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Home Appliances Control Using RF

Paper Type: Free Essay Subject: Information Technology
Wordcount: 2430 words Published: 2nd Jan 2018

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The project “HOME APPLIANCES CONTROL USING RF” is an alternate of the job done by human like switch on/off by hand. Here job of doing on/off can be done by from a distance by help of remote.

The ckt. Consists of four parts. These are listed below:-

Power supply of 5v and 9v:-

it consist of ic 7805,7809 , two transformer, capacitors and diode.


it consists of m/c AT89S52 , reset ckt.

RF module:-

It consists of ic HT-12D AND HT-12E

relay part:-

two ralays, two diode,two bulbs



In this rf based project our data to control home appliance is send from remote to control them, here user only have to press the switch of remote.

In other words, one could remotely turn on light in ones lawn or the air conditioning at home, or turn on/off the light of room by help of remote sitting at one palace in home,

The operation cost and power required is also less.


In this project our signal is transmitted through air from RF transmitter to RF receiver, which decoded the signal received, now decoded signal is send by 4 line to microcontroller.

Microcontroller do the work on received data according to programming, which will turn on/off the relays, then bulbs are also on/off.





Fig. 2


Fig. 3



There are two power supplies one of 5v and second of 9v. Power supplies are made by bridge wave rectifier. For making 5v supply we use 4doide, one capacitor of 470 micro F, ic regulator 7805, similarly the second power supply. 5v supply is given to AT89S52 and 9V to operate the relay.

Firstly the rf signal is generated by ic HT-12E and transmitted through air by help of rf transmitter module, the received data is now decoded by rf ic HT-12D and send to microcontroller to work on it. Some connections are made be ready the functioning of both ics. When signal is decoded by ic HT-12D it gives output by its pin no. 10 to 13.

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These output lines feed to m/c to pin no. 10 to 13 to make the m/c in action some connection are made as shown in fig of ckt.(Reset ckt. At pin no. 9, oscillator of value 11.0592 at pin no. 18 and 19 and power at pin no 40) Now, button of remote is pressed by user then m/c do low or high to the pin no p2.0 and p2.1 output line from m/c connected to TIP 122 base. These are high power transistor whose base is connected to to pin no p2.0 and p2.1 of m/c through resistance. If high power is given to TIP than it will be on due to which the relay make the connection between 3 and 4, and bulb be on. If low is at base of TIP then TIP will not work and connection of relay will be 3 and 4 due to which bulb be off.

So we can do on/off the home appliance by help of remote.

In our project one bulb be on by pressing button 1, second by help of 2, both will be on by button no. 3. And both will be offed by button no. 4.



By using home appliance control using rf we can control all the electrical devices of a home with the help of remote. We can on/off the devices by a distance.

With the help of this concept we can make a robotic hand to handle the objects which a far away from us.

With this we can also design car whose motion can be controlled by a remote. For a specific movement of car we will define a specific command for forward movement we will press button no. 1 for backward button no. 2 for left by help of button no. 3 and right by button by help of button no. 4

Other applications

Burglar alarm system

Smoke and fire alarm system

Garage door controllers

Car door controllers

Car alarm system

Security system

Cordless telephones

Other remote control systems



While controlling home appliances using RF we have to face some following problems:-

We have used it to a particular range abt. of some meters not in range of kilometer or more distance.

If m/c hanged we want to do on/off the switch then we are not confirmed abt. it’s on/off states.


This project is very useful for electricity saving purpose. Because we can do on/off the switch very quickly, otherwise due to laziness we avoid to on/off them.

Project can easily be used by any one because to use this project one should not need to learn any special things and this project is very economical due to its simple circuit and by use of cheap components.


Serial no.



















TIP 122




IN 4001N







AT 89S52










Fig. 4 ref(3)

The Intel AT89S52 is a Harvard architecture, single chip microcontroller (µC) which was developed by Intel in 1980 for use in embedded systems. It was popular in the 1980s and early 1990s, but today it has largely been superseded by a vast range of enhanced devices with AT89S52-compatible processor cores that are manufactured by more than 20 independent manufacturers including Atmel, Infineon Technologies, Maxim Integrated Products (via its Dallas Semiconductor subsidiary), NXP (formerly Philips Semiconductor), Winbond, ST Microelectronics, Silicon Laboratories (formerly Cygnal), Texas Instruments and Cypress Semiconductor. Intel’s official designation for the AT89S52 family of µCs is MCS 51.

Intel’s original AT89S52 family was developed using NMOS technology, but later versions, identified by a letter “C” in their name, e.g. 80C51, used CMOS technology and were less power-hungry than their NMOS predecessors – this made them eminently more suitable for battery-powered devices

Important features and applications:-

It provides many functions (CPU, RAM, ROM, I/O, interrupt logic, timer, etc.) in a single package

8-bit data bus – It can access 8 bits of data in one operation (hence it is an 8-bit microcontroller)

16-bit address bus – It can access 216 memory locations – 64 kB each of RAM and ROM

On-chip RAM – 128 bytes (“Data Memory”)

On-chip ROM – 4 kB (“Program Memory”)

Four byte bi-directional input/output port

UART (serial port)

Two 16-bit timers

Two-level interrupt priority

Power saving mode

A particularly useful feature of the AT89S52 core is the inclusion of a boolean processing engine which allows bit-level boolean logic operations to be carried out directly and efficiently on internal registers and RAM. This feature helped to cement the 8051’s popularity in industrial control applications. Another valued feature is that it has four separate register sets, which can be used to greatly reduce interrupt latency compared to the more common method of storing interrupt context on a stack.

The AT89S52UART an be configured to use a 9th data bit that can provide addressable communications in an RS-485 multi-point communications environment.

