> So basically I disagree that the voltage on the open drain output being
> clearly specified for the 16F84. It is ignored completely. Electrical
> specifications have always been a weak spot for Microchip.

I said it was in the manual because it is in the manual for other PICs, I've
never used an 16F84, and don't have a manual around.  Your comment caused me
to get out the CD and check.  Yes, it's annoying that the recent 16F84 data
sheet is "preliminary", even though this chip has been out quite a while.

However, the spec sheet does clearly state that the maximum voltage of all
input pins except MCLR is Vdd + 600mV.  There is no special mention of RA4
in places where other PIC data sheets do mention it.  I take this as
unambiguously meaning that RA4 shouldn't be pulled higher than 600mV above
Vdd.  This is only unclear if you have a preconcieved notion that RA4 can
tolerate a higher voltage.  Now that I've read the spec sheet, I would not
put a 16F84 into production with an RA4 voltage more than 600mV above Vdd.
If you need RA4 to tolerate a higher voltage, don't use the 16F84.


********************************************************************
Olin Lathrop, embedded systems consultant in Littleton Massachusetts
(978) 742-9014, olin@embedinc.com, http://www.embedinc.com

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics