Microcontroller based remote controlling project using mobile phone. with implementing this u can remotely control ur home appliances like fan, light, tv even industrial machines through a mobile phone being in a long distance.

1. DTMF BASED REMOTE CONTROLLING OF
HOME APPLIANCES USINGMOBILE
PHONE
A project for the partial fulfillment of requirements for the
B.Sc.(Honors) degree.
Project Supervisor
FarhanaBinte Sufi
Lecturer
Department of Applied Physics & Electronic Engineering
University of Rajshahi
Submitted by
Roll no.-09034939
Registration no.-1701
Session 2008-2009

2. CERTIFICATION
This is to certify that the project “DTMF BASED REMOTECONTROLLING OF
HOME APPLIANCES USING MOBILE PHONE” has been carried out by examinee
Roll: 09034939, Session: 2008-09 under my supervision for the B.Sc. (Hons.)
Part-IV Examination-2012.
The examinee has completed the project in due time and successfully.
FARHANA BINTE SUFI
Lecturer
Dept. Of Applied Physics and
Electronic Engineering
University of Rajshahi
Rajshai-6205

3. ACKNOWLADGEMENT
I would like to take this opportunity to express my deepest sense of gratitude
and respect to my honorable teacher & project supervisor “ FarhanaBinte Sufi “
, Lecturer , Department of Applied Physics & Electronic Engineering,
University of Rajshahi, who guided me in this project and help me in every
stage where any difficulty comes. And she has given me valuable suggestions
on the development of my project and suggested me to prepare this project
paper.
I am also thankful to Professor A.B. Md. Ismail, Chairman, Department of
Applied Physics & Electronic Engineering, University of Rajshahi, for his
kindness in providing me access to the seminar library, internet connections and
lab facilities. My heartiest thank to all my respectable teachers, and my
classmates for providing moral support and encouragement to enhance my
knowledge on Microcontroller.
Foremost and finally, it is generosity and guidance of Almighty God to honor
me with power and persistence to get this work done.
Bipro Roy Chanchal
Date: 17/11/2012 TheAuthor

4. CONTENTS
page
1. Introduction…………………………………………………………. 01
2. DTMF Basics……………………………………………………….. 02
3. Decoder Description………………………………………………… 05
4. ATMega 16 Microcontroller……………………………………....... 07
5. Design Basics…………………………………………………………11
6. Implementation& Discussion………………………………………..15
7. Conclusion………………………………………………………........16
8. Appendix……………………………………………………………..17
9. Reference…………………………………………………………….. 23

5. ABSTRACT
The project demonstrates a novel method which enables users to control
their home appliances and systems for remotely using a cell phone-based
interface. To access the control unit, the user should send an authentication code
Dual Tone Multi Frequency along with the required function to his/her home
control system via Global System for Mobile communication (GSM). Upon
being properly authenticated, the cell phone-based interface at home (control
unit) would relay the commands to a microcontroller that would perform the
required function.
Four mobile keypad buttons generate four different DTMF signals at
input which is sent to the mobile at output section via GSM. Then the signal is
transferred to a Microcontroller. Microcontroller output is used to make active
or inactive two magnetic relays for four different state (i.e. keypad button 2 is
used make two relays idle. Keypad button 4 is used to make one relay one and
so on.)

6. DEDICATED
TO
MY
PARENTS

7. INTRODUCTION
The remote control technologies have been used in the fields like
factory automation, space exploration, in places where human access is difficult.
As this has been achieved in the domestic systems partially, many corporations
and laboratories are researching the methods which enable human to control and
monitor efficiently and easily in the house or outdoor. Controlling the domestic
system regardless of time and space is an important challenge. As the mobile
phone enables us to connect with the outside devices via mobile communication
network regardless of time and space, the mobile phone is a suitable device to
control domestic systems. [1]
This project proposes a method to control a domestic system using a
mobile phone, irrespective of the phone model and mobile phone carrier. The
system suggested consists of the mobile phone normally registered in
communication service and a mobile phone that can receive a call from another
phone. Existing methods for control and monitoring, using mobile phones have
usage problems because the cost and need for continuous control. One of the
disadvantage, being the lack of feedback during the process. This paper
proposes to solve the problems of existing methods of control that use simple
voice call. Method proposed uses the DTMF (Dual Tone Multi Frequency)
generated when a keypad button of the mobile phone is pressed by the user. The
mobile phone user controls the system by sending the DTMF tone to the access
point. Mobile communication network coverage is larger than that of LANs,
thus user can take advantage of mobile phones to control the system.

