Dtmf Based Home Automation 5j5x1m

TABLE OF CONTENTS

Sr. No.

CONTENT

PAGE NO.

1)

CERTIFICATE ………………………………………...

i

2)

ACKNOWLEDGEMENT ……………………………...

ii

3)

IMAGE OF PROJECT …………………………………

iii

4)

TABLE OF CONTENTS ……………………………….

5) 6)

ABSTRACT ………..…………………………………... 1-2 INTRODUCTION …………………………………… … 3-4

7)

HOME AUTOMATION ...………………………………. 5-6

8)

GSM ………………. ……………………………………… 7-9

9)

COMPONENTS USED……….. ………………………...10-11

10)

CIRCUIT DIAGRAM ……………………………………12-14

iv

11) PROGRAM USED… ……………………………………. 15-17 12)

ADVANTAGES AND DISADVANTAGES….…………18-25

13)

POSSIBLE IMPROVEMENTS…….…………………… 26-29

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CONCULSION …..................…………………………… 30-41

15)

BIBLOGRAPHY……………….. ………………………...42-56

ABSTRACT

This project demonstrates a novel method which enables s to control industrial appliances and systems from remote using a cell phone-based interface. In its most simple form Home Automation is the ability to control lighting & household appliances remotely. Almost everyone already has a limited amount of Home Automation. Home Automation is analogous to earlier developments in factory and office automation. It includes the remote control and monitoring of domestic appliances, home security and energy management. To access the control unit, the should send an authentication code (DTMF) along with the required/desired function/action to his/her home control system via Global System for Mobile communication (GSM). Upon being properly authenticated, the cell phone-based interface at home (control unit) would relay the commands to a microcontroller that would perform the required function/action, and return a function completion code that would be sent to the source of the original command (’s cell phone).

INTRODUCTION

Imagine being able to control all the electrical appliances of your home from virtually any place you are in the world! For example, say one cold winter day, you are stuck in traffic on the motorway after a long day at work. By pressing a few keystrokes on your mobile phone, you activate a macro which turns on the heating, prepares your Jacuzzi, and switches on your electrical fireplace and lava-lamps at your premises. In today's times the GSM mobile terminal has become one of the items that are constantly with us. Just like our wallet/purse, keys or watch, the GSM mobile terminal provides us with a communication channel that enables us to communicate with the world. The want for a person to be reachable or to call anyone at any time is very appealing. Using the cybernetic concept of action space, we in fact extend the action space of the human with the mobile terminal, enabling the subscriber to talk to another subscriber and thus exchange information, issue or receive commands. This Project is used to control our household electrical devices from anywhere through the cell phone. The circuit consists of a DTMF tone detector and a powerful 8 bit Microcontroller AT89C51. The microcontroller controls all the system. In this project we control total four devices. The Microcontroller senses the DTMF signal through the DTMF decoder IC MT8870 and it switch on/off the corresponding devices according to the need. The circuit has an inbuilt phone ring sensor circuit and the system will take over the phone control if it was not taken manually. Press the corresponding numbers to turn on/off the devices. The aim of the project is to investigate a cost effective solution that will provide controlling of home appliances remotely and will also enable home security against intrusion in the absence of home owner. The motivation is to facilitate the s to automate their homes having ubiquitous access. The system provides availability due to development of a low cost system. The home appliances control system with an affordable cost was thought to be built that should be mobile providing remote access to the appliances and allowing home security. Home security has been a major issue where crime is increasing and everybody wants to take proper measures to prevent intrusion. In addition there was a need to automate home so that can take advantage of the technological advancement in such a way that a person getting

off the office does not get melted with the hot climate. Therefore this paper proposes a system that allows to be control home appliances ubiquitously and also provide security on detection of intrusion via SMS using GSM technology. The home automation today needs to make use of the latest technological components available. In this project, we present the design and implementation of a home automation system

where

communication

technologies

GSM

(Global

System

for

Mobile

Communication). This technique is successfully merged in a single wireless home automation system. This system offers a complete, low cost, powerful and friendly way of real-time monitoring and remote control of a house. It has 2 independent relay switches with normally open and normally closed switch s, these can be programmed to switch on for a pre-determined length of time whenever the GSM-AUTO is called. The relay switches can also be temporarily or permanently switched on or off by sending the GSM-AUTO a command.

INDUSTRIAL AUTOMATION

Industrial automation is the residential extension of "building automation". It is automation of the home, housework or household activity. Industrial automation may include centralized control of lighting, HVAC (heating, ventilation and air conditioning), appliances, and other systems, to provide improved convenience, comfort, energy efficiency and security. Home automation for the elderly and disabled can provide increased quality of life for persons who might otherwise require caregivers or institutional care. A home automation system integrates electrical devices in a house with each other. The techniques employed in home automation include those in building automation as well as the control of domestic activities, such as home entertainment systems, houseplant and yard watering, pet feeding, changing the ambiance "scenes" for different events (such as dinners or parties), and the use of domestic robots. Devices may be connected through a computer network to allow control by a personal computer, and may allow remote access from the internet. Through the integration of information technologies with the home environment, systems and appliances are able to communicate in an integrated manner which results in convenience, energy efficiency, and safety benefits. Industrial automation can also provide a remote interface to home appliances or the automation system itself, via telephone line, wireless transmission or the internet, to provide control and monitoring via a smart phone or web browser. An example of a remote monitoring in home automation could be when a smoke detector detects a fire or smoke condition, then all lights in the house will blink to alert any occupants of the house to the possible fire. If the house is equipped with a home theatre, a home automation system can shut down all audio and video components to avoid distractions, or make an audible announcement. The system could also call the home owner on their mobile phone to alert them, or call the fire department or alarm monitoring company. With Industrial Automation, the consumer can select and watch cameras live from an Internet source to their home or business. Security cameras can be controlled, allowing the to observe activity around a house or business right from a Monitor or touch . Security systems can include motion sensors that will detect any kind of unauthorized movement and notify the through the security system or via cell phone.

