Re: one wire sensors

[Jeff <dont_bug_me@xxxxxx>]

Marc_F_Hult wrote:

> On Fri, 06 Jul 2007 13:12:14 GMT, Jeff <dont_bug_me@xxxxxx> wrote in message
> <Ocrji.5158$zA4.3511@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>:
>
>
>>  I'd like to control ventilation and some other household functions
>>with some kind of home automation. I'd like to be able to track temp and
>>humidity in various parts of the house also. I have some knowledge of
>>programming, electronics and making circuit boards for that matter (not
>>that I want to make any circuit boards)!
>>
>>  Not knowing much about this, here is what I'm thinking and please
>>feel free to tell me what is crap!
>>
>>  I've seen these one wire sensors. That would seem to me the way to go
>>but I'm unsure how this interfaces with the automation. How does this
>>work? Can this be interfaced with any of the STAMP modules that are
>>available?
>>
>>  The way I picture this is that one wire sensors feed the STAMP (or
>>other automation control) and that is interfaced to a home PC. Is that
>>about right or are these things best done otherwise?
>>
>>  How is the programming handled? I've seen mention of Ada and C on the
>>STAMP level.
>>
>>  Jeff
>
>
> I'd be wary of _depending_ on Dallas / Maxim 1-wire for new applications.

Ouch.

   I suppose that if you put the logic near the sensor then you are less
needing of the capability of one wire.
>
> The Applications Engineer for the 1-Wire and iButton Groups wrote me : " It
> is correct that the DS2890 was recently assigned a NRFND status.  Our
> customer base on this product is very small and ongoing R&D investment is
> large and prohibitive to convert the 6" wafer based design to an 8"
> wafer equivalent that is necessary to continue production in our wafer fabs.
> Our EOL strategy for this device is to build a supply of product that will
> provide a 5yr to 7yr supply to existing customers. "
>
>
> Nonetheless, I've developed a family of pcboards that provide signal
> conditioning, power supply and analog, digital, and 1-wire connectivity for
> what I call THOL (Temperature, Humidity, Occupancy and Lighting). They are
> designed to fit in single gang switch box for wall or ceiling mounting, are
> connected to a multiplexor at one or more central locations for logging via
> DMX, 1-wire and PC-PCI 16-bit AD converters.

That sounds pretty nice.

Have you done anything with picaxe?

<URL: http://www.rev-ed.co.uk/picaxe/ />

   It looks like that should handle the DMX also. Thanks for the tips.

   I'm trying to go solar here. I've got a fairly large solar air heater
on the south wall and am working on 120 ft2 of solar water. When I have
some more time I'd like to run a dessicant solar AC. All of that needs
some logic, some logging and some adjusting! Probably lots of adjusting.

   I'm thinking now of a picaxe for each device and a DMX cable back to
another picaxe for logging and master control:

<URL: http://www.rev-ed.co.uk/docs/AXE110.pdf />

but I'm not crazy about that idea!

Wonder what it would take to write to a USB memory stick as I see that
picaxe can read to USB, but I don't know about the reverse. Could import
the data to a PC later and sort it all out later, though I see that
timestamping is not trivial.

   I expect the first boards back
> in a week or so. If I like the  prototypes, I may put together a large order.
>
> Most HA systems are not very good at data logging (checking, interpreting,
> representing, and storing data). This system is designed to address that need
> in a robust and redundant way.

   From the little I've looked into it, I can see that's a big complex
problem. I suppose it would be easier to dump it off to a PC to process
and store but that negates the whole high availabilty, low power
concept. This gets hard fast!
>
> I'll post more later to my web site ... Marc

   Thanks!

   I thought my 1920 house was old (I peeked through your site!)!

   Cheers,
Jeff
>
> Marc_F_Hult
> www.ECOntrol.org