RE: 1-Wire

["Neil Ball" <neilball@xxxxxxxxxxxxxxx>]

If you have a north facing wall then use that for your external sensor as
it
will not be affected by direct sun. If you have to fit elsewhere then you
will need to construct a solar shield. In either case just make sure that
the sensor element is in free air, not tight against the wall or tight
against any solar shield you construct and you will then get reasonable
accuracy.



Neil B.



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From: ukha_d@xxxxxxx [mailto:ukha_d@xxxxxxx] On Behalf Of
Jim Noble
Sent: 27 January 2006 10:37
To: ukha_d@xxxxxxx
Subject: Re: [ukha_d] 1-Wire



<zoinq>

Slight thread hi-jack. I've finally gotten around to making use of the
TOM10 board I bought a while back.

It's currently sat in the loft above the airing cupboard, connected to
an MSS-100, with 3 (so far) DS1820s attached to various parts of our new
thermal store style cylinder.

A quick perl hack has the temperatures being logged to a rrdtool db
every 30 seconds, with a graph of the preceding 24 hours produced at
regular intervals. eg:

http://www.black-metallic.com/jim/temperature_log.png

(The blue line is a bit fudged. The 1820 is on the end of a bit of cat5,
and it's too chunky to push all the way into the sensor pocket on the
cylinder at the same time as the smartfit insertion sensor, and thus
under reads. So the chart is plotted with a RPN calculation to add a few
degrees offset. The mkII version will have the unused cat5 cut back a
lot further to make the end a bit slimmer!)

Next step of the plan is to add some more sensors around the house (plus
one outside somewhere), and perhaps shift to dumping the logged
temperatures into a generic mysql db (should be easier to make use of
the data for more than just pretty charts). I have some ideas for using
a 1-wire I/O device to monitor the state of the heating valves as well
(the lever on Smartfit valve heads move with the valve, so could be used
for monitoring the state of the valve...).

Jim

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