8. DTMF BASICS
DTMF is a generic communication term for touch tone (a Registered
Trademark of AT&T). The tones produced when dialing on the keypad on the
phone could be used to represent the digits, and a separate tone is used for each
digit. However, there is always a chance that a random sound will be on the
same frequency which will trip up the system. It was suggested that if two tones
were used to represent a digit, the likelihood of a false signal occurring is ruled
out. This is the basis of using dual tone in DTMF communication.[2]
DTMF dialing uses a keypad with 12/16 buttons. Each key pressed on
the phone generates two tones with specific frequencies, so a voice or a random
signal cannot imitate the tones. One tone is generated from a high frequency
group of tones and the other from low frequency group.[2]
The frequencies generated on pressing different phone keys are shown in the
Table 1.
Table 1 – Frequencies generated on Key presses [3]
Button Low
Frequency(Hz)
High
Frequency(Hz)
1 697 1209
2 697 1336
3 697 1477
4 770 1209
5 770 1336
6 770 1477
7 852 1209
8 852 1336
9 852 1477
0 941 1209
* 941 1336
# 941 1477
Each row and column of the keypad corresponds to a certain tone and creates a
specific frequency. Each button lies at the intersection of the two tones as
shown in Table 2.

9. Table 2 – Row and Column Frequency Correspondence [1]
1 2 3 697
4 5 6 770
7 8 9 852
* 0 # 941
1209 1336 1477 Frequency(Hz)
When a button is pressed, both the row and column tones are generated
by the telephone instrument. These two tones will be unique and different from
tones of other keys. So, whenever we say that there is a low and high frequency
associated with a button, it is actually the sumof two waves is transmitted. This
fundamental principle can be extended to various applications. DTMF signals
can be transmitted over a radio to switch on or switch off home appliances,
flash lights, motors, cameras, warning systems, irrigation systems and so on.
These encoded data can be stored in a microcontroller and can be transmitted
serially to another system for processing. Block diagram for the proposed
method is shown in Figure 1. [1]

10. Figure 1 – Block diagram of the scheme [1]

11. DECODER DESCRIPTION
The decoder used is M-8870. For operating functions (see Fig. 2 –
Structure of M-8870). M-8870 includes a band split filter that separates the high
and low tones of the received pair, and a digital decoder that verifies both the
frequency and duration of the received tones before parsing the resulting 4-
bitcode to the output bus. The M-8870 decoder uses a digital counting technique
to determine the frequencies of the limited tones and to verify that they
correspond to standard DTMF frequencies. Table 3 shows values of Decoder
output for various frequencies.
Table 3- Values of Decoder output for various frequencies [3]
Button Low
Frequency(Hz)
High
Frequency(Hz)
Q1 Q2 Q3 Q4
1 697 1209 0 0 0 1
2 697 1336 0 0 1 0
3 697 1477 0 0 1 1
4 770 1209 0 1 0 0
5 770 1336 0 1 0 1
6 770 1477 0 1 1 0
7 852 1209 0 1 1 1
8 852 1336 0 0 0 0
9 852 1477 1 0 0 1
0 941 1209 1 0 1 0
* 941 1336 1 0 1 1
# 941 1477 1 1 0 0

