The Internet Power Line Adapter - University of Queensland

Home Automation, Power Lines and the Internet Quenten Alick
The client microprocessor must collect data from the power measurement
circuitry. An ADC on the microprocessor will be used to collect this data by
sampling the output from the power measurement circuit at a rate of 100Hz.
These samples will then averaged over a minute and the result will then be sent
to the server. The sample rate of 100Hz, sixty samples and one byte per sample
gives 6k bytes storage required.
5.3 PC Operating System
The choice of operating system for the PC needed to be made between DOS,
Windows9x and Linux. Windows9x was discounted almost immediately due to
the added complexity of programming in the visual environment. Also, network
and TCP/IP programming under windows is much more difficult due to the
Microsoft implementation of TCP/IP. This left the choice between DOS and
Linux.
Of these two, Linux was deemed to be a more suitable choice. Linux is a multi-
tasking operating system, which lends itself better to the use of a web server. It
also has built-in TCP/IP support that DOS does not have. Finally, there are
embedded versions of Linux, such as ELKS, which could be used to port
software with a minimum of fuss should this system be converted to use an
embedded processor.
5.4 Web Server & PC Interface
The PC interface to the microprocessor is fairly simple. It consists of setting up
the serial port correctly then transmitting data in the format specified for the
P300 network chip. The actual interface does not need to perform many
operations, just to turn the adapter on or off and to read a power value back from
the client. A short program will be written to perform each of these operations.
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