Energy Metering Circuit Using GSM-Semi Report

8/2/2019 Energy Metering Circuit Using GSM-Semi Report

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Microcontroller

Selection Criteria

1. The first and the foremost criterion for selecting a microcontroller is that it must meetthe task at hand efficiently and cost effectively. In analyzing the need of a

microcontroller based project we must see whether an 8 bit, 16 bit, 32 bit

microcontroller can best handle the computing need of the task most efficiently.

Among other consideration in this category are speed, power consumption, amount of

on chip RAM and ROM, the number of sufficient I/O ports and cost per unit.

2. Second how easy is it to develop product around it. Key considerations are the

availability of an assembler, debugger, emulator and technical support.

3. Its ready availability in needed quantity, both now and in future.

Taking all these considerations we have chosen ATMEL 89C51 microcontroller.

2.3.1.2 Brief History of 8051

In 1981, Intel Corporation introduced an 8 bit microcontroller called 8051, thishad 128 bytes of RAM, 4 bytes of on chip ROM, two timers, one serial port, and 4

ports each 8 bits wide all on a single chip. At this time it was referred to as system on

chip. The 8051 is an 8 bit processor meaning that the CPU can work only on 8 bit at a

time. Data larger than 8 bit has to be broken up into 8 bit pieces to be processed by the

CPU.

The 8051 became widely popular after Intel allowed other manufacturers to make

and market any flavor of 8051 with the condition that they remain code compatible

with 8051. This has lead to many versions of 8051 with a different speed and amount of

on chip ROM marketed by different companies.

Software


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As our project required involved the application of software, on consulting with our

project guide we came to the conclusion that we shall use Embedded C for

programming utilizing the Keil software

Use of embedded processors cars, mobile phones, medical equipment, aerospace

systems etc is widespread. The applications of embedded C are exploited through the

Keil software. Keil was founded in 1986 to market add on products for development

tools provided by many of the silicon vendors. It soon became evident that there was a

void in the market placethat must be filled with quality software development tools. It

was then that Keil introduced the first C compiler designed from the ground-up

specifically for 8051 microcontroller.

The literature about Keil was collected from the net as well as some e-books via

the internet.http://www.keil.com/company is the link of the site from which the basics

of the software was taken.

Chapter 3. ADOPTED METHODOLOGY

Planning in phases:

Before commencement of the project it was decided to plan the project in phases so the

following are the phases in which the project will be done:

The very first phase was planning the project and getting the concepts right about the

project.

This involved lot of reading and understanding about the core concepts and the

applications of our project.

Getting to know about the features of various components present in the circuitry.
http://www.keil.com/companyhttp://www.keil.com/companyhttp://www.keil.com/companyhttp://www.keil.com/company


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Learning about various softwares like keil , Eagle 4.11 etc that will be used in our

project.

Procuring the various components required for the project.

Creating the PCB (printed circuit board) for our project.

Interfacing the monitoring system with GSM module.

Implementing the entire project.

Testing the working of the final monitoring system.

3.3TUTORIAL ON MICROCONTROLLERThe 89C51 microcontroller is from the 8051 family of microcontrollers. The basis

features of all the controllers in this family are the same, except for a few differences

from device to device. The features of the Atmel IC 89C51 is discussed in detail below.

below.

3.3.1 Memory OrganizationThe basic block diagram of the family of the 80x51 is as shown below in the

figure.


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Fig. 3.8

All 80x51 devices have separate address spaces for program and data memory.

The logical separation of program and data memory allows the data memory to be

accessed by 8-bit addresses, which can be quickly stored and manipulated by an 8-bit

CPU. Program memory (ROM, EPROM) can only be read, not written to. There can

be up to 64k bytes of program memory. In the 89C51,there is 4K Bytes of

Reprogrammable Flash Memory(Program Memory) and 128 x 8-bit Internal RAM

(Data Memory).

3.3.2 Special Function Registers3.6.2.1 Description

Special Function Registers (SFRs) ate area of memory that control

functionality of the processor. SFRs are accessed as if they were normal Internal

RAM. The only difference is that Internal RAM is from address 00h through 7Fh

whereas SFR registers exist in the address range of 80h through FFh. Each SFR has

an address (80h through FFh) and a name. The following chart provides a graphical

presentation of the 80C51's SFRs, their names, and their address.


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Fig. 3.9

As you can see, although the address range of 80h through FFh offer 128 possible

addresses, there are only 19 SFRs in a standard 80C51. All other addresses in the SFR

range (80h through FFh) are considered invalid. Writing to or reading from these

registers may produce undefined values or behavior. There are 3 categories of SFRs

namely I/O, control and other.

Whether a given I/O line is high or low and the value read from the line are

controlled by the I/O SFRs. The control SFRs in some way control the operation or

the configuration of some aspect of the 80x51. For example, TCON controls the

timers, SCON controls the serial port.The remaining SFRs, are "other SFRs." These

SFRs can be thought of as auxillary SFRs in the sense that they don't directly

configure the 80x51 but obviously the 80x51 cannot operate without them. For


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example, once the serial port has been configured using SCON, the program may read

or write to the serial port using the SBUF register.

3.6.2.2 Overview of all SFRs

This section will endeavor to quickly overview each of the standard SFRs

found in the above SFR chart map. This section is to just give you a general idea of

what each SFR does.

