Re: one wire sensors

[Marc_F_Hult <MFHult@xxxxxxxxxxxxxxxxxxxxx>]

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.

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.  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.

I'll post more later to my web site ... Marc

Marc_F_Hult
www.ECOntrol.org