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 custom- programmed 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.
![[Initial block diagram of whole system]](summ1.gif)
The microprocessor system was split again into a number of blocks:
![[Initial block diagram of microprocessor system]](summ2.gif)
In the final project, these were modified slightly:
![[Final block diagram of whole system]](summ3.gif)
![[Final block diagram of microprocessor system]](summ4.gif)
Page by Theo Markettos (email at theo [at@] markettos.org.uk), last modified 2001-01-09
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