1. 1
ACKNOWLEDGEMENT
We pay our countless thanks and humilities to the creator of every heaven and earth, the most altruistic, the
most benevolent. The completion of this task is only because of his blessings. With the belief on His majesty we
were able to accomplish this Task.
We would also like to thank our families and friends for their continuous encouragement and moral support.
Malik Muhammad Zaid (2013-EE-37)
2. 2
ABSTRACT
Now-a-days due to advancement of technology , wireless system becoming more and more popular.Every thing
is going to work on the system which takes only commands through wireless systems.The major example is
mobile phone.Smartphones acts as remote controls for car. This technology is not new. Various applications and
technologies are already available that can enable your phone to remotely unlock the door or start your car. So
by using voice interactive response technology (IVR) we can move not only a toy car but even a large car forward
and backward. Companies are working on concepts allowing cars to cruise along on the highway without driver
intervention known as hands free driving. By using this IVR technology we can increase or decrease the speed
of car by just merely dialing numbers. Using this dual tone multi frequency technology we can lock and unlock
the doors and ignite the engine by using mobile phone.Now we can control the House-Hold appliances as well
as industrial appliances through wireless syetem based technology.We have created the project named “Mobile
Controlled Car Through Voice Call” .In this we can control Car through voice call , after that we can handle the
car in every direction where we want along with its speed control.This technology is basically using in “Drones”
now-a-days.In future this technology will be used in most of appliances especially in cars e.t.c
3. 3
Table of Contents
1 PROJECT OVERVIEW:.......................................................................................................................................................5
1.1 DTMF (DUAL TONE MULTI FREQUENCY) CIRCUIT:..................................................................................................6
1.1.1 DTMF Decoder: ...............................................................................................................................................7
1.1.2 Working of DTMF Decoder Circuit:.................................................................................................................7
1.1.3 Components Required: ...................................................................................................................................7
1.1.4 Circuit Diagram of DTMF Circuit: ....................................................................................................................7
1.1.5 Physical Discription of DTMF Circuit:..............................................................................................................8
1.2 Microcontroller:....................................................................................................................................................10
1.2.1 Code explanation: .........................................................................................................................................11
1.2.2 Code : ............................................................................................................................................................11
1.3 Motor Driver Circuit:.............................................................................................................................................14
1.3.1 Advantages of motor driver circuit:..............................................................................................................14
1.3.2 L293D Description:........................................................................................................................................14
2 Interactive voice response (IVR): ..................................................................................................................................15
3 CHALLENGES FACED DURING IMPLEMENTATION:..................................................................................................................15
4 Bibliography ..................................................................................................................................................................15
4. 4
List of figures
Figure 1.1 Circuit diagram of Mobile Control Car Through Voice Call...................................................................................5
Figure 1.2 Block diagram of Mobile Control Car Through Voice Call....................................................................................6
Figure 1.3 Keypad Buttons Frequency ...................................................................................................................................6
Figure 1.4 Circuit Diagram of DTMF circuit............................................................................................................................8
Figure 1.5 Physical Discription of DTMF Circuit .....................................................................................................................9
Figure 1.6 Frequency & Logic of keypad buttons generated by DTMF circuit....................................................................10
Figure 1.7 TIVA ARM TM4C1233H6PM...............................................................................................................................11
5. 5
1 PROJECT OVERVIEW:
The project is basically mobile controlled car through voice call. In this project the car is controlled by a
mobile phone. 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).
Car receives this DTMF tone with the help of phone stacked in the car. The DTMF decoder on the basis
of frequency convert it into binary equivalent.
The received tone is processed by the LM4F120H5QR 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 programmed 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. The motor (L293D) is basically governed by outputs of microcontroller. The mobile phone that
makes the call to the mobile phone stacked in car is transmitter.The mobile phone that is stacked in car
is receiver. On the course of call numbers are dialed from transmitter and tone is generated on receiver
mobile.
So our project consists of three parts:
DTMF circuit
Controller
Motor driver circuit
Figure1.1 CircuitdiagramofMobileControlCarThroughVoiceCall
The following block diagram shows how DTMF decoder , LM4F120H5QR microcontroller and L293D
motors are interlinked.Motor driver circuits will motors to proceed on the basis of microcontroller
outputs.