Home automation security system is a specialized field dealing with specified requirements of homes in the usage of easy-to-use technologies for security and comforts of the residents. Home automation includes all that a building automation provides like the climate controls, door and window controls and security etc plus additionally controlling multimedia home theatres, pet feeding, plant watering, blinds and so on. But there exists a difference in that home automation emphasizes more on comforts through ergonomics and ease of operation. With the fast development in the field, doorways for wireless home automation system are being opened in a big way.

TYPES OF INDUSTRAIL AUTOMATION CONTROLS The new stream, automation home information system has developed into a vast one and the current market is flooded with a flurry of home automation system and device manufacturers. Home consumers like you have a choice to make that suits your pocket and need alike. Here are some of the types that you may want to consider.

INDIVIDUAL CONTROL DEVICES This type is perhaps the first one to hit the market in the early years. Here each device like the heater or your AC will have an independent control dedicated for it unlike the central control system. These are very handy and are friendly.

DISTRIBUTED CONTROL SYSTEMS The main feature of this type of systems is emergency shut-down. Rest of the features includes hardware and software components developed under SCADA (special software) for better control automated control that reduce human interaction. With this you can preset or change the control parameters, for example, the thermostat of several ACs and ON/OFF timings.

CENTRALLY CONTROLLED SYSTEMS These are computerized systems programmed to handle all functions of multiple utilities like ACs, heaters, home entertainments, doors, windows, refrigerators and cooking systems etc regardless of whether you are home or out. You can connect to your control system from office through telephone or internet. The latest information on home automation system can be had from the suppliers who install it. The best part of this is, with computerized control, you can afford to forget things and still be safe and timely on controls.

Automation is the process of automatically performing everyday functions around the home to save you time, energy, money and at the same time offering improved security Home automation saves your time and effort by controlling you home automatically for performing routine functions such as watering your grass, or turning off all lights, setting the thermostat to economy mode, control scheduled appliances operation and arming the security system when you retire for the night. The concept of home automation is to connect all of these systems and devices to a central controller so that they can be controlled from anywhere and react to one another.

GSM OVERVIEW A cellular communication links mobile system subscribers into the public system or to another cellular system’s MS subscriber. Information sent between the MS subscriber and the cellular network uses radio communication .This removes the necessity for the fixed wiring in a traditional telephone installation. Due to this, the MS subscriber is able to move around and become fully mobile, perhaps travelling in a vehicle or on foot.

ADVANTAGES OF CELLULAR COMMUNICATIONS There are many advantages for the network provider as well as the mobile subscriber.       

Flexibility Mobility Convenience Network expansion flexibility Revenue or profit margins Efficiency Easier re-configuration

GSM (Global System for Mobile Communications, originally Groupe Spécial Mobile), is a standard set developed by the European Telecommunications Standards Institute (ETSI) to describe technologies for second generation (or "2G") digital cellular networks. Developed as a replacement for first generation analog cellular networks, the GSM standard originally described a digital, circuit switched network optimized for full duplex voice telephony. The standard was expanded over time to include first circuit switched data transport, then packet data transport via GPRS. Packet data transmission speeds were later increased via EDGE. The GSM standard is succeeded by the third generation (or "3G") UMTS standard developed by the 3GPP. GSM networks will evolve further as they begin to incorporate fourth generation (or "4G") LTE Advanced standards. "GSM" is a trademark owned by the GSM Association.

GSM is the legacy network of the evolution to the third generation (3G) technologies Universal Mobile Telecommunication System (UMTS), also known as WCDMA, and High Speed Packet Access (HSPA). Commonly referred to as the GSM family of technologies, the following diagram represents the evolution from second generation (2G) GSM and General Packet Radio System (GPRS) to 3G Enhanced Data for GSM Evolution (EDGE), UMTS and HSPA. GSM has a straightforward, cost-effective migration path to 3G through GPRS, EDGE and UMTS-HSPA, as well as beyond 3G via the HSPA Evolution (HSPA+), LTE and System Architecture Evolution (SAE) initiatives. Each step in the GSM-based migration path leverages the network infrastructure deployed for the previous steps and is backwards compatible. For example, a UMTS phone can provide voice and data service when connected to a GSM network. This family of technologies also provides a viable, flexible 3G migration path for Code Division Multiple Access (CDMA) and Time Division Multiple Access (TDMA) operators. In fact, the majority of TDMA operators have already migrated to GSM and many CDMA operators have likewise migrated.

