seminar topics: GSM AND OFC BASED HOME AUTOMATION

GSM AND OFC BASED HOME AUTOMATION

1.Introduction

1.1Aim of the project:

The aim of the project is to develop a system, which uses Mobile technology and Ofc that keeps control of the various home appliances.

1.2Significance and applications:

GSM AND OFC BASED HOME AUTOMATION plays a very important role in domestic applications.The ease of operation of the kit and low cost add up as an additional advantage for its usage. Its significance can be proved by considering the following specialties of kit designed by us

Reliability: Reliability is one such factor that every electrical system should have in order to render its services without malfunctioning over along period of time. We have designed our kit using AT89S52 micro controller which is itself very reliable and also operates very efficiently under normal condition

Cost: The design is implemented at a very economical price. The total cost incurred by us in designing this kit is very less and further we have developed the GSM ANDOFCbased HomeAutomation which are more economical rather than just interfacing those which are readily available in the market.For utilization of appliances the new concept has been thought to manage them remotely by using GSM, which enables the user to remotely control switching of domestic appliances. Just by dialing keypad of remote telephone, from where you are calling you can perform ON / OFF operation of the appliances.The ranges of appliances that can be controlled through tele remote systems are many in numbers. Some of them are as follows and this depends upon the usage priority of the appliances i.e. Lights, Music System or other electrical / electronic appliances.

OFC This method of communication is relatively noise free and transmits the signals over a long range without any appreciable attenuation . the size of optical fiber is very small and there diameter is comparable to human hair . AThis help in reducing the congestion in electric wires , optical fibers are very goofd insulators therefore no Electric interference. Hence best for electric appliances

CHAPTER 2

Literature Survey

2.1 Review of related literature:

This project has been made by several people, but most of the times a land line phone is being used. If a land line phone is used than a separate ring detector circuit is required for detecting the number of rings and then picking up the phone. It uses an extra relay and we have to enter inside the mechanism of phone.

In our project we have used the auto answer facility which is present in many of the cell phones today, so we escaped from designing the ring detector circuit.

2.2 Present Scenario:

Possible customers for this product would be home improvement contractors, and supply stores. The benefit of this is the end-product can be sold in large quantities and it can be incorporated into the construction of modernize homes. The end-product will be not be sold in retails stores because reconfiguring of the end-product to control different electrical appliances will be complicated and it should only be attempted by trained technicians. Retail stores would also not be a good target for commercialization due to the system requiring a cellular phone plan in order to operate. Advertising through cellular phone providers would be a more feasible option.

2.3. Present and Future Scope:

This product is aimed toward average consumers who wish to control household appliances remotely from their cell phones provided that the appliances are electrically controllable. Example of feasible appliances and applications under consideration include; enable/disable security systems, fans, lights, kitchen appliances, and heating/ventilation/air conditioning system.

Right now we have designed the project for control of two devices but it can be designed for more number of devices.It can be furthur expanded with a voice interactive system facility. A feedback system can also be included which provides the state of a device(whether it is on/off) to the remote user. And ofc is the future of guided media due to its large bandwidth and imuunity to almost any significant attenuation.

2.4DTMF

When you press a button in the telephone set keypad, a connection is made that generates a resultant signal of two tones at the same time. These two tones are taken from a row frequency and a column frequency. The resultant frequency signal is called "Dual Tone Multiple Frequency". These tones are identical and unique.

A DTMF signal is the algebraic sum of two different audio frequencies, and can be expressed as follows:

f(t) = A₀sin(2*П*f_a*t) + B₀sin(2*П*f_b*t) + ........... ------->(1)

Where f_a and f_b are two different audio frequencies with A and B as their peak amplitudes and f as the resultant DTMF signal. f_a belongs to the low frequency group and f_b belongs to the high frequency group.

Each of the low and high frequency groups comprise four frequencies from the various keys present on the telephone keypad; two different frequencies, one from the high frequency group and another from the low frequency group are used to produce a DTMF signal to represent the pressed key.

The amplitudes of the two sine waves should be such that

(0.7 < (A/B) < 0.9)V -------->(2)

The frequencies are chosen such that they are not the harmonics of each other. The frequencies associated with various keys on the keypad are shown in figure (A).

When you send these DTMF signals to the telephone exchange through cables, the servers in the telephone exchange identifies these signals and makes the connection to the person you are calling.

The row and column frequencies are given below:

Fig (1)

When you press the digit 5 in the keypad it generates a resultant tone signal which is made up of frequencies 770Hz and 1336Hz. Pressing digit 8 will produce the tone taken from tones 852Hz and 1336Hz. In both the cases, the column frequency 1336 Hz is the same. These signals are digital signals which are symmetrical with the sinusoidal wave.

A Typical frequency is shown in the figure below:

Figure (2)

Along with these DTMF generator in our telephone set provides a set of special purpose groups of tones, which is normally not used in our keypad. These tones are identified as 'A''B', 'C', 'D'. These frequencies have the same column frequency but uses row frequenciesgiven in the table in figure (A). These tones are used for communication signaling.

The frequency table is as follows:

Due to its accuracy and uniqueness, these DTMF signals are used in controlling systems using telephones. By using some DTMF generating IC’s (UM91214, UM91214, etc) we can generate DTMF tones without depending on the telephone set.

2.5 GSM TECHNOLOGY
GSM is a global system for mobile communication, GSM is an international digital cellular telecommunication. The GSM standard was released by European Standard Telecommunication Standard (ETSI) back in 1989. The first commercial services were launched in 1991 and after its early introduction in Europe; the standard went global in 1992. Since then, GSM has become the most widely adopted and fastest-growing digital cellular standard, and it is positioned to become the world’s dominant cellular standard. Today’s second-generation GSM networks deliver high quality and secure mobile voice

and data services (such as SMS/ Text Messaging) with full roaming capabilities across the world. GSM platform is a hugely successful technology and as unprecedented story of global achievement. In less than ten years since the first GSM network was commercially launched, it become, the world’s leading and fastest growing mobile standard, spanning over 173 countries. Today, GSM technology is in use by more than one in ten of the world’s population and growth continues to sour with the number of subscriber worldwide expected to surpass one billion by through end of 2003. Today’s GSM platform is living,

growing and evolving and already offers an expanded and feature-rich ‘family’ of voice and enabling services. The Global System for Mobile Communication (GSM) network is a cellular telecommunication network with a versatile architecture complying with the ETSI GSM 900/GSM 1800 standard. Siemen’s implementation is the digital cellular mobile

communication system D900/1800/1900 that uses the very latest technology to meet every requirement of the standard. The Global System of Mobile Communication (GSM) originated in the late 1940s. It was never a widely used system due to its limited frequency spectrum allocation and the high cost required for its equipments. But with its standardization by the European Telecommunication standard Institute (ETSI). The Global System of Mobile Communication has subsequently been adopted worldwide as the international digital mobile standard.
With the introduction of this system in Nigeria, study has shown that most Nigerians do not use up to 30% (thirty percent) of the features in their phone. What Nigerians do is to receive or make calls with their phone and send short messages (SMS). Our thought about this work is to see how we can construct a device with a mobile phone embedded inside it using any of the network providers i.e. MTN (Mobile Telecommunication Network) , GLO (Global Communication) , CELTEL (Cellular Telecommunication), MTEL (Mobile Telecommunication) etc. and use it to control our appliances connected to the system.

