This document describes a cell phone based device control project developed under the guidance of Ms. G. Susmitha. The objective is to turn appliances on and off using a cell phone as a remote control. The system allows controlling up to 6 devices and provides voice status updates. It uses components like a microcontroller, DTMF receiver, relay driver, and other basic electronic components. The circuit diagram and working are explained, including interfacing techniques. Advantages, limitations, software used, and future scope are discussed.

1. CELL PHONE BASED DEVICE CONTROL
UNDER THE GUIDANCE OF “MS.G.SUSMITHA”Asst.Prof.
DEPARTMENT OF ELETRICAL AND ELECTRONICS ENGG.
GROUP MEMBERS:
A.VISHWANATH (09281A0233)
K.BHAVANA (0928A10246)
D.SANTHOSH (09281A0209)

2. OBJECTIVE
Turning on/off the appliance with our cell phone.
Cell phone as the remote control for our home appliances.
System also gives voice acknowledgement of the
appliances status.

3. FEATURES
We can control up to 6 devices
There is no risk for false switching.
Before changing the state of the device we can confirm
the present status of the device.

4. LAYOUT OF THE CIRCUIT

5. COMPONENTS USED
Regulator(7806-6V)
Microcontroller(AT89C51)
DTMF receiver(H9170B)
Relay driver(L293D)
Crystal oscillator(11.0592MHz,3.579MHz)
Resistors(1K,10K,100K)
Diode(IN4007)
LED(5mm)
Capacitors(0.1uf,4.7uf,10uf,33pf)
Electret microphone
Mobile phone headset connector
Push to on switch
2 way DIP Switch

6. Power Supply Circuit

7. CIRCUIT DIAGRAM

8. INTERFACING OF SWITCHES WITH
MICROCONTROLLER
TABLE- I
SWITCHES MOBILE KEYS FUNCTION
S1 1 Select Device 1:On/Off
S2 2 Select Device 2:On/Off
S3 3 Select Device 3:On/Off
S4 4 Select Device 4:On/Off
S5 5 Select Device 5:On/Off
S6 6 Select Device 6:On/Off
S7 * Initialize to inform the
status of the device

9. CONTROL SOURCE SELECTION USING
DIP SWITCHES
TABLE-II
S17 S18 CONTROL STATUS
0 0 Rest Status
0 1 Switches Only
1 0 Mobile Only
1 1 Switches and Mobile

10. RECORDING AND PLAYBACK TABLE
TABLE III
SWITCHES TRIGGER OF IC FUNCTIONS
S9 1 NAME OF DEVICE 1
S10 2 NAME OF DEVICE 2
S11 3 NAME OF DEVICE 3
S12 4 NAME OF DEVICE 4
S13 5 NAME OF DEVICE 5
S14 6 NAME OF DEVICE 6
S15 7 STATUS” ON”
S16 8 STATUS” OFF”

11. INTRODUCTION TO MICROCONTROLLER
A single chip that contains:
a)Processor(CPU)
b)Non volatile memory(ROM)
c)Volatile memory(RAM)
d)Clock
CPU RAM ROM
e)I/O controlling unit
I/O TIMER SERIAL
COM
PORT

12. AT89C51
Feature Quantity
ROM 4K bytes
RAM 128 bytes
Timer 2
I/O pins 32
Serial port 1
Interrupt sources 6

13. INTERFACING DRIVER USING IC-L293D
L293D is a dual motor driver integrated circuit (IC).
Motor drivers act as current amplifiers since they take
a low-current control signal and provide a higher-
current signal. This higher current signal is used to
drive the motors.
In its common mode of operation, two DC motors
can be driven simultaneously, both in forward and
reverse direction. The motor operations of two
motors can be controlled by input logic at pins 2 & 7
and 10 & 15. Input logic 00 or 11 will stop the
corresponding motor. Logic 01 and 10 will rotate it in
clockwise and anticlockwise directions, respectively.

14. DTMF DECODING USING IC-HT9170B.
Decodes the mobile signal.
It gets DTMF tone from the mobile headset’s
speaker pins.

15. DECODING TABLE
TABLE IV
KEY STD Q3 Q2 Q1 Q0
1 H 0 0 0 1
2 H 0 0 1 0
3 H 0 0 1 1
4 H 0 1 0 0
5 H 0 1 0 1
6 H 0 1 1 0
* H 1 0 1 1
# H 1 1 0 0

16. Comparison between 8051 and Atmel
• 8051 and 89c51 are same architecture but difference is
ROM memory .
• ROM less for 8051 while ROM (flash) for 89c51.
• it advanced EEPROM (flash) is difference.
• it becomes possible for the 8051 designer to directly
start using 89SXX and 89S20XX microcontrollers
without any more efforts in learning these
microcontrollers.

17. ADVANTAGES OF THE PROJECT
Utilization Of Electrical power.
Power Conservation.
Design is small and portable.
Easy to use.
Economical.

18. LIMITATIONS
The receiver must reside where sufficient signal can be
received from a cellular phone network.
The receiver must have a power source attached at all
times.
 Only 6 devices can be connected to the system.

19. SOFTWARE
The program (Device_Control.BAS) for the
microcontroller is written using BASCOM microcontroller
programming software.
In the program, first, initialize the ports (P0-P3) for
corresponding controls. Thereafter, declare the variables
for the program. After declaration, assign some initial
value to variables. Here, microcontroller ports are
initialized to make all the devices ‘off’ initially .

20. FUTURE SCOPE
In this project we are monitoring and controlling the
home appliances from remote places by using the
mobile technology. This project can be further
enhanced to the High voltage A.C Applications by
changing the ratings of the Relay.
By this we can control and monitoring the high speed
induction motors as well as synchronous motors. This
can be done in an economical way

21. CONCLUSION
• The project “Development of Cell-phone Based
Device Control " an effective switching system for
controlling home and office appliances.”

22. BIBLIOGRAPHY
Reference Books:
1)Electronic Devices & circuits by J.B.GUPTA.
2)The 8051 Microcontroller And Embedded Systems by M.A.MAZIDI
3)Electronics For You Magazine.
Reference Websites:
1) www.engineersgarage.com
2)www.efy.com
3)www.electronicsforu.com

23. THANK YOU