CHAPTER 1 INTRODUCTION

1.1 OVERVIEW From the early days till today meter reading for electricity consumption and billing is done by human operators from houses to houses. This therefore requires a very large number of human operators and long working hours to acquire complete data reading and billing in a particular area. However, there may be cases where human operators miss to bill few houses in an area or restricted and slowed down by bad weather condition, transportation problems, etc. Moreover human operators are very much likely to make mistake while billing or reading a meter and sometimes the houses electric power meter may be placed in a location where it is not easily accessible. Again printed billing has the tendency of being lost in the mail box or being never delivered. Day by day due to the increasing number of residential housings and commercial buildings, more human operators and longer working hours is needed to complete the meter reading task which eventually increases the energy provider operation costs for meter reading.

To achieve efficient meter reading, reduce billing error and operation costs, an Automatic Electric Meter reading system can be introduced with every energy meter in an area. It is an effective means of data collection that allow substantial saving through the reduction of meter re read, greater data accuracy, frequent reading, improved billing and customer service, more energy profiles and consumption trends updates and better deployment of human resource."Electricity meter reading using GSM" implements the emerging applications of the GSM technology. GSM is a Global system for mobile communication (GSM) and is a wide area wireless communications system that uses digital radio transmission to provide voice, data, and multimedia communication services. A GSM system coordinates the communication between mobile telephones (mobile stations), base stations (cell sites), and switching systems. Each GSM radio channel is 200 KHz wide channels that are further divided into frames that hold 8 time slots. The GSM system includes mobile telephones (mobile stations), radio towers (base stations), and interconnection switching systems. We have selected a particular GSM modem SIM300 for our project. The message are sent from the mobile set that contain commands in written form which are then processed accordingly to perform the required task. The proposed approach for designing this system is to implement microcontroller based control module that receives its instructions and command from a cellular phone over the GSM network. The microcontroller then will carry out the issued commands and then communicate the status of a given appliance or device back to the cellular phone. First, the sent SMS is stored and polled from the receiver mobile station and then the required control signal is generated and sent to the intermediate hardware that we have designed according to the command received in form of the sent message.1.2 OBJECTIVE OF THE PROJECTThe main objectives of the project are:(i) To co-ordinate appliances and other devices through Short Message Service (SMS).(ii) To efficiently receive and transmit data via SMS.(iii) Minimize power and time wastage.(iv) To eliminate the need of being physically present in any location for tasks involving the operation of appliances within a household/office.(v) To design a circuit that can automatically switch ON and OFF the home appliance.

1.3 NEED FOR GSM BASED EB SYSTEM WITH LOAD CONTROL The present day electricity billing (EB) system therefore requires a very large number of human operators and long working hours to acquire complete data reading and billing in a particular area. Inorder to reduce the man power and to save time automation in billing system is required. This automation is achieved by interfacing a GSM module along with the energy meter. The GSM module is interfaced using a microcontroller. The GSM module gets the meter reading and it sends the current reading information to the customers mobile in the form of SMS. The customers mobile number is to be registered before in the GSM module. There for the billing information is sent to the electricity distribution office and even to the user .Therefore a lot of time is saved and man power requirement is also reduced. Certain attempts have been made to achieve automation in electricity billing system. Many companies came up with automatic meter reading system with GSM and few companies came up with smart home technologies which involve control of home appliances. Here control of home appliances includes ON and OFF of electrical and electronic home appliances. Our project involves both automatic meter reading system and load control system. Therefore our project provides billing information to the user as well as also helps the user to control the load (home appliance).

1.4 RELATED WORKThis section provides a previous study of related work regarding the application of SMS services in a various fields. Some previous researches have been studied to gain more information about current existing GSM control system that was previously implemented. It is necessary to know and understand how the software and hardware were used in the SMS controlled system development. This is to ensure that the study that currently being conducted contribute at certain level of application thus it become more efficient and practical. Several smart home projects such as Home Security with Messaging System , Security & Control System , and Remote and Security Control via SMS were the three alarm system that were designed using SMS application to securely monitor the home condition when the owner are away or at night. A system as suggested by messaging system triggered by SMS to the home owner to notify the owner of any incident happened around the house such as robbery or fire.

Meanwhile, the system developed by tan, H.G.R Lee, C.H.R Mok is automating the power reading meter to send the energy consumed to e-billing system at authorized office. The system works by integrating the GSM modem that was embedded with digital kWh power meter. It utilizes the GSM network to send power usage reading using SMS to the authorized office. The authorized office collect and manage the received SMS message contains the meter reading to generate the billing cost and send back the cost to the respective consumer through SMS. The work presented by mohd helmy is about the development of Integrated Water Billing System with SMS capability. The system is designed to facilitate the Water authorized to manage the monthly billing system without the use of human services. The system receives SMS from the meter to central databases. Then the information received is processed to generate current billing. The system again sends a SMS notification to the user regarding the total amount that has been billed. The system was implemented using Visual Basic and database in order to perform the prototype and the system works successfully in sending SMS to user for notification.

1.5 PROBLEM FORMULATION

The Electricity meter reading using GSM system takes the advantage of existing GSM infrastructure that have virtually full coverage of all housing and building area across the country which lead to low infrastructure implementation cost, simple and easy installation of GSM system at consumer side as this system is no difference from existing ordinary analogue or digital meter installation. The complete Electricity Meter Reading Using GSM required an ICT expertise personnel to setup, run and maintain all the servers. The Electricity Meter Reading Using GSM provides effective, reliable and efficient wireless automatic electric meter readiFng, billing and notification through the use of GSM network, thus reducing human operator meter reading operation cost.The importance of proposed work can be well understood if we keep in mind the amount of electricity being stolen every day. As a user can get his or her bill at any instant and can even pay it at any instant, so any kind of misuse by any other person can be avoided. The message are sent from the mobile set that contain commands in written form which are then processed accordingly to perform the required task. The proposed approach for designing this system is to implement microcontroller based control module that receives its instructions and command from a cellular phone over the GSM network. The microcontroller then will carry out the issued commands and then communicate the status of a given appliance or device back to the cellular phone. First, the sent SMS is stored and polled from the receiver mobile station and then the required control signal is generated and sent to the intermediate hardware that we have designed according to the command received in form of the sent message