SP (Stack Pointer, Address 81h): This is the stack pointer of the

microcontroller. This SFR indicates where the next value to be taken from the stack

will be read from in Internal RAM. If you push a value onto the stack, the value will

be written to the address of SP + 1. That is to say, if SP holds the value 07h, a PUSH

instruction will push the value onto the stack at address 08h. This SFR is modified by

all instructions which modify the stack, such as PUSH, POP, LCALL, RET, RETI,

and whenever interrupts are provoked by the microcontroller.

DPL/DPH (Data Pointer Low/High, Addresses 82h/83h): The SFRs DPL and

DPH work together to represent a 16-bit value called the Data Pointer. The data

pointer is used in operations regarding external RAM and some instructions involving

code memory. Since it is an unsigned two-byte integer value, it can represent values

from 0000h to FFFFh (0 through 65,535 decimal).

PCON (Power Control, Addresses 87h): The Power Control SFR is used to

control the power control modes. Certain operation modes allow the to go into a type

of "sleep" mode which requires much less power. These modes of operation are

controlled through PCON. Additionally, one of the bits in PCON is used to double the

effective baud rate of the serial port.

TCON (Timer Control, Addresses 88h, Bit-Addressable): The Timer Control

SFR is used to configure and modify the way in which the two timers operate. This

SFR controls whether each of the two timers is running or stopped and contains a flag

to indicate that each timer has overflowed. Additionally, some non-timer related bits


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are located in the TCON SFR. These bits are used to configure the way in which the

external interrupts are activated and also contain the external interrupt flags which are

set when an external interrupt has occured.

TMOD (Timer Mode, Addresses 89h): The Timer Mode SFR is used to

configure the mode of operation of each of the two timers. Using this SFR your

program may configure each timer to be a 16-bit timer, an 8-bit autoreload timer, a

13-bit timer, or two separate timers. Additionally, you may configure the timers to

only count when an external pin is activated or to count "events" that are indicated on

an external pin.

TL0/TH0 (Timer 0 Low/High, Addresses 8Ah/8Ch): These two SFRs, taken

together, represent timer 0. Their exact behavior depends on how the timer is

configured in the TMOD SFR; however, these timers always count up. What is

configurable is how and when they increment in value.

TL1/TH1 (Timer 1 Low/High, Addresses 8Bh/8Dh): These two SFRs, taken

together, represent timer 1. Their exact behavior depends on how the timer is

configured in the TMOD SFR; however, these timers always count up. What is

configurable is how and when they increment in value.

P1 (Port 1, Address 90h, Bit-Addressable): This is input/output port 1. Each bit

of this SFR corresponds to one of the pins on the microcontroller. For example, bit 0

of port 1 is pin P1.0, bit 7 is pin P1.7. Writing a value of 1 to a bit of this SFR will

send a high level on the corresponding I/O pin whereas a value of 0 will bring it to a

low level.

SCON (Serial Control, Addresses 98h, Bit-Addressable): The Serial Control

SFR is used to configure the behavior of the on-board serial port. This SFR controls

the baud rate of the serial port, whether the serial port is activated to receive data, and

also contains flags that are set when a byte is successfully sent or received.


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bank select flags which are used to select which of the "R" register banks are

currently selected.

ACC (Accumulator, Addresses E0h, Bit-Addressable): The Accumulator is

one of the most-used SFRs, since it is involved in so many instructions. The

Accumulator resides as an SFR at E0h, which means the instruction MOV A,#20h is

really the same as MOV E0h,#20h. However, it is a good idea to use the first method

since it only requires two bytes whereas the second option requires three bytes.

B (B Register, Addresses F0h, Bit-Addressable): The "B" register is used in

two instructions: the multiply and divide operations. The B register is also commonly

used by programmers as an auxiliary register to temporarily store values.

3.6.3 Timers/Counters

3.6.3.1 General Description

The MCS-51 has two 16 bit Timer/ Counter register Timer 0 and Timer 1. Both

can be configured to operate either as timers or event counter. Microcontroller can be

used as timer or counter as you need. Microcontroller will act as timer when switch

position on upper and microcontroller will act as counter when switch position on

lower by controlling C/T bit on TMOD register. The diagram below shows the logic

of the timer/counter circuit.


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TFx: Timer overflow flag. Set by hardware on Timer/Counter overflow. Cleared

by hardware when processor vector to interrupt routine, or clearing the bit in

software.

TRx: Timer Run control bit . Set/ cleared by software to turn Timer/ Counter

on/off

IEx: Interrupt Edge flag. Set by hardware when external interrupt edge detected.

Cleared when interrupt processed.

ITx: Interrupt type control bit. Set/ cleared by software to specefy falling edge/

low level trigerred external interrupts

3.6.3.2 Modes of the timer

M1 M0 Operating

0 0 13 bit Timer, TLx serves as 5 bit prescaler

0 116 bit Timer/Counter THx and TLx are cascaded, there is no

prescaler

1 0 8 bit auto reaload Timer/ Counter THx holds a value which is

tobe reloaded into TLx each time it overflows

1 1

(Timer 0) TL0 is an 8 bit Timer/ Counter controlled by the

standard timer 0 control bits

(Timer 1) Timer/ Counter 1 stopped

Mode 0 (13-bit Timer mode) :

Figure shows the Mode 0 operation as it applies to Timer 1. In this mode,

the Timer register is configured as a 13-bit register. As the count rolls over from all

1s to all 0s, it sets the Timer interrupt flag TF1. The counted input is enabled to the

Timer when TR1 = 1 and either GATE = 0 or INT1 = 1. (Setting GATE = 1 allows

the Timer to be controlled by external input INT1, to facilitate pulse width


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measurements). The 13-bit register consists of all 8 bits of TH1 and the lower 5 bits

of TL1. The upper 3 bits of TL1 are indeterminate and should be ignored. Setting the

run flag (TR1) does not clear the registers. Mode 0 operation is the same for the

Timer 0 as for Timer 1.