2.6 GSM SERVICES

GSM services follow ISDN guidelines and classified as either tele services or data
services. Tele services may be divided into three major categories:
• Telephone services, include emergency calling and facsimile. GSM also supports
Videotex and Teletex, through they are not integral parts of the GSM standard.
• Bearer services or Data services, which are limited to layers 1, 2 and 3 of the OSI
reference model. Data may be transmitted using either a transparent mode or nontransparent mode.
• Supplementary ISDN services, are digital in nature, and include call diversion, closed user group, and caller identification. Supplementary services also include the short message service (SMS).

2.7OFC

BRIEF OVER VIEW OF FIBER OPTIC CABLE ADVANTAGESOVERCOPPER:

• SPEED: Fiber optic networks operate at high speeds - up into the gigabits
• BANDWIDTH: large carrying capacity
• DISTANCE: Signals can be transmitted further without needing to be "refreshed" or strengthened.
• RESISTANCE: Greater resistance to electromagnetic noise such as radios, motors or other nearby cables.
• MAINTENANCE: Fiber optic cables costs much less to maintain.

In recent years it has become apparent that fiber-optics are steadily replacing copper wire as an appropriate means of communication signal transmission. They span the long distances between local phone systems as well as providing the backbone for many network systems. Other system users include cable television services, university campuses, office buildings, industrial plants, and electric utility companies.

A fiber-optic system is similar to the copper wire system that fiber-optics is replacing. The

difference is that fiber-optics use light pulses to transmit information down fiber lines instead of using electronic pulses to transmit information down copper lines. Looking at the components in a fiber-optic chain will give a better understanding of how the system works in conjunction with wire based systems.

At one end of the system is a transmitter. This is the place of origin for information coming on to fiber-optic lines. The transmitter accepts coded electronic pulse information coming from copper wire. It then processes and translates that information into equivalently coded light pulses. A light-emitting diode (LED) or an injection-laser diode (ILD) can be used for generating the light pulses. Using a lens, the light pulses are funneled into the fiber-optic medium where they travel down the cable. The light (near infrared) is most often 850nm for shorter distances and 1,300nm for longer distances on Multi-mode fiber and 1300nm for single-mode fiber and 1,500nm is used for for longer distances.

Think of a fiber cable in terms of very long cardboard roll (from the inside roll of paper towel) that is coated with a mirror on the inside.
If you shine a flashlight in one end you can see light come out at the far end - even if it's been bent around a corner.

Light pulses move easily down the fiber-optic line because of a principle known as total internal reflection. "This principle of total internal reflection states that when the angle of incidence exceeds a critical value, light cannot get out of the glass; instead, the light bounces back in. When this principle is applied to the construction of the fiber-optic strand, it is possible to transmit information down fiber lines in the form of light pulses. The core must a very clear and pure material for the light or in most cases near infrared light (850nm, 1300nm and 1500nm). The core can be Plastic (used for very short distances) but most are made from glass. Glass optical fibers are almost always made from pure silica, but some other materials, such as fluorozirconate, fluoroaluminate, and chalcogenide glasses, are used for longer-wavelength infrared applications.

There are three types of fiber optic cable commonly used: single mode, multimode and plastic optical fiber (POF).

Transparent glass or plastic fibers which allow light to be guided from one end to the other with minimal loss.

Fiber optic cable functions as a "light guide," guiding the light introduced at one end of the cable through to the other end. The light source can either be a light-emitting diode (LED)) or a laser.

The light source is pulsed on and off, and a light-sensitive receiver on the other end of the cable converts the pulses back into the digital ones and zeros of the original signal.

Even laser light shining through a fiber optic cable is subject to loss of strength, primarily through dispersion and scattering of the light, within the cable itself. The faster the laser fluctuates, the greater the risk of dispersion. Light strengtheners, called repeaters, may be necessary to refresh the signal in certain applications.

While fiber optic cable itself has become cheaper over time - a equivalent length of copper cable cost less per foot but not in capacity. Fiber optic cable connectors and the equipment needed to install them are still more expensive than their copper counterparts.

Single Mode cable is a single stand (most applications use 2 fibers) of glass fiber with a diameter of 8.3 to 10 microns that has one mode of transmission. Single Mode Fiber with a relatively narrow diameter, through which only one mode will propagate typically 1310 or 1550nm. Carries higher bandwidth than multimode fiber, but requires a light source with a narrow spectral width. Synonyms mono-mode optical fiber, single-mode fiber, single-mode optical waveguide, uni-mode fiber.

Single Modem fiber is used in many applications where data is sent at multi-frequency (WDM Wave-Division-Multiplexing) so only one cable is needed - (single-mode on one single fiber)

Single-mode fiber gives you a higher transmission rate and up to 50 times more distance than multimode, but it also costs more. Single-mode fiber has a much smaller core than multimode. The small core and single light-wave virtually eliminate any distortion that could result from overlapping light pulses, providing the least signal attenuation and the highest transmission speeds of any fiber cable type.

Single-mode optical fiber is an optical fiber in which only the lowest order bound mode can propagate at the wavelength of interest typically 1300 to 1320nm.

jump to single mode fiber page

FIGURE 5

Multi-Mode cable has a little bit bigger diameter, with a common diameters in the 50-to-100 micron range for the light carry component (in the US the most common size is 62.5um). Most applications in which Multi-mode fiber is used, 2 fibers are used (WDM is not normally used on multi-mode fiber). POF is a newer plastic-based cable which

promises performance similar to glass cable on very short runs, but at a lower cost.