CHAPTER 2 HARDWARE DEVELOPMENT2.1 BLOCK DIAGRAM

Figure 2.1 Block diagram of GSM based electricity system with load control

BLOCKSCOMPONENT USED

TransformerStep down transformer

RectifierBridge rectifier

Voltage RegulatorLM7805

Micro ControllerAT89S52

Energy MeterElectro-mechanical type

ComparatorLM358

GSM ModemSIM 300

Crystal Oscillator11.0592 MHz

Relay DriverULN2003A

RelaySPDT Relay

LoadAny electrical appliance

LCD Display162 LCD Display

Table 2.1 Block description2.2 POWER SUPPLY Every electronic system whether an entertainment gadget or a test and measurement equipment requires one or more than one DC voltages for its operation, most of the time it is essential and almost always desirable that these DC voltages are nicely filtered and well regulated. Power supply does the job of providing required DC voltages from available AC mains in case of mains operated systems and DC input in case of portable systems. Power supplies are often classified as linear power supplies depending upon the nature of regulation circuit.

Figure 2.2 Block Diagram of Power SupplyLinear power supply unit essentially comprises of: Mains Transformer Rectifier Filter Regulator Here 5V D.C. output is used as power supply to AT89S52 Microcontroller, RF Transmitter & Receiver pair and LCD display etc and 12 Volt D.C. power supply is mainly used for relays.2.2.1 DESCRIPTION OF A POWER SUPPLY UNIT A 220v ac to 12-0-12v transformer is used and for rectification, four diodes IN4007 are connected for rectification of the step down ac supply. Filter capacitor of 1000F is used. It is regulated to +5v using a regulator 7805.2.2.1.1 Transformer A bridge rectifier coupled with a step down transformer is used for our design. The voltage rating of transformer used is 0-12V and the current rating is 500mA. When AC voltage of 230V is applied across the primary winding an output AC voltage of 12V is obtained. One alteration of input causes the top of transformer to be positive and the bottom negative. The next alteration will temporarily cause the reverse.

2.2.1.2 Rectifier In the power supply unit, rectification is normally achieved using a solid state diode. Diode has the property that will let the electron flow easily at one direction at proper biasing condition. Bridge rectifiers of 4 diodes are used to achieve full wave rectification. Two diodes will conduct during the negative cycle and the other two will conduct during the positive half cycle.

2.2.1.3 Filtering Unit Filter circuit which is usually a capacitor acts as a surge arrester always follows the rectifier unit. This capacitor is also called as a decoupling capacitor or a bypass capacitor, is used not only to short the ripple with frequency to ground but also leave the frequency of the DC to appear at the output.

2.2.1.4 Voltage Regulators The voltage regulators play an important role in any power supply unit. The primary purpose of a regulator is to aid the rectifier and filter circuit in providing a constant DC voltage to the device. Power supplies without regulators have an inherent problem of changing DC voltage values due to variations in the load or due to fluctuations in the AC line voltage. With a regulator connected to DC output, the voltage can be maintained within a close tolerant region of the desired output. Figure 2.3 LM78052.2.2 OPERATION The transformer provides voltage transformation and produces AC voltage required for producing the desired DC voltages across its secondary windings. It also provides electrical isolation between the power supply input i.e., AC mains and output. The rectifier circuit changes the AC voltages appearing at transformer secondary to DC. Commonly used rectifier circuits include half-wave rectifier, conventional full-wave rectifier requiring a tapped secondary or a bridge rectifier.

Figure 2.4 A Simple 5V DC Regulated Power System

The rectified voltage will always have some AC content known as power supply ripple. The filter circuit levels the ripple of the rectified voltage. The filtering action of the capacitor connected across the output of the rectifier comes from the fact that it offers a low reactance to AC components. The ripple in nature is inversely proportional to capacitance. Thus, the capacitor connected across the output of the rectifier, which provides the filtering action, must be large enough to avoid the ripple.

The regulated circuit is a type of feedback circuit that ensures the output DC voltage does not change from its normal value due to changes in line voltage or load current. It is the nature of regulator circuit that distinguishes the linear power supply from a switching supply. In a linear power supply, the active device (linear regulator) that provides regulation, usually bipolar transistor is operated anywhere between cut-off and saturation i.e., in active region whereas in switching mode power supply, switching regulator is operated either in cut-off or in saturation. 7812 or 7805 are linear, fixed voltage series regulators, which provide regulated 12V and 5V DC respectively. In case of a series regulator a change in the output voltage due to a change in input voltage or load current results in a change in the voltage drop across the regulator transistor so as to maintain a constant output voltage across the load. 12V and 5V regulated DC power supplies are obtained across 10 micro farad capacitors. 2.3 MICRO CONTROLLER The AT89S52 is a low-power, high-performance CMOS 8-bit microcontroller with 8K bytes of in-system programmable Flash memory. The device is manufactured using Atmels high-density nonvolatile memory technology and is compatible with the industry-standard 80C51 instruction set and pin out. The on-chip Flash allows the program memory to be reprogrammed in-system or by a conventional nonvolatile memory programmer. By combining a versatile 8-bit CPU with in-system programmable Flash on a monolithic chip, the Atmel AT89S52 is a powerful microcontroller which provides a highly-flexible and cost-effective solution to many embedded control applications. The AT89S52 provides the following standard features: 8K bytes of Flash, 256 bytes of RAM, 32 I/O lines, Watchdog timer, two data pointers, three 16-bit timer/counters, a six-vector two-level interrupt architecture, a full duplex serial port, on-chip oscillator, and clock circuitry. In addition, the AT89S52 is designed with static logic for operation down to zero frequency and supports two software selectable power saving modes. The Idle Mode stops the CPU while allowing the RAM, timer/counters, serial port, and interrupt system to continue functioning. The Power-down mode saves the RAM contents but freezes the oscillator, disabling all other chip functions until the next interrupt or hardware reset.2.3.1 FEATURES Compatible with MCS-51 Products. 8K Bytes of In-System Programmable (ISP) Flash Memory. Endurance: 10,000 Write/Erase Cycles. 4.0V to 5.5V Operating Range. Fully Static Operation: 0 Hz to 33 MHz. Three-level Program Memory Lock. 256 x 8-bit Internal RAM. 32 Programmable I/O Lines. Three 16-bit Timer/Counters. Eight Interrupt Sources. Full Duplex UART Serial Channel. Low-power Idle and Power-down Modes. Interrupt Recovery from Power-down Mode. Watchdog Timer. Dual Data Pointer. Power-off Flag. Fast Programming Time. Flexible ISP Programming (Byte and Page Mode). Green (Pb/Halide-free) Packaging Option.

