Download A-level Electronics Major Project Theodore

Summary
The aim of this project was to build a home automation system so that the householder could dial
into their house with a modem, from the office or even the other side of the world, and control
their home appliances.
The main part of the system had to be microprocessor based, because of the requirement to
communicate intelligently with a person at the other end of a telephone line. A reasonably
powerful system was chosen to perform the task competently. This formed a flexible
multipurpose system not tied to this project. The modem input was replaced with a computer
terminal because I did not have access to two telephone lines for testing.
The main control unit talks to a module fitted in each appliance, which contains a small customprogrammed microcontroller. Originally I intended the module to communicate with the main
system over the mains wiring, but problems caused by not having direct mains access meant a
wire link had to be used instead. This was designed to be easily converted to a mains link if
required.
Overall, the system works, but the software could be substantially improved. This is a large
project, so it was not possible to refine it in the time available.
Telephone
line
Modem
Microprocessor
system
Transmission
system
Mains
wiring
forming
data
link
Appliance
to be controlled
Remote control
module
Receiving
system
Initial block diagram
The microprocessor system was split again into a number of blocks:
Copyright Theo Markettos 1997. This may be used for educational and non-profit making purposes
only. The author may be reached at [email protected]
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