Eric Vickery wrote:
> I disagree. 85 is a valid reading since the chip can read from -10 to 
You disagree with what...?  If with "It's inconsequential in the scheme 
of things." I meant to say in the scheme of things in my software.  It 
*may not* be inconsequential for engineers who are trying to work with 
the device.  This last statement is yet to be shown true, IMHO.
> +125 and nowhere in the spec document does it state that 85 cannot be a 
> valid reading. It just states that 85 is the power-on reset value.
My guess is that discerning the POR value is done by comparing the 
returned value out to a certain precision.  (In my code I just check for 
85.0 which paints a broader bruch).  For example 85.000 may well 
indicate POR whereas 85.125 would not, of course.  I haven't worked it out.

This point may be worth a little math.  Where is Dan Awtrey when you 
need him? :)
> 
> I think it would have been better for Dallas to have the power-on value 
> something on the extreme high or low end to make it easier to tell when 
> an error occurred.
I agree, but my guess is that that they chose this value because it's at 
the end of the chip's normally-designed range of -10 +85C.  At this 
range the chip is good to 0.5 degrees C.  Outside of this range the chip 
is good to +/- 2.0 degrees C which may be useful to only a few.

/m


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