2.3.2 PIN DIAGRAM Figure 2.5 Pin Diagram of AT89S52

2.3.3 PIN DESCRIPTIONVCC: Supply voltage.GND: Ground.Port 0: Port 0 is an 8-bit open drain bidirectional I/O port. As an output port, each pin can sink eight TTL inputs. When 1s are written to port 0 pins, the pins can be used as high-impedance inputs. Port 0 can also be configured to be the multiplexed low-order address/data bus during accesses to external program and data memory. In this mode, P0 has internal pull-ups. Port 0 also receives the code bytes during Flash programming and outputs the code bytes during program verification. External pull-ups are required during program verification.Port 1: Port 1 is an 8-bit bidirectional I/O port with internal pull-ups. The Port 1 output buffers can sink/source four TTL inputs. When 1s are written to Port 1 pins, they are pulled high by the internal pull-ups and can be used as inputs. As inputs, Port 1 pins that are externally being pulled low will source current (IIL) because of the internal pull-ups. In addition, P1.0 and P1.1 can be configured to be the timer/counter 2 external count input (P1.0/T2) and the timer/counter 2 trigger input (P1.1/T2EX), respectively, as shown in the following table. Port 1 also receives the low-order address bytes during Flash programming and verification.Port PinAlternate Functions

P1.0T2(external count input to Timer/Counter 2), clock-out

P1.1T2EX (Timer/Counter 2 capture/reload trigger and direction control)

P1.5MOSI (used for In-System Programming)

P1.6MISO (used for In-System Programming)

P1.7SCK (used for In-System Programming)

Table 2.2 Alternate functions of Port 1Port 2: Port 2 is an 8-bit bidirectional I/O port with internal pull-ups. The Port 2 output buffers can sink/source four TTL inputs. When 1s are written to Port 2 pins, they are pulled high by the internal pull-ups and can be used as inputs. As inputs, Port 2 pins that are externally being pulled low will source current (IIL) because of the internal pull-ups. Port 2 emits the high-order address byte during fetches from external program memory and during accesses to external data memory that uses 16-bit addresses (MOVX @ DPTR). In this application, Port 2 uses strong internal pull-ups when emitting 1s. During accesses to external data memory that uses 8-bit addresses (MOVX @ RI), Port 2 emits the contents of the P2 Special Function Register. Port 2 also receives the high-order address bits and some control signals during Flash programming and verification.Port 3: Port 3 is an 8-bit bidirectional I/O port with internal pull-ups. The Port 3 output buffers can sink/source four TTL inputs. When 1s are written to Port 3 pins, they are pulled high by the internal pull-ups and can be used as inputs. As inputs, Port 3 pins that are externally being pulled low will source current (IIL) because of the pull-ups. Port 3 receives some control signals for Flash programming and verification. Port 3 also serves the functions of various special features of the AT89S52, as shown in the following table.Port PinAlternate Functions

P3.0RXD (serial input port)

P3.1TXD (serial output port)

P3.2 (external interrupt 0)

P3.3 (external interrupt 1)

P3.4T0 (timer 0 external input)

P3.5T1 (timer 1 external input)

P3.6 (external data memory write strobe)

P3.7 (external data memory read strobe)

Table 2.3 Alternate Functions of Port 3RST: Reset input. A high on this pin for two machine cycles while the oscillator is running resets the device. This pin drives high for 98 oscillator periods after the Watchdog times out. The DISRTO bit in SFR AUXR (address 8EH) can be used to disable this feature. In the default state of bit DISRTO, the RESET HIGH out feature is enabled.ALE/PROG: Address Latch Enable (ALE) is an output pulse for latching the low byte of the address during accesses to external memory. This pin is also the program pulse input (PROG) during Flash programming. In normal operation, ALE is emitted at a constant rate of 1/6 the oscillator frequency and may be used for external timing or clocking purposes. Note, however, that one ALE pulse is skipped during each access to external data memory. If desired, ALE operation can be disabled by setting bit 0 of SFR location 8EH. With the bit set, ALE is active only during a MOVX or MOVC instruction. Otherwise, the pin is weakly pulled high. Setting the ALE-disable bit has no effect if the microcontroller is in external execution mode.PSEN: Program Store Enable (PSEN) is the read strobe to external program memory. When the AT89S52 is executing code from external program memory, PSEN is activated twice each machine cycle, except that two PSEN activations are skipped during each access to external data memory.EA/VPP: External Access Enable. EA must be strapped to GND in order to enable the device to fetch code from external program memory locations starting at 0000H up to FFFFH. Note, however, that if lock bit 1 is programmed, EA will be internally latched on reset. EA should be strapped to VCC for internal program executions. This pin also receives the 12-volt programming enable voltage (VPP) during Flash programming.XTAL1: Input to the inverting oscillator amplifier and input to the internal clock operating circuit.XTAL2: Output from the inverting oscillator amplifier.Memory Organization: MCS-51 devices have a separate address space for Program and Data Memory. Up to 64K bytes each of external Program and Data Memory can be addressed.Program Memory: If the EA pin is connected to GND, all program fetches are directed to external memory. On the AT89S52, if EA is connected to VCC, program fetches to addresses 0000H through 1FFFH are directed to internal memory and fetches to addresses 2000H through FFFFH are to external memory.Data Memory: The AT89S52 implements 256 bytes of on-chip RAM. The upper 128 bytes occupy a parallel address space to the Special Function Registers. This means that the upper 128 bytes have the same addresses as the SFR space but are physically separate from SFR space. When an instruction accesses an internal location above address 7FH, the address mode used in the instruction specifies whether the CPU accesses the upper 128 bytes of RAM or the SFR space. Instructions which use direct addressing access the SFR space. For example, the following direct addressing instruction accesses the SFR at location 0A0H (which is P2). MOV 0A0H, #data instructions that use indirect addressing access the upper 128 bytes of RAM. For example, the following indirect addressing instruction, where R0 contains 0A0H, accesses the data byte at address 0A0H, rather than P2 (whose address is 0A0H). MOV @R0, #data Note that stack operations are examples of indirect addressing, so the upper 128 bytes of data RAM are available as stack space.Oscillator Characteristics XTAL1 and XTAL2 are the input and output, respectively, of an inverting amplifier that can be configured for use as an on-chip oscillator, as shown in Figure 16-1. Either a quartz crystal or ceramic resonator may be used. To drive the device from an external clock source, XTAL2 should be left unconnected while XTAL1 is driven, as shown in Figure 16-2. There are no requirements on the duty cycle of the external clock signal, since the input to the internal clocking circuitry is through a divide-by-two flip-flop, but minimum and maximum voltage high and low time specifications must be observed. Figure 2.6 Oscillator characteristics C1, C2 = 30pF 10pF for Crystals = 40pF 10pF for Ceramic Resonator

