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Introduction

This project is based on DTMF technology i.e. dual transmission multi

frequency. Using DTMF here a robot is controlled hence called the mobile

controlled robot. Using DTMF we can be able to control our device from a

very long range only necessary thing is that there should be mobile network.

One can be able to control his home appliances while sitting in his office.

DTMF Mobile ROBOT is a machine that can be controlled with a mobile. In

this project, the robot is controlled by a mobile phone that makes a call to

the mobile phone attached to the robot.

In the course of a call, if any button is pressed, a tone

Corresponding to the button pressed is heard at the other end of the call.

This tone is called "Dual Tone Multiple-Frequency"(DTMF) tone.

The robot perceives this DTMF tone with the help of the phone stacked on

the robot. The received tone is processed by the microcontroller with the

help of DTMF Decoder.

The microcontroller then transmits the signal to the motor driver ICs to

operate the motors & our robot starts moving Conventionally, Wireless-

controlled robots use Rf circuits, which have the drawbacks of limited

working range,

Limited frequency range and the limited control. Use of a mobile phone for

robotic control can overcome these limitations. It provides the advantage of

robust control, working range as large as the coverage area of the service

provider, no interference with other controllers and up to twelve controls.

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WIRELESS CONTROL VIA MOBILE COMMUNICATION

-Use of DTMF signals

WHAT IS DTMF SIGNAL?

The 12 keys on a cell phone (0, 1… 8, 9,*, #) has unique signal associated

with itself. This is DTMF signal.

When the call is on, the pressing of any numerical key leads to generation

of DTMF signal which is audible on the other side.

TRY YOUR SELF!!!

Take any Nokia cell phone (others I haven’t tested), turn on keypad tones,

press any key, the tone your hear is DTMF tone.

Note: Don’t confuse keypad tones with the tone that is heard on other side

while call is on. The tone heard on other side (while call is on) is DTMF tone.

Keypad tones can be different than DTMF tones (as in Samsung that use Sa

Re Ga Ma … tone). It is just Nokia mobile manufacturer that uses DTMF tones

for keypad tones also.

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Hardware Description List of components used :-

1. MT8870 dtmf decoder IC

2. 100k resistor 2pc.

3. 300k resistor 1pc.

4. 3.57945 MHz crystal oscillator

5. 0.1 uf capacitor 2pc.

6. 4 LED

7. Connecting wires....

Working:--‐While the input from the mobile using a headphone is connected b/w the

0.1uf capacitor and the ground, DTMF tones can be Transferred to the

decoder ic(8870) and once The ic is powered up the o/p can be seen by

connecting LED's at Q!, Q2, Q3 and Q4 o/p of the decoder ic.

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The output on the Q1 to Q4 pins of the decoder IC has

been shown in the image.

The o/p of the decoder ic then can be connected to a motor driver ic like

(L298 or L293D) to drive some motors or relays as a switch to operate some

devices remotely as The Mobile phone connected can be called From

anywhere in the world and by pressing The keys the DTMF tones can be

transmitted To the receiving end mobile and hence any Device connected

can be operated globally.

Block Diagram :1

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Figure: a

DTMF TONE

• The DTMF technique outputs distinct representation of 16 common

alphanumeric characters (0-9, A-D, *, #) on the telephone. The lowest

frequency used is 697Hz and the highest frequency used is 1633Hz.

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Block Diagram :2

Table : i

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Figure: b

The MT-8870 is a DTMF Receiver that integrates both band split filter and

decoder functions into a single 18-pin DIP or SOIC package. It is

manufactured using CMOS process technology. The MT-8870 offers low

power consumption (35 mW max) and precise data handling. Its filter section

uses switched capacitor technology for both the high and low group filters

and for dial tone rejection. Its decoder uses digital counting techniques to

detect and decode all 16 DTMF tone pairs into a 4-bit code. Minimal external

components required includes a low-cost 3.579545 MHz color burst crystal, a

timing resistor, and a timing capacitor.

