Re: [ha] Basics
Thu, 15 Oct 1998 07:32:56 -0700

You wrote:

> Before we announce the list and web pages to the home automation
> newsgroup, are we agreed on the general principles for the project?
> Almost by definition, the charter is to discuss the design of a protocol,
> hardware and software for a home automation system. Zeb has mentioned
> some design goals which seem like a good idea to me. I would summarise
> them roughly in order of importance:
> public domain (no proprietary protocols)
> robust (will cope gracefully with failure)
> can be built by a keen hobbyist (needs soldering skills)
> modular (will operate without central control)
> simple (can be operated by someone who doesn't know the system)
> extensible (can accept all kinds of new device ideas)
> does not need a PC for normal operation
> I would add for myself:
> easy to install (no need to run new wiring everywhere)
> low cost for simple modules (wall switches and the like that you
> probably need lots of should be just a few pounds each)
> PC interface (so I can use a net connection to do stuff remotely)

Actually, the inclusion of "extensible" would also mean that "PC interface" would
be one of the "device ideas" that the ha system would accept.

As a base product these seem like design goals that are worthy and attainable.
As they stand here they probably sound like the case of "a quart in a pint pot"
but we'll be able to cut this and trim it and enhance it as we go on.

How about functional specifications? Hardware and software specs? I kind of remember
one comment that the homeowner shouldn't need access to an EPROM burner but without
some kind of logic store I'm not sure we'll be able to implement a great amount
of intelligence to the system, which is first and foremost the goal as I understand it.

What about a packaged control system like The Stamp (a microcomputer/ROM based
BASIC system) as 'brains?'

Finally, a thought about "low cost for simple modules" and Robin's comment about
light switches, etc. In the US at least, and I'm sure the other countries represented
here have similar laws, you need to be sensitive to the requirements of UL.
IIRC they have some stringent guidelines when dealing with power control circuits
which may make an enterprise like this, even hobbyist as it is, fraught with
danger. And a lot of times the design effort to gain compliance will drive
up the cost of the product significantly.