2.3.4 BLOCK DIAGRAM

Figure 2.7 Block diagram of 8051 micro controller2.3.5 MODES 2.3.5.1 Idle Mode In idle mode, the CPU puts itself to sleep while all the on-chip peripherals remain active. The mode is invoked by software. The content of the on-chip RAM and all the special functions registers remain unchanged during this mode. The idle mode can be terminated by any enabled interrupt or by a hardware reset. Note that when idle mode is terminated by a hardware reset, the device normally resumes pro-gram execution from where it left off, up to two machine cycles before the internal reset algorithm takes control. On-chip hardware inhibits access to internal RAM in this event, but access to the port pins is not inhibited. To eliminate the possibility of an unexpected write to a port pin when idle mode is terminated by a reset, the instruction following the one that invokes idle mode should not write to a port pin or to external memory. 2.3.5.2 Power-Down Mode In the Power-down mode, the oscillator is stopped, and the instruction that invokes Power-down is the last instruction executed. The on-chip RAM and Special Function Registers retain their values until the Power-down mode is terminated. Exit from Power-down mode can be initiated either by a hardware reset or by an enabled external interrupt. Reset redefines the SFRs but does not change the on-chip RAM. The reset should not be activated before VCC is restored to its normal operating level and must be held active long enough to allow the oscillator to restart and stabilize.ModeProgram MemoryALEPort 0Port 1Port 2Port 3

IdleInternal11DataDataDataData

IdleExternal11FloatDataAddressData

Power-DownInternal00DataDataDataData

Power-DownExternal00FloatDataDataData

Table 2.4 Status of External Pins During Idle and Power-Down Mode2.4 COMPARATOR & CRYSTAL OSCILLATOR

2.4.1 COMPARATOR (LM358) A Dual Op-Amp IC with high gain, frequency compensated operational amplifier with single power source. These circuits consist of two independent, high gain, internally frequency-compensated op-amps, specifically designed to operate from a single power supply over a wide range of voltages. The low-power supply drain is independent of the magnitude of the power supply voltage. Application areas include transducer amplifiers, DC gain blocks and all the conventional op-amp circuits, which can now be more easily implemented in single power supply systems. For example, these circuits can be directly supplied with the standard +5 V, which is used in logic systems and will easily provide the required interface electronics with no additional power supply.

Figure 2.8 LM358 IC

2.4.1.1 Features Large DC voltage gain: 100 dB Wide bandwidth (unity gain): 1.1 MHz (temperature compensated) Very low supply current per operator essentially independent of supply voltage Low input bias current: 20 nA (temperature compensated) Low input offset voltage: 2 mV Low input offset current: 2 nA Input common-mode voltage range includes negative rails Differential input voltage range equal to the power supply voltage Large output voltage swing 0 V to (VCC + -1.5 V)

2.4.1.2 Specification Supply Voltage: 3.0 V to 32 V Output Current: 40mA per Channel Package: 8 pin DIP package.

2.4.1.3 Pin Diagram

Figure 2.9 Pin diagram of LM358 IC

2.4.2 CRYSTAL OSCILLATOR Acrystal oscillatoris anelectronic oscillatorcircuit that uses the mechanicalresonanceof a vibratingcrystalofpiezoelectric materialto create an electrical signal with a very precisefrequency. This frequency is commonly used to keep track of time (as inquartz wristwatches), to provide a stableclock signalfordigitalintegrated circuits, and to stabilize frequencies forradio transmittersandreceivers. The most common type of piezoelectric resonator used is thequartzcrystal, so oscillator circuits incorporating them became known as crystal oscillators, but other piezoelectric materials including polycrystalline ceramics are used in similar circuits. Quartz crystals are manufactured for frequencies from a few tens ofkilohertzto hundreds of megahertz. More than two billion crystals are manufactured annually. Most are used for consumer devices such aswristwatches,clocks,radios,computers, and cell phones. Quartz crystals are also found inside test and measurement equipment, such as counters,signal generators, and oscilloscopes.