Multimode fiber gives you high bandwidth at high speeds (10 to 100MBS - Gigabit to 275m to 2km) over medium distances. Light waves are dispersed into numerous paths, or modes, as they travel through the cable's core typically 850 or 1300nm. Typical multimode fiber core diameters are 50, 62.5, and 100 micrometers. However, in long cable runs (greater than 3000 feet [914.4 meters), multiple paths of light can cause signal distortion at the receiving end, resulting in an unclear and incomplete data transmission so designers now call for single mode fiber in new applications using Gigabit and beyond.

FIGURE 6

FIGURE7

The use of fiber-optics was generally not available until 1970 when Corning Glass Works was able to produce a fiber with a loss of 20 dB/km. It was recognized that optical fiber would be feasible for telecommunication transmission only if glass could be developed so pure that attenuation would be 20dB/km or less. That is, 1% of the light would remain after traveling 1 km. Today's optical fiber attenuation ranges from 0.5dB/km to 1000dB/km depending on the optical fiber used. Attenuation limits are based on intended application.

The applications of optical fiber communications have increased at a rapid rate, since the first commercial installation of a fiber-optic system in 1977. Telephone companies began early on, replacing their old copper wire systems with optical fiber lines. Today's telephone companies use optical fiber throughout their system as the backbone architecture and as the long-distance connection between city phone systems.

Cable television companies have also began integrating fiber-optics into their cable systems. The trunk lines that connect central offices have generally been replaced with optical fiber. Some providers have begun experimenting with fiber to the curb using a fiber/coaxial hybrid. Such a hybrid allows for the integration of fiber and coaxial at a neighborhood location. This location, called a node, would provide the optical receiver that converts the light impulses back to electronic signals. The signals could then be fed to individual homes via coaxial cable.

Local Area Networks (LAN) is a collective group of computers, or computer systems, connected to each other allowing for shared program software or data bases. Colleges, universities, office buildings, and industrial plants, just to name a few, all make use of optical fiber within their LAN systems.

Power companies are an emerging group that have begun to utilize fiber-optics in their communication systems. Most power utilities already have fiber-optic communication systems in use for monitoring their power grid systems.

Fiber

by John MacChesney - Fellow at Bell Laboratories, Lucent Technologies

Some 10 billion digital bits can be transmitted per second along an optical fiber link in a commercial network, enough to carry tens of thousands of telephone calls. Hair-thin fibers consist of two concentric layers of high-purity silica glass the core and the cladding, which are enclosed by a protective sheath. Light rays modulated into digital pulses with a laser or a light-emitting diode move along the core without penetrating the cladding.

The light stays confined to the core because the cladding has a lower refractive index—a measure of its ability to bend light. Refinements in optical fibers, along with the development of new lasers and diodes, may one day allow commercial fiber-optic networks to carry trillions of bits of data per second.

Total internal refection confines light within optical fibers (similar to looking down a mirror made in the shape of a long paper towel tube). Because the cladding has a lower refractive index, light rays reflect back into the core if they encounter the cladding at a shallow angle (red lines). A ray that exceeds a certain "critical" angle escapes from the fiber (yellow line).

STEP-INDEX MULTIMODE FIBER has a large core, up to 100 microns in diameter. As a result, some of the light rays that make up the digital pulse may travel a direct route, whereas others zigzag as they bounce off the cladding. These alternative pathways cause the different groupings of light rays, referred to as modes, to arrive separately at a receiving point. The pulse, an aggregate of different modes, begins to spread out, losing its well-defined shape. The need to leave spacing between pulses to prevent overlapping limits bandwidth that is, the amount of information that can be sent. Consequently, this type of fiber is best suited for transmission over short distances, in an endoscope, for instance.

GRADED-INDEX MULTIMODE FIBER contains a core in which the refractive index diminishes gradually from the center axis out toward the cladding. The higher refractive index at the center makes the light rays moving down the axis advance more slowly than those near the cladding. Also, rather than zigzagging off the cladding, light in the core curves helically because of the graded index, reducing its travel distance. The shortened path and the higher speed allow light at the periphery to arrive at a receiver at about the same time as the slow but straight rays in the core axis. The result: a digital pulse suffers less dispersion.

SINGLE-MODE FIBER has a narrow core (eight microns or less), and the index of refraction between the core and the cladding changes less than it does for multimode fibers. Light thus travels parallel to the axis, creating little pulse dispersion. Telephone and cable television networks install millions of kilometers of this fiber every year.

BASIC CABLE DESIGN

1 - Two basic cable designs are:
Loose-tube cable, used in the majority of outside-plant installations in North America, and tight-buffered cable, primarily used inside buildings.
The modular design of loose-tube cables typically holds up to 12 fibers per buffer tube with a maximum per cable fiber count of more than 200 fibers. Loose-tube cables can be all-dielectric or optionally armored. The modular buffer-tube design permits easy drop-off of groups of fibers at intermediate points, without interfering with other protected buffer tubes being routed to other locations. The loose-tube design also helps in the identification and administration of fibers in the system.
Single-fiber tight-buffered cables are used as pigtails, patch cords and jumpers to terminate loose-tube cables directly into opto-electronic transmitters, receivers and other active and passive components.
Multi-fiber tight-buffered cables also are available and are used primarily for alternative routing and handling flexibility and ease within buildings.

2 - Loose-Tube Cable

In a loose-tube cable design, color-coded plastic buffer tubes house and protect optical fibers. A gel filling compound impedes water penetration. Excess fiber length (relative to buffer tube length) insulates fibers from stresses of installation and environmental loading. Buffer tubes are stranded around a dielectric or steel central member, which serves as an anti-buckling element.
The cable core, typically uses aramid yarn, as the primary tensile strength member. The outer polyethylene jacket is extruded over the core. If armoring is required, a corrugated steel tape is formed around a single jacketed cable with an additional jacket extruded over the armor.
Loose-tube cables typically are used for outside-plant installation in aerial, duct and direct-buried applications.

3 - Tight-Buffered Cable

With tight-buffered cable designs, the buffering material is in direct contact with the fiber. This design is suited for "jumper cables" which connect outside plant cables to terminal equipment, and also for linking various devices in a premises network.
Multi-fiber, tight-buffered cables often are used for intra-building, risers, general building and plenum applications.
The tight-buffered design provides a rugged cable structure to protect individual fibers during handling, routing and connectorization. Yarn strength members keep the tensile load away from the fiber.
As with loose-tube cables, optical specifications for tight-buffered cables also should include the maximum performance of all fibers over the operating temperature range and life of the cable. Averages should not be acceptable.

