DTMF BASED HOME APPLIANCES CONTROL

 INTRODUCTION:

Today’s the demand for better home security systems has drifted over to a need for home automation. Not only does a home need to be secure but home appliances need a more refined control system. Home appliances should not be limited to only local control. There needs to be a simple and elegant way to avoid this type of situation and allow people the freedom of having complete control of their house from anywhere. With this fact in mind we have build a project for the home automation controls. The key to this control system will be the use of a telephone for a two way communication path to the central control unit.
With this  system, it is possible to operate domestic electrical devices safety by using public or mobile phones from any places all over the world.
The basic idea of this project is to take advantage of the vast network of telephone lines and the proliferation of cell phones to extend human’s reach and possibilities. The system, through telephone networks, connects the user  home appliances at home and gives him/her the ability to switch them ON or OFF. The user dials the home telephone number like an ordinary telephone call. The telephone at home rings and if nobody picks the call, then the system picks up the call. The system then asks for the password. The user enters the password. Once the password is entered, the user will be offered a voice menu and asked to choose from that menu. The user chooses an item from the menu by pressing a button on the phone keypad. Pressing a button on the phone generates a DTMF signal which, through the telephone network, will reach the system at home. The system will recognize the received signal and based on that will switch on/off the chosen appliance.
This project uses DTMF technology for the controls.
DTMF, better known as touch-tone, is a system of signal tones used in telecommunications. Applications include voice mail, help desks, telephone banking, etc.
There are twelve DTMF signals, each of which is made up of two tones from the following selection: 697 Hz, 770 Hz, 852 Hz, 941 Hz, 1209 Hz, 1336 Hz, 1477 Hz. The tones are divided


                          
  AIM & OBJECTIVE                                   
                                        
 AIM:-
1.To make a CELL-PHONE operated DTMF HOME AUTOMATION  SYSTEM.
 2.To make a home security system.  
 3.To prepare remote sensing security system.

OBJECTIVE:-
In the view today society demand it is essential to  made a better home security systems. Not only does a home need to be secure but home appliances need a more refined control system. Home appliances should not be limited to only local control.
From the above point of view we have tried to prepare a model for home automation control and security system.











     COMPONENTS USED                              

                                                    

Component name	specification	quantity
Microcontroller AT89C51	-	1
Diode	IN4007	2
Crystal Oscillator	12 MHz 3.57Mhz	1 1
Capacitor	0.1µF,63V 33pf	3 2
Relay	10 A,120 V,50 Hz	2
Resistors Pull up	100 KΩ 1KΩ 4.7 KΩ 10 KΩ	2 4 6 1
BC547(npn)	-	3
2 pin connector Female male	5V 220V 220V	2 2 2
bulb	60W,230V	1
6 pin connector	-	1
4 pin switch		1
Buzzer	5V	1
LCD base	-	1
LCD	5V	1
IC base	40 pin 20 pin 18 pin	1 1 1
General purpose PCB	14x9 cm	1

   HOME AUTOMATION MODEL

The core of the project is the 8051 microcontroller; it will determine what actions need to be sent out to the rest of the system. The microcontroller will determine when each sub part needs to be activated .Other parts include the Phone interface, the decoder and the appliance connected through the relay.

                         

              

Phone Interface:

The telephone line is hooked to the another phone attached to the system This will communicate directly with the microcontroller through the CM8870 decoder which decodes all 16 DTMF tone pairs into a four bit code.

CM8870/70C (DTMF decoder):

CM8870/70C is a Full DTMF receiver, uses less than 35mW power consumption, uses quartz crystal or ceramic resonators, has adjustable acquisition and release times, works in Industrial temperature range and is available in 18-pin DIP, 18-pin DIP EIAJ, 18-pin SOIC, 20-pin
PLCC.
.

 Pin Diagram of  CM8870C

ATMEL AT89C52 (Microcontroller):

he AT89C52 is a low-power, high-performance CMOS 8-bit microcomputer with 8K Flash bytes of Flash programmable and erasable read only memory (PEROM). The device is manufactured using Atmel’s high-density nonvolatile memory technology and is compatible with the industry-standard 80C51 and 80C52 instruction set and pinout. 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 Flash on a monolithic chip, the Atmel AT89C52 is a powerful microcomputer which provides a highly-flexible and cost-effective solution to many embedded control applications.

                                                                       Pin Diagram of AT89C52

1N 4007 DIODE:

It has the following features:
1.    Low forward voltage drop
2.    High surge current capacity
3.    Low reverse leakage current
4.    V(rrm) = peak repetitive reverse voltage = 1000 V
5.    I (fsm) = average rectified forward current = 1A
6.    V(f) = forward voltage = 1.1 V

BC 548 TRANSISTOR:
It is general purpose NPN transistor, having the following features:
1.    Vcbo     = 30 V
2.    Ic    = 100 mA
3.    Ptotal     = 50 mW
4.    f     = 300 MHz

LM7805 DC POWER REGULATOR :

It has the following characteristics:
1.    Operating current     -     1 A
2.    Operating voltages     -    5 , 6 , 8 , 9 Vetc

RF TAG:

It has a 4-bit data input

16 X 2 LCD :

It has 16 characters, 2-line display and is used for general purpose.

 IC 74LS147 :

It is a 10 to 4 line priority encoder. It encodes 10-line decimal to 4-line BCD.

LCD (JHD162A series)

Display Content: 16 Char x 2 Row
Character Dots: 5 x 8
Driving mode: 1/16D

Available Types: 
Reflective with EL or Led Backlight
EL/100 V AC 400 Hz
LED/4.2 V DC


 LCD pin Diagram:

RELAY:

A relay is a type of electrically operated switch which is controlled by an electronic circuit. Within the relay is a coil of wire which generates a magnetic field when a current flows through it. If sufficient current at the correct voltage flows through the coil, the generated magnetic field attracts a metal lever which changes the position of the switch.


                                 

The advantage of a relay is that it permits a low voltage DC circuit to control a completely  separate high-power circuit - for example a 240V AC mains electricity powered appliance.


CIRCUIT DIAGRAM:                                        

REFRENCES

    www.en.wikipedia.org/wiki/Dual-tone_multi-frequency
    www.polar-electric.com/DTMF/Index.html
    www.alldatasheet.com
    CM8870 (DTMF decoder) datasheet.
    AT89s51 (Microcontroller) datasheet.
    JHD162A Series (LCD) datasheet.
    Automotive series “Understanding Relays” by Kevin R.Sullivan, prof of Automotive Technology Skyline College.
    Keil software help.
ISP software help