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International Journal of Emerging Technology and Advanced EngineeringWebsite: www.ijetae.com (ISSN 2250-2459, Volume 2, Issue 10, October 2012)

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Cellphone Based Device Control With VoiceAcknowledgementAvigyan Datta Gupta1, Sayan Samanta2, Avishek Acharjee3

1,2 Future Institute of Engineering and Management, Kolkata-7001503 Techno India, Kolkata-700150

Abstract In this paper we have presented a circuit that

lets one to operate home appliances like light and water pump

from office or any other remote place. So if one forgets to

switch off light or other appliances while going out, it helps to

turn off them with your cell phone.The cell phone works as

the remote control for home appliances.One can control the

desired appliance by pressing the corresponding key. The

system also gives you voice acknowledgement of the appliance

status.

KeywordsMicrocontroller,Embedded System, Circuit

Description, Detailed Pin Description.

I. INTRODUCTIONIn recent years, there has been a rapid increase in

wireless network deployment and mobile device market

penetration. With various research that promises higher

data rates, future wireless networks will likely become an

integral part of the global communication infrastructure.

Ultimately, wireless users will demand the same reliable

service as today's wire-line network provides. Through ourdevice controller we can represent a safe & secure wireless

communication with proper authentication and less loss of

data.

The circuit of our proposed project has two parts:

(i)The hardware part (ii)The softwarepart

The hardware part comprises of microcontroller

AT89C51, DTMF decoder MT8870, voice

recording/playback device APR9600 and a few discrete

components. MicrocontrollerAT89C51 is the heart of the

circuit. It is a low-power, high performance, 8bit

microcontroller with 4 KB of flash programmable and

erasable read only memory used as on-chip program

memory, 128 bytes of RAM, 32 individually programmableinput/output lines, a five vector two-level interrupt

architecture, on-chip oscillator and clock circuitry.

The software part consists of a program for the

microcontroller is written using BASCOM microcontroller

programming software.

A. Components RequiredHardware Components: Hardware components comprises

of the following:-

Microcontroller [AT89C51] Voice recording and playback device[APR9600] DTMF receiver [MT8870] Relay [ULN2003] Power supply LED Resistors Capacitors Diodes Switch Crystal Oscillator Electric mic Speaker Cellphone with headsetSoftware Components: Software components comprises of

the following:-

BASCOM microcontroller programming software Assembly languageB.Introduction To Embedded SystemsI)Definition: Embedded System

Any sort of device which includes a programmable

computer, but itself is not intended to be a general-purpose

computer[1].

II)What is an Embedded SystemAn embedded system is a microcontroller / digital signal

microprocessor based system that is designed to be flexible

and built to control or monitor the functions of equipment,

machinery, plant and many devices in common use today.

III) Desktop vs. Embedded SystemIn contrast to Desktops that performs a Variety of tasks

an Embedded System performs a Single, Well-DefinedTask. The System has a Processor, Associated Peripherals,

and Software for a Specific Purpose.

For example, in a Mobile Phone the Embedded

Processor needs to Process Voice (to Send and Receive

Speech Signals) as well as implement Communication

Protocols. The Hardware is Custom Built for the Specific

Purpose. Unlike a PC, embedded system is not designed

to be programmed by an end user. Embedded system

always runs a fixed application.

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International Journal of Emerging Technology and Advanced EngineeringWebsite: www.ijetae.com (ISSN 2250-2459, Volume 2, Issue 10, October 2012)

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II. METHODOLOGYA. Problem Description

In recent years our modern life style becomes so busy

and full of task schedule that we often forget to do some

simple duties. Such as forget to switch of our household

appliances. We don't bother about our these types of

carelessness every time, but this can give us real trouble

sometime. Unnecessarily energy is consumed. For too

much consumption of energy, the generated heat can

damage the device. This damage cause a seriousinterruption in our task schedule, besides some loss of

money and time also. But it is not always possible for us to

switch off the devices from the remote place. So our aim is

to control the household devices from the remote places.

We use wireless network to implement our project.