In case of optical fiber side of the project there is a dtmf switch panel correspond to control of a particular appliance. When the user press any particular switc then the dtmf encoder ICUM91215B will generate unique pair of frequencies,from the transmitter is passed through the fiber. This code sequence will fed to an led which will emit the light according to sequence generated ie. Is it will turn on on logic1 and off on logic0. On the reciver side it is decoded and fed up to at89 s 52 for processing and uln 2803 which are relay driver and device corresponding to particular relay operated.

Organization of the report:

The report totally consists of five chapters-

Chapter 1 gives the introduction

Chapter 2 gives the overview of the project,

Chapter 3 gives the description of hardware used,

Chapter 4 describes the algorithm, and finally

Chapter 5 gives theconclusions.

CHAPTER3

Overview of project

3.1.1Block diagram Cell phone control

1.Dtmf Encoder

DTMF encoder integrated circuit, Chip UM 91214B. This IC produces DTMF signals. It contains four row frequencies & three column frequencies. The pins of IC 91214 B from 12 to 14 produces high frequency column group and pins from 15 to 18 produces the low frequency row group. By pressing any key in the keyboard corresponding DTMF signal is available in its output pin at pin no.7. For producing the appropriate signals it is necessary that a crystal oscillator of 3.58MHz is connected across its pins 3 & 4 so that it makes a part of its internal oscillator.

2.Dtmf Decoder:

It is not easy to detect and recognize DTMF with satisfactory precision. Often, dedicated integrated circuits are used. It is rather complicated, so it is used only marginally. Most often, a MT 8870 or compatible circuit would be used.
The MT8870 is a complete DTMF receiver integrating both the band split filter and digital decoder functions. The filter section uses switched capacitor techniques for high and low group filters; the decoder uses digital counting techniques to detect and decode all 16 DTMF tone-pairs into a 4-bit code. External component count is minimized by on chip provision of a differential input amplifier, clock oscillator and latched three-state bus interface.

Features of DTMF decoder

Complete DTMF Receiver
Low power consumption
Internal gain setting amplifier
Adjustable guard time
Central office quality
Power-down mode
Inhibit mode
Backward compatible with MT8870C/MT8870C-1

2. Microcontroller:

A microcontroller (also MCU or µC) is a small computer on a single integrated circuit consisting of a relatively simple CPU combined with support functions such as a crystal oscillator, timers, watchdog, serial and analog I/O etc. Program memory in the form of NOR flash or OTP ROM is also often included on chip, as well as a, typically small, read/write memory.

They will generally have the ability to retain functionality while waiting for an event such as a button press or other interrupt; power consumption while sleeping (CPU clock and most peripherals off) may be just nanowatts, making many of them well suited for long lasting battery applications.

The AT89S51 is a low-power, high-performance CMOS 8-bit microcontroller with 4K bytes of In-System Programmable Flash memory. The device is manufactured using Atmel’s 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 AT89S51 is a powerful microcontroller which provides a

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

The AT89S51 provides the following standard features: 4K bytes of Flash, 128 bytes of

RAM, 32 I/O lines, Watchdog timer, two data pointers, two 16-bit timer/counters, a fivevector

two-level interrupt architecture, a full duplex serial port, on-chip oscillator, and

clock circuitry. In addition, the AT89S51 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 external

interrupt or hardware reset.

3. Current amplifier:

Current amplification is done through darlington pair

A Darlington pair is two transistors that act as a single transistor but with a much higher current gain.

Transistors have a characteristic called current gain. This is referred to as its hFE. The amount of current that can pass

through the load when connected to a transistor that is turned on equals the input current x the gain of the transistor (hFE)

The current gain varies for different transistor..

4.Relays:

A relay is an electrical switch that opens and closes under the control of another electrical circuit. In the original form, the switch is operated by an electromagnet to open or close one or many sets of contacts. It was invented by Joseph Henry in 1835. Because a relay is able to control an output circuit of higher power than the input circuit, it can be considered to be, in a broad sense, a form of an electrical amplifier.

When an electric current is passed through the coil, the resulting magnetic field attracts the armature, and the consequent movement of the movable contact or contacts either makes or breaks a connection with a fixed contact.

5. Appliances: Various types of electrical appliances can be controlled through the help of this project.

FIGUR13

3.1.5Description

In this project we are going to control general home appliances based on the mobile communication AND Optical fiber . The idea behind this particular work is to give user the full flexibility to control the appliances from remote distances when there is a busy schedule concerned to his daily routine and to have congestion and electric interference free wire system.

The main parts of this schematic diagram are:

1. POWER SUPPLY.

2. (AT89s51) MICROCONTROLLER UNIT.

3. DTMF ENCODER UM 91215 B

4. DTMF DECODER MT 8870

5. ULN 2803 APG

6. RELAYS

7. APPLIANCES

The process to operate this project is first make a mobile to mobile connection wirelessly or with a single mobile onboard wired. But here we are using to mobiles to make is a wireless application. Start with making a connection with the onboard mobile from remote distance, then when connection is established lets control the project with the data as follows:

3.1.6Working:-

On dialing a no. from the cell phone or landline, the bell starts ringing at the receiver end. When the person picks the call the process of communication takes place between the receiver and the transmitter. The voice signal at the transmitter end is modulated by the phone. GSM act as carrier. On the other hand the signal at the receiver end is first demodulated and the resultant information signal is produced at the speaker of the phone.

DTMF is the world standard frequency which is present in the keypad of all the phones.

Reason being if different countries have different frequencies then the modulated signal produced at the transmitter end cannot be demodulated at the phone (present in some other country) because of mismatch in frequency.

When we dial the no. of the phone attached with our device. The auto answer in the phone will pick the call. When we come to know that phone has been picked then we select the device through the keypad button. According to the button pressed Dtmf gets generated, modulated and send by the Gsm to the other phone. We will get the same tone from the speaker after demodulation.

