANDRIKA

in partial fulfillment for the award of the degree

of

BACHELOR OF TECHNOLOGY

In

ELECTRICAL & ELECTRONICS ENGINEERINGUnder the guidance

Of

Mr.J.S.S.Kalyan, M.Tech

Assistant Professor

USHA RAMA COLLEGE OF ENGINEERING & TECHNOLOGYOn NH-5, Telaprolu, Near Gannavaram, Unguturu (M), Krishna Dist. A.P.-521 109

Approved by AICTE, New Delhi

Affiliated to

JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY KAKINADA

KAKINADA, A.P - 533 003

APRIL 2012

USHA RAMA COLLEGE OF ENGINEERING & TECHNOLOGYOn NH-5, Telaprolu, Near Gannavaram, Unguturu (M), Krishna Dist. A.P.-521 109

approved by AICTE, New Delhi, India.

Affiliated to

JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY KAKINADA

KAKINADA, A.P – 533 005

BONAFIDE CERTIFICATE

Certified that this project report”PREPAID ENERGY METER WITH TARIFF INDICATOR” is the bonafide work of G.VIJAYA KRISHNA , M.DURGA PRASAD , J.VISHNU VARDHAN REDDY & K.VINEELA CHANDRIKA registration numbers 08NG1A0239 , 08NG1A0206, 08NG1A0259 & 08NG1A0240 who carried out the project work under my supervision.

Mr. Ravi Kumar Jujjuvarapu, M.Tech, (Ph.D) PROJECT GUIDE

HEAD OF THE DEPARTMENT-EEE Mr. J.S.S.Kalyan, M.Tech

Assistant Professor

SIGNATURE

EXTERNAL EXAMINER

AKNOWLEDGEMENT

We feel privileged to express our deepest sense of gratitude and sincere

thanks to our project guide CH.KALYAN SIR for his excellent guidance

throughout our project work. His prompt and kind help led to the completion of the

dissertation work.

We would also like to thank our H.O.D. J.RAVI KUMAR SIR

for approving our project and giving us ideas regarding the project.We also wish to

thank them for their patience and co-operation, which proved beneficial for us.

We owe a substantial share of our success to the whole faculty and staff

members of Electrical & Electronics Engineering Department, which provided us

the requisite facilities required to complete the project work.

Finally, we wish to express our sincere appreciation and thanks to our

college library and all those who have guided and helped us directly or indirectly

for accomplishing our goal.

REGARDS:

G.VIJAYA KRISHNA(08NG1A0239)

M.DURGA PRASAD(08NG1A0206)

J.VISHNU VARDHAN REDDY(08NG1A0259)

K.VINEELA CHANDRIKA(08NG1A0240)

ABSTRACT Indian power sector is facing serious problem of lean revenue collection as against

energy supplied due to energy thefts and network losses. All the steps taken so far,

regarding the improvement of the revenue collection did not yield satisfactory

results. It is reported that the most faulty sub system is the metering and meter

reading system.

The traditional billing systems are discrete, inaccuratecostly,

slow,and lack flexibility as well as reliability. Therefore, several attempts were

made to automate the billing systems. Even though accurate and fast readings are

obtained, bill payment is still performed based on the old billing procedure. They

require an individual/agent to physically come and take down the readings and

report to house hold/office the amount one has to pay.

Here we are designing and developing a

pre-paid energy metering system with tariff idicator which provides both the

suppliers and the consumers with better services regarding this meter billing and

payment problems.The metering equipment and smart card technology, allows the

power utility to save time and money while providing a new payment option for the

customer.

This is a very good microcontroller based

application. This unit will accept the number of units recharged by the concerned

department person, counts the number of units consumed by the customer and as

soon as the customer exceeds the recharged amount, it will disconnect the power

supply to the customer until the next recharge.

TABLE OF CONTENTS

CHAPTER TITLE PAGE NO

1. INTRODUCTION -

1.1 INTRODUCTIO -

1.2Thesis -

2. HARDWARE DESCRIPTION -

2.1.EEPROM -

2.2.MICROCONTROLLER -

2.3.ENERGY METER -

2.4.REAL TIME CLOCK -

2.5.LCD DISPLAY -

2.6.BUZZER -

2.7.POWER SUPPLY -

2.8.RELAY DRIVER -

2.9.CARD READER -

2.10.DIODE -

2.11.CAPACITOR -

2.12.RESISTOR -

2.13.REGULATOR -

2.14.TRANSFORMER -

2.15.RELAY -

2.16.OPTOCOUPLER -

3. BLOCK DIAGRAM&CICUIT DIAGRAM -

CHAPTER TITLE PAGE NO

4. BENEFITS OF PREPAID ENERGY METER -

5. ADVANTAGES OF PREPAID ENERGY METER -

6. SOFTWARE DESCIPTION&PROGRAM -

7. FUTURE SCOPE &CONCLUSION -

8. REFERENCE -

CHAPTER-1

INTRODUCTION

1.1Introduction on our project:

The Electrical metering instrument technology has come a long

way from what it Was more than 100 years ago. From the original bulky meters

with heavy magnets and coils, there have been many innovations that have

resulted in size & weight reduction in addition to improvement in features and

specifications. Resolution and accuracy of the meter have seen substantial

improvements over the years. Introduction of the digital meter in the later part of

last century has completely changed the way Electrical parameters are measured.

Starting with Voltmeters & Ammeters, the digital meter has conquered the entire

spectrum of measuring instruments due to their advantages like ease of reading,

better resolution and rugged construction. Of particular significance is the

introduction of the Electronic Energy Meter in the mid eighties. Now a days, the

energy consumption and energy distribution has became a big subject for

discussion because of huge difference in energy production and consumption. In

this regard, energy consumers are facing so many problems due to the frequent

power failures; another important reason for power cuts is due to the un-limited

energy consumption of rich people. In this aspect, to minimize the power cuts and

to distribute the energy equally to all areas, some restriction should have over the

power consumption of each and every energy consumer, and according to that the

Government should implement a policy, by introducing Autonomous Energy

Meters everywhere in domestic sector. Hence, the need has come to think on this

line and a solution has to be emerged out.

Electrical Metering Instrument Technology

Today the metering instrument technology grown up significantly, such

that the Consumed energy can be calculated mathematically, displayed, data can be

stored, data can be transmitted, etc. Presently the microcontrollers are playing

major role in metering instrument technology. The present project work is

designed to collect the consumed energy data of a particular energy consumer

through wireless communication system (without going to consumer house), the

system can be called as automatic meter reading (AMR) system. The Automatic

Meter readingsystem is intended to remotely collect the meter readings of a

locality using a communication system, without persons physically going and

reading the meters visually.

Details About Electronic Energy Meter

The following are the advantages of electronic energy meter:

Accuracy

While electromechanical meters are normally available with Class 2

accuracy, Electronic meters of Class 1 accuracy are very common.

Low Current Performance

Most of the electromechanical meters tend to run slow after a few years

and stoprecording at low loads typically below 40% of their basic current. This is

due to increased friction at their bearings. This results in large losses in revenue

since most of the residential consumers will be running at very low loads for

almost 20 hours in a day. Electronic meters record consistently and accurately even

at 5% of their basic current. Also they are guaranteed to start recording energy at

0.4% of their basic current.

Low Voltage Performance

Most of the mechanical meters become inaccurate at voltages below

75% of ratedvoltage whereas electronic meters record accurately even at 50% of

rated voltage. This is a major advantage where low voltage problem is very

common.

Installation

The mechanical meter is very sensitive to the position in which it is

installed. If it is not mounted vertically, it will run slow, resulting in revenue loss.

Electronic meters are not sensitive

Tamper

The mechanical meters can be tampered very easily even without

disturbing the Wiring either by using an external magnet or by inserting a thin film

into the meter to touch the rotating disc. In addition to these methods, in the case

of a single-phase meter, there are more than 20 conditions of external wiring that

can make the meter record less. In the case of 3 Phase meter, external wiring can

be manipulated in 4 ways to make it slow. Hence, any of these methods cannot

tamper electronic meters. Moreover they can detect the tampering of meter by

using LED.

New Features

Electronic meters provide many new features like prepaid

metering and remote Metering that can improve the efficiency of the utility.

Remote Metering of Energy Meters

The introduction of electronic energy meters for electrical energy

metering hasresulted in various improvements in the operations of utilities apart

from the increase in revenue due to better recording of energy consumption. One

such additional benefit is the possibility of reading the meters automatically using

meter-reading instruments even without going near the meter. Meter reading

instruments (MRI) are intelligent devices with built in memory and keyboard. The

meter reader can download the energy consumption and related information from

the electronic meter into the meter reading instrument either by connecting the

MRI physically to the meter using their communication ports or by communicating

with the meter from a distance using Radio Frequency (RF) communication media.

RF communication method is similar to a cordless telephone, which is quite

common these days. The meter and the MRI are provided with an antenna. When

the meter reader presses a button on the MRI, it communicates with the meter

through RF and asks for all the data that are preset. The meter responds with all

relevant data like meter identification number, cumulative energy consumed till

that time etc. After reading many meters like that in one MRI, the meter reader can

go to the office and transfer all these data into a computer, which will have all

these data for the previous billing period. Using these two data, the computer

calculates the consumption for the current billing period and prepares the bill for

each consumer.

The use of RF communication enables the utility to install the meters

on top of theelectric pole out of reach of the consumers thereby eliminating

chances of tamper of the meter. Frequencies in the range of 400 MHz to 900

MHzare commonly used for this purpose. However other frequencies can also be

used. If the distance between meter and MRI is of the order of 10 or 15 meters, this

communication can be achieved using low power transmitters at reasonable costs.

Power line carrier communication is another method of remote metering. In this

method, the meter data is transferred to an MRI or computer by using the power

line itself as the medium of transmission. This solution is generally cheaper than

RF but needs good quality power lines to avoid loss of data. This method is more

attractive for limited distance communication. Third medium of communication

possible is telephone line. This is viable only for industrial meters like the

Trivector meter because of the cost of Modems required and the need for a

telephone line, which may not be available in every house. This medium has the

advantage of unlimited distance range. Remote metering is typically not a default

option, but something provided for selected customers. The preferred customer

base may include suspicious clients or those located very close to others, such as in

a high-rise building. In the latter case, tens or hundreds of meters may use RF to

send billing data to a common collector unit, which then decodes the data with

microcontrollers or computers.