Fig. 3.11

Mode 1 (16-bit Timer mode) :

Mode 1 is the same as Mode 0, except that the Timer register is being run

with all 16 bits.

Fig. 3.12


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Mode 2 (8-bit Auto Reload):

Mode 2 configures the Timer register as an 8-bit Counter (TL1) with

automatic reload, as shown in Figure. Overflow from TL1 not only sets TF1, but also

reloads TL1 with the contents of TH1, which is preset by software. The reload leaves

TH1 unchanged.

Fig. 3.13

Mode 3 (2 8-bit Counter/Timer):

Timer 1 in Mode 3 simply holds its count. The effect is the same as settingTR1=0. Timer 0 in Mode 3 establishes TL0 and TH0 as two separate counters. The

logic for Mode 3 on Timer 0 is shown in Figure. TL0 uses the Timer 0 control bits:

C/T, GATE, TR0, INT0, and TF0. TH0 is locked into a timer function (counting

machine cycles) and takes over the use of TR1 and TF1 from Timer 1. Thus, TH0

now controls the Timer 1 interrupt. Mode 3 is provided for applications requiring

an extra 8-bit timer on the counter. With Timer 0 in Mode 3, an 80C51 can look like

it has three Timer/Counters. When Timer 0 is in Mode 3, Timer 1 can be turned on

and off by switching it out of and into its own Mode 3, or can still be used by the

serial port as a baud rate generator, or in fact, in any application not requiring an

interrupt.


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Fig 3.14

3.7 SERIAL COMMUNICATION :

3.7.1 Serial Port in 89C51

The serial port is full duplex, meaning it can transmit and receive

simultaneously. It is also receive-buffered, meaning it can commence reception of a

second byte before a previously received byte has been read from the register.

The serial port receive and transmit registers are both accessed at Special Function

Register SBUF. Writing to SBUF loads the transmit register, and reading SBUF

accesses a physically separate receive register.


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Fig. 3.15

The serial port can operate in 4 modes:

Mode 0:

Serial data enters and exits through RxD. TxD outputs the shift clock. 8

bits are transmitted/received (LSB first). The baud rate is fixed at 1/12 the oscillator

frequency.

Mode 1:

10 bits are transmitted (through TxD) or received (through RxD): a start

bit (0), 8 data bits (LSB first), and a stop bit (1). On receive, the stop bit goes into

RB8 in Special Function Register SCON. The baud rate is variable.

Mode 2:

11 bits are transmitted (through TxD) or received (through RxD): start bit

(0), 8 data bits (LSB first), a programmable 9th data bit, and a stop bit (1). On

Transmit, the 9th data bit (TB8 in SCON) can be assigned the value of 0 or 1. On

receive, the 9th data bit goes into RB8 in Special Function Register SCON, while the

stop bit is ignored. The baud rate is programmable to either 1/32 or 1/64 the oscillator

frequency.

Mode 3:

11 bits are transmitted (through TxD) or received (through RxD): a start

bit (0), 8 data bits (LSB first), a programmable 9th data bit, and a stop bit (1). In fact,

Mode 3 is the same as Mode 2 in all respects except baud rate. The baud rate in Mode

3 is variable.


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In all four modes, transmission is initiated by any instruction that uses SBUF as a

destination register. Reception is initiated in Mode 0 by the condition RI = 0 and

REN = 1. Reception is initiated in the other modes by the incoming start bit if REN =

1.

3.7.2 RS232 Standards :

In telecommunications, RS-232 (Recommended Standard 232) is a

standard for serial binary data signals connecting between a DTE (Data terminal

equipment) and a DCE (Data Circuit-terminating Equipment). It is commonly used in

computer serial ports. The RS-232 standard defines the voltage levels that correspond

to logical one and logical zero levels. The standard has been renamed several times

during its history as the sponsoring organization changed its name, and has been

variously known as EIA RS 232, EIA 232, and most recently as TIA 232. Valid

signals are plus or minus 3 to 15 volts. The range near zero volts is not a valid RS-

232 level; logic one is defined as a negative voltage, the signal condition is called

marking, and has the functional significance of OFF. Logic zero is positive, the signal

condition is spacing, and has the function ON. The standard specifies a maximum

open-circuit voltage of 25 volts. The region -3 to +3 is called as a dead band, since

the voltages are undefined in this region. For this reason to use RS232 to any

microcontroller we must first use voltage converters like MAX232 to convert TTL

logic to RS232 logic and vice versa. Such chips are commonly known as line drivers.

3.7.3 MAX232

A standard serial interfacing for PC, RS232C, requires negative logic, i.e.,

logic '1' is -3V to -12V and logic '0' is +3V to +12V. To convert a TTL logic, say,

TxD and RxD pins of the uC chips, thus need a converter chip. A MAX232 chip has

long been using in many uC boards. It provides 2-channel RS232C port and requires

external 10uF capacitors. This I.C. also includes two receivers and two transmitters in

the same package. This is useful in many cases when you only want to use the


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Transmit and Receive data Lines. You don't need to use two chips, one for the receive

line and one for the transmission.

Fig. 3.16

Chapter 4. ANALYSIS EXPERIMENTATION AND

RESULTS

4.1 IC DESCRIPTION

4.1.1 MICROCONTROLLER ATMEL AT89C51

4.1.1.1 Features

Compatible with MCS51 Products

4K Bytes of Reprogrammable Flash Memory

2.7V to 6V Operating Range

Fully Static Operation: 0 Hz to 24 MHz

Two-level Program Memory Lock

128 x 8-bit Internal RAM 15 Programmable I/O Lines

Two 16-bit Timer/Counters

Six Interrupt Sources

Programmable Serial UART Channel

Direct LED Drive Outputs


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On-chip Analog Comparator

Low-power Idle and Power-down Modes

Brown-out Detection Power-On Reset (POR)

Green (Pb/Halide-free/RoHS Compliant) Packaging Endurance: 1,000

Write/Erase Cycles

4.1.1.2.Description

The AT89C51 is a low-voltage, high-performance CMOS 8-bit

microcontroller with 4K bytes of Flash programmable and erasable read-only

memory. The device is manufactured using Atmels high-density nonvolatile

memory technology and is compatible with the industry-standard MCS-51

instruction set. By combining a versatile 8-bit CPU with Flash on a monolithic

chip, the Atmel AT89C51 is a powerful microcontroller which provides a highly-

flexible and cost-effective solution to many embedded control applications.

The AT89C51 provides the following standard features: 4K bytes of

Flash, 128 bytes of RAM, 15 I/O lines, two 16-bit timer/counters, a five-vector,

two-level interrupt architecture, a full duplex serial port, a precision analog

comparator, on-chip oscillator and clock circuitry. In addition, the AT89C51 is

designed with static logic for operation down to zero frequency and supports two

software-selectable power saving modes. The Idle Mode stops the CPU while

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

functioning. The power-down mode saves the RAM contents but freezes the

oscillator disabling all other chip functions until the next hardware reset.


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4.1.1.4. Internal Block Diagram

Fig. 4.2

4.1.1.5. Pin Description

VCC


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Supply voltage.

GND

Ground.

Port 1

Port 1 is an 8-bit bi-directional I/O port. Port pins P1.2 to P1.7 provide internal

pullups. P1.0 and P1.1 require external pullups. P1.0 and P1.1 also serve as the

positive input (AIN0) and the negative input (AIN1), respectively, of the on-chip

precision analog comparator. The Port 1 output buffers can sink 20 mA and can

drive LED displays directly. When 1s are written to Port 1 pins, they can be used

as inputs. When pins P1.2 to P1.7 are used as inputs and are externally pulled low,

they will source current (IIL) because of the internal pullups. Port 1 also receives

code data during Flash programming and verification.

Port 3

Port 3 pins P3.0 to P3.5, P3.7 are seven bi-directional I/O pins with internal

pullups. P3.6 is hard-wired as an input to the output of the on-chip comparator

and is not accessible as a general- purpose I/O pin. The Port 3 output buffers can

sink 20 mA. When 1s are written to Port 3 pins they are pulled high by the

internal pullups and can be used as inputs. As inputs, Port 3 pins that are

externally being pulled low will source current (IIL) because of the pullups. Port 3

also serves the functions of various special features of the AT89C51 as listed

below: Port 3 also receives some control signals for Flash programming and

verification.

Port Pin Alternate Functions


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P3.0 RXD (serial input port)

P3.1 TXD (serial output port)

P3.2 INT0 (external interrupt 0)

P3.3 INT1 (external interrupt 1)

P3.4 T0 (timer 0 external input)

P3.5 T1 (timer 1 external input)

RST

Reset input. All I/O pins are reset to 1s as soon as RST goes high. Holding the

RST pin high for two machine cycles while the oscillator is running resets the

device. Each machine cycle takes 12 oscillator or clock cycles.

XTAL1

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

circuit.

XTAL2Output from the inverting oscillator amplifier.

4.1.2 MAX232

4.1.2.1 Features

Meets or Exceeds TIA/EIA-232-F and ITU Recommendation V.28

Operates From a Single 5-V Power Supply With 1.0-uF Charge-Pump

Capacitors

Operates Up To 120 kbit/s

Two Drivers and Two Receivers

30-V Input Levels

Low Supply Current . . . 8 mA Typical


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ESD Protection Exceeds JESD 22-2000-V Human-Body Model (A114-A)

Upgrade With Improved ESD (15-kV HBM)and 0.1-_F Charge-Pump

Capacitors is available With the MAX202

Applications :TIA/EIA-232-F, Battery-Powered Systems, Terminals,

Modems, and Computers

4.1.2.2 Description

The MAX232 is a dual driver/receiver that includes a capacitive

voltage generator to supply TIA/EIA-232-F voltage levels from a single 5-V

supply. Each receiver converts TIA/EIA-232-F inputs to 5-V TTL/CMOS levels.

These receivers have a typical threshold of 1.3 V, a typical hysteresis of 0.5 V,

and can accept 30-V inputs. Each driver converts TTL/CMOS input levels into

TIA/EIA-232-F levels. The driver, receiver, and voltage-generator functions are

available as cells in the Texas Instruments LinASIC library.

4.1.2.3Pin Diagram

Fig. 4.3


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4.1.2.4Interfacing DiagramThe diagram below shows the interfacing pin configuration of the IC

MAX232 with the DB9 (Female) serial port connector and the Microcontroller.

16X2 LCD DISPLAY

4.1.5.1 Features

Maximum input voltage: 5.3VDC

Operating input voltage: 5VDC

8-bit interface data bus

Controller: HD47780 equivalent

Character font size: 0.125"W x 0.200"H

16 pin/terminals

Display size: 2.5"L x 0.7"W

Module size: 3.4"L x 1.2"W x 0.5"T

4.1.5.2 Description

This is a 16 character by 2 line display, with the standard HD44780

chipset. It works great with any microcontroller and it is very easy to interface. This LCD

has 8-bit parallel interface. It is possible to use all 8 bits plus 3 control signals or 4 bits

plus the control signals.


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4.1.5.3 Pin Diagram

Fig. 4.6

Fig. 4.7

4.1.5.4 LCD Interfacing diagram

The diagram below gives the interfacing configuration of the LCD with

the microcontroller.


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Energy Metering Circuit:

This enrgy meter is manly built around the IC 7751, an ANALOG DEVICEELECTRONIC ENERGY METERING IC, which converts the analog input energy

reading into output as pulse for displaying the count value which is equivalent to the

energy consumption. In addition to monitoring the energy consumption and data

transmission & reception, the meter also provides protection against high voltage, over

current and theft by immediately disconnecting metering circuit from the supply and

altering the consumer by giving an audible alarm, so that the consumer or maintenance

personal to take corrective action.

This circuit takes two current samples in terms of voltage form then takes one voltage

sample, and then generates a series of pulses depending upon the load connected.

It contains analog to digital converter section internal to it, and it also ahs its own

reference, it work s on the fixed frequency source generated by the crystal connected to it

externally.

There is also fault detection facility provided in the metering IC, So whenever the two

currents i.e. Phase and neutral, differs by the value more than 12% fault indication is

provided.

2.1 ENERGY MEASUREMENT BLOCK:


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This block takes the proportional voltage, proportional current in a fixed duration

so that the energy consumed V*I*t. To obtained the voltage supply 230V is potentially

dived with the help of respective network and thus part of AC voltage under

measurement is obtained. Similarly, to obtain the current measurement differential input

signals are taken using current transformers.

These two signals (V & I) are fed to AD 7751. This IC internally multiply current

and voltage signal and generate instantaneous power signal. This signal is low pass

filtered and converted to frequency F1 and F2 using digital to frequency converter, these

signals are taken across pin no 23 and 24. Thus the o/p is a frequency signal proportional

to the consumed energy.

The internal block diagram schematic of the 7751 is shown below,


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Opto Coupler Ic :


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Is is a 4 termianl device,it provides isolation between two different circuits, it enables in

sending the information through optical medium,

What it does is it provides isolation from the electrical circuit which is having the AC gnd

and the micro controller circuit which is having DC gnd.

If isolation was not there then because of presence of neutral as AC Gnd, which would

have been get combined with the DC gnd, then it would have created the short circuit the

complete damaging of the digital circuitry.

That is why there exits a opto coupler.

Two numbers of opto couplers are used in cascade manner that is in series so that both

the get the same pulse at the same time.

One opto coupler sends pulses to the stationary counting micro controller circuit and

other sends signal to remote station.

Micro controller block:

This block contains the main circuitry which measures the enrgy in terms of the

pulses,here micro controller AVR is configured as counting the in put pulses as well as

diplaying the reading on the back light LCD.

Mocro contreoller is to be configured as a counter by putting the appropriate vlue in its

TMOD register,sele cting the preticular timer as a counter and selecrting the particular

poin as input pin for receiving the pulses.then also configure the modes aof the operation

of the counting, mode 0 is selcted inthis application,as it has 8 bit wide register it counts

upto 255 and with 5 bit prescaler so combining both we get the last counting value upto

1fffh.it counts in mod32 manner.So if 1kwhr=3200 pulses then 100 count of the 32 is to

be displayed o the LCD display.

Display:-

Display section include 16*1 back light LCD interfaced with the microcontroller. It has

own processor to control the display information. So the interfacing of the LCD is done


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same as peripherals. It has own commands, addresses for the different locations on

different lines. Here 16 character one line LCD with 5 * 7 dot matrix pattern LCD is used

it require 5v supply for operation & same 5v for back light LED. The back light is having

greenish yellow shade of light. It has 8 data lines for sending the data over it & 3 control

lines to communicate with the LCD. Before reading & writing to LCD its busy status

need to be checked.

LCD gives more advantages & as compaired to the LED 7 segment displays. They are as

follows

1) The decline in price of LCD

2) The ability to display number, character & graphics. This is in contrast to LED which

are limited to numbers & few character.

3)In corporation of refreshing controller into the LCD, thereby relieving the CPU of the

task of refreshing the LDC. In contrast, the LED must be refreshed by the CPU (or in

some other way) to keep displaying the data.

4)Ease of programming for characters & graphics.

LCD:

It is a back light LCD, It has its own processor so it can be called as intelligent LCD. It is

treated as other peripheral device. So it needs to be interfaced like any other device.

It has 8 data lines and 3 control lines,

Using these 3 control lines one can read and write into the LCD, it also has internal

RAM.

IT also has address location specifying the particular location on particular lines. For 1

line the address starts from 80H through 8F so one can specify the location of the

character or number be displayed.