Dtmf is an analog signal and as microcontroller is the digital device so it cannot read the Dtmf signal. That’s why we have used Dtmf decoder Mt8870 in which we have given the input at pin no.2 through the capacitor. When signal is interfaced then Dtmf decodes into a 4 bit binary output through the pins 11, 12, 13 and 14(more information can be obtained through datasheet). Yellow Colour inverted Led’s display the binary output. When Led’s are glowing then the output is zero and when it is not glowing then the output is one.11, 12, 13 and 14 pins are connected to the port one of the microcontroller. When microcontroller receives this 4 bit binary signal then according to the program it controls the functioning of the device connected to the port 2. Now the signal at the output of the controller lacks sufficient current therefore it cannot control the functioning of the devices which require large current. Therefore we connect the output of the controller to the ULN2803 which is a 8 bit Darlington array. It gives the output current upto the value of 500mA. The relays are connected to the output of the ULN2803. A relay is an electrical switch that opens and closes under the control of another electrical circuit. In the original form, the switch is operated by an electromagnet to open or close one or many sets of operation. Thus it can be used to control the functioning of the high current devices when connected to the output of ULN2803.

Devices like AC or other electrical appliances are connected to the relay. Thus their functioning is controlled through cell phone.

Device corresponding to particular relay operated.

Chapter 4 HARDWARE DESCRIPTION

The block diagram of the system is as shown in the fig. The system basically consists of a

1. Micro controller,

2. DTMF encoder and decoder

3. Power SUPPLY

4. 7 segment display

4.MICROCONTROLLER

4.1.1A Brief History of 8051

In 1981, Intel Corporation introduced an 8 bit microcontroller called 8051. This microcontroller had 128 bytes of RAM, 4K bytes of chip ROM, two timers, one serial port, and four ports all on a single chip. At the time it was also referred as “A SYSTEM ON A CHIP”

The 8051 is an 8-bit processor meaning that the CPU can work only on 8 bits data at a time. Data larger than 8 bits has to be broken into 8 bits pieces to be processed by the CPU. The 8051 has a total of four I\O ports each 8 bit wide.

There are many versions of 8051 with different speeds and amount of on-chip ROM and they are all compatible with the original 8051. This means that if you write a program for one it will run on any of them.

The 8052 is an original member of the 8051 family. There are two other members in the

8051 family of microcontrollers. They are 8052 and 8031. All the three microcontrollers will have the same internal architecture, but they differ in the following

aspects.

1. 8031 has 128 bytes of RAM, two timers and 6 interrupts.

2. 89S51 has 4KB ROM, 128 bytes of RAM, two timers and 6 interrupts.

4.1.2Block Diagram ofMicrocontroller

FIGURE 14

4.1.3Description of 89S52 Microcontroller

The AT89S52 provides the following standard features: 8Kbytes of Flash, 256 bytes

of RAM, 32 I/O lines, three 16-bit timer/counters, 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 hardware reset.

By combining a versatile 8-bit CPU with Flash on a monolithic chip, the AT89S52 is a powerful microcomputer which provides a highly flexible and cost effective solution to many embedded control applications.

Features of Microcontroller (89S52)

3. Compatible with MCS-51 Products

4. 8 Kbytes of In-System Reprogrammable Flash Memory

5. Endurance: 1,000 Write/Erase Cycles

6. Fully Static Operation: 0 Hz to 24 MHz

7. Three-Level Program Memory Lock

8. 256 x 8-Bit Internal RAM

9. 32 Programmable I/O Lines

8 Three 16-Bit Timer/Counters

9 Eight vector two level Interrupt Sources

10 Programmable Serial Channel

11 Low Power Idle and Power Down Modes

12 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 hardwre

4.1.4Pin Configurations

FIGURE15

Figure 3.1 Pin Diagram of 89S52

VCC Supply voltage (all packages except 42-PDIP).

GND Ground (all packages except 42-PDIP; for 42-PDIP GND connects only the logic core and the embedded program memory).

VDD Supply voltage for the 42-PDIP which connects only the logic core and the embedded program memory.

PWRVDD Supply voltage for the 42-PDIP which connects only the I/O Pad Drivers. The application board must connect both VDD and PWRVDD to the board supply voltage.

PWRGND Ground for the 42-PDIP which connects only the I/O Pad Drivers. PWRGND and GND are weakly connected through the common silicon substrate, but not through any metal link. The application board MUST connect both GND and PWRGND to the board ground.

Port 0 Port 0 is an 8-bit open drain bi-directional 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 bi-directional 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.

Port 1 also receives the low-order address bytes during Flash programming and verification.

Port 2 Port 2 is an 8-bit bi-directional 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 use 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 bi-directional 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 AT89S51, as shown in the following table.

RST Reset input. A high on this pin for two machine cycles while the oscillator is running resets the device. This pin drives High for 98 oscillator periods after the Watchdog times out. The DISRTO bit in SFR AUXR (address 8EH) can be used to disable this feature. In the default state of bit DISRTO, the RESET HIGH out feature is enabled.

ALE/PROG Address Latch Enable (ALE) is an output pulse for latching the low byte of the address during accesses to external memory. This pin is also the program pulse input (PROG) during Flash programming.

In normal operation, ALE is emitted at a constant rate of 1/6 the oscillator frequency and may be used for external timing or clocking purposes. Note, however, that one ALE pulse is skipped during each access to external data memory.

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 AT89S51 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

4.1.5

DTMF ENCODER & DECODER

1 DTMF

When we dial on the keypad on the phone there is production of tone and these tone can represent the digits and a we can represent each digit for an each tone. There is random sound on a same frequency and if we use a single frequency for a system, then it can lead to trip of the system. If we use two tone to represent a digit, then occurring of false signal can be eradicated. This is the basis of Dual Tone Multi Frequency (DTMF).When we press a key on the phone,

there is generation of two tones of specific frequency. One tone is generated from high frequency and low frequency.

DTMF represents Dual Tone Multi Frequency. On DTMF signals baseband multiplexing is absent. The signal produced from a DTMF encoder is the direct algebraic summation of the amplitudes of the two cosine(sine) waves of different frequencies, i.e. pressing '0' will send a tone made by adding 1336 Hz and 941 Hz to the other end of the line.

The touch tone system uses two number of tones to shows the different keys. There is a "low tone" and a "high tone" connected with each button (0 through 9, plus * (star) and # (octothorpe or pound symbol). The tones are represented as follows:

3.7.1 Matrix form of a DTMF

or:

1 is summation of 697+1209

2 is summation of 697+1336

3 is summation of 697+1477

4 is summation of 770+1209

5 is summation of 770+1336

6 is summation of 770+1477

7 is summation of 852+1209

8 is summation of 852+1336

9 is summation of 852+1477

0 is summation of 941+1336

* is summation of 941+1209

# is summation of 941+1477

A is summation of 697+1633

B is summation of 770+1633

C is summation of 852+1633

D is summation of 941+1633

When we press the button, the 770 Hz and 1209 Hz tones are sent together from the DTMF encoder. The DTMF decoder decodes the tone and generates the equivalent of the key number at the output.