PREPAYMENT METERING

Yet another advantage of the electronic meter is the possibility of

introducing Prepaid metering system. Prepaid metering system is the one in which

the consumer pays money in advance to the utility and then feeds this information

into his meter. The meter then updates the credit available to the consumer and

starts deducting his consumption from available credit. Once the credit reaches a

minimum specified value, meter raises an alarm. If the credit is completely

exhausted, the meter switches off the loads of the consumer. Main advantage of this system is that the utility can eliminate

meter readers. Another benefit is that they get paid in advance. The consumer

benefits due to elimination of penalty for late payment. Also it enables him to plan

his electricity bill expenses in a better manner. Due tothe intelligence built in into

the electronic meters, introduction of prepaid metering becomes much easier than

in the case of electromechanical meters.

Prepaid Energy Metering

Energy meters, the only direct revenue interface between utilities and

the consumers, have undergone several advancements in the last decade. The

conventional electro-mechanical meters are being replaced with electronic meters

to improve accuracy in meter reading. Asian countries are currently looking to

introduce prepaid electricity meters across their distribution network, buoyed up by

the success of this novel methodology in South Africa. The existing inherent

problems with the post-paid system and privatization of state held power

distribution companies are the major driving factors for this market in Asia.

Over 40 countries have implemented prepaid meters in their markets.

In United Kingdom the system, has been in use for well over 70 years with about

3.5 million consumers. The prepaid program in South Africa was started in 1992

since then they have installed over 6 million meters. Other African counties such

as Sudan, Madagascar are following the South African success. The concept has

found ground in Argentina and New Zealand with few thousands ofinstallations.

The prepaid meters in the market today are coming up with smart cards to hold

information on units consumed or equivalent money value. When the card is

inserted, the energy meter reads it, connects the supply to the consumer loads, and

debits the value. The meters are equipped with light emitting diodes (LED) to

inform consumers when 75 percent of the credit energy has been consumed. The

consumer then recharges the prepaid card from a sales terminal or distribution

point, and during this process any changes in the tariff can also be loaded in the

smart card.

1.2THESIS: The thesis explains the implementation of ”prepaid energy meter with

tariff indicator “ .The organization of thesis is expalind here.

Chapter1:Introduction about prepaid energy meter.It gives over all information

about prepaid energy meter

Chapter2:presents the hard ware description.where all components which are used

in project are brefily described.

Chapter3:presents about block diagram &circuit diagram.

Chapter4:presents the benefits of prepaid energy meter.

Chapter5:presents the advantages of perpaid energy meter.

Chapter6:it consists of brief note on software and program used in our project

Chapter7:It gives the future scope and conclusion.

CHAPTER-2

HARDWARE DESCRIPTION

COMPONENTS USED IN OUR PROJECT ARE AS FOLLOWS:

2.1EEPROM(24C02):-

AT24C02 is an electrically erasable and programmable ROM. It

Has a 2Kbits of memory size arranged in 32 pages of 8 byte each. There are 256

(32 x 8) words each of one byte. The data is transferred and received serially

throughserial data (SDA) pin.

The SCL is clock input and is used to synchronize EEPROM with

microcontroller for various operations. When data is to be read or write, first a start

condition is created followed by device address, byte address and the data itself.

Finally a stop condition is provided. The start condition occurs when SDA and

SCL get high to low simultaneously. The stop condition is when SDA remains low

while SCL goes from high to low. The data is read or written between the start and

stop conditions on every transition of SCL from high to low. For more details on

different operations and addressing, refer interfacing 24C02 with 8051.

A total of eight EEPROMs can be connected through a bus. There are

three address pins in AT24C02 for selecting a particular chip. The device can be

addressed serially by the software. It makes use of an internal register of the

EEPROM whose 4 MSB bits are 1010, the next three are the EEPROM address

bits and the LSB signifies whether data is to be read or written. This last bit is 1 for

write and 0 for read operation.

For example, if in an EEPROM all address bits are grounded, then

for write operation a hex value 0xA1 (1010 0001) will be sent. Here 000, in last

bits, addresses the EEPROM and 1 in LSB indicates a write operation. Similarly

for read operation the device address to be sent is 0xA0 (1010 0000). Next, the

byte or page address is sent followed by the data byte. This data byte is to be

written on or read by the microcontroller.

FEATURES:

• Low-voltage and Standard-voltage Operation– 2.7 (VCC = 2.7V to 5.5V)– 1.8 (VCC = 1.8V to 5.5V)

• Internally Organized 128 x 8 (1K), 256 x 8 (2K), 512 x 8 (4K),1024 x 8 (8K) or 2048 x 8 (16K)

• Two-wire Serial Interface

• Schmitt Trigger, Filtered Inputs for Noise Suppression

• Bidirectional Data Transfer Protocol

• 100 kHz (1.8V) and 400 kHz (2.7V, 5V) Compatibility

• Write Protect Pin for Hardware Data Protection

• 8-byte Page (1K, 2K), 16-byte Page (4K, 8K, 16K) Write Modes

• Partial Page Writes Allowed

• Self-timed Write Cycle (5 ms max)

• High-reliability– Endurance: 1 Million Write Cycles– Data Retention: 100 Years

• Automotive Devices Available

• 8-lead JEDEC PDIP, 8-lead JEDEC SOIC, 8-lead Ultra Thin Mini-MAP (MLP 2x3), 5-lead

SOT23, 8-lead TSSOP and 8-ball dBGA2 Packages

• Die Sales: Wafer Form, Waffle Pack and Bumped Wafers

PIN DIAGARAM

PINS DESCRIPTION:

Figure shows pin Description of 24c02 EEPROM IC.

SERIAL CLOCK (SCL): The SCL input is used to positive edge clock data into each EEPROM

device and negative edge clock data out of each device.

SERIAL DATA (SDA): The SDA pin is bidirectional for serial data transfer. This pin is open-

drain driven and may be wire-ORed with any number of other open-drain or

open-collector devices.

DEVICE/PAGE ADDRESSES (A2, A1, A0): The A2, A1 and A0 pins are device address inputs that are hard wired

for the AT24C02. As many as eight 1K/2K devices may be addressed on a single

bus system (device addressing is discussed in detail underthe Device Addressing

section).

WRITE PROTECT (WP): The AT24C02 has a Write Protect pin that provides hardware data

protection. The Write Protect pin allows normal Read/Write operations when

connected to ground (GND). When the Write Protect pin is connected to VCC, the

write protection feature is enabled and operates. WP pin status Part of Array

Protected 24c02 .At VCC Full (2K) Array. At GND Normal Read/Write

Operations. The ST24C02A is a 2k bit electrically erasable programmable memory,

organized as 256x8 bits. The memory is compatible with I2C bus standard,two

data bus and serial clock. The STA240C2A carries a built in a bit unique device

information code corresponding to the I2C bus definition. This is used together

with a 3-bit chip enable input to form a 7-bit memory select signal. In this way up

to 8 ST24C02A’S may be connected to the I2C bus and selected individually.

The ST24C02A behaves as a slave device in the I2C protocol with all

memory operations synchronized by the serial clock. Read and write operations are

initiated by start condition generated by the bus master. The start condition is

followed by a stream of 7 device select bit plus one read/write bit and terminated

by an acknowledge bit. When writing data to the memory it respond to the 8 bits

received by asserting an acknowledge bit during the ninth bit time. Data transfers

are terminated with a stop conditions.

OPERATING MODES:- There are both read and write modes. Each is entered by the correct

sequence of serial bits sent to the device on the SDA line. For some write modes

the status of the mode input is also used to set the operating mode. The 8bits sent

after a start condition are made up of a bits that identify the device type, 3 chip

enable bits and one direction indicator bit. Whether the controller wants to read

from the device or write to the device is decided by the very first byte sent to it on

the SDA line. The last bit of very first sent to E2PROM is directional indicator. If

this bit is ‘Zero’ the direction of data flow is from controller to the E2PROM and if

‘One’ it is from E2PROM to the controller. Following are the different modes for

reading or writing from the E2PROM.

1). Byte Write: - In this mode a device select is sent with the R/W bit at ‘0’ followed

by the address of the byte. This is followed by the 8 bit data to be written during

the programmingcycle.

2). Multi byte Write And Page Write: - In these modes up to 4 or 8 bytes respectively may be written

in one programming cycle. Multi-byte write mode is activated when the mode pin

is at V/H level and page write when mode is at V/L. A device select is sent with

the R/W bit at ‘0’ followed by the data bytes to write. The bytes are written in the

programming cycle 8 bytes written in the page write mode must have the same five

upper address bits

3). Current Address: In this mode device select is sent with the R/W bit at ‘1’. The

address of various byte accessed is automatically incremented and the new byte

read.

4). Random Address Read: - This mode allows random access to the memory. A device select is sent

with R/W bit at ‘0’ (write) followed by the address .Then a new start condition is

forced with the same device select is sent with the R/W bit at ‘1’ (read) and the

byte is read.

5). Sequential Read: - This mode starts with either a current address or random address read

sequence it reads consecutive bytes as long as the bus master acknowledges each

one without generating a stop condition.

Device operation based on I2c protocol : The 24C02 family uses two I/O lines for interfacing: SCL

(Serial Clock) and SDA (Serial Data). SCL edges have different functions,

depending on whether a device is being read from or written to. When clocking

data into the device, the positive edges of the clock latch the data. The negative

clock edges clock data out of the device. The SDA signal is bi-directional, and is

physically an open-drain so that multiple EEPROMs or other devices can share the

pin. Both SCL and SDA must be pulled high externally. The protocol used by the

EEPROM is based in part on an ACK (acknowledge) bit sent by the EEPROM, if

the data sent to it has been received. All addresses and data are sent in 8-bit words.