Through our device controller project we try to represent a

safe & secure wireless communication to control the

devices.[2],[3],[4],[5]

To Decode

Fig-1 Functional Block Diagram

Switch

Board

AT89C51

Microcontroller

Status Indicator

Relay Driver

Voice Controlling &

Playback Device

DTMF Decoder

Microphone

Speaker

Cellphone

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International Journal of Emerging Technology and Advanced EngineeringWebsite: www.ijetae.com (ISSN 2250-2459, Volume 2, Issue 10, October 2012)

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Fig- 2 Circuit Diagram

B. Circuit DescriptionIt comprises of microcontroller AT89C51, DTMF

decoder MT8870, voice recording/playback device

APR9600 and a few discrete components. Microcontroller

AT89C51 is at the heart of the circuit. It is a low power,

high-performance, 8-bit microcontroller with 4kB of

PEROM used as on-chip program memory, 128 bytes of

RAM used as internal data memory, 32 individually

programmable I/O lines divided into four 8-bit ports, two

16-bit programmable timers/counters, a five-vector two-

level interrupt architecture, on-chip oscillator and clock

circuitry .A 11.0859 MHZ crystal (Xtal1) is used to provide

basic clock frequency of microcontroller. Capacitor C3 and

resistor R3 from the power-on reset circuit, while push-to-

on switch S20 is used for manual reset .Port pins P1.0

through P1.7 of the microcontroller are configured to get

the input from switches S1 through S8.pins from port P1

are pulled high via resistor network RNW1.

Port pins P2.0 through P2.4 are configured to receive the

decoded DTMF signal from DTMF receiver MT8870.The

DTMF decoder is used for decoding the mobile signal.

It gets DTMF tone from the mobile headsets speaker

pins and decodes it into 4-bit digital signal. The DTMF

decoder is operated with a 3.579MHz crystal (Xtal2).In

DTMF receiver MT8870 (IC3), capacitor C12 is used to

filter the noise and resistors R6 and R7 helps to amplify the

input signal using the internal amplifier. Pin 16 of IC3connected to resistor R5 provides the early steering output.

It goes high immediately when the digital algorithm detects

a valid tone pair (signal condition). Any momentary loss of

signal condition causes ESt to return to low state. Pin 17 of

Ic3 connected to capacitor C11 is bidirectional, acting as

steering input/guard time output (St/Gt). A voltage greater

than threshold of the steering logic Vtst detected at St

causes the device to register the detected tone pair.

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International Journal of Emerging Technology and Advanced EngineeringWebsite: www.ijetae.com (ISSN 2250-2459, Volume 2, Issue 10, October 2012)

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The guard time output resets the external steering timeconstant , and its state is a function of ESt and the voltage

at St. Port P3 pins P3.6 and P3.7 of IC1 are configured to

select the control source for the devices. These are connected toDIPswitches S17 & S18 and pulled high via resistors R2 and R1,respectively.

Here, we are using two control sources, switches and

mobile's key. DIP switches S17 & S18 select the control

sources. Pin 2.5 of Port P2 is configured to show the rest

status. That is, if none of the control sources is selected by

DIP switches S17 & S18, LED1 glows. Resistor R14 limits

the current through LED1.

Voice acknowledgement is provided by APR9600 (IC2).

It is a single-chip voice recording and play back device thatcan record and play multiple message at random or in

sequential mode for 60 seconds. The user can select sample

rates with corresponding-quality recording lengths.

Microphone amplifier, automatic gain control circuits,

internal output amplifier and message management are

some of the features of the APR9600.Here the APR9600 is

configured in random-access mode, which supports two,

four & eight messages of fixed durations. The length of

each message is the total recordings length available

divided by the total number of memory segments/tracks

enabled. Audio processor can store up to eight voice

messages. Port P0 pins & P2.7 are configured to

communicate with IC2. Port P0pins trigger selection of the

message. Port pin P2.7 is the input signal to identify

whether the voice message is playing or not.

Pins P3.0 through P3.5 of port P3 control the devices

with the help of relays RL1 through RL6 via relay IC4.A

speaker is connected to IC2 for audio output. The speaker

output drives the microphone input of the mobile for audio

acknowledgement. An electrets microphone MIC1 is

connected to IC2 to record the voice in IC2. Led2 flashes to

show the busy status of IC2 during recording & playback.

The audio message to be recorded in APR9600, by using

trigger switches S9 through S16. SPST switch S19 is

closed for recording and switch S19 is opened for

playback.

