The concept of smart home is an emerging issue to the modern technology dependent society.Controlling household appliances through computer can be a possible solution. But it cannot fulfil the current demand which is to control home appliances from remote places.GSM-SMS technology can be used to control household appliances from remote places.Here a system of the PC remote Controlling with the Mobile Telephone through
accessing the main PC ports:the serial and parallel ports.Serial
port is used for transferring data from Mobile phone to PC and parallel port for interfacing the PC with real time controlling hardware.This system is implemented by
using the SMS(short messaging service). The software used are:Mobile to PC through
serial port is the software that ships with the Nokia mobile devices. The software to access SMS file and control all parts of system is designed by using Microsoft Visual C++ Ver. 6 .
PC interfacing system
for the purpose of interfacing with the real
time control applications, the PC parallel port is used.The parallel port pins are TTL levels output.there are 8 bits for data input/output, which can produce 256
different control signal statuses. C++ which can access the ports more efficiently than
other available computer program languages.In c++, the command _outp( ) which is a
member in conio.h header file could be used to directly
access all data port signals.By sending appropriate signals to the parallel port, all homeâ„¢s
appliances can be controlled. Interface hardware may contain Transistors used as a switch mode operation and the mini contactors.Buffer stages are used to protect the PC from any feedback.
Controlling the system remotely
This is done using two mobile phones that must support SMS and can work with the
network that provide the services of SMS.here, PC is read and receives the SMS from the
mobile phone that connected to it through serial port.the mobile phone is recognized by the PC and it receives the SMS message from any other mobile phone,
and the message is sent to the PC. The PC read the
message and storesit in a temporary file.Parsing the received SMS message for any
available control words this is done by using the appropriate program.The program used here will continuously parse the received SMS for any probability of containing
the control words, so if the control words are not found in
the received message, the program will delete the entire
message file. When a control word is found, program will prepare and
initialize the parallel port to send the proportional signal
to the interface hardware that designed that appropriately controls the home appliance.
System algorithm and program
The algorithm of the program can be briefly described as:
1) The parallel port is initialised.
2)The software recieves, stores the message in a file for eg 'inbox.dat', and reads the sms.
3)It searches for any control words in the message.control words should come between the specified codes that protocol between user of far mobile phone and
the mobile phone that connected to the PC.
4)If there are no such codes, the program will delete
the content of the Inbox.dat file and prepares itself
to receive a new message.
5)If the program found the acceptable codes, then
system compares them with a list of control words that the system is
designed for controlling the corresponding home appliances.
6)The software sends a suitable signal bit to the interface hardware through the parallel port so as to control the home appliances.
7)the program again resets the content of Inbox.dat file, and make it to
be ready to receive a new message.
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