1. ORGANIZATION : ECIL
SUBMITTED BY: VISHWANATH
BRANCH: ELECTRICAL
ROLL NO: 09281A0233

2. CONTENTS
INTRODUCTION OF PROJECT
INTRODUCTION OF MICROCONTROLLER 8051
INTRODUCTION OF DTMF
INTRODUCTION OF MAX 232
WORK DETAIL
RESULT
CONCLUSION

3. INTRODUCTION OF PROJECT
• This project is to develop a device that allows for a user to
remotely control home appliances using a cellular phone.
This system will be a powerful and flexible tool that will
offer this service at any time, and from anywhere .
The control system will include two separate units: the
cellular phone, and the control unit.
There will be two operating environments. The cellular
phone operates indoor and outdoor and control unit
operates indoor.

5. INTRODUCTION OF MICROCONTROLLER
A microcontroller is an economical computer-on-a-
chip.It is a small and low-cost computer ,which
performes specific task.
Microcontroller has an input device in order to get the
input and an output device (such as LED or LCD
Display) to exhibit the final process.
The 8051 has three very general types of memory to
effectively program the 8051 it is On-Chip Memory,
External Code Memory, External RAM.
A microcontroller has a CPU(a microprocessor) in
addition to fixed amount of RAM, ROM, I/O port and
a timer all on single chip. therefore the designer
cannot add any external memory, I/O ports or timer
to it.

6. BLOCK DIAGRAM OF
MICROCONTROLLER

7. INTRODUCTION OF DTMF
The DTMF tone decoder IC converts the received tones to
their respective binary values and then gives them as an
input to the microcontroller.
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.

8. The DTMF keypad is laid out in 4*4 matrix with each row
representing a low frequency and each column representing
a high frequency
The DTMF tone decoder IC’s internal architecture consists
of a band split filter section which separates the low and the
high tone of the received tone pair.

9. DTMF KEYPAD FREQUENCIES
DTMF keypad frequencies (with sound clips)
1209 Hz 1336 Hz 1477 Hz 1633 Hz
697 Hz 1 2 3 A
770 Hz 4 5 6 B
852 Hz 7 8 9 C
941 Hz * 0 # D

10. INTRODUCTION OF MAX 232
The Max 232 is a dual driver/receiver that includes a
capacitive voltage generator to supply EIA-232 voltage
levels from a single 5V supply.
The MAX 232 is to connect a serial port device to a
serial port which uses the RS232 standard
The serial port device is usually a UART(universal
asynchronous receiver/transmitter)

12. WORK DETAIL
 This project is to develop a device that allows for a user to
remotely control home appliances using a cellular phone.
 The system requires two phones out of which the one present at
the control unit has to be a cell phone with auto answer facility.
 The person who wants to switch on/off any device makes a call
from mobile phone.
 Once the call gets picked up, presses the key for a corresponding
device.
 The mobile phone on the receiver side picks up the phone
automatically after 5seconds, and then makes the tones available
to the DTMF tone decoder IC through the headphone jack of the
phone.

13. The DTMF tone decoder IC converts the received tones to
their respective binary values and then gives them as an
input to the microcontroller.
 DTMF verifies both the frequency and duration of the
received tones and pass the resultant 4-bit code to the
output bus.
The output from DTMF IC is given into the
MICROCONTROLLER 8051.

15. RESULT & CONCLUSION
We have successfully completed the project “DEVICE
ON OFF THROUGH MOBILE PHONE”
This project is very useful now a days as well as its
cost is very low, so anyone can afford it and use it.