12. Figure 2 - Structure of 8870 Decoder [3]

13. ATMEGA 16 MICROCONTROLLER
The ATmega16 is a low-power CMOS 8-bit microcontroller based on
the AVR enhanced RISC architecture. By executing powerful instructions in a
single clock cycle, the ATmega16 achieves throughputs approaching 1 MIPS
per MHz allowing the system designer to optimize power consumption versus
processing speed.
The AVR core combines a rich instruction set with 32 general
purpose working registers. All the32 registers are directly connected to the
Arithmetic Logic Unit (ALU), allowing two independent registers to be
accessed in one single instruction executed in one clock cycle. The resulting
architecture is more code efficient while achieving throughputs up to ten times
faster than conventional CISC microcontrollers.
The ATmega16 provides the following features: 16 Kbytes of In-
System Programmable Flash Program memory with Read-While-Write
capabilities, 512 bytes EEPROM, 1 Kbyte SRAM, 32 general purpose I/O lines,
32 general purpose working registers, a JTAG interface for Boundary scan, On-
chip Debugging support and programming, three flexible Timer/Counters with
compare modes, Internal and External Interrupts, a serial programmable
USART, a byte oriented Two-wire Serial Interface, an 8-channel, 10-bit ADC
with optional differential input stage with programmable gain (TQFP package
only), a programmable Watchdog Timer with Internal Oscillator, an SPI serial
port, and six software selectable power saving modes.
.
The Idle mode stops the CPU while allowing the USART, Two-wire
interface, A/D Converter, SRAM, Timer/Counters, SPI port, and interrupt
system to continue functioning. The Power-down mode saves the register
contents but freezes the Oscillator, disabling all other chip functions until the
next External Interrupt or Hardware Reset. In Power-save mode, the
Asynchronous Timer continues to run, allowing the user to maintain a timer
base while the rest of the device is sleeping. The ADC Noise Reduction mode
stops the CPU and all I/O modules except Asynchronous Timer and ADC, to
minimize switching noise during ADC conversions. In Standby mode, the
crystal/resonator Oscillator is running while the rest of the device is sleeping.
This allows very fast start-up combined with low-power consumption. In
Extended Standby mode, both the main Oscillator and the Asynchronous Timer
continue to run. The device is manufactured using Atmel‟s high density
nonvolatile memory technology. The On chip ISP Flash allows the program
memory to be reprogrammed in-system through an SPI serial interface, by a
conventional nonvolatile memory programmer, or by an On-chip Boot program

14. running on the AVR core. The boot program can use any interface to download
the application program in the Application Flash memory. Software in the Boot
Flash section will continue to run while the Application Flash section is
updated, providing true Read-While-Write operation. By combining an 8-bit
RISC CPU with In-System Self-Programmable Flash on a monolithic chip, the
Atmel ATmega16 is a powerful microcontroller that provides a highly-flexible
and cost-effective solution to many embedded control applications. The
ATmega16 AVR is supported with a full suite of program and system
development tools including: C compilers, macro assemblers, program
debugger/simulators, in-circuit emulators, and evaluation kits.[4]
Pin Descriptions
VCC Digital supply voltage.
GND Ground.
Port A (PA7..PA0) Port A serves as the analog inputs to the A/D Converter.
Port A also serves as an 8-bit bi-directional I/O port, if the A/D Converter is not
used. Port pins can provide internal pull-up resistors (selected for each bit). The
Port A output buffers have symmetrical drive characteristics with both high sink
and source capability. When pins PA0 to PA7 are used as inputs and are
externally pulled low, they will source current if the internal pull-up resistors
are activated. The Port A pins are tri-stated when a reset condition becomes
active, even if the clock is not running.
Port B (PB7..PB0) Port B is an 8-bit bi-directional I/O port with internal pull-
up resistors (selected for each bit). The Port B output buffers have symmetrical
drive characteristics with both high sink and source capability. As inputs, Port B
pins that are externally pulled low will source current if the pull-up resistors are
activated. The Port B pins are tri-stated when a reset condition becomes active,
even if the clock is not running. Port B also serves the functions of various
special features of the ATmega16.
Port C (PC7..PC0) Port C is an 8-bit bi-directional I/O port with internal pull-
up resistors (selected for each bit). The Port C output buffers have symmetrical
drive characteristics with both high sink and source capability. As inputs, Port C
pins that are externally pulled low will source current if the pull-up resistors are
activated. The Port C pins are tri-stated when a reset condition becomes active,
even if the clock is not running. If the JTAG interface is enabled, the pull-up
resistors on pins PC5(TDI), PC3(TMS) and PC2(TCK) will be activated even if
a reset occurs. Port C also serves the functions of the JTAG interface and other
special features of the ATmega16.
Port D (PD7..PD0) Port D is an 8-bit bi-directional I/O port with internal pull-
up resistors (selected for each bit). The Port D output buffers have symmetrical