The EEPROM sends the ACK as a low bit period during the ninth clock cycle. The

EEPROM looks for specific transitions on the SCL and SDA pins to qualify READ

and WRITE. Data on the SDA pin may change only during the time SCL is low.

Data changes during SCL high periods indicate a START or STOP condition. A

START condition is a high-to-low transition of SDA with SCL high. All data

transfers must begin with a START condition. A STOP condition is a low-to-high

transition of SDA with SCL high. All data transfers must end with a STOP

condition. After a READ, the STOP places the EEPROM in a standby power

mode. Refer to Figure 1 for START and STOP conditions. Figure 1. START and

STOP conditions.

Device Addressing The 24C02 has 3 physical pins, designated A2, A1, and A0, which

are tied to logic 1 or 0 levels. This allows eight unique hardware addresses, so that

up to eight 24C02s can share the SCL and SDA lines without conflict. There is an

internal address comparator that looks for a match between the address sent by the

master controller and the 24C02's unique 7-bit address, determined in part by A2,

A1, and A0. Refer to Table 1below. Table 1. 24C02 Device Address

MSB LSB1 0 1 0 A2 A1 A0 R/~W

The device address is sent immediately after a START condition. The first four

bits are the sequence "1010", which is a simple "noise filter" which prevents a

random noise burst on the lines from accessing the device. The last bit sent is a 1

for READ and a 0 for WRITE. The code example below is for random

READ/WRITE operations. The part can also perform Page Write/Sequential Read

with slight code modifications. See the 24C02 data sheet for more information.

Byte Write to Memory:

The Byte Write sequence is shown in Figure 2. After receiving a START

condition and a device address, the EEPROM sends an ACK if the device address

matches its own unique address. The MAX7651 waits for the ACK and aborts

communication if it is not present. Next, an 8-bit byte address is sent, followed by

another ACK. The MAX7651 then sends the 8-bit data byte, waits for the third

ACK, and sends a STOP condition.

WRITE operation. It is important to note that after the STOP condition is received, the

EEPROM internally waits for the data to be stored into its internal memory array.

This can take as long as 10ms. The 24C02 will ignore attempted accesses while the

internal EEPROM is being programmed. The part can be polled for completion of

the internal write cycle. This involves sending another START condition (also

called a REPEATED START), followed by the device address byte. Note, in this

case, thereis no STOP condition sent. The EEPROM will send an ACK if the

internal programming cycle is completed. The MAX7651 can also be programmed

to wait10ms before proceeding.

Hardware connection EEPROM is based on i2c protocol ,two wired serial

protocol. For that we need two pins. We use p3.6 for SCL and p3.7 for SDA .

a0,a1,a2 are address lines to select EEPROM chip. That is hard wired and fix for

each EEPROM. To send address, data, start-stop condition data we use SCL and

SDA.

2.2MICROCONTROLLER(AT89S52):-

Description :-

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 nonvolatile memory

technology and is compatible with the indus-try-standard 80C51 instruction set and

pinout. The on-chip Flash allows the program memory to be reprogrammed in-

system or by a conventional nonvolatile memory pro-grammer. By combining a

versatile 8-bit CPU with in-system programmable Flash on a monolithic chip, the

Atmel AT89S52 is a powerful microcontroller which provides a highly-flexible

and cost-effective solution to many embedded control applications. The AT89S52 provides the following standard features:

8K bytes of Flash, 256 bytes of RAM, 32 I/O lines, Watchdog timer, two data

pointers, three 16-bit timer/counters, a six-vector two-level interrupt architecture, a

full duplex serial port, on-chip oscillator, and clock circuitry. In addition, the

AT89S52 is designed with static logic for operation down to zero frequency and

supports two software selectable power saving modes. The Idle Mode stops the

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

continue functioning. The Power-down mode saves the RAM con-tents but freezes

the oscillator, disabling all other chip functions until the next interrupt or hardware

reset.

FEARTURES:

Compatible with MCS-51 Products

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

Endurance: 1,000 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

Interrupt Recovery from Power-down Mode

Eight Interrupt Sources

Full Duplex UART Serial Channel

Low-power Idle and Power-down Modes

PIN DIAGRAM

Vital role of Micro controller-AT89S52:

1) It will acts a master to communicate with memory

2) Whenever command is sent to reset the memory ,controller resets the memory

3) Controller takes the pulses from the energy meter and increments the Unit which

depends upon the calculations and stores in memory.

4) Microcontroller also switches off the energy meter whenever the command is

sent from the server. This happens when the owner has not paid the bill.

BLOCK DIAGRAM

ARCHITECHTURE OF MICROCONTROLLER AT89S52

DEVICE OPERATION:

CLOCK and DATA TRANSITIONS: The SDA pin is normally pulled high with

an external device. Data on the SDA pin may change only during SCL low time

periods. Data changes during SCL high periods will indicate a start or stop

condition as defined below.

Figure : Data validity

START CONDITION: A high-to-low transition of SDA with SCL high is a start

condition which must precede any other command.

STOP CONDITION: A low-to-high transition of SDA with SCL high is a stop

condition. After a read sequence, the stop command will place the EEPROM in a

standby power mode .

Figure : Start & Stop condition

ACKNOWLEDGE: All addresses and data words are serially transmitted to and

from the EEPROM in 8-bit words. The EEPROM sends a zero to acknowledge that

it has received each word. This happens during the ninth clock cycle.

Figure : Acknowledge

STANDBY MODE: The AT24C01A/02/04/08A/16A features a low-power

standby mode which is enabled: (a) upon power-up and (b) after the receipt of the

STOP bit and the completion of any internal operations.

MEMORY RESET: After an interruption in protocol, power loss or system reset,

any 2-wire part can be reset by following these steps:

1. Clock up to 9 cycles.

2. Look for SDA high in each cycle while SCL is high.

3. Create a start condition.

Device Addressing

The 1K, 2K, 4K, 8K and 16K EEPROM devices all require an 8-bit

device address word following a start condition to enable the chip for a read or

write operation .The device address word consists of a mandatory one, zero

sequence for the first four most significant bits as shown. This is common to all the

EEPROM devices. The next 3 bits are the A2, A1 and A0 device address bits for

the 1K/2K EEPROM. These 3 bits must compare to their corresponding hard-

wired input pins. The 4K EEPROM only uses the A2 and A1 device address bits

with the third bit being a memory page address bit. The two device address bits

must compare to their corresponding hard-wired input pins. The A0 pin is no

connect. The 8K EEPROM only uses the A2 device address bit with the next 2 bits

being for memory page addressing. The A2 bit must compare to its corresponding

hard-wired input pin. The A1 and A0 pins are no connect. The 16K does not use

any device address bits but instead the 3 bits are used for memory page addressing.

These page addressing bits on the 4K, 8K and 16K devices should be considered

the most significant bits of the data word address which follows. The A0, A1 and

A2 pins are no connect. The eighth bit of the device address is the read/write

operation select bit. A read operation is initiated if this bit is high and a write

operation is initiated if this bit is low. Upon a compare of the device address, the

EEPROM will output a zero. If a compare is not made, the chip will return to a

standby state.

Figure: Device Addressing

Write Operations

BYTE WRITE: A write operation requires an 8-bit data word address following

the device address word and acknowledgment. Upon receipt of this address, the

EEPROM will again respond with a zero and then clock in the first 8-bit data

word. Following receipt of the 8-bit data word, the EEPROM will output a zero

and the addressing device, such as a microcontroller, must terminate the write

sequence with a stop condition. At this time the EEPROM enters an internally

timed write cycle, tWR, to the nonvolatile memory. All inputs are disabled during

this write cycle and the EEPROM will not respond until the write is complete.

Figure : Byte Write

PAGE WRITE: The 1K/2K EEPROM is capable of an 8-byte page write, and the

4K, 8K and 16K devices are capable of 16-byte page writes. A page write is

initiated the same as a byte write, but the microcontroller does not send a stop

condition after the first data word is clocked in. Instead, after the EEPROM

acknowledges receipt of the first data word, the microcontroller can transmit up to

seven (1K/2K) or fifteen (4K, 8K, 16K) more data words. The EEPROM will

respond with a zero after each data word received. The microcontroller must

terminate the page write sequence with a stop condition.

The data word address lower three (1K/2K) or four (4K, 8K, 16K) bits are

internally incremented following the receipt of each data word. The higher data

word address bits are not incremented, retaining the memory page row location.

When the word address, internally generated, reaches the page boundary, the

following byte is placed at the beginning of the same page. If more than eight

(1K/2K) or sixteen (4K, 8K, 16K) data words are transmitted to the EEPROM, the

data word address will “roll over” and previous data will be overwritten.

ACKNOWLEDGE POLLING: Once the internally timed write cycle has started

and the EEPROM inputs are disabled, acknowledge polling can be initiated. This

involves sending a start condition followed by the device address word. The

read/write bit is representative of the operation desired. Only if the internal write

cycle has completed will the EEPROM respond with a zero allowing the read or

write sequence to continue.

Read Operations

Read operations are initiated the same way as write operations with the

exception that the read/write select bit in the device address word is set to one.

There are three read operations:

CURRENT ADDRESS READ: The internal data word address counter maintains

the last address accessed during the last read or write operation, incremented by

one. This address stays valid between operations as long as the chip power is

maintained. The address “roll over” during read is from the last byte of the last

memory page to the first byte of the first page. The address “roll over” during write

is from the last byte of the current page to the first byte of the same page. Once the

device address with the read/write select bit set to one is clocked in and

acknowledged by the EEPROM, the current address data word is serially clocked

out. The microcontroller does not respond with an input zero but does generate a

following stop condition

RANDOM READ: A random read requires a “dummy” byte write sequence to

load in the data word address. Once the device address word and data word address

are clocked in and acknowledged by the EEPROM, the microcontroller must

generate another start condition.

The microcontroller now initiates a current address read by sending a device

address with the read/write select bit high. The EEPROM acknowledges the device

address and serially clocks out the data word. The microcontroller does not

respond with a zero but does generate a following stop condition.