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The filter section is used for separation of the low-group and high group

tones and it is achieved by applying the DTMF signal to the inputs of two

sixth order switched capacitor band pass filters, the bandwidths of which

corresponds to the low and high group frequencies. The filter section also

incorporates notches at 350 and 440 Hz for exceptional dial tone rejection.

Each filter output is followed by a single order switched capacitor filter

section which smoothes the signals prior to limiting. Limiting is performed by

high-gain comparators which are provided with hysteresis to prevent

detection of unwanted low-level signals. The outputs of the comparators

provide full rail logic swings at the frequencies of the incoming DTMF signals.

Following the filter section is a decoder employing digital counting

techniques to determine the frequencies of the incoming tones and to verify

that they correspond to the standard DTMF frequencies

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Test Circuit

Figure: c

Following are the outputs produced by the DTMF decoder when the

respective keys are pressed

Table: ii

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MICRO CONTROLLER:

Micro controller is a programmable logical devise which can be used to control

robots, any appliance. Here we use ATMEGA-16 micro controller in our circuit to

control the robot .At mega 16 is a 40 pin Ic which is easily available in the

market. The following diagram gives the pin description of the micro controller

Figure: d

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Program required to control the robot is written and burnt into this controller

and when the required input gets into the controller it produces the desired

output as per our logic written in the program it is to be noted that each and

every motor has two terminals one of them represents positive terminal and

other represents negative. Taking this point into account the logic is formed

in the following way.

The following table gives you the logic to drive the dc motors

Table: iii

1 = 5 v (volts)

0 = Gnd (Ground)

The output from this micro controller is taken and given to a motor driver

circuit which will amplify the incoming signal to the required level we use

l293d Ic as motor driver. The following circuit gives you the circuit

How to Control DC Motors

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Table: iv

Figure: e

Mobile phone is connected to ear phones and the earphones are dissected in the

following way

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Direction Logic

Clockwise 10 10

Anti Clockwise 01 01

Left 00 10

Right 10 00

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Figure: f

Positive terminal –Tip

Negative terminal-Ring

Above mentioned terminals are connected as per the circuit.

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Following is the circuit diagram.

Figure: g

Components used in this circuit

Decoder

Microcontroller

H-bridge

Crystal Oscillator

Resistors

Capacitors

Diodes

Power supply

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Software Used

Professional Proteus

Win Avr

Avr studio

Extreme burne

Figure: h

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Figure: i

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Program source code

#include<avr/io.h >

#include<lcd_lib.h>

#include <stdio.h>

#include <util/delay.h>

#define ADC_VREF_TYPE 0x00

unsigned int

read_adc(unsigned char adc_input)

{

ADMUX=adc_input|ADC_VREF_TYPE;

// Start the AD conversion

ADCSRA|=0x40;

// Wait for the AD

conversion to complete

while ((ADCSRA & 0x10)==0);

ADCSRA|=0x10;

return ADCW;

}

void main()

{

int x;

int y;

int Z;

int W;

DDRB=0xff;

DDRD=0xff;

DDRC=0xff;

char a[15];

char B[15];

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ADMUX=ADC_VREF_TYPE;

ADCSRA=0x85;

LCDinit();

LCDclr( );

while(1)

{

x=read_adc(0);

sprintf(a,"x=%4d",x);

LCDGotoXY(0,0);

LCDstring(a,6);

y=read_adc(2);

sprintf(a,"y=%4d",y);

LCDGotoXY(0,1);

LCDstring(a,6);

Z=read_adc(4);

sprintf(B,"Z= %4d",Z);

LCDGotoXY(8,0);

LCDstring(B,7);

W=read_adc(6);

sprintf(B,"W= %4d",W);

LCDGotoXY(8,1);

LCDstring(B,7);

if(x<350 && y<350 && Z>1000

&& W<350 ) //press 02

{

PORTD=0b10100000;