15. drive characteristics with both high sink and source capability. As inputs, Port D
pins that are externally pulled low will source current if the pull-up resistors are
activated. The Port D pins are tri-stated when a reset condition becomes active,
even if the clock is not running. Port D also serves the functions of various
special features of the ATmega16.
RESET Reset Input. A low level on this pin for longer than the minimum pulse
length will generate a reset, even if the clock is not running. Shorter pulses are
not guaranteed to generate a reset.
XTAL1 Input to the inverting Oscillator amplifier and input to the internal
clock operating circuit.
XTAL2 Output from the inverting Oscillator amplifier.
AVCC AVCC is the supply voltage pin for Port A and the A/D Converter. It
should be externally connected to VCC, even if the ADC is not used. If the
ADC is used, it should be connected to VCC through a low-pass filter.
AREF AREF is the analog reference pin for the A/D Convert.

16. Figure 3 - Pin Configuration of AT Mega16 microcontroller. [2]

17. DESIGN BASICS
The operation is initiated by calling the second mobile phone (which is
connected to the DTMF as shown in the Fig.1) and typing in the desired number
corresponding to the required control effort at the transmitter end.
When the handset of the phone at the receiver end is picked up or the
phone is picked up automatically, the receiver end comprises of input device,
decoder, microcontroller, and relays. The input section consists of a mobile
phone and a condenser microphone. For the decoder section, the underlying
concept is DTMF signal reception and the decoded signal is fed to the
microcontroller. The microcontroller output is connected to relays which
perform the required action. Once the connection is established between the two
phones, whatever phone key is pressed at the transmitting end, the
corresponding DTMF tone is heard in the ear piece of the receiver phone. The
ear piece is connected to a condenser microphone which picks up the DTMF
tone and this output is fed to the DTMF decoder. The DTMF decoder will give
the corresponding BCD value of the tone. The output of DTMF decoder is
inverted by IC 74LS04, which is the input of microcontroller. This output is
connected to PORT A of the Atmega 16L microcontroller. Then
microcontroller‟s output from PORT D is fed to the relays. Microcontroller is
programmed as by pressing a button of caller handset it activates or deactivates
the corresponding relay to switch on or off the home appliances.
Table-4 Actions performed corresponding to the key pressed
Number
pressed
by user
Output of
DTMF
decoder
Input to
microcontroller
Output from
microcontroller
Action
performed
2 0x02
00000010
0x0D
00001101
0x00
00000000
Both relays
off
4 0x04
00000100
0x0B
00001011
0x01
00000001
One relay on
6 0x06
00000110
0x09
00001001
0x02
00000010
Another relay
on
8 0x08
00001000
0x07
00000111
0x03
00000011
Both relays on

18. On a word each key press at transmitter end reflects as a BCD value Q1Q2Q3Q4
at the outputs of 8870 DTMF decoder. (The corresponding values are shown in
Table 3) Then outputs Q1Q2Q3Q4 are inverted and processed by microcontroller
and sent to the relay which is the basic structure of proposed work.
In this project required power is assumed from 220 V AC main power
line. For this scheme AC voltage is step downed and a 7805 voltage regulator is
used to supply continuous dc voltage.
Main circuit diagram is shown in figure 4.

20. Microcontroller was programmed in C language on AVR Studio 4 software. But
C program is not compatible with ATmega 16, it supports Hex file. The
software AVR Studio 4 builds the Hex file corresponding to the C program. [5]
For working in Proteus an equivalent circuit is used, where 8870 DTMF
decoder is replaced with 4 binary switches. So the microcontroller input is given
by the switches.
Equivalent circuit using Proteus 7.7 is given in figure 5.
Figure 5- Equivalent circuit using Proteus 7.7

