There is nothing in the data read from the sensor that tells if the 85 de=
g C is=20
an error or a real temperature. Sure, you might know that this is out of =
the=20
temperature range for your application but generally speaking you can't r=
ely on=20
this.

In all the 1-wire documents (app notes on 1-wire and DS18x20 and datashee=
ts)=20
from Dallas/Maxim I have read I have never seen that the 85 deg C is an e=
rror=20
message. True - it is what you get when the power is lost during conversi=
on or=20
when the converaion is aborted (not sure about this one, it could be that=
 the=20
old value is still left in the scratchpad ram) but it is still not an err=
or=20
message. The data sheet doesn't even state this as a fact so you can't tr=
ust it=20
to be true always.

Let's just agree that we disagree on this one :-)

Ruben

> It *is* an error message in that it's what you *consisently* will get i=
f=20
> there's not enough power or conversion time.
>=20
> -marc
>=20
> On Tue, 12 Jul 2005, [ISO-8859-1] Ruben J=F6nsson wrote:
>=20
> > Well, it still isn't an error message. It is simply the default value=
 in the
> > temperature registers in the ram at power up.
> >
> > It would be pretty stupid to put 85 degrees C as an error message whe=
n the
> > sensor can operate between -55 deg C to +125 deg C.
> >
> > Ruben
> >
> >
> >> Ruben,
> >>
> >> http://www.buoy.com/pipermail/1-wire-software-development/2004-July/=
000059.html
> >>
> >> -marc
> >>
> >> On Tue, 12 Jul 2005, [ISO-8859-1] Ruben J=F6nsson wrote:
> >>
> >>> It is not an error message (otherwise it couldn't measure 85 deg C =
:-) ). To my
> >>> knowledge there is no such thing as an error message for the temper=
ature
> >>> conversion (perhaps there should be, though).
> >>>
> >>> 85 deg C default is stated under table 2, page 4 in the datasheet I=
 have for
> >>> the DS18B20-PAR 043001 (page 3 for DS18B20 050102).
> >>>
> >>> Regareds / Ruben
> >>>
> >>>> Hey Marc,
> >>>>
> >>>> Is this perhaps defined in some other doc?  Or am I really going b=
lind.
> >>>> Before I posted this message yesterday, I went back thru the datas=
heet and
> >>>> could not find it.
> >>>>
> >>>> Cheers,
> >>>> -Neil.
> >>>>
> >>>>
> >>>> On Tuesday 12 July 2005 11:04 am, Marc Nicholas scribbled:
> >>>>> Isn't that the converting temp error message?
> >>>>>
> >>>>> -marc
> >>>>
> >>>>
> >>>> --
> >>>> http://www.piclist.com PIC/SX FAQ & list archive
> >>>> View/change your membership options at
> >>>> http://mailman.mit.edu/mailman/listinfo/piclist
> >>>>
> >>>
> >>> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D
> >>> Ruben J=F6nsson
> >>> AB Liros Electronic
> >>> Box 9124, 200 39 Malm=F6, Sweden
> >>> TEL INT +46 40142078
> >>> FAX INT +46 40947388
> >>> ruben@pp.sbbs.se
> >>> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D
> >>>
> >>> --
> >>> http://www.piclist.com PIC/SX FAQ & list archive
> >>> View/change your membership options at
> >>> http://mailman.mit.edu/mailman/listinfo/piclist
> >>>
> >
> > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D
> > Ruben J=F6nsson
> > AB Liros Electronic
> > Box 9124, 200 39 Malm=F6, Sweden
> > TEL INT +46 40142078
> > FAX INT +46 40947388
> > ruben@pp.sbbs.se
> > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D
> >
> > --
> > http://www.piclist.com PIC/SX FAQ & list archive
> > View/change your membership options at
> > http://mailman.mit.edu/mailman/listinfo/piclist
> >

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D
Ruben J=F6nsson
AB Liros Electronic
Box 9124, 200 39 Malm=F6, Sweden
TEL INT +46 40142078
FAX INT +46 40947388
ruben@pp.sbbs.se
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D

--=20
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist