Selection Criteria s1

Microcontroller

Selection Criteria

1. The first and the foremost criterion for selecting a microcontroller is that it must meet the 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, this had 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

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.

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 MICROCONTROLLER

The 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 Organization

The basic block diagram of the family of the 80x51 is as shown below in the figure.

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 Registers

3.6.2.1 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. 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 SFR’s 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 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 SFR’s

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 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.

SBUF (Serial Control, Addresses 99h): The Serial Buffer SFR is used to send and receive data via the on-board serial port. Any value written to SBUF will be sent out the serial port's TXD pin. Likewise, any value which it receives via the serial port's RXD pin will be delivered to the user program via SBUF. In other words, SBUF serves as the output port when written to and as an input port when read from.

IE (Interrupt Enable, Addresses A8h): The Interrupt Enable SFR is used to enable and disable specific interrupts. The low 7 bits of the SFR are used to enable/disable the specific interrupts, where as the highest bit is used to enable or disable ALL interrupts. Thus, if the high bit of IE is 0 all interrupts are disabled regardless of whether an individual interrupt is enabled by setting a lower bit.

P3 (Port 3, Address B0h, Bit-Addressable): This is input/output port 3. Each bit of this SFR corresponds to one of the pins on the microcontroller. For example, bit 0 of port 3 is pin P3.0, bit 7 is pin P3.7. 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.

IP (Interrupt Priority, Addresses B8h, Bit-Addressable): The Interrupt Priority SFR is used to specify the relative priority of each interrupt. An interrupt may either be of low (0) priority or high (1) priority. An interrupt may only interrupt interrupts of lower priority. For example, if we configure so that all interrupts are of low priority except the serial interrupt, the serial interrupt will always be able to interrupt the system, even if another interrupt is currently executing. However, if a serial interrupt is executing no other interrupt will be able to interrupt the serial interrupt routine since the serial interrupt routine has the highest priority.

PSW (Program Status Word, Addresses D0h, Bit-Addressable): The Program Status Word is used to store a number of important bits that are set and cleared by instructions. The PSW SFR contains the carry flag, the auxiliary carry flag, the overflow flag, and the parity flag. Additionally, the PSW register contains the register 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.

Fig. 3.10

The timer/counter is controlled by the two registers TMOD and TCON. Both the timers share these registers. The layout of both these registers is given below.

Timer/ Counter Mode Control ( TMOD ) Register

TIMER 1 TIMER 0 GATE C/T M1 M0 GATE C/T M1 M0 GATE: Gating control when set. Timer/ Counter X is enabled only while INTx pin is high and TRx control pin is set

C/T : Timer or Counter Selector cleared for Timer operation (input from internal system clock) and set for counter operation (input from Tx input pin)

M0 M1 : Indicates the mode of the Timer/ Couner

Timer/ Counter Control ( TCON ) Register MSB LSB TF1 TR1 TF0 TR0 IE1 IT1 IE0 IT0 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 16 bit Timer/Counter THx and TLx are cascaded, there is no 0 1 prescaler 8 bit auto reaload Timer/ Counter THx holds a value which is 1 0 tobe reloaded into TLx each time it overflows (Timer 0) TL0 is an 8 bit Timer/ Counter controlled by the 1 1 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 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

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 setting TR1=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.

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.

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.

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 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 MCS®51 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

 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 Atmel’s 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.

4.1.1.3. Pin Diagram Fig. 4.1 4.1.1.4. Internal Block Diagram

Fig. 4.2

4.1.1.5. Pin Description

VCC 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 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.

XTAL2 Output 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  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.

4.1.2.3 Pin Diagram

Fig. 4.3

4.1.2.4 Interfacing Diagram The 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. 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. Energy Metering Circuit:

This enrgy meter is manly built around the IC 7751, an ANALOG DEVICE ELECTRONIC 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: 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,

Opto Coupler Ic :

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 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:-

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 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 volt–amp. 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 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 a filter circuit is used which removes (or filters out) the A.C. components reaching the load. Obviously a filter circuit is installed between rectifier and voltage regulator. In our project we use capacitor filter because of its low cost, small size and little weight and good characteristic. Capacitors are connected in parallel to the rectifier o/p because it passes A.C. but does not pass D.C. at all.

Three terminal voltage regulator :-

A voltage regulator is a ckt. that supplies constant voltage regardless of change in load current. IC voltage regulators are versatile and relatively cheaper. The 7800 series consists of three terminal positive voltage regulator. These ICs are designed as fixed voltage regulator and with adequate heat sink, can deliver o/p current in excess of 1A. These devices do not require external component. This IC also has internal thermal overload protection and internal short circuit and current limiting protection. For our project we use voltage regulator Ics 7812 & 7805. Design of Step down Transformer:- The following information must be available to the designer before he commences for the design of transformer. 1) Power Output. 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.

Ai = ------

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

P1 = Primary voltage.

In transformer P = P 1 2 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

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 2 Bm is flux density in Wb/m

Ai is net area of cross section.

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

Flux density 1.14 1.01 0.91 0.83 0.76

2 Wb/m Turns per volt 40/Ai 45/Ai 50/Ai 55/Ai 60/Ai

Generally lower the flux density better be quality of transformer. 2 For project for 50 H the turns per Volt for 0.91 Wb/m from above table. z

Turns per Volt = 50 / Ai

= 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 Ö2 = 12 x Ö2 = 16.97 D.C. O/p Voltage at rectifier O/p is

Vdc = ------

p 2 x 16.97 = ------p = 10.80 V

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,

C = ------

4Ö3 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.

C = ------

4Ö3 x 0.1 x 50 x 28

= 1030 mf

@ 1000 mf. And voltage rating of filter capacitor is double of Vdc i.e. rectifier o/p which is 20V. So we choose 1000 mf / 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.

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 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

Electrical Characteristic : PCB DESIGNING AND FABRICATION

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 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 Laminates Epoxy 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. Layout The 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 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 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 0.1 – 0.2, and solder pad locations. And conductors can be easily displaced by 0.3 – 0.5 mm

3) Screen Printing The process of screening – printing 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 PCB’s, 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. 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.

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.

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 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 don’t 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