These 3 control lines are R/S: register select

R/W: read Write

E: Enable

Transmitter:-


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It contains the GSM module for transmission of the data in the form of SMS.SMS is send

to the user informing him about the update.GSM module SIM 300 is used in this

project.It is interfaced with the microcontroller using serial communication i.e. RS232

protocol.

Receiver Block:

The transmitted data is received by the mobile phone of the user whose number is fed

into the data base. So that information in the form of SMS is send.

Power Supply:-

For our all IC we require 5V D.C. supply which can be generated by step

down transformer, full wave bridge rectifier, filter condenser & voltage

regulator IC7805.

12V supply for relay is generated separately using the same procedure as

above.

Chapter 4 : Design Details

5.1 Power supply design

Power supply is the first and the most important part of our project. For our

project we require +5V regulated power supply with maximum current rating

500mA Following basic building blocks are required to generate regulated power supply.

Step-down

transformerRectifier

Filter

Ckt.Three

Terminal

Voltage reg.

Regulated O/P

VoltageMains 230 V

A.C.


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Step Down Transformer :-

Step down transformer is the first part of regulated power supply. To

step down the mains 230V A.C. we require step down transformer.

Following are the main characteristic of electronic transformer.

1) Power transformers are usually designed to operate from source of low

impedance at a single freq.

2) It is required to construct with sufficient insulation of necessary

dielectric strength.

3) Transformer ratings are expressed in voltamp. The volt-amp of each

secondary winding or windings are added for the total secondary VA. To

this are added the load losses.

4) Temperature rise of a transformer is decided on two well-known factors

i.e. losses on transformer and heat dissipating or cooling facility provided

unit.

Rectifier Unit :-

Rectifier unit is a ckt. which converts A.C. into pulsating D.C.

Generally semi-conducting diode is used as rectifying element due to its

property of conducting current in one direction only. Generally there are two

types of rectifier.

1) Half wave rectifier

2) Full wave rectifier

In half wave rectifier only half cycle of mains A.C. is rectified so its

efficiency is very poor. So we use full wave bridge type rectifier, in which


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four diodes are used. In each half cycle, two diodes conduct at a time and we

get maximum efficiency at o/p.

Following are the main advantages and disadvantages of a full-wave

bridge type rectifier ckt.

Advantages:-

1) The need of center tapped transformer is eliminated.

2) The o/p is twice that of center tap circuit for the same secondary voltage.

3)The PIV rating of diode is half of the center tap circuit.

Disadvantages:-

1) It requires four diodes.

2) As during each half cycle of A.C. input, two diodes are conducting

therefore voltage drop in internal resistance of rectifying unit will be

twice as compared to center tap circuit.

Filter Circuit :-

Generally a rectifier is required to produce pure D.C. supply for using

at various places in the electronic circuit. However, the o/p of rectifier has

pulsating character i.e. if such a D.C. is applied to electronic circuit it will

produce a hum i.e. it will contain A.C. and D.C. components. The A.C.

components are undesirable and must be kept away from the load. To do so


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2) Operating Voltage.

3) Frequency Range.

4) Efficiency and Regulation.

Size of core

Size of core is one of the first considerations in regard of weight and volume of

transformer. This depends on type of core and winding configuration used. Generally

following formula is used to find area or size of core.

P1

Ai = -----------

0.87

Ai = Area of cross - section in Sq. cm. and

P1 = Primary voltage.

In transformer P1 = P2

For our project we required +5V regulated output. So transformer secondary

rating is 12V, 4A

So secondary power wattage is,

P2 = 12 x 4 w.

= 48w

48


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So Ai = 0.87

= 7.427

Generally 10% of area should be added to core to accommodate all turns for

low Iron losses and compact size.

So Ai = 8.1697

Turns per volt

Turns per volt of transformer are given by relation

10,000

Turns / Volt = -----------------------

4.44 f Bm Ai

Here,

f is the frequency in Hz

Bm is flux density in Wb/m2

Ai is net area of cross section.

Following table gives the value of turns per volt for 50 Hz frequency.

Flux density

Wb/m2

1.14 1.01 0.91 0.83 0.76

Turns per volt 40/Ai 45/Ai 50/Ai 55/Ai 60/Ai

Generally lower the flux density better be quality of transformer.

For project for 50 Hz the turns per Volt for 0.91 Wb/m2 from above table.

Turns per Volt = 50 / Ai


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50

= 8.1697

6.13

Thus for Primary winding = 220 x 6.13 = 1346.43.

& for Secondary winding = 12 x 6.13 = 74

Wire size

As stated above size depends upon the current to be carried out by the

winding, which depends upon current density of 3.1 A/mm2. For less copper

losses 1.6 A/mm2

or 2.4 A/mm2

may be used. Generally even size guage of

wire are used.

Rectifier Design

R.M.S. Secondary voltage at secondary of transformer is 12V.

So maximum voltage Vm across Secondary is

= Rms. Voltage x 2

= 12 x 2

= 16.97

D.C. O/p Voltage at rectifier O/p is

2 Vm

Vdc = ----------

2 x 16.97

= -----------------------

= 10.80 V


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PIV rating of each diode is

PIV = 2 Vm.

= 2 x 16.97

= 34 V

& maximum forward current which flow from each diode is 500mA.

So from above parameter we select diode IN 4007 from diode selection

manual.

Design of Filter Capacitor

Formula for calculating filter capacitor is,

1

C = ----------------------

43 r f RL.r = ripple present at o/p of rectifier.