AT89S52 based microcontrollers typically include one or two UARTs, two or three timers, 128 or 256 bytes of internal data RAM (16 bytes of which are bit addressable), up to 128 bytes of I/O, 512 bytes to 64 kB of internal program memory, and sometimes a quantity of extended data RAM(ERAM) located in the external data space. The original AT89S52 core ran at 12 clock cycles per machine cycle, with most instructions executing in one or two machine cycles. With a 12 MHz clock frequency, the AT89S52 could thus execute 1 million one-cycle instructions per second or 500,000 two-cycle instructions per second. Enhanced 8051 cores are now commonly used which run at six, four, two, or even one clock per machine cycle, and have clock frequencies of up to 100 MHz, and are thus capable of an even greater number of instructions per second. All SILabs, some Dallas and a few Atmel devices have single cycle cores.

Even higher speed single cycle 8051 cores, in the range 130 MHz to 150 MHz, are now available in internet downloadable form for use in programmable logic devices such as FPGAs, and at many hundreds of MHz in ASICs, for example the net list from www.e8051.com.

Common features included in modern 8051 based microcontrollers include built-in reset timers with brown-out detection, on-chip oscillators, self-programmable Flash ROM program memory, boot loader code in ROM, EEPROM non-volatile data storage, I²C, SPI, and USB host interfaces, PWM generators, analog comparators, A/D and D/A converters, RTCs, extra counters and timers, in-circuit debugging facilities, more interrupt sources, and extra power saving modes.



Fig. 5 ref(3)

Pins 1-8: Port 1 Each of these pins can be configured as input or output.

Pin 9: RS Logical one on this pin stops microcontroller’s operating and erases the contents of most registers. By applying logical zero to this pin, the program starts execution from the beginning. In other words, a positive voltage pulse on this pin resets the microcontroller.

Pins10-17: Port 3 Similar to port 1, each of these pins can serve as universal input or output . Besides, all of them have alternative functions:

Pin 10: RXD Serial asynchronous communication input or Serial synchronous communication output.

Pin 11: TXD Serial asynchronous communication output or Serial synchronous communication clock output.

Pin 12: INT0 Interrupt 0 input

Pin 13: INT1 Interrupt 1 input

Pin 14: T0 Counter 0 clock input

Pin 15: T1 Counter 1 clock input

Pin 16: WR Signal for writing to external (additional) RAM

Pin 17: RD Signal for reading from external RAM

Pin 18, 19: X2, X1 Internal oscillator input and output. A quartz crystal which determines operating frequency is usually connected to these pins. Instead of quartz crystal, the miniature ceramics resonators can be also used for frequency stabilization. Later versions of the microcontrollers operate at a frequency of 0 Hz up to over 50 Hz.

Pin 20: GND Ground

Pin 21-28: Port 2 If there is no intention to use external memory then these port pins are configured as universal inputs/outputs. In case external memory is used then the higher address byte, i.e. addresses A8-A15 will appear on this port. It is important to know that even memory with capacity of 64Kb is not used ( i.e. note all bits on port are used for memory addressing) the rest of bits are not available as inputs or outputs.

Pin 29: PSEN If external ROM is used for storing program then it has a logic-0 value every time the microcontroller reads a byte from memory.

Pin 30: ALE Prior to each reading from external memory, the microcontroller will set the lower address byte (A0-A7) on P0 and immediately after that activates the output ALE. Upon receiving signal from the ALE pin, the external register (74HCT373 or 74HCT375 circuit is usually embedded ) memorizes the state of P0 and uses it as an address for memory chip. In the second part of the microcontroller’s machine cycle, a signal on this pin stops being emitted and P0 is used now for data transmission (Data Bus). In this way, by means of only one additional (and cheap) integrated circuit, data multiplexing from the port is performed. This port at the same time used for data and address transmission.

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Pin 31: EA By applying logic zero to this pin, P2 and P3 are used for data and address transmission with no regard to whether there is internal memory or not. That means that even there is a program written to the microcontroller, it will not be executed, the program written to external ROM will be used instead. Otherwise, by applying logic one to the EA pin, the microcontroller will use both memories, first internal and afterwards external (if it exists), up to end of address space.

Pin 32-39: Port 0 Similar to port 2, if external memory is not used, these pins can be used as universal inputs or outputs. Otherwise, P0 is configured as address output (A0-A7) when the ALE pin is at high level (1) and as data output (Data Bus), when logic zero (0) is applied to the ALE pin.

Pin 40: VCC Power supply +5V



7805 is an integrated three-terminal positive fixed linear voltage regulator. It supports an input voltage of 7 volts to 35 volts and output voltage of 5 volts. It typically has a current rating of 1 amp although both higher and lower current models are available. Its output voltage is fixed at 5.0V. The 7805 also have a built-in current limiter as a safety feature.

The 7805 will automatically reduce output current if it gets too hot. It belongs to a family of three-terminal positive fixed regulators with similar specifications and differing fixed voltages from 8 to 15 volts.

The last two digits represent the voltage; for instance, the 7812 is a 12-volt regulator. The 78xx series of regulators is designed to work in complement with the 79xx series of negative voltage regulators in systems that provide both positive and negative regulated voltages, since the 78xx series can’t regulate negative voltages in such a system.

The 7805 is one of the most common and well known of the 78xx series regulators, as its small component count and medium-power regulated 5V make it useful for powering TTL.




Search Enginewww.google.com.

Data Sheets from www.alldatasheet.com

Article on Password Based Security System on www.8051projectinfo.com

Data Sheet of Microcontroller from www.atmel .com

Article on “Password based security system “from Wikipedia.

Text Book on 8051 Microcontroller (Mazidi)

Text book on 8051 Microcontroller(Kenneth J. Ayala)


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