BLOCK DIAGRAM

Mobile Phone

Decoder & Controlling Device

ULN2803

89c51

DTMF DECODER

Incoming Call

Drivers

RELAY

Air Conditioner

RELAY

Refrigerator

RELAY

Jacuzzi

RELAY

Computer

Home Appliances

COMPONENTS USED

1. IC 89c51 2. DTMF IC 8870 3. RELAY 4. OSCILLATOR 5. ULN 2803 IC

1. MICROCONTROLLER 89C51 AT89C51 a low-power, high-performance CMOS 8-bit microcontroller with 4K bytes of insystem programmable Flash memory. The device is manufactured using Atmel’s high-density non-volatile 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 non-volatile memory programmer. By combining a versatile 8-bit U with in-system programmable Flash on a monolithic chip, the Atmel AT89C51 is a powerful microcontroller which provides a highly-flexible and costeffective solution to many embedded control applications. The AT89C51 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 five-vector 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 s two software selectable power saving modes. The Idle Mode stops the U while allowing the RAM, timer/counters, serial port, and interrupt system to continue functioning. The Power-down mode saves the RAM con-tents but freezes the oscillator, disabling all other chip functions until the next interrupter hardware reset.

FEATURES • Compatible with MCS-51™ Products

• 4K Bytes of In-System Reprogrammable Flash Memory • Endurance: 1,000 Write/Erase Cycles • Fully Static Operation: 0 Hz to 24 MHz • Three-level Program Memory Lock • 128 x 8-bit Internal RAM • 32 Programmable I/O Lines • Two 16-bit Timer/Counters • Six Interrupt Sources • Programmable Serial Channel • Low-power Idle and Power-down Modes

A microcontroller (sometimes abbreviated µC, uC or MCU) is a small computer on a single integrated circuit containing a processor core, memory, and programming input/output peripherals. Program memory in the form of NOR Flash or or OTP ROM is also often included on chip, as well as a typically small amount of RAM. Microcontrollers are designed for embedded applications, in contrast to the microprocessors used in personal computers or other general purpose applications. Microcontrollers are used in automatically controlled products and devices, such as automobile engine control systems, implantable medical devices, remote controls, office machines, appliances, power tools, toys and other embedded system. By reducing the size and cost compared to a design that uses a separate microprocessor, memory, and input/output devices, microcontrollers make it economical to digitally control even more devices and processes. Mixed signal microcontrollers are common, integrating analog components needed to control non-digital electronic systems. Some microcontrollers may use four-bit words and operate at clock rate frequencies as low as 4 kHz, for low power consumption (milliwatts or microwatts). 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 (U clock and most peripherals off) may be just nanowatts, making many of them well suited for long lasting battery applications. Other microcontrollers may serve performance-critical roles, where they may need to act more like a digital signal processor(DSP), with higher clock speeds and power consumption.

History The first single-chip microprocessor was the 4-bit Intel 4004 released in 1971, with the Intel 8008 and other more capable microprocessors becoming available over the next several years. However, both processors required external chips to implement a working system, raising total system cost, and making it impossible to economically computerize appliances. The Smithsonian Institution says TI engineers Gary Boone and Michael Cochran succeeded in creating the first microcontroller in 1971. The result of their work was the TMS 1000, which went commercial in 1974. It combined read-only memory, read/write memory, processor and clock on one chip and was targeted at embedded systems. Partly in response to the existence of the single-chip TMS 1000, Intel developed a computer system on a chip optimized for control applications, the Intel 8048, with commercial parts first shipping in 1977. It combined RAM and ROM on the same chip. This chip would find its way into over one billion PC keyboards, and other numerous applications. At that time Intel's President, Luke J. Valenter, stated that the microcontroller was one of the most successful in the company's history, and expanded the division's budget over 25%. Most microcontrollers at this time had two variants. One had an erasable EPROM program memory, which was significantly more expensive than the PROM variant which was only programmable once. Erasing the EPROM required exposure to ultraviolet light through a transparent quartz lid. One-time parts could be made in lower-cost opaque plastic packages. In 1993, the introduction of EEPROM memory allowed microcontrollers (beginning with the Microchip PIC 16x84 to be electrically erased quickly without an expensive package as required for EPROM, allowing both rapid prototyping, and In system programming. The same year, Atmel introduced the first microcontroller using Flash memory. Other companies rapidly followed suit, with both memory types.

Cost has plummeted over time, with the cheapest 8-bit microcontrollers being available for under $0.25 in quantity (thousands) in 2009, and some 32-bit microcontrollers around $1 for similar quantities. Nowadays microcontrollers are cheap and readily available for hobbyists, with large online communities around certain processors. In the future, MRAM could potentially be used in microcontrollers as it has infinite endurance and its incremental semiconductor wafer process cost is relatively low.

Volumes About 55% of all Us sold in the world are 8-bit microcontrollers and microprocessors. According to Semico, over four billion 8-bit microcontrollers were sold in 2006. A typical home in a developed country is likely to have only four general-purpose microprocessors but around three dozen microcontrollers. A typical mid-range automobile has as many as 30 or more microcontrollers. They can also be found in many electrical devices such as washing machines, microwave ovens, and telephones.

EMBEDDED DESIGN A microcontroller can be considered a self-contained system with a processor, memory and peripherals and can be used as an embedded system. The majority of microcontrollers in use today are embedded in other machinery, such as automobiles, telephones, appliances, and peripherals for computer systems. While some embedded systems are very sophisticated, many have minimal requirements for memory and program length, with no operating system, and low software complexity. Typical input and output devices include switches, relays, solenoids, LEDs, small or custom LCD displays, radio frequency devices, and sensors for data such as temperature, humidity, light level etc. Embedded systems usually have no keyboard, screen, disks, printers, or other recognizable I/O devices of a personal computer, and may lack human interaction devices of any kind.