(Which is maximum 0.1 for full wave rectifier.)

F = frequency of mains A.C.

RL = I/p impedance of voltage regulator IC.


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1

C = ------------------------------

43 x 0.1 x 50 x 28= 1030 f 1000 f.

And voltage rating of filter capacitor is double of Vdc i.e. rectifier o/p which

is 20V. So we choose 1000 f / 25V filter capacitor. [Ref : 6]

IC 7812 (Voltage Regulator IC.)

Specifications :

Available o/p D.C. Voltage = +12V.

Line Regulation = 0.03

Load Regulation = 0.5

Vin maximum = 35 V

Ripple Rejection = 66-80 (db)

IC 7805 (Voltage Regulator IC.)

Specifications :

Available o/p D.C. Voltage = + 5V.

1 2 3

1 2 3


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Line Regulation = 0.03

Load Regulation = 0.5

Vin maximum = 35 V

Ripple Rejection = 66-80 (db)

Chapter 2 : Technical Details

IC 78XX (Voltage Regulator IC )

OUTPUT CURRENT UP TO 1.5 A

OUTPUT VOLTAGESOF 5; 5.2; 6; 8; 8.5; 9;

12; 15; 18; 24V

THEOVERLOADPROTECTION

SHORT CIRCUIT PROTECTION

OUTPUT TRANSITION SOA PROTECTION

DESCRIPTION

The L7800 series of three-terminal positive regulators is available in TO-220

TO-220FP TO-3 and D2PAK packages and several fixed output voltages,

making it useful in a wide range of applications. These regulators can

provide local on-card regulation, eliminating the distribution problems


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associated with single point regulation. Each type employs internal current

limiting, thermal shut-down and safe area protection, making it essentially

indestructible. If adequate heat sinking is provided, they can deliver over 1A

output current. Although designed primarily as


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Electrical Characteristic :

PCB DESIGNING AND FABRICATION


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Introduction to printed circuit boards:

It is called PCB in short; printed circuit pattern applied to one or both sides

of an insulating base, depending upon that, and it is called single sided PCB

or double-sided PCB.

Conductor materials available are silver, brass, aluminum and copper;

copper is most widely used which is used here as well. The thickness of

conducting material depends on the current carrying capacity of the circuit.

The printed circuit board usually serves three functions:

1. It provides mechanical support to the components mounted on it.

2. It provides necessary electrical interconnection.

3. It acts as heat sink, i.e., it provides a conduction path leading to

removal of most of the heat generated in the circuit.

Cu clad

The base of laminate is either paper of glass fiber cloth. Cu foil, which is

produced by the method of electroplating, is placed on laminate and both are

kept under hydraulic pressure for proper adhesive pressure for proper

adhesive. These Cu clad are easily available in the market.

Types of Laminates

National Electrical Manufactures Association (NEMA) has various grades of

laminates that are obtained by different resins and filters.

1. Phenol


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Phenol and Formaldehyde produce phenolic paper base laminate it has

phenolic resins with proper filter. This is Brown in color and opaque.

Disadvantage is poor moisture resistance.

2. Epoxy LaminatesEpoxy paper that is also paper based but impregnated with epoxy resin,

yellowish white and translucent.

Epoxy Glass; This base material has high mechanical strength and good

electrical properties usually green in color and semitransparent.

There are a variety of laminates available. We have selected Fiber Glass

epoxy laminate.

PCB fabrication includes following steps:

1) Layout of the circuit

2) Artwork designing

3) Printing

4) Etching

5) Drilling

6) Mounting of components and soldering

7) Finishing

1. LayoutThe layout of a PCB has to incorporate all the board before one can

go onto the all work preparation. Detailed circuit diagram, the design

concept and the philosophy behind the equipment are very important for the

layout.

Layout Scale


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Depending on the accuracy required artwork should be produced at a 1:1 or

2:1 or even 4:1 scale. The layout is best prepared on the same scale as the

artwork to prevent the entire problem, which might be caused by redrawing

of the layout to the artwork scale. The layout/ artwork scale commonly

applied is 2:1 with a 1:1 scale, no demanding single sided boards can be

designed but sufficient care should be taken, particularly during the artwork

preparation.

Procedure

The first rule is to replace each and every PCB layout as viewed from

the component side. This rule must be strictly followed to avoid confusion,

which would otherwise be caused.

Another important rule is not to start the designing of a layout unless an

absolutely clear circuit diagram is available.

Among the components, the larger ones are placed first and the space in

between is filled with smaller ones. Components requiring input/output

connecting come near the connector. All components are placed in such a

manner that de-soldering of other components is not necessary if they have

to be replaced.

Layout sketch

The end product of the layout designing is the pencil sketched

component and conductor drawing which is caller layout sketched. It

contains all the information for the preparation of the network.

Component holes


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In a given, PCB most all the holes required are one particular

diameter. Holes of a different are shown with a code in the actual layout

sketch.

Conductor Holes

A code can be used for the conductor with a special width. Minimum

spacing should also be provided.

A) Holes B) Conductor Widths

Standard holes Standard width, 0.5 mm

1.1 mm 1 mm

1.5 mm 2 mm

3.2 mm 4 mm

2) Artwork

The generation of PCB artwork should be considered as the first step of the

PCB manufacturing process. The importance of a prefect artwork should not

be under estimated. Problems like inaccurate registered, broken annular

rings or too critical spacing are often due to bad artwork. And even with the

most sophisticated PCB production facilities, PCB can be made better than

the quality of the artwork used.

