HOME APPLIANCES CONTROL BY MOBILE SMS

                                                           INTRODUCTION 

 This project is designed to make home automation easy to control when a user is not at home. The project is designed to allow easy use of a mobile phone to control appliances in the home. Using a mobile phone the development of the control system will be carried out using SMS. This will communicate with another mobile phone, which in turn controls the devices attached to microcontroller modules. When the action has been carried out then a response is sent to the user. The project involves three main areas, research, development\programming, testing and the writing of the report.

The project is aimed at developing and testing the use of mobile phones to remotely control an appliance control system. The microcontroller would then control an device based on the information given to it. The proposed solution will need to be easy to use, simple, secure, robust and be useful on most mobile phones. To achieve this testing will need to be carried out to create a useful system.
The report consists of a background into the area of 8051 microcontroller and mobile communication, how they are interfaced to each other and AT (Attention) commands set used in communication.

HARDWARE USED

AT command supporting GSM mobile phone.
89S52 Microcontroller
Max 232 IC.
Relays
Relay driver IC ULN 2803
Voltage regulator 7805.
Diode IN4007
GSM Phone

THEORY OF OPERATION

In this project we interfaced 8051 microcontroller with Motorola’s C168 GSM mobile phone to decode the received message and do the required action. The protocol used for the communication between the two is AT command. The microcontroller pulls the SMS received by phone, decode it, recognizes theMobile no. and then switches on the relays attached to its port to control the appliances. After successful operation, controller sends back the acknowledgement to the user’s mobile through SMS.


AT-Command set

The following section describes the AT-Command set. The commands can be tried out by connecting a GSM modem to one of the PC’s COM ports. Type in the test-command, adding CR + LF (Carriage return + Line feed = \r\n) before executing. Table gives an overview of the implemented AT-Commands in this application. The use of the commands is described in the later sections.