Interrupts

Microcontrollers must provide real time (predictable, though not necessarily fast) response to events in the embedded system they are controlling. When certain events occur, an interrupt system can signal the processor to suspend processing the current instruction sequence and to begin an interrupt service routine (ISR, or "interrupt handler"). The ISR will perform any processing required based on the source of the interrupt before returning to the original instruction sequence. Possible interrupt sources are device dependent, and often include events such as an internal timer overflow, completing an analog to digital conversion, a logic level change on an input such as from a button being pressed, and data received on a communication link. Where power consumption is important as in battery operated devices, interrupts may also wake a microcontroller from a low power sleep state where the processor is halted until required to do something by a peripheral event.

Programs Typically microcontroller programs must fit in the available on-chip program memory, since it would be costly to provide a system with external, expandable, memory. Compilers and assemblers are used to convert high-level language and assembler language codes into a compact machine code for storage in the microcontroller's memory. Depending on the device, the program memory may be permanent, read-only memory that can only be programmed at the factory, or program memory may be field-alterable flash or erasable read-only memory. Manufacturers have often produced special versions of their microcontrollers in order to help the hardware and software developments of the target system. Originally these included EPROM versions that have a "window" on the top of the device through which program memory can be erased by ultraviolet light, ready for reprogramming after a programming ("burn") and test cycle. Since 1998, EPROM versions are rare and have been replaced by EEPROM and flash, which are easier to use (can be erased electronically) and cheaper to manufacture. Other versions may be available where the ROM is accessed as an external device rather than as internal memory, however these are becoming increasingly rare due to the widespread availability of cheap microcontroller programmers. The use of field-programmable devices on a microcontroller may allow field update of the firmware or permit late factory revisions to products that have been assembled but not yet

shipped. Programmable memory also reduces the lead time required for deployment of a new product. Where hundreds of thousands of identical devices are required, using parts programmed at the time of manufacture can be an economical option. These “mask programmed” parts have the program laid down in the same way as the logic of the chip, at the same time. A customizable microcontroller incorporates a block of digital logic that can be personalized in order to provide additional processing capability, peripherals and interfaces that are adapted to the requirements of the application. For example, the AT91CAP from Atmel has a block of logic that can be customized during manufacturer according to requirements.

Other microcontroller features Microcontrollers usually contain from several to dozens of general purpose input/output pins (GPIO). GPIO pins are software configurable to either an input or an output state. When GPIO pins are configured to an input state, they are often used to read sensors or external signals. Configured to the output state, GPIO pins can drive external devices such as LEDs or motors. Many embedded systems need to read sensors that produce analog signals. This is the purpose of the analog to digital convertor (ADC). Since processors are built to interpret and process digital data, i.e. 1s and 0s, they are not able to do anything with the analog signals that may be sent to it by a device. So the analog to digital converter is used to convert the incoming data into a form that the processor can recognize. A less common feature on some microcontrollers is a digital to analog convertor (DAC) that allows the processor to output analog signals or voltage levels. In addition to the converters, many embedded microprocessors include a variety of timers as well. One of the most common types of timers is the Programmable Interval Timer(PIT). A PIT may either count down from some value to zero, or up to the capacity of the count , overflowing to zero. Once it reaches zero, it sends an interrupt to the processor indicating that it has finished counting. This is useful for devices such as thermostats, which periodically test the temperature around them to see if they need to turn the air conditioner on, the heater on, etc.

A dedicated Pulse Width Modulation(PWM) block makes it possible for the U to control power convertors, resistive loads, motors, etc., without using lots of U resources in tight timer loops. Universal Asynchronous Receiver/Transmitter (UART) block makes it possible to receive and transmit data over a serial line with very little load on the U. Dedicated onchip hardware also often includes capabilities to communicate with other devices (chips) in digital formats such as IC and Serial Peripheral Interfaces(SPI).

Higher Integration Micro-controllers may not implement an external address or data bus as they integrate RAM and non-volatile memory on the same chip as the U. Using fewer pins, the chip can be placed in a much smaller, cheaper package. Integrating the memory and other peripherals on a single chip and testing them as a unit increases the cost of that chip, but often results in decreased net cost of the embedded system as a whole. Even if the cost of a U that has integrated peripherals is slightly more than the cost of a U and external peripherals, having fewer chips typically allows a smaller and cheaper circuit board, and reduces the labor required to assemble and test the circuit board. A micro-controller is a single integrated system, commonly with the following features: 

Central processing unit- ranging from small and simple 4-bit processors to complex 32- or 64-bit processors



volatile memory (RAM) for data storage



ROM, EPROM, EEPROM or Flash memory for program and operating parameter storage



discrete input and output bits, allowing control or detection of the logic state of an individual package pin



serial input/output such as serial ports (UARTs)



other serial

communications interfaces like

IC, Serial

Interface and Controller Area Network for system interconnect

Peripheral



peripherals such as timers, event counters, PWM generators, and watchdog



clock generator - often an oscillator for a quartz timing crystal, resonator or RC circuit



many include analog-to-digital converters, some include digital-to-analog converters