}

if(x<350 && y>350 && Z<350

&& W<350) //press 04

{

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PORTD=0b01100000;

}

if(x<350 && y>350 &&Z>350 &&

W<350) //press 06

{

PORTD=0b10010000;

}

if(x>350 && y<350 &&Z<350 &&

W<350) //press 08

{

PORTD=0b01010000;

}

if(x<350 && y>350 &&Z<350 &&

W>350) // press 05

{

PORTD=0b00000000;

}

}

}

End

PROJECT OVERVIEW

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Block Diagram: 3

Table: v

In this project the robot, is controlled by a mobile phone that makes call to

the mobile phone attached to the robot in the course of the call, if any button

is pressed control corresponding to the button pressed is heard at the other

end of the call. This tone is called dual tone multi frequency tome (DTMF)

robot receives this DTMF tone with the help of phone stacked in the robot 

The received tone is processed by the atmega16 microcontroller with the

help of DTMF decoder MT8870 the decoder decodes the DTMF tone in to its

equivalent binary digit and this binary number is send to the microcontroller,

the microcontroller is preprogrammed to take a decision for any give input

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and outputs its decision to motor drivers in order to drive the motors for

forward or backward motion or a turn. 

The mobile that makes a call to the mobile phone stacked in the robot acts

as a remote. So this simple robotic project does not require the construction

of receiver and transmitter units. 

DTMF signaling is used for telephone signaling over the line in the voice

frequency band to the call switching center. The version of DTMF used for

telephone dialing is known as touch tone. 

DTMF assigns a specific frequency (consisting of two separate tones) to each

key s that it can easily be identified by the electronic circuit. The signal

generated by the DTMF encoder is the direct al-gebric submission, in real

time of the amplitudes of two sine(cosine) waves of different frequencies, i.e.

,pressing 5will send a tone made by adding 1336hz and 770hz to the other

end of the mobile. The tones and assignments in a dtmf system shown below

Circuit Description :

Figure: j

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Block Diagram:4

Figures shows the block diagram and cicuit diagram of the microcontroller-

based robot. The important components of this robot are DTMF decoder,

Microcontroller and motor driver. 

An MT8870 series dtmf decoder is used here. All types of the mt8870 series

use digital counting techniques to detect and decode all the sixteen DTMF

tone pairs in to a four bit code output. The built -in dila tone rejection circuit

eliminated the need for pre- filtering. When the input signal given at pin2

(IN-) single ended input configuration is recognized to be effective, the

correct four bit decode signal of the DTMF tone is transferred to Q1 (pin11)

through Q4(pin14) outputs. 

The atmega 16 is a low power, 8 bit, cmos microcontroller based on the AVR

enhanced RISC architecture. It provides the following feature: 16kb of in

system programmable flash memory with read write capabilities, 512bytes of

EEPROM, 1KB SRAM, 32 general purpose input/output lines. 32 general

purpose working registers. All the 32 registers are directly connected to the

arithmetic logic unit, allowing two independent registers to be accessed in

one signal instruction executed in one clock cycle. The resulting architecture

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is more code efficient. Outputs from port pins PD0 through PD3 and PD7 of

the microcontroller are fed to inputs IN1 through IN4 and enable pins (EN1

and EN2) of motor driver L293d respectively, to drive geared motors. Switch

S1 is used for manual reset. 

the notations are : 

ic1 - mt8870 

ic2 - atmega16 

ic3 - l293d 

ic4 - cd7004 

r1,r2 - 100k resistances 

r3 - 330k resistances 

r4-r8 - 10k resistances 

c1- 0.47 micro farat capacitor 

c2,c3,c5,c6 - 22pfarat capacitor 

c4 - 0.1micro farat capacitor 

xtal1 - 3.57 mhz crytal 

xtal2 - 12mhz crystal 

s1 - push to on switch 

m1,m2 - 6v 50rpm motor 

batt- 6v 

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Block Diagram: 5

In order to control the robot, you have to make a call to the cell phone

attached to the robot from any phone. 

now the phone is picked by the phone on the robot through auto answer

mode(which is in the phn, just enable it). 

now when you press 2 the robot will move forward 

when you press 4 the robot will move left 

when you press 8 the robot will move backwards 

when you press 6 the robot will move right 

when you press 5 the robot will stop. 