To avoid other problems and harmonics, we use tone frequencies that may be produced when two tones are sent and received. Accurate transmission from the encoder and accurate decoding on the decoder is important. When we dial the numbers, they sound musical (and representations of many popular tunes are possible).

The tones that are used should all be +/- 1.5% of nominal. The high frequency tone should be at least loud and it would be good if it is louder than the low frequency. This would be as much as 4 db louder. This factor we call it "twist." If a Touchtone signal has +3db of twist, then it represents that the low frequency is 3 db slower than the high frequency. Negative twist happens when the low frequency is louder than high frequency.

2) Encoding DTMF

Figure (17). Circuit diagram of the DTMF encoder

This encoder IC requires a voltage of 3V. For that IC is wired around 4.5V battery. And 3V backup Vcc for this IC is supplied by using 3.2v zener diode. The Encoder IC Pins 1 and 2 are used as DTMF mode select and chip select pins respectively. When the row pin 12 and column pin 15 are shorted to each other, there is a output from its pin 7 corresponding to digit 1 of DTMF tones.

There are many ways to generate DTMF tone. Using oscillator and filter array is one of the method also this can be designed by using lookup table in the digital method. The Integrated IC version is having one key board section, on receiving proper row column section the tone generator section generator generates DTMF tone output.

FIGURE 18

3)DTMF DECODER

The MT8870 is a complete DTMF receiver integrating both the band split filter and digital decoder functions. The filter section uses switched capacitor techniques for high and low group filters; the decoder uses digital counting techniques to detect and decode all 16 DTMF tone-pairs into a 4-bit code. External component count is minimized by on chip provision of a differential input amplifier, clock oscillator and latched three-state bus interface.

Features of DTMF decoder

Complete DTMF Receiver
Low power consumption
Internal gain setting amplifier
Adjustable guard time
Central office quality
Power-down mode
Inhibit mode
Backward compatible with MT8870C

BLOCK DIAGRAM

FIGUR19

4)Working of IC MT8870:

The MT-8870 is a full DTMF Receiver that integrates both band split filter and decoder functions into a single 18-pin DIP. Its filter section uses switched capacitor technology for both the high and low group filters and for dial tone rejection. Its decoder uses digital counting techniques to detect and decode all 16 DTMF tone pairs into a 4-bit code. External component count is minimized by provision of an on-chip differential input amplifier, clock generator, and latched tri-state interface bus. Minimal external components required include a low-cost 3.579545 MHz crystal, a

timing resistor, and a timing capacitor. The MT-8870-02 can also inhibit the decoding of fourth column digits.

MT-8870 operating functions include a band split filter that separates the high and low tones of the received pair, and a digital decoder that verifies both the frequency and duration of the received tones before passing the resulting 4-bit code to the output bus.

The low and high group tones are separated by applying the dual-tone signal to the inputs of two 6^th order switched capacitor band pass filters with bandwidths that correspond to the bands enclosing the low and high group tones.

The filter also incorporates notches at 350 and 440 Hz, providing excellent dial tone rejection. Each filter output is followed by a single-order switched capacitor section that smoothes the signals prior to limiting. Signal limiting is performed by high gain comparators provided with hysteresis to prevent detection of unwanted low-level signals and noise. The MT-8870 decoder uses a digital counting technique to determine the frequencies of the limited tones and to verify that they correspond to standard DTMF frequencies. When the detector recognizes the simultaneous presence of two valid tones (known as signal condition), it raises the Early Steering flag (ESt). Any subsequent loss of signal condition will cause ESt to fall. Before a decoded tone pair is registered, the receiver checks for valid signal duration (referred to as character- recognition-condition). This check is performed by an external RC time constant driven by ESt. A short delay to allow the output latch to settle, the delayed steering output flag (StD) goes high, signaling that a received tone pair has been registered. The contents of the output latch are made available on the 4-bit output bus by raising the three state control input (OE) to logic high. Inhibit mode is enabled by a logic high input to pin 5 (INH). It inhibits the detection of 1633 Hz.

The output code will remain the same as the previous detected code. On the M- 8870 models, this pin is tied to ground (logic low).

The input arrangement of the MT-8870 provides a differential input operational amplifier as well as a bias source (VREF) to bias the inputs at mid-rail. Provision is made for connection of a feedback resistor to the op-amp output (GS) for gain adjustment.

The internal clock circuit is completed with the addition of a standard 3.579545 MHz crystal.

5)Decoder IC Operation

The frequency modulated Dual Tone Multi Frequency signals are taken by the FM(Frequency Modulator) receiver and the output (DTMF tones) are given to the dedicated IC KT3170 works as a DTMF-to-BCD converter. This IC gives the corresponding BCD output when we give DTMF tone. For example, when digit 2 is pressed, the output is 0010 and when digit 3 is pressed the output is 0011. There is a requirement of 3058Mz crystal for the operation of IC KT3147

4. ULN2803 & RELAY:-

FIGURE 20

ULN2803 is the Darlington array which is a current amplifier which amplifies the current of the signal coming from the microcontroller.

Relay is an electro mechanical switch which converts electrical signal into mechanical output and provides the isolation between the two connections.

The signal so received is of very small amplitude in order to amplify it current amplifier is used. The current amplifier used in this project is ULN2803.

FIGURE21

Featuring continuous load current ratings to 500 mA for each of the drivers, the Series ULN28xxA/LW and ULQ28xxA/LW high voltage, high-current Darlington arrays are ideally suited for interfacing between low-level logic circuitry and multiple peripheral power loads. Typical power loads totaling over 260 W (350 mA x 8, 95 V) can be controlled at an appropriate duty cycle depending on ambient temperature and number of drivers turned on simultaneously. Typical loads include relays, solenoids, stepping motors, magnetic print hammers, multiplexed LED and incandescent displays, and heaters. All devices feature open-collector outputs with integral clamp diodes.

The ULx2803A, ULx2803LW, ULx2823A, and ULN2823LW have series input resistors selected for operation directly with 5 V TTL or CMOS. These devices will handle numerous interface needs — particularly those beyond the capabilities of standard logic buffers.

The ULx2804A, ULx2804LW, ULx2824A, and ULN2824LW have series input resistors for operation directly from 6 V to 15 V CMOS or PMOS logic outputs.