in-circuit programming and debugging

This integration drastically reduces the number of chips and the amount of wiring and circuit board space that would be needed to produce equivalent systems using separate chips. Furthermore, on low pin count devices in particular, each pin may interface to several internal peripherals, with the pin function selected by software. This allows a part to be used in a wider variety of applications than if pins had dedicated functions. Micro-controllers have proved to be highly popular in embedded systems since their introduction in the 1970s. Some microcontrollers use a Harvard architecture: separate memory buses for instructions and data, allowing accesses to take place concurrently. Where a Harvard architecture is used, instruction words for the processor may be a different bit size than the length of internal memory and s; for example: 12-bit instructions used with 8-bit data s. The decision of which peripheral to integrate is often difficult. The microcontroller vendors often trade operating frequencies and system design flexibility against time-to-market requirements from their customers and overall lower system cost. Manufacturers have to balance the need to minimize the chip size against additional functionality. Microcontroller architectures vary widely. Some designs include general-purpose microprocessor cores, with one or more ROM, RAM, or I/O functions integrated onto the package. Other designs are purpose built for control applications. A micro-controller instruction set usually has many instructions intended for bit-wise operations to make control programs more compact. For example, a general purpose processor might require several instructions to test a bit in a and branch if the bit is set, where a micro-controller could have a single instruction to provide that commonly-required function. Microcontrollers typically do not have a math coprocessor, so floating point arithmetic is performed by software.

PROGRAMMING ENVIRONMENTS

Microcontrollers were originally programmed only in assembly language, but various highlevel programming languages are now also in common use to target microcontrollers. These languages are either designed especially for the purpose, or versions of general purpose languages such as the language. Compilers for general purpose languages will typically have some restrictions as well as enhancements to better the unique characteristics of microcontrollers. Some microcontrollers have environments to aid developing certain types of applications. Microcontroller vendors often make tools freely available to make it easier to adopt their hardware. Many microcontrollers are so quirky that they effectively require their own non-standard dialects of C, such as SDCC for the 8051, which prevent using standard tools (such as code libraries or static analysis tools) even for code unrelated to hardware features. Interpreters are often used to hide such low level quirks. Interpreter firmware is also available for some microcontrollers. For example, BASIC on the early microcontrollers Intel 8052; BASIC and FORTH on the Zilog Z8 as well as some modern devices. Typically these interpreters interactive programming. Simulators are available for some microcontrollers. These allow a developer to analyze what the behavior of the microcontroller and their program should be if they were using the actual part. A simulator will show the internal processor state and also that of the outputs, as well as allowing input signals to be generated. While on the one hand most simulators will be limited from being unable to simulate much other hardware in a system, they can exercise conditions that may otherwise be hard to reproduce at will in the physical implementation, and can be the quickest way to debug and analyze problems. Recent microcontrollers are often integrated with on-chip debug circuitry that when accessed by an in-circuit emulator via JTAG, allow debugging of the firmware with a debugger.

TYPES OF MICROCONTROLLER As of 2008 there are several dozen microcontroller architectures and vendors including: 

ARM core processors (from many vendors)



Atmel AVR (8-bit), AVR32 (32-bit), and AT91SAM (32-bit)



Cypress Semiconductor's M8C Core used in their PSoC (Programmable System-onChip)



Freescale ColdFire (32-bit) and S08 (8-bit)



Freescale 68HC11 (8-bit)



Intel 8051

Many others exist, some of which are used in very narrow range of applications or are more like applications processors than microcontrollers. The microcontroller market is extremely fragmented, with numerous vendors, technologies, and markets. Note that many vendors sell or have sold multiple architectures.

PIN DIAGRAM

Pin Description

VCC 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 may 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. Port 1 also receives the low-order address bytes during Flash programming and program verification. Port 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 pullups 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 pullups. 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 it 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 . 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 pullups. 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 pullups and can be used as inputs. As inputs, Port 3 pins that are externally being pulled low will source current (IIL) because of the pullups. Port 3 also serves the functions of various special features of the AT89C51 as listed below:

Port 3 also receives some control signals for Flash programming and Programming verification.

RST Reset input. A high on this pin for two machine cycles while the oscillator is running resets the device. ALE/PROG Address Latch Enable 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 is the read strobe to external program memory. When the AT89C51 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 receive the 12-volt programming enable voltage (VPP) during flash programming, for parts that require 12-volt VPP.

XTAL1 Input to the inverting oscillator amplifier and input to the internal clock operating circuit. XTAL2 Output from the inverting oscillator amplifier.

2. DTMF ( IC 8870) Most telephone equipment use a DTMF receiver IC. One common DTMF receiver IC is the Motorola MT8870 that is widely used in electronic communications circuits. The MT8870 is an 18-pin IC. It is used in telephones and a variety of other applications. When a proper output is not obtained in projects using this IC, engineers or technicians need to test this IC separately. A quick testing of this IC could save a lot of time in research labs and manufacturing industries of communication instruments. Here’s a small and handy tester circuit for the DTMF IC. It can be assembled on a multipurpose PCB with an 18-pin IC base. One can also test the IC on a simple breadboard. For optimum working of telephone equipment, the DTMF receiver must be designed to recognise a valid tone pair greater than 40 ms in duration and to accept successive digit tone-pairs that are greater than 40 ms apart. However, for other applications like remote controls and radio communications, the tone duration may differ due to noise considerations. Therefore, by adding an extra resistor and steering diode the tone duration can be set to different values. The circuit is configured in balanced line mode. To reject common-mode noise signals, a balanced differential amplifier input is used. The circuit also provides an excellent bridging interface across a properly terminated telephone line. Transient protection may be achieved by splitting the input resistors and inserting zener diodes (ZD1 and ZD2) to achieve voltage clamping. This allows the transient energy to be dissipated in the resistors and diodes, and limits the maximum voltage that may appear at the inputs. Whenever you press any key on your local telephone keypad, the delayed steering output of the IC goes high on receiving the tone-pair, causing LED to glow. It will be high for duration depending on the values of capacitor and resistors Dual-tone multi-frequency (DTMF) signalling is used for telecommunication signalling over analog telephone lines in the voice-frequency band between telephone handsets and other communications devices and the switching centre. The version of DTMF used

