http://www.edgefxkits.com/

TV Remote Operated Domestic Appliances Control

http://www.edgefxkits.com/

Abstract

A typical TV remote sends coded infrared data that is read by a IR sensor with the help of a Microcontroller.

This is traditionally RC5 code as followed by remotes from PHILIPS.

The same data is then burnt to a microcontroller to drive desired output load through relays or opto isolators and triacs.

All the buttons of the remote can be used for as much number of loads to be operated.

All the above functions are monitored and controlled by the 8 bit microcontroller

http://www.edgefxkits.com/

Introduction

The project is designed to operate electrical loads using a TV remote.

The remote transmits coded infrared data which is then received by a sensor interfaced to the control unit.

The system operates electrical loads depending on the data transmitted from the TV remote.

Operating conventional wall switches is difficult for elderly or physically handicapped people.

This proposed system solves the problem by integrating house hold appliances to a control unit that can be operated by a TV remote.

http://www.edgefxkits.com/

Block Diagram

http://www.edgefxkits.com/

Working

The project uses an IR receiver such a TSOP-1738 that responds to only specific frequency of 38 kHz in order to avoid receiving false signal from normal environmental infrared sources.

The output of this receiver in interfaced to port 3.0 of the microcontroller.

A standard TV remote that delivers infrared codes at 38khz is thus received by the TSOP receiver feeding a 14 bit data so emitted from the remote to the microcontroller through receiver.

The output from the MC is fed to the relay driver IC to switch ON & switch OFF the load as sent from the TV remote.

http://www.edgefxkits.com/

Hardware Requirement

POWER SUPPLY BLOCK

MICROCONTROLLER (AT89S52/AT89C51)

RC5 CODE

RELAY

ULN 2003

TSOP

http://www.edgefxkits.com/

230 V AC 50 Hz

Bridge rectifier

Filter(470µf)

5v Regulator

5V DC

12V step down transformer

Power supply

http://www.edgefxkits.com/

CPU

On-chip RAM

On-chip ROM for program code

4 I/O Ports

Timer 0

Serial PortOSC

Interrupt Control

External interrupts

Timer 1

Timer/Counter

Bus Control

TxD RxDP0 P1 P2 P3

Address/Data

Counter Inputs

Block diagram of MC

http://www.edgefxkits.com/

MC components explanation

ROM:

A code of 4K memory is incorporated as on-chip ROM in 8051.

RAM:

The 8051 microcontroller is composed of 128 bytes of internal RAM.

Interrupt Control:

An event which is used to suspend or halt the normal program execution for a temporary period of time in order to serve the request of another program or hardware device is called an interrupt.

http://www.edgefxkits.com/

MC components explanation

Parallel Input/Output Ports:

PORT P0: When there is no external memory present, this port acts as a general purpose input/output port.

PORT P1: This port is used for various interfacing activities.

PORT P2: This port can be used as a general purpose port when there is no external memory but when external memory is present it works in conjunction with PORT PO as an address bus.

PORT P3: PORT P3 behaves as a dedicated I/O port.

http://www.edgefxkits.com/

MC components explanation

Address Bus:

A bus is group of wires using which data transfer takes place from one location to another within a system.

Timers and Counters:

Synchronization among internal operations can be achieved with the help of clock circuits which are responsible for generating clock pulses.

Internal operations can be synchronized using clock circuits which produce clock pulses.

http://www.edgefxkits.com/

Pin diagram of 8052

http://www.edgefxkits.com/

8052 pin diagram explanation

Port 0(p0.0 to p0.7):

It is 8-bit bi-directional I/O port. It is bit/ byte addressable. During external memory access, it functions as multiplexed data and low-order address bus AD0-AD7.

Port 1 (p1.0 to p1.7):

It is 8-bit bi-directional I/O port. When logic '1' is written into port latch then it works as input mode. It functions as simply I/O port and it does not have any alternative function.

http://www.edgefxkits.com/

8052 pin diagram explanation

Port 2 (p2.0 to p2.7):

It is 8-bit bi-directional I/O port. It is bit/ byte addressable.

Port 3(p3.0 to port 3.7):

It is 8-bit I/O port. In an alternating function each pins can be used as a special function I/O pin.

RESET:

It is active high I/P signal. It should be maintained high for at least two machine cycle while oscillator is running then 8051 microcontroller resets.

http://www.edgefxkits.com/

A common used standard protocol for infrared data communication is the RC5 code, originally developed by Phillips.

This code has an instruction set of 2048 different instructions and is divided into 32 address so this makes it possible to change the volume of the TV without change the volume of the hifi.

The transmitted code is a data word which consists of 14 bits and is defined as: 2 start bits for the automatic gain control in the infrared receiver. 1 toggle bit (change every time when a new button is pressed on

the ir transmitter 5 address bits for the system address 6 instruction bits for the pressed key

RC5 CODE

http://www.edgefxkits.com/

TSOP1738 Features

Photo detector and preamplifier in one package

Internal filter for PCM frequency Improved shielding against electrical field

disturbance TTL and CMOS compatibility Output active low Low power consumption High immunity against ambient light Continuous data transmission possible (up

to 2400 bps) Suitable burst length .10 cycles/burst

http://www.edgefxkits.com/

TSOP17 Description

The TSOP17 – series are miniaturized receivers for infrared remote control systems.

PIN diode and preamplifier are assembled on lead frame, the epoxy package is designed as IR filter.

The demodulated output signal can directly be decoded by a microcontroller.

TSOP1738 is the standard IR remote control receiver series, supporting all major transmission codes.

http://www.edgefxkits.com/

ULN2003 is a high voltage and high current Darlington transistor array.

It consists of seven NPN Darlington pairs that feature high-voltage outputs with common-cathode Clamp diode for switching inductive loads.

The ULN2003 has a 2.7kW series base resistor for each Darlington pair for operation directly with TTL or 5V CMOS devices.

Current, Output Max:500mA Voltage, Input Max:5V Voltage, Output Max:50V

ULN2003

http://www.edgefxkits.com/

It is a electro magnetic switch

Used to control the electrical devices

Copper core magnetic flux plays main role here

Relay

http://www.edgefxkits.com/

Software requirements

Keil an ARM Company makes C compilers, macro assemblers, real-time kernels, debuggers, simulators, integrated environments, evaluation boards, and emulators for ARM7/ARM9/Cortex-M3, XC16x/C16x/ST10, 251, and 8051 MCU families.

Compilers are programs used to convert a High Level Language to object code. Desktop compilers produce an output object code for the underlying microprocessor, but not for other microprocessors.

http://www.edgefxkits.com/

Conclusion

The TV Remote Operated Domestic Appliances Control can be enhanced by using radio frequency technology where the operational range shall be independent of line of sight distance as often encountered with IR type of remote control.

Here Edgefx provides you a lot of information about electrical instruments that are particularly useful for all Engineering students.

http://www.edgefxkits.com/