Figure 2.10 Crystal Oscillator 11.0592 MHz 2.5 RELAY DRIVER & RELAY SWITCH 2.5.1 RELAY DRIVER (ULN 2003) The ULN2003 is a monolithic high voltage and high current Darlington transistor arrays. It consists of seven NPN darlington pairs that features high-voltage outputs with common-cathode clamp diode for switching inductive loads. The collector-current rating of a single darlington pair is 500mA. The darlington pairs may be paralleled for higher current capability. Applications include relay drivers, hammer drivers, lamp drivers, display drivers (LED gas discharge), line drivers, and logic buffers. The ULN2003 has a 2.7k series base resistor for each darlington pair for operation directly with TTL or 5V CMOS devices. Figure 2.11 ULN2003 IC

2.5.2 FEATURES * 500mA rated collector current (Single output) * High-voltage outputs: 50V * Inputs compatible with various types of logic. * Relay driver application

2.5.3 PIN DIAGRAM

Figure 2.12 Pin diagram of ULN2003

2.5.2 RELAY SWITCH Arelayis anelectricallyoperatedswitch. Many relays use anelectromagnetto mechanically operate a switch, but other operating principles are also used, such assolid-state relays. Relays are used where it is necessary to control a circuit by a low-power signal or where several circuits must be controlled by one signal. The first relays were used in long distancetelegraphcircuits as amplifiers: they repeated the signal coming in from one circuit and re-transmitted it on another circuit. Relays were used extensively in telephone exchanges and early computers to perform logical operations.The Single Pole Double Throw Relay

Figure 2.13 SPDT relayA single pole double throw (SPDT) relay configuration switches one common pole to two other poles, flipping between them. As shown in the schematic diagram, the common point E completes a circuit with C when the relay coil is at rest, that is, no voltage is applied to it. This circuit is "closed." A gap between the contacts of point E and D creates an "open" circuit. When you apply power to the coil, a metal level is pulled down, closing the circuit between points E and D and opening the circuit between E and C. A single pole double throw relay can be used to alternate which circuit a voltage or signal will be sent to.

2.6 LINEAR ELEMENTS 2.6.1 CAPACITOR A capacitor is a passive two-terminal electrical component used to store energy electro-statically in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors (plates) separated by a dielectric (i.e. insulator). The conductors can be thin films, foils or sintered beads of metal or conductive electrolyte, etc. The non-conducting dielectric acts to increase the capacitor's charge capacity. A dielectric can be glass, ceramic, plastic film, air ,vacuum, paper, mica, oxide layer etc. Capacitors are widely used as parts of electrical circuits in many common electrical devices. Unlike a resistor, an ideal capacitor does not dissipate energy. Instead, a capacitor stores energy in the form of an electrostatic field between its plates. Capacitors used in the project are 10F, 100F, 1000F. Figure 2.14 Capacitor working Figure 2.15 100F capacitor Figure 2.16 1000F capacitor Figure 2.17 10F capacitor

2.6.2 RESISTORS Aresistoris apassivetwo-terminalelectrical componentthat implementselectrical resistanceas a circuit element. Resistors act to reduce current flow, and, at the same time, act to lower voltage levels within circuits. In electronic circuits resistors are used to limit current flow, to adjust signal levels,biasactive elements, terminatetransmission linesamong other uses. High-power resistors that can dissipate manywattsof electrical power as heat may be used as part of motor controls, in power distribution systems, or as test loads forgenerators. Fixed resistors have resistances that only change slightly with temperature, time or operating voltage. Variable resistors can be used to adjust circuit elements (such as a volume control or a lamp dimmer), or as sensing devices for heat, light, humidity, force, or chemical activity.The resistors used in the project are mainly 1K and 10K.

Figure 2.18 1K and 10K resistors 2.6.3 CONNECTORS Connector is a device for keeping two parts of an electric circuit in contact. A connector is best known for providing the physical link between two components. Connections differ in various ways, which help in determining where that type of connector can be used. These features include: Shape Size Gender Connection mechanism Function2.6.3.1 JumpersJumpers are small blocks on a circuit board with two or more pins emerging from them. Plastic plugs containing a wire fit down over the pins. The wire connects the pins and creates a circuit. To change a jumper setting, pull the plug off its pin(s) and carefully fit it down onto the pin(s) indicated. A jumper is referred to as open or unjumpered when the plug is pushed down over only one pin or if there is no plug at all. When the plug is pushed down over two pins, the jumper is referred to as jumpered. The jumper setting is often shown in text as two numbers, such as 1-2. The number 1 is printed on the circuit board so that you can identify each pin number based on the location of pin 1. There are two types of jumper connectors:1. Male jumper connector

Figure 2.19 Male jumper connector 2. Female jumper connector Figure 2.20 Female jumper connector 2.7 GSM MODULE GSM(Global System for Mobile Communications) is a standard developed by theEuropean Telecommunications Standards Institute(ETSI) to describe protocols for second-generation (2G) digitalcellular networksused bymobile phones. As of 2014it has become the default global standard for mobile communications - with over 90% market share, operating in over 219 countries and territories. 2G networks developed as a replacement for first generation (1G) analog cellular networks, and the GSM standard originally described a digital, circuit-switched network optimized forfull duplexvoicetelephony. This expanded over time to include data communications, first by circuit-switched transport, then bypacketdata transport viaGPRS(General Packet Radio Services) andEDGE(Enhanced Data rates for GSM Evolution or EGPRS).Subsequently, the3GPPdeveloped third-generation (3G)UMTSstandards followed by fourth-generation (4G)LTE Advancedstandards, which do not form part of the ETSI GSM standard.

Figure 2.21 SIM 300 GSM Module

2.7.1 NETWORK STRUCTUREThe network is structured into a number of discrete sections: Base Station Subsystem the base stations and their controllers explained Network and Switching Subsystem the part of the network most similar to a fixed network, sometimes just called the "core network" GPRS Core Network the optional part which allows packet-based Internet connections Operations support system(OSS) network maintenance

Figure 2.22 Structure of a GSM network2.7.1.1 Base Station SubsystemGSM is acellular network, which means thatcell phonesconnect to it by searching for cells in the immediate vicinity. There are five different cell sizes in a GSM networkmacro,micro,pico,femto, andumbrella cells. The coverage area of each cell varies according to the implementation environment. Macro cells can be regarded as cells where thebase stationantennais installed on a mast or a building above average rooftop level. Micro cells are cells whose antenna height is under average rooftop level; they are typically used in urban areas. Picocells are small cells whose coverage diameter is a few dozen metres; they are mainly used indoors. Femtocells are cells designed for use in residential or small business environments and