SEQUENTIAL READ: Sequential reads are initiated by either a current address

read or a random address read. After the microcontroller receives a data word, it

responds with an acknowledge. As long as the EEPROM receives an acknowledge,

it will continue to increment the data word address and serially clock out sequential

data words. When the memory address limit is reached, the data word address will

“roll over” and the sequential read will continue. The sequential read operation is

terminated when the microcontroller does not respond with a zero but does

generate a following stop condition.

Figure : Current Address Read

Figure : Random Read

Figure : Sequential Read

2.3SINGLE PHASE ENERGY METER:

An electric meter or energy meter is a device that measures the

amount of electrical energy supplied to or produced by a residence, business or

machine.

The most common type is a kilowatt hour meter. When used in electricity

retailing, the utilities record the values measured by these meters to generate an

invoice for the electricity. They may also record other variables including the time

when the electricity was used.

Modern electricity meters operate by continuously measuring the

instantaneous voltage (volts) and current (amperes) and finding the product of

these to give instantaneous electrical power (watts) which is then integrated against

time to give energy used (joules, kilowatt-hours etc). The meters fall into two basic

categories, electromechanical and electronic.

Electromechanical meters The most common type of electricity meter is the Thomson or

electromechanical induction watt-hour meter, invented by Elihu Thomson in

1888.

Technology

The electromechanical induction meter operates by counting the

revolutions of an aluminum disc which is made to rotate at a speed proportional to

the power. The number of revolutions is thus proportional to the energy usage. It

consumes a small amount of power, typically around 2 watts.

The metallic disc is acted upon by two coils. One coil is connected in

such a way that it produces a magnetic flux in proportion to the voltage and the

other produces a magnetic flux in proportion to the current. The field of the voltage

coil is delayed by 90 degrees using a lag coil. [1]This produces eddy currents in the

disc and the effect is such that a force is exerted on the disc in proportion to the

product of the instantaneous current and voltage. A permanent magnet exerts an

opposing force proportional to the speed of rotation of the disc - this acts as a brake

which causes the disc to stop spinning when power stops being drawn rather than

allowing it to spin faster and faster. This causes the disc to rotate at a speed

proportional to the power being used. The type of meter described above is used on a single-phase AC

supply. Different phase configurations use additional voltage and current coils.

Reading

The aluminum disc is supported by a spindle which has a worm gear which

drives the register. The register is a series of dials which record the amount of

energy used. The dials may be of the cyclometer type, an odometer-like display

that is easy to read where for each dial a single digit is shown through a window in

the face of the meter, or of the pointer type where a pointer indicates each digit. It

should be noted that with the dial pointer type, adjacent pointers generally rotate in

opposite directions due to the gearing mechanism. The amount of energy represented by one revolution of the disc is

denoted by the symbol Kh which is given in units of watt-hours per revolution. The

Single phase energy meter

value 7.2 is commonly seen. Using the value of Kh, one can determine their power

consumption at any given time by timing the disc with a stopwatch. If the time in

seconds taken by the disc to complete one revolution is t, then the power in watts is

. For example, if Kh = 7.2, as above, and one revolution took place in 14.4 seconds,

the power is 1800 watts. This method can be used to determine the power

consumption of household devices by switching them on one by one.

Most domestic electricity meters must be read manually, whether by a

representative of the power company or by the customer. Where the customer

reads the meter, the reading may be supplied to the power company by telephone,

post or over the internet. The electricity company will normally require a visit by a

company representative at least annually in order to verify customer-supplied

readings and to make a basic safety check of the meter.

Accuracy In an induction type meter, creep is a phenomenon that can adversely affect

accuracy, that occurs when the meter disc rotates continuously with potential

applied and the load terminals open circuited. A test for error due to creep is called

a creep test.

2.4REAL TIME CLOCK (DS1307):

DESCRIPTION:

The DS1307 serial real-time clock (RTC) is a low-power, full binary-

Coded decimal (BCD) clock/calendar plus 56 bytes of NV SRAM. Address and

data are transferred serially through an I²C, bidirectional bus. The clock/calendar

provides seconds, minutes, hours, day, date, month, and year information. The end

of the month date is automatically adjusted for months with fewer than 31 days,

Including corrections for leap year. The clock operates in either the 24-hour or 12-

hour format with AM/PM indicator. The DS1307 has a built-in power-sense circuit

that detects power failures and automatically switches to the backup supply.

Timekeeping operation continues while the part operates from the backup supply.

KEY FEATURES:

Real-Time Clock (RTC) Counts Seconds, Minutes, Hours, Date of the Month,

Month, Day of the week, and Year with Leap-Year Compensation Valid Up to

2100

56-Byte, Battery-Backed, General-Purpose RAM with Unlimited Writes I²C Serial Interface Programmable Square-Wave Output Signal Automatic Power-Fail Detect and Switch Circuitry Consumes Less than 500nA in Battery-Backup Mode with Oscillator Running Optional Industrial Temperature Range: -40°C to +85°C Available in 8-Pin Plastic

DIP or SO

DIAGRAM:

2.5 LCD DISPLAY:

For display purpose we are using a 16x2 character LCD. The display

contains 14 pins , in which 1st and 2nd pins are the GND and VCC respectively.

The 3rd pin VEE determines the contrast of the display. For adjusting the contrast, a

variable resistor is used in between the VCC and GND and output is connected to

the VEE. RS, R/W, and E control lines are directly connected to the

microcontroller’s P1.3, P1.4 and P1.5 respectively. The data line D0 to D7 is

connected to the P0. SinceP0 lacks the internal pull up resistor; an external array of

8 resistors (10K) is used as the pull up. The LCD module contains an internal

LCD backlight, which is normally a LED based. For controlling the backlight, the

pin is connected the microcontroller’s P2.7 pin. The port pin is configured as

sinking mode.

LCD PIN DESCRIPTION

The LCD discuss in this section has the most common connector used for the

Hitatchi 44780 based LCD is 14 pins in a row and modes of operation and how to

program andinterface with microcontroller is describes in this section.

LCD DISPLAY

VCC, VSS, VEE

The voltage VCC and VSS provided by +5V and ground respectively while VEE is

used for controlling LCD contrast. Variable voltage between Ground and Vcc is

used to specify the contrast (or "darkness") of the characters on the LCD screen.

RS (register select)

There are two important registers inside the LCD. The RS pin is used for their

selection asfollows. If RS=0, the instruction command code register is selected,

then allowing to user to send a command such as clear display, cursor at home etc..

If RS=1, the data register is selected, allowing the user to send data to be displayed

on the LCD.

R/W (read/write)

The R/W (read/write) input allowing the user to write information from it. R/W=1,

when it read and R/W=0, when it writing.

EN (enable)

The enable pin is used by the LCD to latch information presented to its data pins.

When data is supplied to data pins, a high power, a high-to-low pulse must be

applied to this pin in order to for the LCD to latch in the data presented at the data

pins.

D0-D7 (data lines)

The 8-bit data pins, D0-D7, are used to send information to the LCD or read the

contents of the LCD’s internal registers. To displays the letters and numbers, we

send ASCII codes for the letters A-Z, a-z, and numbers 0-9 to these pins while

making RS =1. There are also command codes that can be sent to clear the display

or force the cursor to the home position or blink the cursor. We also use RS =0 to

check the busy flag bit to see if the LCD is ready to receive the information. The

busy flag is D7 and can be read when R/W =1 and RS =0, as follows: if R/W =1

and RS =0, when D7 =1(busy flag =1), the LCD is busy taking care of internal

operations and will not accept any information. When D7 =0, the LCD is ready to

receive new information

INTERFACING OF MICRO CONTROLLER WITH LCD DISPLAY:

In most applications, the "R/W" line is grounded. This simplifies the

applicationbecause when data is read back, the microcontroller I/O pins have to be

alternated between input and output modes. In this case, "R/W" to ground and just

wait the maximum amount of time for each instruction (4.1 msecs for clearing the

display or moving the cursor/display to the "home position", 160 usecs for all other

commands) and also the application software is simpler, it also frees up a

microcontroller pin for other uses. Different LCD execute instructions at different

rates and to avoid problems later on (such as if the LCD is changed to a slower

unit). Before sending commands or data to the LCD module, the Module must be

initialized. Once the initialization is complete, the LCD can be written to with data

or instructions as required. Each character to display is written like the control

bytes, except that the "RS" line is set. During initialization, by setting the "S/C" bit

during the "Move Cursor/Shift Display" command, after each character is sent to

the LCD, the cursor built into the LCD will increment to the next position (either

right or left). Normally, the "S/C" bit is set (equal to ".

2.6BUZZER:

The Buzzer driver is a simple transistor based circuit designed to

drive a buzzer. The circuit consists of a NPN transistor BC548. The base of the

BC548 is connected to the microcontroller pin 17(P3.7) through a 560Ω resistor.

The 5V supply is connected to the collector pin through the buzzer. When the

microcontroller puts a HIGH on the p3.7, the transistor will be in ON state and as a

result, the Buzzer beeps. When the pin LOW, transistor goes to OFF state and the

buzzer is also in OFF state.

2.7Power Supply

The power supply is designed with the normal transformer

based supply. The 230V AC line voltage is step down to the 9V AC using a step

down transformer. The step downed voltage is driven to a full wave bridge

rectifier, which consists of 4 1N4007 diodes (D1-D4). The DC voltage from the

rectifier is connected through a capacitor C1, 1000uF. The capacitor acts as a filter

by removing the ripples/ ac contents in the supply. The filter voltage is connected

to the 1st pin of the LM7805, a 5V regulator IC. The regulated 5V out is taken from

the 3rd pin and used for the systems power supply. Capacitors C2 and C16 are used

as second stage filter for removing the transients from the supply. A LED is

connected through a resistor for the indication of the power.