The ULx2803A/LW and ULx2804A/LW are the standard Darlington arrays. The outputs are capable of sinking 500 mA and will withstand at least 50 V in the off state. Outputs may be paralleled for higher load current capability. The ULx2823A/LW and ULx2824A/LW will withstand 95 V in the off state.

These Darlington arrays are furnished in 18-pin dual in-line plastic packages (suffix ‘A’) or 18-lead small-outline plastic packages (suffix ‘LW’). All devices are pinned with outputs opposite inputs to facilitate ease of circuit board layout. Prefix ‘ULN’ devices are rated for operation over the temperature range of -20°C to +85°C; prefix ‘ULQ’ devices are rated for operation to -40°C.

RELAY:-

A relay is an electrically operated switch. Current flowing through the coil of the relay creates a magnetic field which attracts a lever and changes the switch contacts. The coil current can be on or off so relays have two switch positions and most have double throw (changeover) switch contacts as shown in the diagram.

Relays allow one circuit to switch a second circuit which can be completely separate from the first. For example a low voltage battery circuit can use a relay to switch a 230V AC mains circuit. There is no electrical connection inside the relay between the two circuits, the link is magnetic and mechanical.

FIGURE 23

Circuit symbol for a relay

Relays

Relay showing coil and switch contacts

The coil of a relay passes a relatively large current, typically 30mA for a 12V relay, but it can be as much as 100mA for relays designed to operate from lower voltages. Most ICs (chips) cannot provide this current and a transistor is usually used to amplify the small IC current to the larger value required for the relay coil. The maximum output current for the popular 555 timer IC is 200mA so these devices can supply relay coils directly without amplification.

Relays are usually SPDT or DPDT but they can have many more sets of switch contacts, for example relays with 4 sets of changeover contacts are readily available. For further information about switch contacts and the terms used to describe them please see the page on switches.

Most relays are designed for PCB mounting but you can solder wires directly to the pins providing you take care to avoid melting the plastic case of the relay.

The supplier's catalogue should show you the relay's connections. The coil will be obvious and it may be connected either way round. Relay coils produce brief high voltage 'spikes' when they are switched off and this can destroy transistors and ICs in the circuit. To prevent damage you must connect a protection diode across the relay coil.

The animated picture shows a working relay with its coil and switch contacts. You can see a lever on the left being attracted by magnetism when the coil is switched on. This lever moves the switch contacts. There is one set of contacts (SPDT) in the foreground and another behind them, making the relay DPDT.

The relay's switch connections are usually labeled COM, NC and NO:

COM = Common, always connect to this; it is the moving part of the switch.
NC = Normally Closed, COM is connected to this when the relay coil is off.
NO = Normally Open, COM is connected to this when the relay coil is on.
Connect to COM and NO if you want the switched circuit to be on when the relay coil is on.
Connect to COM and NC if you want the switched circuit to be on when the relay coil is off.

Choosing a relay

You need to consider several features when choosing a relay:

1. Physical size and pin arrangement

If you are choosing a relay for an existing PCB you will need to ensure that its dimensions and pin arrangement are suitable. You should find this information in the supplier's catalogue.

2. Coil voltage

The relay's coil voltage rating and resistance must suit the circuit powering the relay coil. Many relays have a coil rated for a 12V supply but 5V and 24V relays are also readily available. Some relays operate perfectly well with a supply voltage which is a little lower than their rated value.

3. Coil resistance

The circuit must be able to supply the current required by the relay coil. You can use Ohm's law to calculate the current:

Power Supply:-

FIGURE 24

Power supply is used to drive the circuit. Inappropriate voltage will damage the entire circuitry therefore it constitutes a very important part of the circuit.

Every electronic circuit requires power for its operation. Every function simple or complex is controlled by the power supply. Even a little variation in voltage can damage all the circuitry. So power supply is of prime importance in all the circuits. The power supply which we get is a.c. operating at 220Volts.But as our electronic circuits work only on d.c. therefore; we cannot employ direct usage of supply which we get. In order to overcome this, we require various process namely transformation, rectification, smoothing or filtering and regulation. These entire process using bridge rectifier are illustrated below:

FIGURE 25

Now let’s study the detail of all the processes step by step.

TRANSFORMATION:-

As already discussed the supply which we get is 220V A.C. supply. In order to decrease the magnitude of the voltage we make use of step down transformer. This transformer has more windings in the primary coil than in the secondary coil. So the voltage output at the secondary is an A.C. supply with magnitude less than 220V as shown below:

FIGURE 26

RECTIFICATION:-

As all the electronic circuits work on DC therefore this low voltage A.C. cannot be directly fed to our circuit. Thus a process of rectification is required. In this process, A.C. voltage is converted into D.C. voltage using two semiconductor rectifying diodes as shown below:

FIGURE 27

Now as the two diodes D1 and D2 are connected in the opposite manner. Therefore one of the diode gets forward biased during the positive half of the a.c input and other gets forward biased during the negative half of the a.c. input. Thus during the positive half cycle rectification takes place through diode D1(diode D2 being reverse biased, cannot rectify) and during the negative half cycle, the rectification takes place through the diode D2(diode D1 being reverse biased, cannot rectify). But as at least one of the diode always remain in the conducting mode therefore both the halves of the a.c. input gets rectified and hence the name full wave rectifier.

SMOOTHING/FILTRATION

The output of the rectification process is a varying D.C. As the D.C. waveform cannot be varying so it means that rectification is not 100% efficient due to which there is still some component of the input A.C. present in the D.C. voltage which is responsible for the variation. So in order to remove this A.C. component we require filtration or smoothing of the signal. This can be done using an electrolytic capacitor of 2200uf. As the capacitor offers infinite impedance to the D.C. signal and Zero impedance to the A.C. signal therefore, it allows the A.C. component to pass through and blocks the D.C. component. This means it will filter out the D.C. component from the input signal. Thus the output of the process will be a pure D.C. supply as shown below:

FIGURE 28

Now there is still some variation indicating that output D.C. voltage is not having constant magnitude. This is due to the capacitor used for filtration. Its time of charging and discharging are not equal due to which the filtration is not up to the mark. For making the output voltage assume a constant value we need a voltage regulator.