21. IMPLEMENTATION AND DISCUSSION
The circuit was build and tested. Refer fig. 4 for the picture of the tested circuit.
At first the circuit was simulated with software PROTEUS7.7. After successful
simulation in PROTEUS the circuit was implemented on a project board. Here
relays were checked and each of two relays from microcontroller output was
connected with 220V AC light. Relay acts as a switch [6]. The device controlled
two 220V / 40W bulb. Then main circuit was implemented onto PCB (Printed
Circuit Board).
Required VCC for microcontroller and VDD for DTMF decoder were supplied
from main 220V AC power line. 220VAC was firstly step downed to 9V with a
step down transformer. Then it was rectified and passed through a 5V voltage
regulator IC7805 to VCC and VDD of microcontroller and DTMF decoder.
Handset at transmitting end must be in General mode or profile, thus it can
generate audible keypad tones. Handset at receiving end must have the facility
of automatic receiving the calls.

22. CONCLUSION
This paper presents a method to control a domestic system using the
DTMF tone generated by transmitting telephone instrument when the user
pushes the keypad buttons of the mobile phone connected to the remote
domestic system. This control method uses commercial mobile communication
networks as the path of data transmission. This enables the user to control the
system continuously by sending the mobile phone DTMF tone. This system is
implemented in the 2G mobile communication network, so video data cannot be
obtained. Future work includes research on the robot control system in the 3G
mobile communication networks. This will facilitate controlling the remote
robot, using the DTMF of mobile phone with video data from the remote mobile
robot‟s camera. The project is also useful in industry automation.
This setup with a little modification can be adapted to the following
applications. [1]
1) Combination Lock
2) Home Security System
3) Mobile / Wireless Robot control
4) Wireless Radio Control
5) Continuous monitoring of system status
6) Remote Switches etc.

23. APPENDIX
Appendix 1 -List of Components used
1) IC 7805
2) Rectifier Diode 1N4007
3) 220v-9v Transformer
4) Condenser Microphone
5) 12MHz Crystal Oscillator
6) 3.57 MHz Crystal Oscillator
7) 8870 DTMF Decoder
8) 7404 NOT Gate
9) ATmega 16L Microcontroller
10) Transistor BC 547
11) 6 volts Relay
12) Capacitors of different values
13) Resistors of different values.

24. Appendix 2- Microcontroller Program
#include<avr/io.h>
Void main(void)
{
Unsigned intk,h ;
DDRA= 0X00;
DDRD=0XFF;
While (1)
{
k=~PINA;
h=k & 0X0F;
switch (h)
{
case 0X0D ;
{
PORTD=0x00;
break;
}
case 0x0B;
{
PORTD=0x01;
break;
}

25. case 0x09;
{
PORTD=0x02;
break;
}
case 0x07;
{
PORTD=0x03;
break;
}
}
}
}

26. Appendix 3-ATmega Programming Logic/Port Control Example Guide
Hex Values:
0xFF = all bits set (turned on/high/1/5V) ----------------------- binary equivalent
is 0b11111111
0x00 = all bits cleared (turned off/low/0/0V) ------------------- binary equivalent
is 0b00000000
0xF0 = bits 0-3 are cleared (0) and bits 4-7 are set (1) ------ binary equivalent is
0b11110000
0x88 = bits 3 and 7 set (1) the rest are cleared (0) ----------- binary equivalent is
0b10001000
Look up : hexadecimal for an entire list of possible hex values. ATmega pin
number equivalents example:
Number 7 6 5 4 3 2 1 0 – Pin numbers on the port (and bit
numbers)
0x0F==0b00001111 0 0 0 0 1 1 1 1– set to high and low with hex/binary
values
Setting Bit Values:
Many times we would like to set the voltage high for only a single pin of a port,
and to do that you create what is called a „bit mask‟, which is a binary number
that has single 1-bit in the location corresponding to the pin you want to set, and
all the rest of the bits are zero. You then use this number with a bitwise logical
operator to finish the task. To create such a number, we should use the
command:
_BV(PXn) // Where X is the port letter, and n is the pin number. For
example, suppose you would like to make pin 2 on PORTA to be an output.
You therefore need a bit mask with a 1 in bit number 2 location. The
corresponding bit mask is easily built
by the command: _BV(PA2)
Setting the port‟s data direction (input or output) on an ATmega:
DDRX = 0x00; // Clears all the bits in the PORTx register, which makes all
the associated pins to be inputs (keep in mind there are only ports A, B, C, and