for telephone tone dialling is known by the trademarked term Touch-Tone (cancelled March 13, 1984), and is standardized by ITU-T Recommendation. It is also known in the UK as MF4. Other multi-frequency systems are used for signalling internal to the telephone network. As a method of in-band signalling, DTMF tones were also used by cable television broadcasters to indicate the start and stop times

of

local

commercial insertion points during station breaks for the benefit of cable companies. Until better

out-of-band signalling

equipment was

developed in the 1990s, fast,

unacknowledged, and loud DTMF tone sequences could be heard

during the

commercial breaks of cable channels in the United States and elsewhere.

PIN DIAGRAM

3. 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 s. The coil current can be on or off so relays have two switch positions and most have double throw (changeover) switch s 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.

The coil of a relay es 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 s, for example relays with 4 sets of changeover s are readily available. For further information about switch s and the 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 s. You can see a lever on the left being attracted by magnetism when the coil is switched on. This lever moves the switch s. There is one set of s (spdt) in the foreground and another behind them, making the relay dpdt.

The relay's switch connections are usually labelled 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.

A relay is an electrically operated switch. Many relays use an electromagnet to operate a switching mechanism mechanically, but other operating principles are also used. Relays are

used where it is necessary to control a circuit by a low-power signal (with complete electrical isolation between control and controlled circuits), or where several circuits must be controlled by one signal. The first relays were used in long distance telegraph circuits, repeating the signal coming in from one circuit and re-transmitting it to another. Relays were used extensively in telephone exchanges and early computers to perform logical operations. A type of relay that can handle the high power required to directly control an electric motor or other loads is called a or. Solid-state relays control power circuits with no moving parts, instead using a semiconductor device to perform switching. Relays with calibrated operating characteristics and sometimes multiple operating coils are used to protect electrical circuits from overload or faults; in modern electric power systems these functions are performed by digital instruments still called "protective relays".

BASIC DESIGN AND OPERATION

Simple electromechanical relay.

Small "cradle" relay often used in electronics. The "cradle" term refers to the shape of the relay's armature. A simple electromagnetic relay consists of a coil of wire wrapped around a soft iron core, an iron yoke which provides a low reluctance path for magnetic flux, a movable iron armature, and one or more sets of s (there are two in the relay pictured). The armature is hinged to the yoke and mechanically linked to one or more sets of moving s. It is held in place by a spring so that when the relay is de-energized there is an air gap in the magnetic circuit. In this condition, one of the two sets of s in the relay pictured is closed, and the other set is open. Other relays may have more or fewer sets of s depending on their function. The relay in the picture also has a wire connecting the armature to the yoke. This ensures continuity of the circuit between the moving s on the armature, and the circuit track on the printed circuit board (PCB) via the yoke, which is soldered to the PCB. When an electric current is ed through the coil it generates a magnetic field that activates the armature, and the consequent movement of the movable (s) either makes or breaks (depending upon construction) a connection with a fixed . If the set of s was closed when the relay was de-energized, then the movement opens the s and breaks the connection, and vice versa if the s were open. When the current to the coil is switched off, the armature is returned by a force, approximately half as strong as the magnetic force, to its relaxed position. Usually this force is provided by a spring, but gravity is also used commonly in industrial motor starters. Most relays are manufactured to operate quickly. In a low-voltage application this reduces noise; in a high voltage or current application it reduces arcing. When the coil is energized with direct current, a diode is often placed across the coil to dissipate the energy from the collapsing magnetic field at deactivation, which would

otherwise generate a voltage spike dangerous to semiconductor circuit components. Some automotive relays include a diode inside the relay case. Alternatively, a protection network consisting of a capacitor and resistor in series (snubber circuit) may absorb the surge. If the coil is designed to be energized with alternating current (AC), a small copper "shading ring" can be crimped to the end of the solenoid, creating a small out-of-phase current which increases the minimum pull on the armature during the AC cycle.[1] A solid-state relay uses a thyristor or other solid-state switching device, activated by the control signal, to switch the controlled load, instead of a solenoid. An optocoupler (a lightemitting diode (LED) coupled with a photo transistor) can be used to isolate control and controlled circuits.

Since relays are switches, the terminology applied to switches is also applied to relays. A relay will switch one or morepoles, each of whose s can be thrown by energizing the coil in one of three ways: 

Normally-open (NO) s connect the circuit when the relay is activated; the circuit is disconnected when the relay is inactive. It is also called a Form A or "make" . NO s can also be distinguished as "early-make" or NOEM, which means that the s will close before the button or switch is fully engaged.



Normally-closed (NC) s disconnect the circuit when the relay is activated; the circuit is connected when the relay is inactive. It is also called a Form B or "break" . NC s can also be distinguished as "late-break" or NCLB, which means that the s will stay closed until the button or switch is fully disengaged.



Change-over (CO), or double-throw (DT), s control two circuits: one normally-open and one normally-closed with a common terminal. It is also called a Form C or "transfer" ("break before make"). If this type of utilizes a "make before break" functionality, then it is called a Form D .

The following designations are commonly encountered: 

SPST – Single Pole Single Throw. These have two terminals which can be connected or disconnected. Including two for the coil, such a relay has four terminals in total. It is ambiguous whether the pole is normally open or normally closed. The terminology "SPNO" and "SPNC" is sometimes used to resolve the ambiguity.