Basic Approaches

For ink drawing on white cardboard paper, good quality Indian ink and

ink-pen set are minimum requirements.

Drawing practice ---drawing procedure is very at-least by 0.10.2, and

solder pad locations.

And conductors can be easily displaced by 0.30.5 mm


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3) Screen Printing

The process of screeningprinting is well known to the printing

industry because of its inherent capabilities of printing a wide range of inks

on almost any kind of surface including glass, metal, plastic fabrics etc.

Found their way into an extremely broad field of applications.

Screen-printing offers the advantage of wide control on the ink deposition,

thickness though the selection of suitable mass density and composition. In

the production of PCBs, it is successfully employed in printing of

Etch resists Plate resists

Solder stop lacquers

Notation printing

In its basic form, the screen-printing process is very simple. A screen fabric

with uniform meshes and opening is stretched and fixed on a solid frame of

metal or wood. The circuit pattern area open, while the meshes in the rest of

the area is closed.

In the actual printing step, ink is forced by the moving squeeze thorough the

open meshes onto the surface of the material to be printed.

The ink deposition, in a magnified cross section, shows the shape of a

trapezoid.

Pattern transfer onto the Screen

There are two different methods in use, and each method has its own

advantages and disadvantages.

With the direct method, the screen is prepared by coating a photographic

emulsion directly onto the screen fabric and exposing it in the pattern area.


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The indirect method makes use of a separate screen process film, supported

on a backing sheet. The film on its backing sheet that is there after pressed

onto the screen fabric and sticks there. Finally, the backing sheet is peeled

off, opening all those screen meshes, which are not covered by the film

pattern.

The direct method provides very durable screen stencils with a higher

dimensional accuracy but the finest details are not reproduced. The indirect

method is more suitable for smaller series and where the finest details to be

reproduced. The indirect method is faster but dimensionally less accurate

and the screen stencils are less durable, more sensitive to mechanical

damages and interruption in printing.

4) Etching

In all subtractive PCB process, etching is one of the most important steps.

The final copper pattern is formed by selective removal of all the unwanted

copper, which is not protected by an etching unit.

Solutions, which are used in etching process, are known as enchants.

I) Ferric Chloride

II) Cupric Chloride

III) Chromic Acid

IV) Alkaline Ammonia.

Of these Ferric Chloride is widely used because it has short etching time and

it can be stored for a long time. Etching of PCBs as required in modern

electronic equipment production, is usually done in spray type etching

machines.

Tank or bubble etching, in which the boards kept in tank, were lowered and

fully immersed into the agitated, has almost disappeared.


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5) Component Mounting

Careful mounting of components on PCB increases the reliability of

assembly.

1) The leads must be cleaned before they are inserted in PCB holes.

Asymmetric lead bending must be avoided; the ENT leads must fit into

holes properly so that they can be soldered.

2) When space is to be saved then vertical mounting is to be preferred.

The vertical leads must have an insulating sleeve.

3) Where jumper wire crosses over conductors, they must be insulated.

4) For mounting of PCBs, TO5, DIP packages special jigs must be used

of easy insertion.

5) While mounting transistors, each lead must insulating sleeve. All the

flat radial components such as resistors, diodes and inductors are mounted

and soldered. Then IC bases are soldered. The vertical components such as

transistors, gang condenser and FET are mounted & soldered.

6) Soldering

The next process after the component mounting is soldering; solder pint is

achieved by heating the solder and base metal about the melting point of the

solders used.

The necessary heat depends upon:

1) The nature and type of joints

2) Melting temperature of solder

3) Flux

Soldering techniques are of so many types but we are using iron soldering.


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Iron soldering

Soldering iron consists of an insulating handle connected through a metal

shaft, of a bit accurately makes contact with the component parts of the joint

and solder and heats them up. The electrical heating element is located in the

hollow shank or handle to heat the bit.

Functions of the Bit

It stored heat and convey it from the heat source to the work. It may be

required to store surplus solder from the joint. It may be required to store

molten solder and flux to the work.

The surface must be lined and wetted; this encourages flow of solder into the

joint. When the surface of the work becomes tested by the solder, a

continuous flow of liquid metal between the bit and the work provides a path

of high thermal conductivity through which heat can flow into the work

piece.

Solder bit are made up of copper; this metal has good wetting property, heat

capability and thermal conductivity. Tin-lead solder affects copper during

soldering operation. Production of copper bit can be made with thick iron

coating followed by Ni/Tin plating. The life of the bit is increased by a

factor of 10 to 15. Solder irons are specified in terms of wattage. Depending

on heat input intended for working and types of work ( continuous or

individual) the choice of the solder iron can be made.

Procedure of Soldering

The points to be joined must be cleaned first and fluxed. The hard solder

iron and solder wire is applied to the work. The melted solder becomes


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bright and fluid. The iron must be removed after sufficient time and joint is

allowed to coal.

At the end, finishing is done.

PCB, Designing using computer aided designing (CAD):

CAD has many advantages over manual designing, important among then is:

1) Changes can be easily made because we dont have to erase our pencil

work on paper repeatedly.

2) Time is saved.

3) Before taking printout we can have preview of the design etc.

The software which we have used is Quick-route.

Circuit diagram

Layout


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Energy Metering Circuit Using GSM-Semi Report

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Transcript of Energy Metering Circuit Using GSM-Semi Report