2.8Relay Driver IC ULN2003 :

The ULN2003 is a monolithic high voltage and high current

Darlington transistor arrays. It consists of seven NPN darlington pairs that features

high-voltage outputs with common-cathode clamp diode for switching inductive

loads. The collector-current Rating of a single darlington pair is 500mA. The

darlington pairs May be paralleled for higher current capability. Applications

include Relay drivers, hammer drivers, lamp drivers, display drivers (LED gas

discharge), line drivers, and logic buffers. The ULN2003 has a 2.7k series base

resistor for each Darlington pair for operation directly with TTL or 5VCMOS

devices.

Features:

500mA rated collector current (Single output)

High-voltage outputs: 50V

Inputs compatible with various types of logic.

Relay driver application

Role of Relay Driver:

1) To control the triggering of the Relay

ULN 2003 –Seven Darlington Array:

DESCRIPTION The ULN2003 is a monolithic high voltage and high current Darlington

transistor arrays. It consists of seven NPN darlington pairs that features high-

voltage outputs with common-cathode clamp diode for switching inductive loads.

The collector-currentrating of a single darlington pair is 500mA. The darlington

pairsmay be parrlleled for higher current capability. Applications include relay

drivers,hammer drivers, lampdrivers,display drivers(LED gas discharge),line

drivers, and logic buffers. The ULN2003 has a 2.7kseries base resistor for each

darlington pair for operation directly with TTL or 5V CMOS

FEATURES

* 500mA rated collector current(Single output)

* High-voltage outputs: 50V

* Inputs compatibale with various types of logic.

* Relay driver application

Pin diagram of ULN2003:

2.9CARD READER:

A card reader is a data input device that reads data from a card-shaped storage

medium. A smart card reader is an electronic device that reads smart cards.

Some keyboards have a built-in card reader. There are external devices and

internal drive bay card reader devices for PC. Some laptops have a built-in smart

card reader. External devices may have keyboard to enter PIN or other

information. Those devices usually are called "card readers with PIN pad". Some

laptops have a flash upgradeable firmware. The card reader supplies the integrated

circuit on the smart card with electricity. Communication is done via protocols and

you can read and write to a fixed address on the card.

2.10DIODE:

In electronics, a diode is a two-terminal device ( thermionic diodes may

also have one or two ancillary terminals for a heater).Diodes have two active

electrodes between which the signal of interest may flow, and most are used for

their unidirectional electric current property. The varicap diode is used as an

electrically adjustable capacitor.

The directionality of current flow most diodes exhibit is sometimes

generically called the rectifying property. The most common function of a diode is

to allow an electric current to pass in one direction (called the forward biased

condition) and to block the current in the opposite direction (the reverse biased

condition). Thus, the diode can be thought of as an electronic version of a check

valve.

Various types of diodes

Real diodes do not display such a perfect on-off directionality but have a more

complex non-linear electrical characteristic, which depends on the particular type

of diode technology. Diodes also have many other functions in which they are not

designed to operate in this on-off manner.

Semiconductor diodes

Most modern diodes are based on semiconductor p-n junctions. In a p-n

diode, conventional current can flow from the p-type side (the anode) to the n-type

side (the cathode), but cannot flow in the opposite direction. Another type of

semiconductor diode, the Schottky diode, is formed from the contact between a

metal and a semiconductor rather than by a p-n junction.

Current–voltage characteristic

A semiconductor diode's current–voltage characteristic, or I–V curve, is

related to the transport of carriers through the so-called depletion layer or depletion

region that exists at the p-n junction between differing semiconductors. When a p-n

junction is first created, conduction band (mobile) electrons from the N-doped

region diffuse into the P-doped region where there is a large population of holes

(places for electrons in which no electron is present) with which the electrons

"recombine". When a mobile electron recombines with a hole, both hole and

electron vanish, leaving behind an immobile positively charged donor on the N-

side and negatively charged acceptor on the P-side. The region around the p-n

junction becomes depleted of charge carriers and thus behaves as an insulator.

V-I Characteristics of P-N Junction Diode

However, the depletion width cannot grow without limit. For each

electron-hole pair that recombines, a positively-charged dopant ion is left behind in

the N-doped region, and a negatively charged dopant ion is left behind in the P-

doped region. As recombination proceeds and more ions are created, an increasing

electric field develops through the depletion zone which acts to slow and then

finally stop recombination. At this point, there is a "built-in" potential across the

depletion zone.

If an external voltage is placed across the diode with the same polarity as

the built-in potential, the depletion zone continues to act as an insulator, preventing

any significant electric current flow. This is the reverse bias phenomenon.

However, if the polarity of the external voltage opposes the built-in potential,

recombination can once again proceed, resulting in substantial electric current

through the p-n junction. For silicon diodes, the built-in potential is approximately

0.6 V. Thus, if an external current is passed through the diode, about 0.6 V will be

developed across the diode such that the P-doped region is positive with respect to

the N-doped region and the diode is said to be "turned on" as it has a forward bias.

A diode’s I–V characteristic can be approximated by four regions of

operation (see the figure at right).At very large reverse bias, beyond the peak

inverse voltage or PIV, a process called reverse breakdown occurs which causes a

large increase in current that usually damages the device permanently. The

avalanche diode is deliberately designed for use in the avalanche region. In the

zener diode, the concept of PIV is not applicable. A zener diode contains a heavily

doped p-n junction allowing electrons to tunnel from the valence band of the p-

type material to the conduction band of the n-type material, such that the reverse

voltage is "clamped" to a known value (called the zener voltage), and avalanche

does not occur. Both devices, however, do have a limit to the maximum current

and power in the clamped reverse voltage region. Also, following the end of

forward conduction in any diode, there is reverse current for a short time. The

device does not attain its full blocking capability until the reverse current ceases.

The second region, at reverse biases more positive than the PIV, has only

a very small reverse saturation current. In the reverse bias region for a normal P-N

rectifier diode, the current through the device is very low (in the µA range).The

third region is forward but small bias, where only a small forward current is

conducted.

As the potential difference is increased above an arbitrarily defined "cut-

in voltage" or "on-voltage" or "diode forward voltage drop (Vd)", the diode current

becomes appreciable (the level of current considered "appreciable" and the value

of cut-in voltage depends on the application), and the diode presents a very low

resistance.

Types of semiconductor diode

There are several types of junction diodes, which either emphasize a

different physical aspect of a diode often by geometric scaling, doping level,

choosing the right electrodes, are just an application of a diode in a special circuit,

or are really different devices like the Gunn and laser diode and the MOSFET:

Symbol of Diode

Normal (p-n) diodes, which operate as described above, are usually made of doped

silicon or, more rarely, germanium. Before the development of modern silicon

power rectifier diodes, cuprous oxide and later selenium was used; its low

efficiency gave it a much higher forward voltage drop (typically 1.4–1.7 V per

“cell”, with multiple cells stacked to increase the peak inverse voltage rating in

high voltage rectifiers), and required a large heat sink (often an extension of the

diode’s metal substrate), much larger than a silicon diode of the same current

ratings would require. The vast majority of all diodes are the p-n diodes found in

CMOS integrated circuits, which include two diodes per pin and many other

internal diodes.

Avalanche diodes

Diodes that conduct in the reverse direction when the reverse bias voltage

exceeds the breakdown voltage. These are electrically very similar to Zener diodes,

and are often mistakenly called Zener diodes, but break down by a different

mechanism, the avalanche effect.

Tunnel diodes:

These have a region of operation showing negative resistance caused by

quantum tunneling, thus allowing amplification of signals and very simple bistable

circuits. These diodes are also the type most resistant to nuclear radiation.

Symbol of Tunnel Diode

Gunn diodes

These are similar to tunnel diodes in that they are made of materials such

as GaAs or InP that exhibit a region of negative differential resistance. With

appropriate biasing, dipole domains form and travel across the diode, allowing

high frequency microwave oscillators to be built

Light-emitting diodes (LEDs)

In a diode formed from a direct band-gap semiconductor, such as

gallium arsenide, carriers that cross the junction emit photons when they

recombine with the majority carrier on the other side. Depending on the material,

wavelengths (or colors) from the infrared to the near ultraviolet may be produced.

Symbol of LED

Laser diodes

When an LED-like structure is contained in a resonant cavity formed by

polishing the parallel end faces, a laser can be formed. Laser diodes are commonly

used in optical storage devices and for high speed optical communication.

Photodiodes

All semiconductors are subject to optical charge carrier generation. This

is typically an undesired effect, so most semiconductors are packaged in light

blocking material. Photodiodes are intended to sense light(photodetector), so they

are packaged in materials that allow light to pass, and are usually PIN (the kind of

diode most sensitive to light).

Symbol of Photo diode

Varactor diodes

These are used as voltage-controlled capacitors. These are important in PLL

(phase-locked loop) and FLL (frequency-locked loop) circuits, allowing tuning

circuits, such as those in television receivers, to lock quickly, replacing older

designs that took a long time to warm up and lock.

Symbol of Varactor diode

Zener diodes

Diodes that can be made to conduct backwards. This effect, called Zener

breakdown, occurs at a precisely defined voltage, allowing the diode to be used as

a precision voltage reference. In practical voltage reference circuits Zener and

switching diodes are connected in series and opposite directions to balance the

temperature coefficient to near zero.

Symbol of Zener diode

RECTIFIER DIODE:

These diodes are used diodes are used to convert AC to DC these are used as half

wave rectifier to full wave rectifier.

FEATURE

Low forward voltageHigh current capabilityLow leakage currentHigh surge capabilityLow cost

Rectifier diode

2.11CAPACITOR:

A capacitor is a passive electrical component that can store energy in the

electric field between a pair of conductors (called "plates"). The process of storing

energy in the capacitor is known as "charging", and involves electric charges of

equal magnitude, but opposite polarity, building up on each plate. A capacitor's

ability to store charge is measured by its capacitance, in units of farads.

Capacitors are often used in electric and electronic circuits as energy-

storage devices. They can also be used to differentiate between high-frequency and

low-frequency signals. This property makes them useful in electronic filters.

Practical capacitors have series resistance, internal leakage of charge, series

inductance and other non-ideal properties not found in a theoretical, ideal,

capacitor.

