Re: one wire sensors

[Marc_F_Hult <MFHult@xxxxxxxxxxxxxxxxxxxxx>]

On Wed, 11 Jul 2007 04:39:35 GMT, "Robert L Bass" <RobertLBass@xxxxxxxxxxx>
wrote in message  <baZki.1887$YH3.1193@trnddc08>:

>>>> ... 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.
>>>
>>> Are you planning to market these?  If so,
>>> please give me a call.
>>
>> Alas, I don't have a commercial bone in my
>> body ;-) This is mostly a hobby for me.
>
>Too bad.  You might be sitting on a gold mine.

Then perhaps HomeSeer should rename itself "HomeStake" ? -- and risk the
deprecative "HomeMistake'? ;-)

http://store.homeseer.com/store/Z-Wave-Multi-Sensor-HomeSeer-P438C57.aspx

The  HSM100 Z-Wave Multi-Sensor  is a $99  battery-operated occupancy +
temperature + light level sensor that supposedly begins shipping this week
(never-ending battery replacement not included ...).

HA may be a hobby for me, but decades of trying to keep battery-operated
scientific environmental instrumentation working reliably in the field with
batteries has caused me to develop an aversion to battery operation and
replacement. Even with checklists, schedules, good field technicians and the
best of intentions, IME they are/were the single most frequent cause of
instrument failure. YMMV.

Power supplies matter a lot IMO. And so Dallas / Maxim "1-wire" is best
implemented as a 4-wire system when used on long leads. One twisted pair is
used for Vcc and power ground and a second twisted pair for 1-wire signal and
signal ground. The 1-wire signal ground can be shared as the ground conductor
for analog DC signals. So 4-pair CAT5 can provide power w/ ground, reliable
1-wire communication and four un-multiplexed analog signals with a low-offset
voltage signal return ground.  Leastwise that's my design.

... Marc
Marc_F_Hult
www.ECOntrol.org