> > Now how is a programmer going to indentify an unknown
> (flash) chip? Is
> > it always allowed to Vcc-before-Vpp? Or is it always allowed to
> > Vpp-before-Vcc?
>
> The code I posted last week tries both methods if necessary to get the
> device ID.  Once the ID is available, regardless of how it
> was determined,
> the particulars for that chip including the Vpp/Vcc method
> are looked up
> in a host file.  This algorithm has been tested and seems to work for
> 12F6xx, 16F6xx, 16F87x, 18Fxx2, and 18Fxx8.

And of course there are the two very different protocols for the 14-bit
and the 16-bit cores....

Did you find instances where Vpp-before-Vcc did *not* put the chip in
programming mode?

Wouter van Ooijen

-- -------------------------------------------
Van Ooijen Technische Informatica: www.voti.nl
consultancy, development, PICmicro products

--
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