Home Automation Control System Using DTMF Telephone Line

Presented by : Veena Geetha (1NT08EC401) (1NT07EC041)

Gumpali Satya Mythili Greeshma M.Swamy

(1NT07EC043) (1NT07EC042) Under the guidance of :

Mrs.Bhuvaneshvari

Problem Definition:In today’s World, there are Electric crises, we should try to use theElectric power in a proper way and not leading to nationalwaste. Sometimes we might forget to switch off a device and we might know it when we are in a remote section and need to be switched off or it might cause damage and the energy consumed is of a waste.There are many reasons for accident s to happen due to this electricpower so one who want s to take care must be sure and know the status of the devices.These are the reasons or problems encountered, our Project ensures that the operator knows the status of the device he/she selects and also allows them to turn ON & OFF the selected devices.

AIM OF THE PROJECT: The Aim of our project is to design a microcontroller based

“Home Automation System” that investigates the information send by the user and operates, as asked for.

Dial your number using DTMF phone or Cell phone from anywhere in world and remotely turn On/Off any of 8 relays. The Microcontroller on the interface senses Telephone ring, Automatic telephone pick up, and line HANG up, displays information on a 16*2 LCD module and controllers the relay switching.

INTROUDCTION: This project “HOME AUTOMATION CONTROL USING

DTMF TELEPHONE LINE” is mainly Used for the houses , it can also be used in places where cont rolling for electricity is needed, but one should know that the Telephone which they are using should be in Tone mode, since our project is more concerned on this DTMF(Dual Tone Multi Frequency).

BLOCK DIAGRAM OF THE SYSTEM TEL LINE IN MCT2E

TO TEL

MICRO CONTROLLER AT89C051

RING DETECT

LINE PICK UP

ACK TONE

DTMF DECODER

16*2 LCD

SERIAL EEPROM

RELAY DRIVER

12V & 5V DC POWER SUPPLY

How the project works :

The Microcontroller controls entire operation of the circuit.Presently we have done only one Application of this project , i.e. to

switch ON and OFF the 8–devices which are connected to Microcontroller through switching circuit.

These switches are connected in series with the manual switches, so that they can operate i.e. control ON and OFF state of the devices.

To switch ON or OFF the device we have to give the command for the circuit either through cell-phone or from any DTMF Land line.

These information’s are Decoded by DTMF and sends the signals to microcontroller which operates according to these information.

SCHEMATIC

MAIN CIRCUIT It mainly consists of two boards

The first board consists of, the MICROCONTROLLER RING DETECTER LINE PICK-UP ACK TONE DTMF DECODER VOLTAGE REGULATOR SERIAL EEPROM AND LCD DISPLAY

The second board consists of, The RELAY driver circuit, which are controlled through microcontroller.

MICROCONTROLLER(AT89C051):

FEATURES:

4 Kbytes of In-System Reprogrammable Flash Memory. 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 handling device.

Ring Detector(IC MT2E):-It is used to detect the ring signal from the telephone line. It gives out a logical output to the microcontroller. An optocoupler MCT2E is used as ring detector. If ring is present –logic 0 Else-logic 1Normal time voltage in telephone line=48V d.cOFF hook voltage-12V d.cRing signal voltage-75V a.c

RING DETECTOR:

FEATURES:

Gallium Arsenide Diode Infrared Source Optically Coupled to a Silicon npn Phototransistor.

High Direct-Current Transfer Ratio.High-Voltage Electrical Isolation 1.5-kV, or 3.55-kV

Rating. Plastic Dual-In-Line Package.High-Speed Switching: tr = 5 μs, tf = 5 μs Typical.Designed to be carried with General Instrument MCT2E.

DTMF DecoderDetecting DTMF with satisfactory precision is a hard thing. We use a dedicated IC MT8870 for this purpose. It uses two 6th order band-pass filters using switched capacitor filters and it suppresses any harmonics. Hence they can produce pretty good sine waves from distorted input.

DTMF DECODER (M-8870): FEATURES:

Low power consumption. Adjustable acquisition and release timesPower-down and inhibit modes (-02 only). Inexpensive 3.58 MHz time base. Single 5 volt power supply. Dial tone suppression. Applications include: telephone switch equipment, remote

data entry, paging systems, personal computers, credit card systems.

LATCH

DIGITALDETECTI

ONALGORIT

HM

STEERING LOGIC

ES

STDST/GTOE

Q4

Q3

Q1

Q2

INH

LOWGROUPFILTER

HIGHGROUPFILTER

VREF

BIASCKT

VSS

VDD

PD

DIALTONE

FILTER

+++

IN+

IN-

GS

OSC1

0SC2

CLK

CHIP POWE

R

CHIPBIAS

REF

ZEROCROSSING

DETECTERS

-2 only

-2 only

BLOCK DIAGRAM OF DTMF DECODER

DESCRIPTION:

1. IN+: Non-inverting input Connections to the front-end differential amplifier.

2. IN-: Inverting input.3. GS: Gain select. Gives access to output of front-end

amplifier for connection of feedback resistor.4. VREF: Reference voltage output (nominally VDD/2).5. INH: Inhibits detection of tones representing keys A, B,

C, and D.6. PD: Power down. Logic high powers down the device

and inhibits the oscillator.