THEORY OF OPERATION

A capacitor consists of two conductive electrodes, or plates, separated by

a dielectric, which prevents charge from moving directly between the plates.

Charge may however move from one plate to the other through an external circuit,

such as a battery connected between the terminals.

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

separation of d.

When any external connection is removed, the charge on the plates

persists. The separated charges attract each other, and an electric field is present

between the plates. The simplest practical capacitor consists of two wide, flat,

parallel plates separated by a thin dielectric layer.

CAPACITANCE

A capacitor's ability to store charge is measured by its capacitance

‘C’, the ratio of the amount of charge stored on each plate to the voltage:

For an ideal parallel plate capacitor with a plate area ‘A’ and a plate separation ‘d’:

In SI units, a capacitor has a capacitance of one farad when one coulomb

of charge stored on each plate causes a voltage difference of one volt between its

plates. Since the farad is a very large unit, capacitance is usually expressed in

microfarads (µF), nanofarads (nF), or picofarads (pF). In general, capacitance is

greater in devices with large plate areas, separated by small distances. When a

dielectric is present between two charged plates, its molecules become polarized

and reduce the internal electric field and hence the voltage. This allows the

capacitor to store more charge for a given voltage, so a dielectric increases the

capacitance of a capacitor, by an amount given by the dielectric constant, , of the

material.

ELECTROLYTIC CAPACITORS

Electrolytic capacitors are the most popular type for values greater than

about 1 microfarad. Electrolytic capacitors are constructed using a thin film of

oxide on an aluminium foil. An electrolyte is used to make contact with the other

plate. The two plates are wound around on one another and then placed into a can

that is often aluminium.

Electrolytic Capacitors

Electrolytic capacitors are polarised, and care should be taken to ensure

they are placed in circuit the correct way round. If they are connected incorrectly

they can be damaged, and in some extreme instances they can explode. Electrolytic

capacitors have a wide tolerance. Typically the value of the component may be

stated with a tolerance of -50% +100%. Despite this they are widely used in audio

applications as coupling capacitors, and in smoothing applications for power

supplies.

Electrolytic capacitors are available in both leaded and surface

mount formats. The surface mount electrolytic capacitors are available in

rectangular packages whereas the leaded versions are normally contained in a

tubular aluminium can, each end being marked to show its polarity.

CERAMIC CAPACITOR

Ceramic capacitors are normally used for radio frequency and some audio

applications. Ceramic capacitors range in value from figures as low as a few

picofarads to around 0.1 microfarads. In view of their wide range and suitability

for RF applications they are used for coupling and decoupling applications in

particular. Here these ceramic capacitors are by far the most commonly used type

being cheap and reliable and their loss factor is particularly low although this is

dependent on the exact dielectric in use. Their stability and tolerance is not nearly

as good as silver mica types, but their cost is much less. In view of their

constructional properties, these capacitors are widely used both in leaded and

surface mount formats.

There are a number of dielectrics that can be used with

ceramic capacitors. For low values a dielectric designated "C0G" is normally used.

This has the lowest dielectric constant but gives the highest stability and lowest

loss. Where higher values are required in a given size, a dielectric with a higher

dielectric constant must be used. Types with designations X7R and for higher

values, Z5U are used, however their stability and loss are not as good as the

capacitors made with C0G dielectric.

SILVER MICA CAPACITOR

Silver mica capacitors are not as widely used these days as they used to

be. However these electronic components can still be obtained and are used where

stability of value is of the utmost importance and where low loss is required. In

view of this one of their major uses is within the tuned elements of circuits like

oscillators, or within filters.Values are normally in the range between a few

picofarads up to two or possibly three thousand picofarads.

Silver Mica Capacitor

For this type of capacitor the silver electrodes are plated directly on to the mica

dielectric. Again several layers are used to achieve the required capacitance. Wires

for the connections are added and then the whole assembly is encapsulated.

TANTALUM CAPACITOR

Ordinary aluminium electrolytic capacitors are rather large

for many uses. In applications where size is of importance tantalum capacitors may

be used. These are much smaller than the aluminium electrolytic capacitors and

instead of using a film of oxide on aluminium they us a film of oxide on tantalum.

Tantalum capacitors do not normally have high working voltages, 35V is normally

the maximum, and some even have values of only a volt or so.

Like electrolytic capacitors, tantalum capacitors are

also polarised and they are very intolerant of being reverse biased, often exploding

when placed under stress. However their small size makes them very attractive for

many applications. They are available in both leaded and surface mount formats.

2.12RESISTOR:

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. The resistance R is equal to

the voltage drop V across the resistor divided by the current I through the resistor.

Symbol of Fixed Resistor Symbol of Variable Resistor

Resistors are characterized primarily by their resistance and the power they

can dissipate. Other characteristics include temperature coefficient, noise, and

inductance. Practical resistors can be made of resistive wire, and various

compounds and films, and they can be integrated into hybrid and printed circuits.

Size, and position of leads are relevant to equipment designers; resistors must be

physically large enough not to overheat when dissipating their power. Variable

resistors, adjustable by changing the position of a tapping on the resistive element,

and resistors with a movable tap ("potentiometers"), either adjustable by the user of

equipment or contained within, are also used.Resistors are used as part of electrical

networks and electronic circuits.

There are special types of resistor whose resistance varies with various

quantities, most of which have names, and articles, of their own: the resistance of

thermistors varies greatly with temperature, whether external or due to dissipation,

so they can be used for temperature or current sensing; metal oxide varistors drop

to a very low resistance when a high voltage is applied, making them suitable for

over-voltage protection; the resistance of a strain gauge varies with mechanical

load; the resistance of photoresistors varies with illumination; the resistance of a

Quantum Tunnelling Composite can vary by a factor of 1012 with mechanical

pressure applied; and so on.

V-I Characteristics

UNITS

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

Ohm. The most commonly used multiples and submultiples in electrical and

electronic usage are the milliohm, ohm, kilohm, and megohm.

TYPES OF RESISTORS

Although resistors come in various forms we can divide them up into just two

basic types:-

1. Fixed resistors

2. Variable resistors (or ‘potentiometers’)

A fixed resistor is a component with two wires which obeys Ohm's Law — i.e. it's

a bit of material which behaves as we described in the last section. Electronic

engineers and manufacturers have adopted some standards for resistors. These are

intended to keep the cost down and make it easier for you to buy them from

whichever supplier you like without having to redesign the equipment you want to

put them in.

Fixed Resistors

In an electrical circuit, some objects may need a lesser amount of

current than the input value. In such cases, fixed resistors are used to reduce the

flow of current. They are placed in such a way that a higher voltage must first pass

through them before it flows further. The value of the resistance is fixed and does

not change with change in the applied voltage or current flowing through it. The

resistance value is measured in ohms and the value ranges from a few milliohms to

about a giga-ohm.

Variable resistors consist of a resistance track with connections at

both ends and a wiper which moves along the track as you turn the spindle. The

track may be made from carbon, cermet (ceramic and metal mixture) or a coil of

wire (for low resistances). The track is usually rotary but straight track versions,

usually called sliders, are also available. Variable resistors may be used as a

rheostat with two connections (the wiper and just one end of the track) or as a

potentiometer with all three connections in use. Miniature versions called presets

are made for setting up circuits which will not require further adjustment.

Variable Resistor

Variable resistors are often called potentiometers in books and catalogues. They

are specified by their maximum resistance, linear or logarithmic track, and their

physical size. The standard spindle diameter is 6mm.

RESISTOR COLOR CODE

4-Band Color Code of Resistor

CALCULATING RESISTOR VALUES

The "left-hand" or the most significant coloured band is the band which is nearest to a connecting lead with the colour coded bands being read from left-to-right as follows;

Digit, Digit, Multiplier = Colour, Colour x 10 colour in Ohm's (Ω's)

For example, a Resistor has the following coloured markings;

Yellow Violet Red = 4 7 2 = 4 7 x 10 2 = 4700Ω or 4k7.

The fourth band if used determines the percentage tolerance of the resistor and is given as;

Brown = 1%, Red = 2%, Gold = 5%, Silver = 10 %

If resistor has no fourth tolerance band then the default tolerance would be at 20%.

It is sometimes easier to remember the resistor colour codes by using mnemonics,

which is a saying that has a separate word to represent each of the Ten + Two

colours in the code. However, these sayings are often crude but never the less

effective and here are a few of the more "cleaner" versions:

Bad Booze Rots Our Young Guts But Vodka Goes Well

Bad Boys Ring Our Young Girls But Vicky Goes Without

Bad Boys Ring Our Young Girls But Vicky Gives Willingly -- Get Some Now

(This one is only slightly better because it includes the tolerance bands of Gold,

Silver, and None).

2.13 .7812,7805 IC REGULATORS:

They are commonly used in electronic circuits requiring a regulated

power supply due to their ease-of-use and low cost. They are positive voltage

regulators: they produce a voltage that is positive relative to a common ground.

These devices support an input voltage anywhere from a couple of volts over the

intended output voltage, up to a maximum of 35 or 40 volts, and typically provide

1 or 1.5 amperes of current (though smaller or larger packages may have a lower or

higher current rating).

ADVANTAGES:

ICs do not require additional components to provide a constant, regulated source of power, making them easy to use, as well as economical and efficient uses of space.

They are easy to use and handle

IC REGULATORS

2.14.TRANSFORMERS:

A transformer is a device that transfers electrical energy from one

circuit to another through inductively coupled conductors — the transformer's coils

or "windings". Except for air-core transformers, the conductors are commonly

wound around a single iron-rich core, or around separate but magnetically-coupled

cores. A varying current in the first or "primary" winding creates a varying

magnetic field in the core (or cores) of the transformer. This varying magnetic field

induces a varying electromotive force (EMF) or"voltage" in the "secondary"

winding. This effect is called mutual induction

If a load is connected to the secondary circuit, electric charge will flow in the

secondary winding of the transformer and transfer energy from the primary circuit

to the load connected in the secondary circuit. The secondary induced voltage VS,

of an ideal transformer, is scaled from the primary VP by a factor equal to the ratio

of the number of turns of wire in their respective windings:

By appropriate selection of the numbers of turns, a transformer thus

allows an alternatingvoltage to be stepped up — by making NS more than NP — or

stepped down, by making it

BASIC PARTS OF A TRANSFORMER:

In its most basic form a transformer consists of:

A primary coil or winding.