Figure 2.23 Base stationconnect to the service providers network via a broadband internet connection. Umbrella cells are used to cover shadowed regions of smaller cells and fill in gaps in coverage between those cells. Cell horizontal radius varies depending on antenna height, antenna gain, and propagation conditions from a couple of hundred meters to several tens of kilometres. The longest distance the GSM specification supports in practical use is 35 kilometres (22mi). There are also several implementations of the concept of an extended cell,where the cell radius could be double or even more, depending on the antenna system, the type of terrain, and thetiming advance.Indoor coverage is also supported by GSM and may be achieved by using an indoor picocell base station, or anindoor repeaterwith distributed indoor antennas fed through power splitters, to deliver the radio signals from an antenna outdoors to the separate indoor distributed antenna system. These are typically deployed when significant call capacity is needed indoors, like in shopping centers or airports. However, this is not a prerequisite, since indoor coverage is also provided by in-building penetration of the radio signals from any nearby cell.2.7.2 GSM CARRIER FREQUENCIESGSM networks operate in a number of different carrier frequency ranges (separated intoGSM frequency rangesfor 2G andUMTS frequency bandsfor 3G), with most2GGSM networks operating in the 900MHz or 1800MHz bands. Where these bands were already allocated, the 850MHz and 1900MHz bands were used instead (for example in Canada and the United States). In rare cases the 400 and 450MHz frequency bands are assigned in some countries because they were previously used for first-generation systems.Most3Gnetworks in Europe operate in the 2100MHz frequency band. For more information on worldwide GSM frequency usage, seeGSM frequency bands.Regardless of the frequency selected by an operator, it is divided intotimeslotsfor individual phones. This allows eight full-rate or sixteen half-rate speech channels perradio frequency. These eight radio timeslots (orburstperiods) are grouped into aTDMAframe. Half-rate channels use alternate frames in the same timeslot. The channel data rate for all8 channelsis270.833 kbit/s,and the frame duration is4.615 ms.The transmission power in the handset is limited to a maximum of 2 watts inGSM 850/900and1 wattinGSM 1800/1900.2.7.3 SUBSCRIBER IDENTITY MODULE (SIM)One of the key features of GSM is theSubscriber Identity Module, commonly known as aSIM card. The SIM is a detachablesmart cardcontaining the user's subscription information and phone book. This allows the user to retain his or her information after switching handsets. Alternatively, the user can also change operators while retaining the handset simply by changing the SIM. Some operators will block this by allowing the phone to use only a single SIM, or only a SIM issued by them; this practice is known asSIM locking. 2.7.4 GSM SERVICE SECURITY GSM was designed with a moderate level of service security. The system was designed to authenticate the subscriber using apre-shared keyandchallenge-response. Communications between the subscriber and the base station can be encrypted. The development ofUMTSintroduces an optionalUniversal Subscriber Identity Module(USIM), that uses a longer authentication key to give greater security, as well as mutually authenticating the network and the user, whereas GSM only authenticates the user to the network (and not vice versa). The security model therefore offers confidentiality and authentication, but limited authorization capabilities, and nonon-repudiation.GSM uses several cryptographic algorithms for security. TheA5/1,A5/2, andA5/3stream ciphersare used for ensuring over-the-air voice privacy. A5/1 was developed first and is a stronger algorithm used within Europe and the United States; A5/2 is weaker and used in other countries. Serious weaknesses have been found in both algorithms: it is possible to break A5/2 in real-time with aciphertext-only attack, and in January 2007,The Hacker's Choicestarted the A5/1 cracking project with plans to useFPGAsthat allow A5/1 to be broken with arainbow tableattack.The system supports multiple algorithms so operators may replace that cipher with a stronger one. New attacks have been observed that take advantage of poor security implementations, architecture, and development for smart phoneapplications. Some wiretapping and eavesdropping techniqueshijackthe audio input and output providing an opportunity for a third party to listen in to the conversation. GSM usesGeneral Packet Radio Service(GPRS) for data transmissions like browsing the web. The most commonly deployed GPRS ciphers were publicly broken in 2011. The researchers revealed flaws in the commonly used GEA/1 and GEA/2 ciphers and published the open-source "gprs decode" software forsniffingGPRS networks. They also noted that some carriers do not encrypt the data (i.e., using GEA/0) in order to detect the use of traffic or protocols they do not like (e.g.,Skype), leaving customers unprotected. GEA/3 seems to remain relatively hard to break and is said to be in use on some more modern networks. If used withUSIMto prevent connections tofake base stationsand downgrade attacks, users will be protected in the medium term, though migration to 128-bit GEA/4 is still recommended.2.8 ENERGY METER Anelectricity meter,electric meter, orenergy meteris a device that measures the amount ofelectric energyconsumed by aresidence, business, or an electrically powered device. Electric utilitiesuse electric meters installed at customers premises to measure electric energy delivered to their customers for billing purposes. They are typically calibrated in billing units, the most common one being thekilowatt hour[kWh]. They are usually read once each billing period.In settings when energy savings during certain periods are desired, meters may measure demand, the maximum use of power in some interval. "Time of day" metering allows electric rates to be changed during a day, to record usage during peak high-cost periods and off-peak, lower-cost, periods. Also, in some areas meters have relays fordemand responseload shedding during peak load periods.