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Construction

Figure: k

for constructing this robot, you require these components

Components used:-

" MT8870 DTMF DECODER - 1

" Atmega 16 microcontroller - 1

" L293d motor driver ic - 1

" Cd7004 not gate ic - 1

" 1n4007 diode - 1

" 100k resistances - 2

" 10 k resistances - 5

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" 330 k resistances - 1

" 0.47mf capacitors - 1

" 0.1mf capacitors - 1

" 22pf capacitors - 4

" 3.57mhz crystal - 1

" 12mhz crystal - 1

" Push to on switch - 1

" 2 geared motors (6v, 50 rpm) - 2 (4 for four wheel drive)

" Battery 6v - 1

wheels - 4

cell phone - 2 (one urs and one can be ur frnds)

hands free - 1 (for the phn on the rover)

you have to place a cell phone on the rover. The cell phone is connected to

the rover through hands free. Construct the rover in the shape which is given

below.

You can get these parts from any electronic store with ease

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To connect the hands free with the circuit

Figure :l

there are always two connections which come out of the phone, 

these connections are 

1. Tip 

2. Ring 

i'll prefer to use hands free which have a straight jack (similar to the ones

which we use in our iPods, but a thinner one) 

the tip of that jack is called the "tip" 

and the rest part behind the tip after a black strip is the ring So connect

these two connections with the circuit and you will be done

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Mobile Controlled Robot Using DTMF Technology

Project Report

In recent days mobile controlled robot using DTMF technology are playing

vital role in industrial automation and hazardous work conditions. Automated

robots have several advantages in terms of accuracy and reliability, in our

“project Mobile Controlled Robot using DTMF i.e. Dual Tone Multi Frequency

tone, Technology”; we implemented a cell phone operated robot using DTMF

technology, these systems are applicable in defense like bomb detector, spy

robot and also in surveillance, in this DTMF based robot project we discuss

about the design and implementation of the automated robot.

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Advantages

Used to control house hold appliances

In industries and factories for remote sensing

Using 3g technology we can spy a place

Long distance remote sensing

Can be implemented in avionics to switch auto pilot from ground station by

sending a particular frequency

Disadvantages

Not at all useful if we do not have network

Call charges

Head phones which would be damaged very frequently

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Proposed mobile phone controlled robot

The DTMF robot we use a mobile phone to control the operations of the

robot, the robot has a mobile phone internally so when we make calls to that

mobile the corresponding tone is here’d at the other end. Using DTMF code

the direction and motion of the robot is controlled. Presently the robot

system can sense the smoke and gas emission and can intimate to the

operators with the help of alarm.

Technical specifications

The key aspect in this mobile phone controlled robot is the monitoring action

performed by the micro controller. The ATMEGA-16 micro controller used in

this project is low power and high performance CMOS 8- bit 4k byte EPROM

which is ideal for low power consumption applications. The pin configuration

and features of the micro controller are explained in later sections.

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Conclusion & Future Scope

So far the present system is designed mainly for the supervision applications. In

the area of suspectance, the robot can be directed and if any smoke or gas is

identified the robot can produce alarm and also informs the operator. The

comments from the operator can also be transmitted to the area where the robot

moves. Further the key board can be interfaced with the TV connected at

receiver side to increase the number of comments given to the robot. Amplifier is

needed to be connected to the speaker of the mobile interfaced with the robot to

pass the comments directly through mobile from the remote mobile. The above

system can also used for military purpose as bomb detection and as spy robot.

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