A secondary coil or winding.

A core that supports the coils or windings.

Refer to the transformer circuit in figure as you read the following explanation:

The primary winding is connected to a 60-hertz ac voltage source. The magnetic

field (flux) builds up (expands) and collapses (contracts) about the primary

winding. The expanding and contracting magnetic field around the primary

winding cuts the secondary winding and induces an alternating voltage into the

winding. This voltage causes alternating current to flow through the load. The

voltage may be stepped up or down depending on the design of the primary and

secondary windings.

THE COMPONENTS OF A TRANSFORMER:

Two coils of wire (called windings) are wound on some type of core material. In

some cases the coils of wire are wound on a cylindrical or rectangular cardboard

form. In effect, the core material is air and the transformer is called an AIR-CORE

TRANSFORMER. Transformers used at low frequencies, such as 60 hertz and 400

hertz, require a core of low-reluctance magnetic material, usually iron. This type of

transformer is called an IRON-CORE TRANSFORMER. Most power transformers

are of the ironcore type. The principle parts of a transformer and their functions

are:

The CORE, which provides a path for the magnetic lines of flux.

The PRIMARY WINDING, which receives energy from the ac source.

The SECONDARY WINDING, which receives energy from the primary windingand delivers it to the load.

2.16.Relay :

A relay is an electrically operated switch. Many relays use an electromagnet to

operate a switching mechanism, but other operating principles are also used.

Relays find applications where it is necessary to control a circuit by a low-power

signal, or where several circuits must be controlled by one

RELAY

The first relays were used in long distance telegraph circuits, repeating the signal

coming in from one circuit and re-transmitting it to another. Relays found

extensive use in telephone exchanges and early computers to perform logical

operations. A type of relay that can handle the high power required to directly

drive an electric motor is called a contactor. Solid-state relays control power

circuits with no moving parts, instead using a semiconductor device to perform

switching. Relays with calibrated operating characteristics and sometimes multiple

operating coils are used to protect electrical circuits from overload or faults; in

modern electric power systems these functions are performed by digital

instruments still called "protection relays".

2.17 OPTO COUPLER:

How They Are Used:Basically the simplest way to visualise an optocoupler is in terms of its two main components: the input LED and theoutput transistor or diac. As the two are electrically isolated, this gives a fair amount of flexibility when it comes to connecting them into circuit. All we really have to do is work out a convenient way of turning the input LED on and off, and using the resulting switching of the photo-transistor/diac to generate an output waveform or logic.

The optocoupler application or function in the circuit is to:

Monitor high voltage Output voltage sampling for regulation System control micro for power on/off Ground isolation

An optocoupler is a combination of a light source and a photosensitive detector. In the optocoupler, or photon coupled pair, the coupling is achieved by light being generated on one side of a transparent insulating gap and being detected on the other side of the gap without an electrical connection between the two sides(except for a minor amount of coupling capacitance).

CHAPTER-3

BLOCK DIAGRAM &CIRCUIT DIAGRAM

BLOCK DIAGRAM:

ENERGY METER

MICROCONTROLLER

DIGITAL DISPLAY

SMART CARD READ/WRITE

BUZZER

POWER SUPPLY

CIRCUIT DIAGRAM:

CHAPTER-4

BENEFITS OF PREPAID ENERGY METER

Benefits of Prepaid Energy Metering

Improved operational efficiencies: The prepaid meters are likely to cut the cost

of meter reading as no meter readers are required. In addition, they eliminate

administrative hassles associated with disconnection and reconnection. Besides,

going by South Africa’s experience, prepaid meters could help control

appropriation of electricity in a better way than conventional meters.

Reduced financial risks: Since the payment is up-front, it reduces the financial

risk by improving the cash flows and necessitates an improved revenue

management system.

Better customer service: The system eliminates billing delay, removes cost

involved in disconnection/reconnection, enables controlled use of energy, and

helps customers to save money through better energy management.

Market Drivers

Power sector reforms: The upcoming competitive and customer focused

deregulated power distribution market will force the market participants to make

the existing metering and billing process more competent. This is likely to drive

the prepaid market.

Increasing non-technical losses: Metering errors, tampering with meters leading

to low registration and calibration related frauds are some of the key components

of non-technical losses. India reports greater than 10 percent of non-technical

losses. It has been reported that prepaid meters control non-technical losses better

than conventional ones.

Opportunities in the emerging electrifying markets: Most of the Asian

countries do not have 100 percent electrification; hence new markets are being

created by the increasing generating capacity. Prepaid systems can be more easily

introduced in such new markets rather than the existing ones.

1.3.3 Market Restraints

Consumer behavior: Consumers have not had any major problems with the

existing post-paid system, and hence it is likely to be difficult to convince them to

change over to prepaid system. Consumers might not appreciate the concept of

"pay and use" as far as electricity is concerned because it might be perceived as an

instrument to control common man’s life style.

Initial investment: Utilities might be discouraged by the huge initial investment,

which includes the cost of instrument, marketing campaign, establishing

distribution channel, and other management costs.

Rapid technology changes: The rapid technology changes happening in the

metering market are expected to delay the decision to go for prepaid system.

Uncertainty over the success: Prepaid system is not as proven a concept in all the

markets as South Africa; hence there is bound to be uncertainty over its success, if

implemented. The success of the system depends on the commitment by utilities

and for this they need to get convinced on the real benefits of prepaid meters

1.3.4 Recent Initiatives The Sabah Electricity Sdn Bhd (SESB), Malaysia, has awarded a contract to

a local manufacturer to supply 1,080 prepaid meters

Countries such as Thailand, Bangladesh, Singapore, and Iran have been

showing increased interest in adopting prepaid system

In India, the State of West Bengal has decided to introduce the smart card

operated prepaid energy meters in remote islands of Sunderbans. In

Mumbai, pre-paid power isprovided by the Brihanmumbai Electricity

Supply and Transport (BEST)Undertaking.Tata Power plans to introduce

pre-paid electricity in Delhi. Tata Steel islikely to install prepaid electricity

meters at its employee township in Jamshedpur.

CHAPTER-5 ADVANTAGES OF PREPAID ENERGY METER

ADVANTAGES OF PREPAID ENERGY METER

Improved operational efficiencies:

The prepaid meters are likely to cut the cost of meter reading as no meter

readers are required. In addition, they eliminate administrative hassles associated

with disconnection and reconnection. Besides, going by South Africa’s experience,

prepaid meters could help control appropriation of electricity in a better way than

conventional meters.

Reduced financial risks:

Since the payment is up-front, it reduces the financial risk by

improving the cash flows and necessitates an improved revenue management

system.

Better customer service: The system eliminates billing delay, removes cost involved in

disconnection/reconnection, enables controlled use of energy, and helps

customers to save money through better energy management

CHAPTER-6 SOFTWARE DESCRIPTION & PROGRAM USED

Software Description A firmware developed in C language is programmed into the

microcontroller’s code memory area. The firmware control’s the working of the

entire hardware part. Usually the microcontrollers and the processors execute their

instructions which are in machine code. In early days the applications were written

in assembly language. The development of the huge application is very difficult by

using the normal assembly language, because of their less readability. Later for the

fast developments, the high level languages are introduced into the embedded

system. C language is one of the most commonly used in the embedded system

field. The ANSI C version is modified by adding specific hardware related

functionality and information. The modified C language is commonly termed as

Embedded C. The Keil Uvision 3 IDE is used for the development of the

embedded system application development.

Keil software:

Keil Software is used provide you with software development

tools for 8051 based microcontrollers. With the Keil tools, you can generate

embedded applications for virtually every 8051 derivative. The supported

microcontrollers are listed in the μ-vision.

Firmware code // main.c

#include"main.h" Unsigned int count; unsigned int databuf[4]; unsigned int pulseCount,unitConsume,balAmount,tariff,balUnit,totalConsume ; bit RelyOn = 0; bit alarm = 0 ;

// Interrupt function for the Pulse sensingvoid pulseISR() interrupt 0

//unsigned int i;EX0 = 0;if(RelyOn) // If rely is ON

if(balAmount >= tariff)pulseCount++; // Count LED Pulses

if(pulseCount >= ONE_UNIT) // Reaches One Unit Of Electricity

pulseCount = 0;unitConsume++; // count usage of each unitLEDRED = 0;delayMore(5);LEDRED = 1;//totalConsume++;if(balAmount >= tariff)

balAmount = balAmount - tariff;else

balAmount = 0;totalConsume = totalConsume + unitConsume;// Memorise the current Total Unit used

EX0 = 1;

void Timer0Int() interrupt 1 // Interrupt function for the timer 0

TF0 = 0;TR0 = 0;ET0 = 0;count--;TH0 = 0x4B; // value for 50msec delay

TL0 = 0xFC;ET0 = 1;if(count==0)

DisplayDateTime();count = 1200;

TR0 = 1;

void main() // main funtion unsigned char i;

BUZ = 0; LCD_init(); // Initialise LCD RTC_init(); LCD_command(0x01); LCD_BCKL = 0; LCD_command(0x80); LCD_sendString(" Prepaid Energy"); LCD_command(0xC0); LCD_sendString(" Metering"); delayMore(400); TimerInit(); IntInit(); //LCD_BCKL = 1; LCD_command(0x01); #define ONBOARD Device_init(databuf); // Read EEPROM and Store values into RAM #undef ONBOARD //pulseCount = databuf[0]; // pulse counted totalConsume = databuf[1]; // if(totalConsume >= 9999) totalConsume = 0; balAmount = databuf[2]; // balence amount if(balAmount >= 2000) balAmount = 0;

tariff = databuf[3]; if((tariff == 0)||(tariff==0xFF)) tariff = 1; balUnit = balAmount/tariff; //#undef ONBOARD DeviceSetting(); //UpdateUnit(); Validate_Recharge(); // Check for the starting condition Program_SmrtCard(); // Check smartcard programming before starting actual process