27. D on the ATmega328), so you can read various signals from things such as
switches, sensors, or for analog to digital conversion, etc. (by default all pins
are set to input, but you should always set them to make sure anyway.)
DDRX = 0xFF; // Sets all the bits in the PORTx register, which makes all
the associated pins to be outputs (keep in mind there are only ports A,B,C, and
D on the ATmega328), so you can control devices, such as motors, LED’s,
speakers, etc., pretty much anything you would want the microcontroller to
control (keep in mind that the ATmega cannot source much current, so you will
probably need to use a transistor between the microcontroller and whatever you
are trying to control if it needs more than 10 mA of current).
Initializing Port Values:
PORTX = 0xFF; // Clears all the bits in the PORTx register, and
assuming that the pins are outputs, will make all the pins in PORTx go high (as
mentioned in the section on Hex values above). So for example, PORTA =
0xFF; would set all pins in port A to on/high/1/5V, which would be the same as
writing: PORTA = 0b11111111; Keep in mind
that the right-most bit corresponds to pin 0 on PORTA in this example.
PORTX = 0x00; // Clears all bits in the PORTx register and makes all pins
in PORTx go low (as mentioned in the section on Hex values above). So for
example, PORTB = 0x00; would clear all bits in the PORTB register and make
all pins in PORTB go off/low/0/0V. This would be the same as writing: PORTB
= 0b00000000;
Bitwise Logic:
PORTX |= 0xF0; // Method for setting bits. Performs a bitwise OR
operation with the current bit values of PORTX and the bit mask represented by
the binary number, 0xF0. The result is that only pins 4-7 in PORTX are set
high, and the other pins are not affected. Equivalent in „long hand‟ would be:
PORTX = PORTX | 0xF0;
PORTX &= ~0x01; // Method for clearing bits. Performs a bitwise AND
operation with the current bit values of PORTX and the bit mask represented by
the binary number, ~(0b00000001) or 0b11111110. The result is that pin 0 is
set low (referred toas „cleared‟), regardless of what was there before. In this

28. example, only pin 0 is cleared, and the state of the other pins are not affected.
Equivalent in „long hand‟ would be PORTX = PORTX & ~0x01;
PORTX ^= 0x02; // Method for toggling bits. Performs a bitwise XOR
operation with the current bit values of PORTX and the bit mask represented by
the binary number, 0x02. The result is that pin 1 is ‘toggled’ between the off
and on states. Think of this operation like a light switch. Each time the
statement is executed, it changes the state to be the opposite of what it was
previously. Similar to the prior statements, this method of toggling only affects
the bits in the locations where there are ones in the bit mask hex value. „Long
hand‟ would be PORTX = PORTX ^ 0x02;
The methods shown above are what we need to do to set up and control all the
functions of the microcontroller. For example, suppose to turn on the ADC
(analog to digital converter). To do so, set bit 7 in the ADCSRA register. See if
can remember how to do this (without disturbing bits 6 – 0) from the description
above1.
1 ADCSRA |= 0x80;
Equivalently, we would have written: ADCSRA |= _BV(ADEN); // (ADEN is
macro-defined to be 7)

29. REFERENCES
[1] Tuljappa M Ladwa, Sanjay M Ladwa, R SudharshanKaarthik ; “Control of
Remote Domestic System Using DTMF” ; ICICI-BME 2009 Bandung,
Indonesia,2009.
[2] Yun Chan Cho and Jae WookJeon ; “Remote Robot control System based
on DTMF of Mobile Phone” ; IEEE International Conference INDIN 2008, July
2008.
[3] 8870 Datasheet,
http://www.clare.com/datasheets/8870-01.pdf
[4] ATmega 16 Microcontroller Datasheet,
http://www.atmel.com/dyn/products/datasheets.asp?family_id=607
[5]Joe Pardue ;“C Programming for Microcontrollers”; 3rd
Ed , 2010.
[6]Kevin R. Sullivan ; “Understanding Relays” .
[7]Relay,
http://en.wikipedia.org/wiki/Relay