C. Component Values and RatingsSL

No.

Name ofthecomponents

Values Ratings

1 AT89C51 4K PEROM,

CMOS, 8 bit

0-20 MHz,

5V15%

2 APR9600 Operating Current:

25 mA typical.Standby Current: 1

uA typical.

5V20%

3 MT8870 3.579545MHz,

MAX: 7V, 10mA,

500mW

5V 5%

4 7806 6v 1A, 6V,4% , Ta

= -40C to

+125C

5 1N4007 diode 8pF junction

capacitance

Peak reverse

voltage:1000v,

peak rev current:

5uA

6 Resistors 10K,100K, 470K,

220K ,39K,4.7K,

1K, 220K, 470 ohm

W, 5%

CARBON

7 Capacitors 33pF, 0.1uF ceramic

8 Capacitors 10uF, 4.7uF, 22uF,

1000uF

16v, 50v

electrolytic

9 Capacitors 0.22uF, 0.47uF polyester

10 Crystal

oscillator

11.0592 MHz, 3.579

MHz

11 Speaker 16ohm 1W

Table 1: Table for component values and ratings

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International Journal of Emerging Technology and Advanced EngineeringWebsite: www.ijetae.com (ISSN 2250-2459, Volume 2, Issue 10, October 2012)

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D. AT89C51 SpecificationI) Diagram of Microcontroller Used ie AT89C51:

Table 1: Pin out diagram of AT89C51

(II) Detailed Pin Description of Microcontroller Usedi.e. AT89C51:

VCC

Supply voltage.

GND

Ground

Port 0

Port 0 is an 8-bit open drain bi-directional 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 can also be configured to be themultiplexed 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 bi-directional 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. In addition, P1.0 and P1.1 can be configured to be

the timer/counter 2 external count input (P1.0/T2) and the

timer/counter 2 trigger input (P1.1/T2EX), respectively, as

shown in the following table.

Port 2

Port 2 is an 8-bit bi-directional I/O port with internalpull-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 pull-ups 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

pull-ups. Port 2 emits the high-order address byte during

fetches from external program memory and during accesses

to external data memory that use 16-bit addresses (MOVX

@ DPTR). In this application, Port 2 uses strong internal

pull-ups when emitting 1s. During accesses to external data

memory that use 8-bit addresses (MOVX @ RI), Port 2

emits the contents of the P2 Special Function Register. Port

2 also receives the high-order address bits and some controlsignals during Flash programming and verification.

Port 3

Port 3 is an 8-bit bi-directional I/O port with internal

pull-ups. 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 pull-ups and can be used as

inputs. As inputs, Port 3 pins that are externally being

pulled low will source current (IIL) because of the pull-ups.

Port 3 also serves the functions of various special features

of the AT89C51, as shown in the following table.

RST

Reset input. A high on this pin for two machine cycleswhile the oscillator is running resets the device.

ALE/PROG

Address Latch Enable is an output pulse for latching the

low byte of the address during accesses to external

memory.

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This pin is also the program pulse input (PROG) duringFlash 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 micro

controller is in external execution mode.

PSEN

Program Store Enable is the read strobe to externalprogram memory. When the AT89C52 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 receives the 12-volt programming

enablevoltage (VPP) during Flash programming when 12-volt programming is selected.

XTAL1

Input to the inverting oscillator amplifier and input to the

internal clock operating circuit.

XTAL2

Output from the inverting oscillator amplifier.

III. CONCLUSIONSo, in this project we have shown that using a simple

extra cellphone, you can control your power hungry home

appliances. This will eventually reduce your carbon

footprint, as well as your electricity bill. Many similar

zigbee based controller are already in market, but that will

limit your within a range upto 100 meters. This costeffective solution has a great potential in our everyday busy

schedule.

REFERENCES

[1 ] Computers as components: principles of embedded computingsystem by Wayne Hendrix Wolf. Chapter 1.2.

[2 ] http://www.atmel.com/dyn/resources/prod_documents/doc0265.pdf[3 ] http://akizukidenshi.com/download/apr9600.pdf[4 ] http://www.diodes.com/datasheets/ds28002.pdf[5 ] http://www.datasheetarchive.com