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List:       owfs-developers
Subject:    [Owfs-developers] Temperature Sensing.
From:       Doug Collinge <doug.collinge () gmail ! com>
Date:       2011-10-27 16:16:52
Message-ID: CABJO2PCEsWr11CsSc8_hJJFoOwGMCMcCgEW3fQdbXjvwfELBhQ () mail ! gmail ! com
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On Thu, Oct 27, 2011 at 06:08, <
owfs-developers-request@lists.sourceforge.net> wrote:

>
> > What I need is for a relay to automatically trigger (or, even better,
> > for 1 of 2 relays to trigger depending on Hi/Lo) *WITHOUT* any
> > commands or communication over the 1-wire network. 1-wire would be
> > used simply to program the device in the first place.
>
> There DS1821 it's almost what you want.
>
> http://www.maxim-ic.com/datasheet/index.mvp/id/2794
>
>
I have done quite a bit of work with the DS1821 and it is definitely NOT
what you want. You can reprogram it out of the circuit but there is no
usable way to reprogram while it is in the circuit it is controlling as a
thermostat. You could engineer some kind of one-chip scheme to isolate it
from its circuit, apply the magic 16-pulse signal, and then connect it to a
one-wire bus - but if you are going to go to all that much trouble you might
just as well use the effort to code a thermostat circuit around a DS1820,
which would give you just what you want.

I agree with some other poster that you could just tape a DS1820 next to a
DS1821 to get temperature monitoring but you would still be unable to change
the thermostat parameters, which is part of your requirement.

[Attachment #5 (text/html)]

<br><br><div class="gmail_quote">On Thu, Oct 27, 2011 at 06:08,  <span \
dir="ltr">&lt;<a href="mailto:owfs-developers-request@lists.sourceforge.net">owfs-developers-request@lists.sourceforge.net</a>&gt;</span> \
wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px \
#ccc solid;padding-left:1ex;"> <br>
&gt; What I need is for a relay to automatically trigger (or, even better,<br>
&gt; for 1 of 2 relays to trigger depending on Hi/Lo) *WITHOUT* any<br>
&gt; commands or communication over the 1-wire network. 1-wire would be<br>
&gt; used simply to program the device in the first place.<br>
<br>
There DS1821 it&#39;s almost what you want.<br>
<br>
<a href="http://www.maxim-ic.com/datasheet/index.mvp/id/2794" \
target="_blank">http://www.maxim-ic.com/datasheet/index.mvp/id/2794</a><br> \
<br></blockquote></div><br>I have done quite a bit of work with the DS1821 and it is \
definitely NOT what you want. You can reprogram it out of the circuit but there is no \
usable way to reprogram while it is in the circuit it is controlling as a thermostat. \
You could engineer some kind of one-chip scheme to isolate it from its circuit, apply \
the magic 16-pulse signal, and then connect it to a one-wire bus - but if you are \
going to go to all that much trouble you might just as well use the effort to code a \
thermostat circuit around a DS1820, which would give you just what you want.<br> \
<br>I agree with some other poster that you could just tape a DS1820 next to a DS1821 \
to get temperature monitoring but you would still be unable to change the thermostat \
parameters, which is part of your requirement.<br> <br><br>



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