Figure 2.24 Energy meterUnits of measurementThe most common unit of measurement on the electricity meter is thekilowatt hour[kWh], which is equal to the amount of energy used by a load of onekilowattover a period of onehour, or 3,600,000joules. Some electricity companies use theSImegajouleinstead. There are two types of energy meters. They are:2.8.1 ELECTROMECHANICAL METERSThe most common type of electricity meter is theelectromechanicalinductionwatt-hour meter. The electromechanicalinductionmeter operates by counting the revolutions of a non-magnetic, but electrically conductive, metal disc which is made to rotate at a speed proportional to the power passing through the meter. The number of revolutions is thus proportional to the energy usage. The voltage coil consumes a small and relatively constant amount of power, typically around 2 watts which is not registered on the meter. The current coil similarly consumes a small amount of power in proportion to the square of the current flowing through it, typically up to a couple of watts at full load, which is registered on the meter.The disc is acted upon by two sets ofcoils, which form, in effect, a two phaseinduction motor. One coil is connected in such a way that it produces amagnetic fluxin proportion to thevoltageand the other produces a magnetic flux in proportion to thecurrent. The field of the voltage coil is delayed by 90 degrees, due to the coil's inductive nature, and calibrated using a lag coil.This produceseddy currentsin the disc and the effect is such that aforceis exerted on the disc in proportion to the product of the instantaneous current, voltage and phase angle (power factor) between them. Apermanent magnetexerts an opposing force proportional to thespeed of rotationof the disc. The equilibrium between these two opposing forces results in the disc rotating at a speedproportionalto the power or rate of energy usage. The disc drives a register mechanism which counts revolutions, much like theodometerin a car, in order to render a measurement of the total energy used. Figure 2.25 Electro-mechanical meter 1 - Voltage coil - many turns of fine wire encased in plastic, connected in parallel with load.2 - Current coil - three turns of thick wire, connected in series with load.3 - Stator - concentrates and confines magnetic field.4 - Aluminum rotor disc.5 - Rotor brake magnets.6 - Spindle with worm gear.7 - Display dials - note that the 1/10, 10 and 1000 dials rotateclockwisewhile the 1, 100 and 10000 dials rotate counter-clockwise. 2.8.2 ELECTRONIC METERSElectronic meters display the energy used on anLCDor LED display, and some can also transmit readings to remote places. In addition to measuring energy used, electronic meters can also record other parameters of the load and supply such as instantaneous and maximum rate of usage demands,voltages,power factorandreactive powerused etc. They can also support time-of-day billing, for example, recording the amount of energy used during on-peak and off-peak hours.

Figure 2.26 Electronic Meter 2.9 LCD DISPLAY (16x2)

LCD (Liquid Crystal Display) screen is an electronic display module and find a wide range of applications. A 16x2 LCD display is very basic module and is very commonly used in various devices and circuits. These modules are preferred overseven segmentsand other multi segmentLEDs. The reasons being: LCDs are economical; easily programmable; have no limitation of displaying special & evencustom characters(unlike in seven segments),animationsand so on.A16x2 LCDmeans it can display 16 characters per line and there are 2 such lines. In this LCD each character is displayed in 5x7 pixel matrix. This LCD has two registers, namely, Command and Data.The command register stores the command instructions given to the LCD. A command is an instruction given to LCD to do a predefined task like initializing it, clearing its screen, setting the cursor position, controlling display etc. The data register stores the data to be displayed on the LCD. The data is the ASCII value of the character to be displayed on the LCD. Click to learn more about internal structure of aLCD.

Figure 2.27 16x2 LCDDisplay

2.9.1 PIN DESCRIPTIONPin NoFunctionName

1Ground (0V)Ground

2Supply voltage; 5V (4.7V 5.3V)Vcc

3Contrast adjustment; through a variable resistorVEE

4Selects command register when low; and data register when highRegister Select

5Low to write to the register; High to read from the registerRead/write

6Sends data to data pins when a high to low pulse is givenEnable

78-bit data pinsDB0

8DB1

9DB2

10DB3

11DB4

12DB5

13DB6

14DB7

15Backlight VCC(5V)Led+

16Backlight Ground (0V)Led-

Table 2.5 Pin description of LCD display

CHAPTER 3 IMPLEMENTATION AND WORKINGImplementation part includes bringing together all the hardware components used in the project and interfacing them to the microcontroller which is the heart of the project. We need to interface GSM modem, LCD display and energy meter to the microcontroller.3.1 INTERFACING GSM MODULE AND LCD DISPLAY

Figure 3.1 Interfacing of GSM and LCD display to microcontroller Serial communication takes place between GSM module and microcontroller. This serial communication is achieved by RS232 serial protocol.3.1.1 RS-232 SERIAL PROTOCOL One of the most common serial interfaces is based on the RS-232 standard. This standard was developed to allow individuals to use remote computer systems over dialup telephone lines with remote terminals. The standard includes provisions for a remote terminal that is connected to a modemthat places a telephone call, a modem that answers the telephone call, and a computer that is connected to thatmodem. The terminal can be connected directly to the computer, eliminating the need for two modems, through the use of a special device called anullmodemadapter. Sometimes this device is built directly into a cable, in which case the cable is called anullmodemcable.3.1.2 AT COMMANDSGSM modem communicates with the microcontroller in the form of AT commands. Here AT refers to attention.

Figure 3.2 Communication between microcontroller and GSM moduleThe microcontroller sends the AT command through the Tx pin and this command is received by the receiver of the GSM module. The GSM module responds to the command and transmits the information required and the result code. This information is received by the microcontroller and it displays the result in the LCD display.

