Arduino dtmf controlled robot

1. DTMF CONTROLLED ROBOT
This is the robot whose actions can be controlled by a mobile phone
from all over the world using the DTMF signaling.
Use of mobile phones for robotic controls provides working range as
large as the coverage area of the service provider and no interference
with other controllers.
Block diagram
DTMF Controlled Robot

2. PROJECT OVERVIEW
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 DTMF (dual-tone-
multiple-frequency).The robot perceives this DTMF tone with the help
of the phone stacked in the robot. The received tone is processed by the
microcontroller residing on the Arduino UNO board with the help of
DTMF decoder IC (MT8870). The decoder decodes the DTMF tone
into its equivalent binary digit and this binary number is sent to the
microcontroller. The microcontroller is programmed to take a decision
for any given input and outputs its decision to motor drivers in order to
drive the motors in forward direction or backward direction or turn. The
mobile phone that makes a call to mobile phone stacked in the robot act
as a remote.
DTMF
DTMF (Dual tone multi frequency) as the name suggests uses a
combination of two sine wave tones to represent a key dialed on a
pushbutton or DTMF keypad.
These tones are called row and column frequencies as they correspond
to the layout of a telephone keypad.

3. DTMF keypad layout
A DTMF keypad (generator or
encoder) generates a sinusoidal
tone which is mixture of the row
and column frequencies. The row
and column frequencies
corresponding to a DTMF keypad have been indicated in the above
figure.
DTMF tones are able to represent one of the 16 different states or
symbols on the keypad.
Hardware components required and their purpose:
1. Arduino UNO board
2. Transmitter and receiver mobile phones
3. DTMF decoder IC (MT8870)
4. DC motor
5. Motor driver IC (L293D)
6. Wheels
7. Power adopter
 Arduino UNO board: This is the brain of this robot in which the
program is loaded to do the required functioning and is interfaced
with decoder IC and the motor driver to make the system work as
required.

4.  Transmitter and receiver mobile phones: Here the transmitting
phone is working as a remote and the receiving phone is attached
to the robot which receives the DTMF signals which are then fed to
decoder IC after converting them to electrical form through audio
jack.
 DTMF decoder IC (MT8870)
The decoder decodes the DTMF tone into its equivalent binary
digit and this binary number is sent to the microcontroller.
DTMF decoder IC (MT8870)
On pressing any key say key 1,
a combination of frequencies
1209 and 697 Hz will be
generated by keypad which is
fed to IC through sound
converter which in turn
produce the output 0001 (Q1,
Q2, Q3, Q4). Following
table shows output of
remaining keys.
MT8870 output

5.  DC Motor: This motor is controlled with DC voltages and can
move in forward and backward direction according to the polarity
of the voltage applied.
 Motor driver IC (L293D): Microcontrollers can’t supply the
current required by DC motor to run. So, to fulfill this requirement
these motor driver ICs are used.
DC motors with Driver IC
 Power adopter: This is used to give appropriate dc power supply
to microcontroller, driver IC sensors and the other passive
components of the robot.
 Wheels: In it three wheels are employed, two at rear end and one at
front end. Rear wheels are attached with the motors and also
control the steering of robot. Front wheel is the loose steered wheel
which moves in the direction of the pressure applied to it.

6. Overview:
Top view of robot
Description
The robot is controlled by a mobile phone that makes call to the
mobile phone attached to the robot and in the course of the call, if any
button is pressed the corresponding DTMF freq. will be heard at the
other end.
DTMF assigns a specific frequency (consisting of two separate tones)
to each key that it can easily be identified by the electronic circuit.
The signal generated by the DTMF encoder is the direct algebraic
submission, in real time of the amplitudes of two sine(cosine) waves
of different frequencies, for example: pressing key5 will send a tone
made by adding 1336hz and 770hz to the other end of the mobile.