REGULATION:-

Voltage regulator is used for this purpose mainly from the series of 78- - of the transistor. For getting the constant output of 5 volts we make use of 7805 voltage regulator. This process takes place as shown below: This completes all the processes. Now we have a constant D.C. supply with us which can be fed to any electronic circuit without any problem

List of components

S.No.	Code	Value	Price	Quantity
1.	Resistors	390k 1k 10k	0.25	2 10 1
2.	Capacitor	0.22uf 0.1uf 33pf 2200uf	5 1 1 15	1 1 2 1
3.	Semiconductor	MT8870 At89s51 ULN2803 LM7805 Diode 1n4007	55 50 20 10 1	1 1 1 1 4
4.	Miscellaneous	12V SPDT Relay Transformer 12V/500mA at 220V AC	45 60	4 1

TABLE 2

Voltage Regulator (regulator), usually having three legs, converts varying input voltage and produces a constant regulated output voltage. They are available in a variety of outputs.

The most common part numbers start with the numbers 78 or 79 and finish with two digits indicating the output voltage. The number 78 represents positive voltage and 79 negative one. The 78XX series of voltage regulators are designed for positive input. And the 79XX series is designed for negative input.

Examples:

 5V DC Regulator Name: LM7805 or MC7805

 -5V DC Regulator Name: LM7905 or MC7905

 6V DC Regulator Name: LM7806 or MC7806

 -9V DC Regulator Name: LM7909 or MC7909

The LM78XX series typically has the ability to drive current up to 1A. For application requirements up to 150mA, 78LXX can be used. As mentioned above, the component has three legs: Input leg which can hold up to 36VDC Common leg (GND) and an output leg with the regulator's voltage. For maximum voltage regulation, adding a capacitor in parallel between the common leg and the output is usually recommended. Typically a 0.1MF capacitor is used. This eliminates any high frequency AC voltage that could otherwise combine with the output voltage. See below circuit diagram which represents a typical use of a voltage regulator.

FIGURE 29

Lm7805 Heat sink

Note:

As a general rule the input voltage should be limited to 2 to 3 volts above the output voltage. The LM78XX series can handle up to 36 volts input, be advised that the power difference between the input and output appears as heat. If the input voltage is unnecessarily high, the regulator will overheat. Unless sufficient heat dissipation is provided through heat sinking, the regulator will shut down.

7 SEGMENT

A seven-segment display (abbreviation: "7-seg(ment) display"), less commonly known as a seven-segment indicator, is a form of electronic display device for displaying decimal numerals that is an alternative to the more complex dot-matrix displays. Seven-segment displays are widely used in digital clocks, electronic meters, and other electronic devices for displaying numerical information.

The seven segments are arranged as a rectangle of two vertical segments on each side with one horizontal segment on the top, middle, and bottom. Additionally, the seventh segment bisects the rectangle horizontally. There are also fourteen-segment displays and sixteen-segment displays (for full alphanumeric); however, these have mostly been replaced by dot-matrix displays.

The segments of a 7-segment display are referred to by the letters A to G, where the optional DP decimal point (an "eighth segment") is used for the display of non-integer numbers.

CHAPTER-5

CONCLUSION

THE PROJECT “GSM AND OFC BASED HOME AUTOMATION” has been successfully designed and tested . Integrating features of all hardware components used has developed it. Presence of each module has been reasoned out and placed carefully thus contributing to best working of the unit. Secondly using highly advance IC’s AND THE Growing technology the project has been successfully implemented. EMBEDED SYSTEM are emerging as technology with high potential. In the past microprocessor based system ruled the market. The last decade witness the revolution of microcontroller based embedded system. With regards to the requirements gathered the manual work and the complexity in counting can be achieved with the help of electronic devices.

BIBLIOGRAPHY

NAME OF THE SITES

www.mitl.databook.com

www.atmel.databook.com

3) www.datasheetarchive.com

APPENDIX1

1. ACALL: Absolute Call

2. ADD, ADDC: Add Accumulator (With Carry)

3. AJMP: Absolute Jump

4. ANL: Bitwise AND

5. CJNE: Compare and Jump if Not Equal

6. CLR: Clear Register

7. CPL: Complement Register

8. DA: Decimal Adjust

9. DEC: Decrement Register

10. DIV: Divide Accumulator by B

11. DJNZ: Decrement Register and Jump if Not Zero

12. INC: Increment Register

13. JB: Jump if Bit Set

14. JBC: Jump if Bit Set and Clear Bit

15. JC: Jump if Carry Set

16. JMP: Jump to Address

17. JNB: Jump if Bit Not Set

18. JNC: Jump if Carry Not Set

19. JNZ: Jump if Accumulator Not Zero

20. JZ: Jump if Accumulator Zero

21. LCALL: Long Call

22. LJMP: Long Jump

23. MOV: Move Memory

24. MOVC: Move Code Memory

25. MOVX: Move Extended Memory

26. MUL: Multiply Accumulator by B

27. NOP: No Operation

28. ORL: Bitwise OR

29. POP: Pop Value From Stack

30. PUSH: Push Value Onto Stack

31. RET: Return From Subroutine

32. RETI: Return From Interrupt

33. RL: Rotate Accumulator Left

34. RLC: Rotate Accumulator Left Through Carry

35. RR: Rotate Accumulator Right

36. RRC: Rotate Accumulator Right Through Carry

37. SETB: Set Bit

38. SJMP: Short Jump

39. SUBB: Subtract From Accumulator With Borrow

40. SWAP: Swap Accumulator Nibbles

41. XCH: Exchange Bytes

42. XRL: Bitwise Exclusive OR

43Undefined: Undefined Instruction

APPENDIX-2

org 00h

mov p0,#040h

mov p1,#0ffh

mov p2,#00h

start: mov a,p1

cjne a,#00000001b,Appliance1 ;1

cpl p2.0

mov p0,#0f9h

AP1: cjne a,#00000010b,Appliance2 ;2

cpl p2.1

mov p0,#024h

AP2: cjne a,#00000011b,Appliance3 ;3

cpl p2.2

mov p0,#030h

AP3: cjne a,#00000100b,Appliance4 ;4

cpl p2.3

mov p0,#019h

AP4: cjne a,#00000101b,Appliance5 ;5

cpl p2.4

mov p0,#012h

AP5: cjne a,#00000110b,Appliance6 ;6

cpl p2.5

mov p0,#002h

AB6: cjne a,#00000111b,Appliance7 ;7

cpl p2.6

mov p0,#0f8h

AB7: cjne a,#00001000b, Appliance8 ;8

cpl p2.7

mov p0,#000h

AB8: cjne a,#00001001b,Appliance9 ;9

mov p2,#000h