3.1.2.1 List of Important AT Commands:

Overview of AT Commands Description

AT+CMGD DELETE SMS MESSAGE

AT+CMGF SELECT SMS MESSAGE FORMAT

AT+CMGL LIST SMS MESSAGES FROM PREFERRED STORE

AT+CMGR READ SMS MESSAGE

AT+CMGS SEND SMS MESSAGE

AT+CMGW WRITE SMS MESSAGE TO MEMORY

AT+CMSS SEND SMS MESSAGE FROM STORAGE

AT+CMGC SEND SMS COMMAND

AT+CNMI NEW SMS MESSAGE INDICATIONS

AT+CPMS PREFERRED SMS MESSAGE STORAGE

AT+CRES RESTORE SMS SETTINGS

AT+CSAS SAVE SMS SETTINGS

AT+CSCA SMS SERVICE CENTER ADDRESS

AT+CSCB SELECT CELL BROADCAST SMS MESSAGES

AT+CSDH SHOW SMS TEXT MODE PARAMETERS

AT+CSMP SET SMS TEXT MODE PARAMETERS

AT+CSMS SELECT MESSAGE SERVICE

Table 3.1 List of AT Commands

3.2 INTERFACING ENERGY METEREnergy meter produces pulses when LED blinks. These pulses produced due to LED blinking are to be given to microcontroller to display to the meter reading in the LCD display. A comparator circuit which is basically an op-amp LM385 IC is used to convert these pulses into 5V dc and the output of the this IC is given to the microcontroller. 3.3 WORKING OF THE PROJECT The energy meter records the amount of power consumption. It does so by an electromechanical system. The system is provided with such a mechanism that an increment in amount of current flow through circuit causes the disc to rotate faster, means that the rotational speed of disc is directly proportional to the amount of current flowing through circuit. This rotation effect of disc causes the gear mechanism to work accordingly. And in similar fashion rate of power consumption increases the blinking rate of LED integrated within the meter. This blinking of LED regards to number of Pulses. The pulses from this LED are fed to comparator circuit that is Op-Amp (LM358), So that the pulse amplitude is level to the required microcontroller voltage. These compared pulses are fed to microcontroller for counting operation i.e. these pulses are counted by microcontroller and readings are stored in registers. Then Microcontroller displays the readings on LCD, and also readings are fed to GSM modem for sending SMS to the registered user number. Whenever a command is sent to the GSM modem , it decodes the commands and works accordingly and sends the same information via wireless network. LOAD CONTROL To control the load first mobile number should be registered and it can be done by sending any SMS to the number installed in GSM modem. Once the SMS is received, System replies Mobile no is Registered and at the same time it is displayed on LCD Mobile no is registered. User should send * to ON the Load, # to OFF the Load and @ for bill request. When modem receives the above Symbols it converts into hex format and it is fed to microcontroller, then microcontroller sends logic 1 or 0 as per the received symbol, to relay driver this switches the relay 1 to ON 0 to OFF and hence load is controlled. CHAPTER 4 RESULTS At first when initializing the Electricity Meter Reading using GSM system, the microcontroller sends command to operate the GSM modem. The GSM modem will now read the immediate incoming messages. Whenever the GSM modem gets the command message i.e. "STATUS", for sending the present meter reading. Then the GSM modem will send the current meter reading to the mobile number which is stored in the microcontroller The project- GSM based Electricity Billing System with load control is designed in such way that it sends the power usage reading to the consumer and the company through an SMS and it can even control the electrical and electronic appliances.

PROJECT OUTLOOK

Figure 4.1 Project Outlook

Figure 4.2 Initial MSG 1 Figure 4.3 Initial MSG 2Firstly an initial message is displayed on the LCD. It indicates that we need to send a message to the stored mobile number in the GSM module.

Figure 4.4 Register our mobile number Figure 4.5 Acknowledgement to mobileIn the first step we need to send a message which may contain any symbol to stored number in GSM module. Then an acknowledgment is received to the mobile which acknowledges us that the mobile number has been registered.

Figure 4.6 Acknowledgement displayed on LCD Figure 4.7 Initial MSGThe acknowledgement is displayed on the LCD. Later it displays an initial message.

Figure 4.8 load ON request Figure 4.9 Acknowledgement on LCD displayIn order to ON the load we need to send symbol * as a message to the GSM modem. The GSM modem sends the symbol to microcontroller. Then the loads are switched ON.

Figure 4.10 Load OFF request Figure 4.11 Acknowledgement on LCD displayThe loads are switched OFF by sending the symbol #. The acknowledgement is displayed on the LCD display.

Figure 4.12 Request for meter reading Figure 4.13 Reading received as SMSTo get the meter reading we have to send @ symbol as text message and the meter reading is displayed on the LCD display as well as an SMS is sent to the mobile also. CONCLUSION

There is a lot of wastage of power due to inefficient consumption of electricity by consumers. The distribution company, most of the time, has to receive huge amounts due to pending bills which results in substantial revenue losses and also causes hurdles to modernization because of lack of funds. The consumer, on the other hand, is facing problems like receiving due bills for bills that have already been paid and poor reliability of electricity supply. The remedy for all these problems is to keep track of the consumers load on a timely basis, which will help assure accurate billing, track maximum demand, and detect online theft. These are all the features to be taken into account for designing an efficient energy billing system. The present project incorporates these features to address the problems faced by both the consumers and the distribution companies.

REFERENCES

1. Dr.T. Vigneswaran, M. Srikarthik and S. Altamash, Modern Electricity Billing System Using GSM, International Conference on Computing and Control Engineering (ICCCE), Vol 40, pp. 315-317,12 and 13April, 20122. M.A. Mazidi and Janice G. Mazidi And Rolin D. Mckinlay, The 8051 Microcontroller and Embedded3. Systems Using Assembly and C Prentice Hall, pp. 300-330.4. Frederic P. Miller, Agnes F. Vandome, GSM: Cellular Network, Subscriber Identity Module 2004.5. The ATMEL AT89S52 8-Bit Microcontroller, 8KB ISP Flash6. http://www.atmel.com/devices/AT89S52.aspx7. Prepaid electricity billing system using GSM mobile http://www.seminarprojects.com/Threadprepaid-energy-meter-using-gsmmobile# ixzz1BUylZEck8. http://probots.co.in/Manuals/SIM300.pdf9. http://www.engineersgarage.com/tutorials/at-commands10. Ramakant A. Gayakwad, Op-Amps and Linear Integrated Circuit PHI Learning, 4th edition, pp. 315-317

APPENDIX

Program code:#include#include#include"serial.h"#define lcd_data P2

sbit lcd_rs = P2^0;sbit lcd_en = P2^1;sbit relay1 = P1^0;sbit relay2= P1^1;sbit mtr = P1^2;int energy_val,relay_val;int amt;unsigned char rcv;unsigned char rcg,pastnumber[11],i,count;

void lcdcmd(unsigned char value) // LCD COMMAND{ lcd_data=value&(0xf0); //send msb 4 bits lcd_rs=0; //select command register lcd_en=1; //enable the lcd to execute command delay(3); lcd_en=0; lcd_data=((value