7. OSC1 : Clock input 3.579545 MHz crystal connected between these pins completes the internal oscillator.

8. OSC2 : Clock output.

9. VSS :Negative power supply (normally connected to 0V).

10. OE :Tri-stable output enable (input).

11. To 14 Q1, Q2,Q3, Q4 : Tri-stable data outputs. When enabled by OE, provides the code corresponding to the last valid tone pair received.

15. StD : Delayed steering output. Presents a logic high when a received tone pair has been registered and the output latch is updated. logic low when the voltage on St/GT falls below VTSt.

16. Est: Early steering output. Presents logic high immediately when the digital algorithm detects a recognizable tone pair. Any momentary loss of signal condition will cause ESt to return to a logic low.

17. St/GT: Steering input/guard time output (bidirectional). A voltage greater than VTSt detected at St Causes the device to register the detected tone pair and update the output latch. A voltage less than VTSt free the device to accept a new tone pair. The GT output acts to reset the external steering time constant and its state is a function of ESt and the voltage on St.

18. VDD: Positive power supply. (Normally +5V).

FILTERS:

The low and high group tones are separated by applying the dual-tone filter.

Each filter output is followed by a single-order switched capacitor section that smoothes the signals.

Signal limiting is performed by high-gain comparators to prevent detection of unwanted low-level signals and noise.

DECODER:

The 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 (“signal condition”), it raises the Early Steering flag. Any subsequent loss of signal condition will cause ESt to fall.

STEERING CIRCUIT:

The steering circuit works in reverse to validate the

continuously pause between signals.

The receiver will tolerate signal interruptions (drop outs) too short to be considered a valid pause.

This gives the capability to select the steering time constants externally, allows the designer to meet a wide variety of system requirements.

POWER-DOWN&INHIBIT MODE:

A logic high applied to pin 6 (PD) will place the device into standby mode to minimize power consumption. It stops the oscillator and the functioning of the filters.

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.

In the M-8870-01 models, this pin is tied to ground (logic low).

DTMF CLOCK CIRCUIT:

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

The crystal can be connected to a single M-8870 between the terminals osc1 & osc2

OSC1 OSC2

3.58 MHz

SERIAL EEPROM (AT 24C04):

FEATURES:

Power Supply Voltage Single Vcc for Read and Programming (Vcc = 2.7 V to 5.5 V). Low Power (Isb = 2μa @ 5.5 V) 2-Wire Serial Interface Support Byte Write and Page Write (8 Bytes) Automatic Page write Operation (maximum 10 ms) Internal Control Timer Internal Data Latches for 8 Bytes High Reliability CMOS Technology with EEPROM CellData Retention : 100 Years

LCD DISPLAY:

FEATURES:

A 16x2 Line LCD module to display the Status and Error Message.

micro controller send the data signals through Pin 26 through 29 and control signal through 23, 24 and 25 of the micro controller.

Pin no 3 of the LCD is used to control the contrast by using preset VR1.

Back light is driven by Microcontroller port 3.0, through LCD pin number 15.

Also during non operation period of LCD the Back light should be turned off so we can save some amount of energy this is done thorough PORT 3.0 of microcontroller.

ACKNOWLEDGE:

All data is serially transmitted in bytes (8 bits) on the SDA (Serial Data) bus.

The acknowledge protocol is used as a handshake signal to indicate successful transmission of a byte of data.

The receiver pulls the SDA bus low during the ninth clock cycle to acknowledge the successful transmission of a byte of data.

ADVANTAGES:

Gives Output to 8 Relay's. Fully micro controller based interface using family of

8051(AT89C51).On board EEPROM that stores Parameters and

password and relay status (no Battery back up). User settable password for security.

Acknowledgement tone output for the user.When the password has been incorrectly

entered four times in a row, the interface an error sound is produced and the receiver replaced on-hook this function thwart any attempt by 'hackers '.

It makes accurate switching, any false switching of device are not done.

APPLICATIONS:

Home security.No additional device at remote section.Switch ON any device and automatically switch OFF with

pre set time.With not much alteration in the Hardware part , and

changing the software, desired operation can be done.

LIMITATIONS:

In case phone connected to telephone line is not disconnected (receiver not placed down), device operation cannot be done.

An auxiliary supply of 12v. Once designed for particular operation, even for

small changes, either an Hardware is added or software is to be changed.

Conclusion:Controlling the home appliances using HOME AUTOMATION CONTROL SYSTEM USINGDTMF TELEPHONE LINE which is connected to the land line, UP TO 8 Devices can be controlledby dialing to that land line number to which system is connected, through any cell phone, landlinefrom Remote place. As per the procedure, the user can control up to 8 devices ie either switchON/OFF the devices, also they can change the setting .ie. Ring_count, Device_Password &Setting_Password.

Acknowledgement will be given for ever successful operation and incorrect Key pressed. If there is 3 times of entered key Error, it Reset’s automatically. It makes accurate switching.Thus the system in one way saves electric power and ensures the system is ON/OFF.

THAN

K

YOU