7. The received tone is processed by the atmega8 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
given input and outputs its decision to motor drivers in order to drive
the motors for forward or backward motion or a turn.
Program:
/*DTMF pins Q1-4 are attached with pins 9-12
left motor attached to pin 5,6 and
right motor attached to pin 7,8 and
*/
int q1=9;
int q2=10;
int q3=11;
int q4=12;
void setup() {
//Initialize serial and wait for port to open:
Serial.begin(9600);
pinMode(q1, INPUT);
pinMode(q2, INPUT);
pinMode(q3, INPUT);
pinMode(q4, INPUT);
pinMode(5, OUTPUT);
pinMode(6, OUTPUT);

8. pinMode(7, OUTPUT);
pinMode(8, OUTPUT);
}
void loop()
{
int v1,v2,v3,v4,value;
v1 = digitalRead(q1);
v2 = digitalRead(q2);
v3 = digitalRead(q3);
v4 = digitalRead(q4);
value=((v4<<3)|(v3<<2)|(v2<<1)|(v1));
switch(value)
{
case 0X02:
{
digitalWrite(6, LOW);
digitalWrite(8, LOW);
digitalWrite(5, HIGH);
digitalWrite(7, HIGH); //switch on both
break;
}
case 6: //RIGHT turn
{
digitalWrite(5, HIGH);
digitalWrite(7, LOW);
digitalWrite(6, LOW);
digitalWrite(8, LOW); //switch on only LEFT motor move to RIGHT
break;
}

9. case 4: //LEFT turn
{
digitalWrite(5, LOW);
digitalWrite(7, HIGH);
digitalWrite(6, LOW);
digitalWrite(8, LOW);
//switch on only RIGHT motor move to LEFT
break;
}
case 8:
{
digitalWrite(5, LOW);
digitalWrite(7, LOW);
digitalWrite(6, HIGH);
digitalWrite(8, HIGH); //both REVERSE
break;
}
default:
{
digitalWrite(5, LOW);
digitalWrite(7, LOW);
digitalWrite(6, LOW);
digitalWrite(8, LOW);
break;
}
}
}

10. Programming Digital I/O pins of Arduino UNO board:
 Each pin is controlled by three commands associated with it which are
designated as:
pinMode()
digitalWrite()
digitalRead()
 pinMode()
This configures the specified pin to behave either as an input or an output.
Syntax
pinMode(pin, mode)
Parameters
pin: the number of the pin whose mode you wish to set
mode: INPUT, OUTPUT.
Returns
None
Example
int ledPin = 13; // LED connected to digital pin 13
void setup()
{
pinMode(ledPin, OUTPUT); // sets the digital pin as output
}
void loop()
{
digitalWrite(ledPin, HIGH); // sets the LED on
delay(1000); // waits for a second
digitalWrite(ledPin, LOW); // sets the LED off
delay(1000); // waits for a second
}

11.  digitalWrite()
Write a HIGH or a LOW value to a digital pin.
If the pin has been configured as an OUTPUT with pinMode(), its voltage
will be set to the corresponding value: 5V (or 3.3V on 3.3V boards) for
HIGH, 0V (ground) for LOW.
Syntax
digitalWrite(pin, value)
Parameters
pin: the pin number
value: HIGH or LOW
Returns
None
Example
Sets pin 13 to HIGH, makes a one-second-long delay, and sets the pin back to LOW.
int ledPin = 13; // LED connected to digital pin 13
void setup()
{
pinMode(ledPin, OUTPUT); // sets the digital pin as output
}
void loop()
{
digitalWrite(ledPin, HIGH); // sets the LED on
delay(1000); // waits for a second
digitalWrite(ledPin, LOW); // sets the LED off
delay(1000); // waits for a second
}

12.  digitalRead()
Reads the value from a specified digital pin, either HIGH or LOW.
Syntax
digitalRead(pin)
Parameters
pin: the number of the digital pin you want to read (int)
Returns
HIGH or LOW
Example
int ledPin = 13; // LED connected to digital pin 13
int inPin = 7; // pushbutton connected to digital pin 7
int val = 0; // variable to store the read value
void setup()
{
pinMode(ledPin, OUTPUT); // sets the digital pin 13 as output
pinMode(inPin, INPUT); // sets the digital pin 7 as input
}
void loop()
{
val = digitalRead(inPin); // read the input pin
digitalWrite(ledPin, val); // sets the LED to the button's value
}