6. 6
Figure1.2 BlockdiagramofMobileControlCarThroughVoiceCall
1.1 DTMF (DUAL TONE MULTI FREQUENCY) CIRCUIT:
A telephone keypad was standardized when the dual-tone multi-frequency system in the new push-button
telephone was introduced in the 1960s, which gradually replaced the rotary dial. When used to dial a
telephone number, pressing a single key will produce a dual-tone multi-frequency signaling pitch
consisting of two simultaneous pure tone sinusoidal frequencies. The row in which the key appears
determines the low frequency, and the column determines the high frequency. For example, pressing the
'1' key will result in a sound composed of both a 697 and a 1209 hertz (Hz) tone as shown in figure
Figure1.3 KeypadButtonsFrequency
To convert this dual tone multi frequency signal which is an in-band tele-communication signaling system
using the voice-frequency band, we need a circuit that converts it into binary equivalent on the basis of
number pressed. This binary will be then processed by microcontroller. For this we use DTMF decoder
IC named as 8870.
7. 7
1.1.1 DTMF Decoder:
This DTMF (Dual Tone Multi Frequency) decoder circuit identifies the dial tone from the telephone line
and decodes the key pressed on the remote telephone. The IC MT8870 is a touch tone decoder IC. It
decodes the input DTMF to 4 binary outputs.
1.1.2 Working of DTMF Decoder Circuit:
Caller generates a dial tone consisting of two frequencies. It is transmitted via the telephone line
(communication media).
DTMF decoder, which decodes the frequencies in to digital code.
1.1.3 Components Required:
Components required for DTMF circuit are as follow:
DTMF decoder IC (M-8870)
Crystal Oscillator 3.5795 MHz
Resistors (100kΩ; 100kΩ; 330kΩ)
7805 Regulators
Capacitors (0.1µF x 2)
9 volt DC battery
Bread board
1.1.4 Circuit Diagram of DTMF Circuit:
Circuit Diagram of DTMF circuit is as follow:
9. 9
Figure1.5 PhysicalDiscriptionofDTMFCircuit
It can be seen from pin configurations in fig 1.4 that output is generated at pin numbers 14,13,12,11 and
pins 6, 5, 9 are grounded and 1, 4 are short circuited. The following figure shows DTMF outputs on
pressing different buttons of transmitter mobile. In this circuit, tip is connected to pin 2 and 3 of DTMF
through capacitor and resistors. Pin 14 is most significant bit and pin 11 is least significant bit.
In this the major logic is when we press the respective button on the keypad of mobile then that button
has its own particular frequency as described in fig 1.3 then our purpose is to convert that particular
frequency into respective logic for this purpose we use crysral oscillator which is used to make the logic
for particular frequency and that logic is generated through DTMF IC , So every button of Keypad has its
own particular frequency so we are converting that frequency into respective logic and we are giving this
logic into micro-controller .The respective frequency as well as respective logic generated by DTMF
circuit for particular button of keypad is shown in figure as shown below
10. 10
Figure1.6 Frequency &LogicofkeypadbuttonsgeneratedbyDTMFcircuit
1.2 Microcontroller:
The four outputs generated from DTMF decoder are basically inputs of microcontroller TM4C123H6PM or
LM4F120H5QR.On the basis of these inputs four different outputs will be generated which through motor
driver will control the direction of car.
The Figure of micro-controller we are using TIVA ARM TM4C1233H6PM is shown below:
11. 11
Figure 1.7 TIVA ARM TM4C1233H6PM
We will configure port B as output and port E as input by means of direction register. Direction register
is enabled for port B and direction register is not enabled for port E. Digital enable is enabled for both
port B and port E. Pull up resistor is enabled for port E.
1.2.1 Code explanation:
Microcontroller is coded in such a way that when DTMF decoder IC gives “2” (0010) as input at port E,
output which is taken at port B generated as 0101 through which motor driver will make both sets of
motors to move in forward direction.When DTMF decoder gives “4” (0100) as input at port E, output at
port B generated as 0001 through which motor driver will make right set of motors to move forward
which in turn results in movement of car towards left side.When DTMF decoder gives “6” (0110) as input
at port E, output at port B generated as 0100 through which motor driver will make left set of motors
to move forward which in turn results in movement of car towards right side.When DTMF decoder gives
8 (1000) as input at port E, output at port B generated as 1010 through which motor driver will make
both sets of motors to move in backward direction and hence car will move backward.
1.2.2 Code :
The code of “MOBILE CONTROL CAR THROUGH VOICE CALL” is as follow:
“C” FILE
14. 14
The header file of project in which all the registers address and addresses of all the ports and
other information related ports are described below in figure 1.9:
Figure1.9 H-codeof“MobileControlCarThroughVoiceCall”
1.3 Motor Driver Circuit:
Third part of circuit is motor driver circuit. Motor driver circuit uses the outputs of microcontroller and
allows the car to move in backward, forward, left and right directions by controlling the motors and
allowning the motors to move in clock-wise as well as in anti-clock wise direction.
1.3.1 Advantages of motor driver circuit:
Advantages of motor driver circuit are as follows:
Use to turn the motor in clockwise and in anti-clockwise direction.
Use to control the speed of motor.
1.3.2 L293D Description:
L293D is a typical Motor driver or Motor Driver IC circuit which allows DC motor to drive on either
direction. L293D is a motor driver circuit which can control a set of two DC motors simultaneously in any
direction. It means that you can control two DC motors with a single L293D at a time. Vcc greater than
36 volts cannot be applied on it. If this motor driver will enable both pins of two motors then car will
move in forward direction. Because of H bridge circuit car can move in backward direction. Enabling pin
of right motor will move the car in left direction, while enabling the pin of left motor will move the car
in right direction. Enabling both the pins allow car to move in forward direction.
15. 15
2 Interactive voice response (IVR):
Interactive voice response (IVR) is a technology that allows a computer to interact with humans through
the use of voice and DTMF tones input via keypad. So this technology which we have used is basically an
IVR technology.
3 CHALLENGES FACED DURING IMPLEMENTATION:
The challenges faced during implementation are as follow:
Our basic challenge is based on DTMF circuit in which there is very difficulty for getting DTMF IC
named MT8870 because this IC is being banned by Pakistani government due to mis-use because
this IC is being using in making automatic voice call based bombs.
Secondly Major challenge that we faced is to control the car with respective buttons because we
have to control the car with 2,4,6,8 button keys only, and when we configure these pins to control
the car then other key buttons also take part to control the car and these buttons affects the car
control very badly and car oftenly goes unstable.
Thirdly we are using Three “3.7 Volts” Rechargeable cells in series which add up to make almost 12
Volts. and when we gave this voltage to Motor Driver Circuit and when we control the car then due
to this high Voltage DC Motors goes Mad and totally unstable which affects badly the car so
previously we were using separate battery to give power of 5 Volts to Microcontroller as well as to
DTMF IC then to remove this defect we remove that 9 Volts separate battery as were using and then
we give the power to Microcontroller as well as DTMF IC with the same 3 pairs of cell then in this
way we devided the voltage of battery into microcontroller and across DTMF IC.
Fourthly The major and most important challenge that we have face is to control the speed of
motors or to control the speed of car which is our major goal in the project. In this we have to give
PWM (pulse width modulation) to Motor driver circuit and when we use this then all the respective
key handlers of Car works differently then we add Pull-up registers to inputs of microcontroller but
then we got the different problem when we press the respective control button then after first
pressing car remains going to work on that button which is pressed first time then we also add pull-
down resistors to input of microcontroller then all the problems related speed control vanishes and
in this way we achieved our goal.
4 Bibliography
Arkin, R. (1989). Motor schema-based mobile robot navigation. In International Journal of Robotics research (pp.
92-112).
Mate, P. M. (n.d.). Cell Phone Operated Robot. Retrieved from slideshare:
http://www.slideshare.net/aniket581988/cell-phone-operated-robot
Muhammad Tahir, K. J. (2015). ARM Microprocessor Systems. Lahore: CRC Press.
Muhammad Tahir, K. J. (2015). ARM Microprocessor Systems. In K. J. Muhammad Tahir, ARM Microprocessor
Systems (pp. 312-314). Lahore: CRC Press.
Sanfeliu, J. A.-C. (2001). Topological map learning for a mobile robot in indoor environments. In J. a. Pla,
Proceedings of the 9th Spanish Symposium on Pattern Recognition and image Analysis (pp. 221-226).
16. 16
Yerraballi, J. V. (2012, May). Parallel I/O ports. Retrieved from Electrical Computer Engineering Department
,University of Texas: http://www.users.ece.utexas.edu
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