SPDT – Single Pole Double Throw. A common terminal connects to either of two others. Including two for the coil, such a relay has five terminals in total.



DPST – Double Pole Single Throw. These have two pairs of terminals. Equivalent to two SPST switches or relays actuated by a single coil. Including two for the coil, such a relay has six terminals in total. The poles may be Form A or Form B (or one of each).



DPDT – Double Pole Double Throw. These have two rows of change-over terminals. Equivalent to two SPDT switches or relays actuated by a single coil. Such a relay has eight terminals, including the coil.

The "S" or "D" may be replaced with a number, indicating multiple switches connected to a single actuator. For example 4PDT indicates a four pole double throw relay (with 14 terminals). EN 50005 are among applicable standards for relay terminal numbering; a typical EN 50005compliant SPDT relay's terminals would be numbered 11, 12, 14, A1 and A2 for the C, NC, NO, and coil connections, respectively.

4. OSCILLATOR A crystal oscillator is an electronic oscillator circuit that uses the mechanical resonance of a vibrating crystal of piezoelectric material to create an electrical signal with a very precise frequency. This frequency is commonly used to keep track of time (as in quartz wristwatches), to provide a stable clock signal for digital integrated circuits, and to stabilize frequencies for radio transmitters and receivers. The most common type of piezoelectric resonator used is the quartz crystal, so oscillator circuits designed around them became known as "crystal oscillators."

An electronic oscillator is an electronic circuit that produces a repetitive electronic signal, often a sine wave or a square wave. They are widely used in many electronic devices. Common examples of signals generated by oscillators include signals broadcast by radio and television transmitters, clock signals that regulate computers and quartz clocks, and the sounds produced by electronic beepers and video games.[1] Oscillators are often characterized by the frequency of their output signal: an audio oscillator produces frequencies in the audio range, about 16 Hz to 20 kHz. An RF oscillator produces signals in the radio frequency (RF) range of about 100 kHz to 100 GHz. A lowfrequency oscillator (LFO) is an electronic oscillator that generates a frequency below ≈20 Hz. This term is typically used in the field of audio synthesizers, to distinguish it from an audio frequency oscillator. Oscillators designed to produce a high-power AC output from a DC supply are usually called inverters. There are two main types of electronic oscillator: the linear or harmonic oscillator and the nonlinear or relaxation oscillator.

The basic form of a linear oscillator is an electronic amplifier connected in a loop with its output fed back into its input through a frequency selective electronic filter to provide positive . When the power supply to the amplifier is first switched on, the amplifier's output consists only of noise. The noise travels around the loop and is filtered and re-amplified until it increasingly resembles a sine wave at a single frequency. Linear oscillator circuits can be classified according to the type of frequency selective filter they use in the loop: 

In an RC oscillator circuit, the filter is a network of resistors and capacitors. RC oscillators are mostly used to generate lower frequencies, for example in the audio range. Common types of RC oscillator circuits are the phase shift oscillator and the Wien bridge oscillator.



In an LC oscillator circuit, the filter is a tuned circuit (often called a tank circuit) consisting of an inductor (L) and capacitor (C) connected together. Charge flows back and forth between the capacitor's plates through the inductor, so the tuned circuit can store electrical energy oscillating at its resonant frequency. There are small losses in the tank circuit, but the amplifier compensates for those losses and supplies the power for the output signal. LC oscillators are often used at radio frequencies, when a tunable frequency source is necessary, such as in signal generators, tunable radio transmitters and the local oscillators in radio receivers. Typical LC oscillator circuits are the Hartley, Colpitts and Clapp circuits.



In a crystal oscillator circuit the filter is a piezoelectric crystal (commonly a quartz crystal). The crystal mechanically vibrates as a resonator, and its frequency of vibration determines the oscillation frequency. Crystals have very high Q-factor and also better temperature stability than tuned circuits, so crystal oscillators have much better frequency stability than LC or RC oscillators. They are used to stabilize the frequency of most radio transmitters, and to generate the clock signal in computers and quartz clocks. Crystal oscillators often use the same circuits as LC oscillators, with the crystal replacing the tuned circuit; the Pierce oscillator circuit is commonly used. Quartz crystals are generally limited to frequencies of 30 MHz or below. Surface acoustic wave (SAW) devices are another kind of piezoelectric resonator used in crystal oscillators, which can achieve much higher frequencies. They are used in specialized applications which require a high frequency reference, for example, in cellular telephones.

In addition to the oscillators described above, which use two-port amplifying active elements such as transistors and op amps, linear oscillators can also be built using one-port devices with negative resistance, such as magnetron tubes, tunnel diodes and Gunn diodes. In these oscillators, a resonator, such as an LC circuit, crystal, or cavity resonator, is connected across the negative resistance device, and a DC bias voltage is applied to supply energy. The negative resistance of the active device can be thought of as cancelling the (positive) effective loss resistance of the resonator and permitting a sustained oscillation. These circuits are frequently used for oscillators at microwave frequencies. RELAXATION OSCILLATOR

A nonlinear or relaxation oscillator produces a non-sinusoidal output, such as a square, sawtooth or triangle wave. It contains an energy-storing element (a capacitor or, more rarely, an inductor) and a nonlinear switching circuit (a latch, Schmitt trigger, or negative resistance element) that periodically charges and discharges the energy stored in the storage element thus causing abrupt changes in the output waveform. Square-wave relaxation oscillators are used to provide the clock signal for sequential logic circuits such as timers and counters, although crystal oscillators are often preferred for their greater stability. Triangle wave or sawtooth oscillators are used in the timebase circuits that generate the horizontal deflection signals for cathode ray tubes in analogue oscilloscopes and television sets. In function generators, this triangle wave may then be further shaped into a close approximation of a sine wave. Ring oscillators are built of a ring of active delay stages. Generally the ring has an odd number of inverting stages, so that there is no single stable state for the internal ring voltages. Instead, a single transition propagates endlessly around the ring.

