In general, the DS18B20 should not need calibration. The usual reason for
differing temperatures is either different environment or self-heating.
There was a manufacturing problem with the sensors in the past losing
calibration data -- specifically the "B7" lot. There is some data in teh
web site and properties exposed under the /errata/ directory for reading
and setting the calibration data. I have no idea if this can also be used
to more precisely calibrate a given sensor.
See:
http://www.1wire.org/en-us/pg_15.html
http://www.elektroniikka.org/thermometer/bin/app247.pdf
On looking up the B7 problem, I came upon a C2 die problem as well -- one
that looks easy to fix:
http://osdir.com/ml/hardware.one-wire.weather/2005-11/msg00045.html
Can you tell me the die version of the chips (under the errata directory)
of your chips?
Paul Alfille
On Thu, Jan 24, 2013 at 2:22 PM, Phil White <[email protected]> wrote:
> Hi All,
>
> I have 30 temperature sensors sitting in front of me at the moment.
> They all report different readings when queried - which I would like
> to fix on a reasonably permenant basis.
>
> Can someone advise how I go about calibrating them? There is, as far
> as I remember, a register I can save into, and I have seen calibrated
> sensors for sale (but can't afford this option) - yet I have no idea
> on the procedure to DIY.
>
> Many thanks,
>
> Phil
>
>
> ------------------------------------------------------------------------------
> Master Visual Studio, SharePoint, SQL, ASP.NET, C# 2012, HTML5, CSS,
> MVC, Windows 8 Apps, JavaScript and much more. Keep your skills current
> with LearnDevNow - 3,200 step-by-step video tutorials by Microsoft
> MVPs and experts. ON SALE this month only -- learn more at:
> http://p.sf.net/sfu/learnnow-d2d
> _______________________________________________
> Owfs-developers mailing list
> [email protected]
> https://lists.sourceforge.net/lists/listinfo/owfs-developers
>
------------------------------------------------------------------------------
Master Visual Studio, SharePoint, SQL, ASP.NET, C# 2012, HTML5, CSS,
MVC, Windows 8 Apps, JavaScript and much more. Keep your skills current
with LearnDevNow - 3,200 step-by-step video tutorials by Microsoft
MVPs and experts. ON SALE this month only -- learn more at:
http://p.sf.net/sfu/learnnow-d2d
_______________________________________________
Owfs-developers mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/owfs-developers