//while(Insert_SmrtCard()); DisplayDateTime(); LCD_command(0xC0); LCD_sendString("B:"); IntToString(balAmount); LCD_sendString(" KWH:"); IntToString(totalConsume); TR0 = 1; while(1) if(Insert_SmrtCard()) // If smart Card is Inserted

TR0 = 0;delayMore(500); // key bounce Delay#define SMARTCARDdelayMore(5);Read_Card(); // read SmartCardValidate Recharge(); // Update the new rechargeErase_Card();delayMore(50); // one time usage of one card LCD_command(0x80);LCD_sendString("Remove Smart Crd");

while(Insert_SmrtCard());LCD_command(0x01);DisplayDateTime();#undef SMARTCARDdelayMore(5);/*#define ONBOARD

Device_init(databuf); // Read EEPROM and Store values into RAM #undef ONBOARD

balAmount = databuf[2]; */balUnit = balAmount/tariff;UpdateUnit(); EX0 = 0;TR0 = 1;LCD_sendString(" ");LCD_command(0xC0);LCD_sendString("B:");

IntToString(balAmount); LCD_sendString(" KWH:"); IntToString(totalConsume);

if(RelyOn) // If rely is ON

if(EnergyPulse()) // If Pulse LED Blinks

//while(EnergyPulse());if(balAmount >= tariff)

pulseCount++; // Count LED Pulsesif(pulseCount >= ONE_UNIT) // Reaches One Unit Of Electricity

pulseCount = 0;unitConsume++; // count usage of each unit//totalConsume++;if(balAmount >= tariff)

balAmount = balAmount - tariff;else

balAmount = 0;for(i=0;i<20;i++)

BUZ = ~BUZ;delayMore(10);

BUZ = 0;

if(balAmount > 30)

GRNON();alarm = 0;

if((balAmount>=10)&&(balAmount<=30))

YELON();if(alarm==0)

BUZ = 1;for(i=0;i<6;i++)

BUZ = ~BUZ;delayMore(10);

alarm = 1;BUZ = 0;

if(balAmount<10)

REDON();if(alarm == 1)

BUZ = 1;for(i=0;i<6;i++)

BUZ = ~BUZ;delayMore(10);

alarm = 0;BUZ = 0;

LCD_command(0xC0);LCD_sendString("B:");

IntToString(balAmount);LCD_sendString(" KWH:");IntToString(totalConsume+unitConsume);//balUnit = balAmount/tariff;//if(unitConsume >= balUnit)if(balAmount < tariff)

for(i=0;i<20;i++)

BUZ = ~BUZ;delayMore(10);

BUZ = 0;totalConsume = totalConsume + unitConsume;UpdateUnit();unitConsume = 0; // Reached The Usage LimitbalUnit = 0;RLYOFF(); // Switch of the O/P of Prepaid enrgy RelyOn = 0;

// Memorise the current Total Unit used

if(balAmount<10)

REDON();

void delayMore(unsigned int d) // a delay function

unsigned int i,j;for(i=0;i<d;i++)

for(j=0;j<1000;j++); void TimerInit() // Initialization of the timer

count = 1200;

TMOD = ( TMOD&0xF0 )| 0x01; TH0 = 0x4B; // value for 50msec delayTL0 = 0xFC;

void IntInit() // Initailization of the interrupts

//EX0 = 1;ET0 = 1; // Timer 0 intEA = 1; // Global Int enable

// Process.c file/**************************************************************************** __0xx_________________0x02____________0x04_____________0x06_______* | |pulseCount(2B) | unitConsume(2B) | balAmount(2B) | tariff(2B) |*****************************************************************************/

#include<main.h>extern unsigned int volatile balAmount,unitConsume,tariff ;extern volatile unsigned int totalConsume; extern bit RelyOn;

void Delay(unsigned int count) // a small delay function

while(count--);

void Read_Card() // read the card data

unsigned int RechargeValue;#undef ONBOARD#define SMARTCARDI2CMEM_readData(0x0A,0x02,&RechargeValue); // read the reacharge value//RechargeValue = *read;switch(RechargeValue)

case 0:balAmount += 0; //Rs NilLCD_command(0x01);LCD_command(0x80);LCD_sendString("Insert Valid Card");

break;case 25:

balAmount += 25; //Rs 25/-LCD_command(0x01);LCD_command(0x80);LCD_sendString("Rs25 Recharged");break;

case 50:balAmount += 50; //Rs 50/-LCD_command(0x01);LCD_command(0x80);LCD_sendString("Rs50 Recharged");

break;case 75:

balAmount += 75; //Rs75/-LCD_command(0x01);LCD_command(0x80);LCD_sendString("Rs75 Recharged");

break;case 100:

balAmount += 100; //Rs 100/-LCD_command(0x01);LCD_command(0x80);LCD_sendString("Rs100 Recharged");

break;default:

balAmount += 0; //Rs NilLCD_command(0x01);LCD_command(0x80);LCD_sendString("Insert Valid Card");

break;

LCD_command(0xC0);LCD_sendString("Bal:");IntToString(balAmount);BUZ = 1;delayMore(10);BUZ = 0;EX0 = 1;delayMore(300);#undef SMARTCARD

void Validate_Recharge()

if(balAmount>0)

RelyOn = 1;RLYON();

void Erase_Card()

unsigned int Erase[1];#undef ONBOARD#define SMARTCARDErase[0] = 0x00;I2CMEM_writeData(0x0A,0x02,Erase); #undef SMARTCARD

void UpdateUnit()

unsigned int buff[3];#define ONBOARDdelayMore(10);//buff[0] = pulseCount;buff[0] = totalConsume;buff[1] = balAmount;buff[2] = tariff;

I2CMEM_writeData(0x02,0x06,buff);delayMore(10);#undef ONBOARD

void Device_init(unsigned int *buf)

I2CMEM_readData(0x00,0x08,buf);unsigned int pulseBalance(unsigned int tariffAmount, unsigned int balance)

return ((balance/tariffAmount)*ONE_UNIT);void Program_SmrtCard()

unsigned int New[1];if(KeyOneIsPressed())

if(!(Insert_SmrtCard()))

LCD_command(0x01);LCD_command(0x80);LCD_sendString("Insert Smart Card");delayMore(3000);return;

#undef ONBOARDdelayMore(10);#define SMARTCARDDelay(1000);LCD_command(0x01);LCD_command(0x80);LCD_sendString("Reprogram Card");LCD_command(0xC0);LCD_sendString("Press 4 3 2 1 ");while(KeyOneIsPressed());

while((!KeyOneIsPressed())&&(!KeyTwoIsPressed())&&(!KeyThreeIsPressed())&&(!KeyFourIsPressed()));

if(KeyOneIsPressed())

Delay(1000);New[0] = 25;I2CMEM_writeData(0x0A,0x02,New);LCD_command(0x01);LCD_command(0x80);LCD_sendString("Rs25 Recharge");LCD_command(0xC0);LCD_sendString("Successful !");

if(KeyTwoIsPressed())

Delay(1000);New[0] = 50;

I2CMEM_writeData(0x0A,0x02,New);LCD_command(0x01);LCD_command(0x80);LCD_sendString("Rs50 Recharge");LCD_command(0xC0);LCD_sendString("Successful !");

if(KeyThreeIsPressed())

Delay(1000);New[0] = 75;

I2CMEM_writeData(0x0A,0x02,New);LCD_command(0x01);LCD_command(0x80);LCD_sendString("Rs75 Recharge");LCD_command(0xC0);LCD_sendString("Successful !");

if(KeyFourIsPressed())

Delay(1000);New[0] = 100;

I2CMEM_writeData(0x0A,0x02,New);

LCD_command(0x01);LCD_command(0x80);LCD_sendString("Rs100 Recharge");LCD_command(0xC0);LCD_sendString("Successful !");

delayMore(200);BUZ = 1;delayMore(10);BUZ = 0;LCD_command(0x01);

LCD_command(0x80);LCD_sendString("Remove The Card");while((Insert_SmrtCard()));#undef SMARTCARD

void DeviceSetting() // function for updating the tariff if(KeyFourIsPressed())

LCD_command(0x01);LCD_command(0x80);LCD_sendString("Current Tariff:");LCD_command(0xC0);IntToString(tariff);while((KeyFourIsPressed()));while(!(KeyFourIsPressed()))

if(KeyTwoIsPressed())

tariff++;LCD_command(0xC0);IntToString(tariff);while(KeyTwoIsPressed());

if(KeyThreeIsPressed())

tariff--;LCD_command(0xC0);IntToString(tariff);while(KeyThreeIsPressed());

UpdateUnit();LCD_command(0x01);LCD_command(0x80);LCD_sendString("Tariff Updated");delayMore(100);

CHAPTER-7

FUTURE SCOPE&CONCLUSION

FUTURE SCOPE:

In the present time of 21st century we have no space for

errors or faults either in any technical system or in general applications.

Prepaid energy meter is an advantageous conc ept for the fu ture .

I t s fac i l i ta tes the exemption from electricity bills. Electricity coupons

will be available at nearby shops. The word prepaid means "pay

before use" one of the advantageous fea ture of th is concept.Prepaid

energy meter is used to prepaid the ongoing supply of electricity to homes, offices

etc

CONCLUSION:

The monopolistic power distribution market in Asia is gradually

transforming into a competitive marketplace. Differentiation in service is

going to be the key competitive factor to improve market share in the

deregulated power markets. Prepaid meters with their advantages over

conventional ones are likely to help power distributors to differentiate and

offer value-added services to consumers. Encourgaing consumers to opt for

prepaid meters on a voluntary basis and offering tariff or non-tariff

incentives to those consumers who prepay their power charges, would help

the utilities to implement this sytem.

REFERENCE:

WWW.SEMINARPROJECTS.COM

WWW.8051PROJECTS.COM

www.wikipedia.comwww.alldatasheet.comwww.8051.com

www.datasheet4u.comwww.efy.com