ULN 2803 IC The eight NPN Darlington connected transistors in this family of arrays are ideally suited for interfacing between low logic level digital circuit (such as TTL, CMOS or PMOS/NMOS) and the higher current/voltage requirements of lamps, relays, printer hammers or other similar loads for a broad range of computer, industrial, and consumer applications. All devices feature open-collector outputs and freewheeling clamp diodes for transient suppression. The ULN2803 is designed to be compatible with standard TTL families while the ULN2804 is optimized for 6 to 15 volt high level CMOS or PMOS.

CIRCUIT DIAGRAM

GSM CIRCUIT

Relay Circuit

Relay Circuit

CIRCUIT DIAGRAM OF THE SYSTEM

PROGRAM USED

#include #include<string.h> sbit relay1=P2^0; sbit relay2=P2^1; sbit relay3=P2^3; void main() { int i=0; char arr[16]; relay1=relay2=relay3=0; P3=0xff; while(1) { while(P3!=0xfc) { if(P3==0xf1) { arr[i++]='1'; while(P3==0xf1); }

else if(P3==0xf2) { arr[i++]='2'; while(P3==0xf2); } else if(P3==0xf3) { arr[i++]='3'; while(P3==0xf3); } else if(P3==0xf4) { arr[i++]='4'; while(P3==0xf4); } else if(P3==0xf5) { arr[i++]='5'; while(P3==0xf5); }

else if(P3==0xf6) { arr[i++]='6'; while(P3==0xf6); } else if(P3==0xf7) { arr[i++]='7'; while(P3==0xf7); } else if(P3==0xf8) { arr[i++]='8'; while(P3==0xf8); } else if(P3==0xf9) { arr[i++]='9'; while(P3==0xf9); }

else if(P3==0xfa) { arr[i++]='0'; while(P3==0xfa); } arr[i]='\0'; } i=0; if(strcmp(arr,"123")==0) relay1=1; else if(strcmp(arr,"321")==0) relay1=0; else if(strcmp(arr,"456")==0) relay2=1; else if(strcmp(arr,"654")==0) relay2=0; else if(strcmp(arr,"789")==0) relay3=1; else if(strcmp(arr,"987")==0) relay3=0;

else if(strcmp(arr,"0")==0) P2=0x00; while(P3==0xfc); } } ADVANTAGES 1. 2. 3. 4. 5. 6.

GLOBAL RANGE LOW COST LOW POWER REQUIREMENT WIRELESS CONTROL NO BOUNDATION OF RANGE USE OF MOBILE TECHNOLOGY WHICH IS PRESENT EVERYWHERE

DISADVANTAGES 1. DELAYS IN MOBILE NETWORKS 2. NEED OF A MOBILE PHONE DEDICATED FOR THIS SYSTEM 3. COST OF THE MOBILE IF INCLUDED

POSSIBLE IMPROVEMENTS 1. CONTROL OF MORE DEVICES: We can use of more and more devices of our home peripherals through the home automation system. Here we have shown only four bulbs as home devices but we can use any type of home appliances to the circuit to avail the facility.

For examples: Television, Fridge, Cooler, Air-conditioner, Fan, Heater etc. 2. USE OF INTERNET: There are two types of technologies to control home appliances, one is using GSM Technology and second is INTERNET service. Through internet we can control the devices. 3. THEFT ALERT: By using sensors and cameras, the security of home may be increased to high level. Special commands and equipment are used to make security. 4. ADDING VOICE RECOGNITION: By adding voice recognition circuit the locking system ( based) accession of home may be create so that unauthorized persons can’t use the home and its devices without permission.

CONCLUSIONS Home Automation has been taken into a new dimension. We have clearly demonstrated that Mobile Home Automation is the birth of a brand new era open to endless possibilities. Mobile Home Automation can be applied for your convenience. For example, living in a city such as Delhi where the temperature can greatly vary between the morning and the evening, Mobile Home Automation can be very beneficial. Say you leave to work in the morning on a

hot summery day and during the day you start to realize that the temperature aiming to go below freezing, you can then remotely turn on the heating at your home. We have shown how Mobile Home Automation can be performed using a main medium of communication in this information age, the mobile phone. The basic level of home appliance control and remote monitoring has been implemented. our project allows for greater development of products. The code is open source and we are providing for development by others for application in several ways. With our software, we could develop it for more complicated applications.

BIBLIOGRAPHY       

http://www.8051projects.info http://www.datasheet4u.com http://www.seminarprojects.com http:// www.ieeexplore.ieee.org http://en.wikipedia.org/wiki/Electronic_oscillator http://en.wikipedia.org/wiki/Relay http://en.wikipedia.org/wiki/Microcontroller



“Programming and Customizing the 8051 Microcontroller” by TATA McGRAW



HILL “The 8051 Microcontroller and Embedded Systems” by Muhammad Ali Mazidi, Janice Gillispie Mazidi.