The interface between the target and the ICD, and the interface between
the ICD and the computer are not published by Microchip, and I doubt
anyone has spent much time discovering them.  Microchip, however, has
released several bits of information so you can either 1) find out
yourself or 2) make your own based on the chip's built in dubugging
capabilities.

To find out the protocols Microchip uses, you could check out the
program running on the ICD chip, which is included in HEX within MPLAB
distributions.  Some have disassembled it, and unless your state falls
under UCITA you have the right to disassemble and inspect the available
code for purposes of interoperability, though tread carefully there, and
remember, IANAL.

To build your own, check out
http://www.microchip.com/Download/lit/pline/picmicro/families/16f87x/51242a.pdf
which goes into deail about the on-chip debugging capabilities,
including breakpoints, halting the chip externally, etc.  It doesn't
provide code, but using that and some simple serial routines (available
everywhere, search the archives or piclist) you'll be able to whip out a
simple debugger in very little time.

There is also code to run the Picstart plus, which may be related in
some of the protocols used.

I hope this helps!

-Adam

S Parkis wrote:

>Re PIC16F87X, is the "debug executive program" <--> target PIC
>communications interface documentation available?  I'm looking for the
>sort of information one would need to design a simple debug tool to
>utilize the chip's onboard debugging capabilities.
>
>The documentation I've found indicates the debug data path is RB.6 and
>RB.7, but says nothing about data content, format, transmission
>scheme...
>
>
>(Apologies for previous msg w/out [PIC] preface---what a PITA
>'feature' IMHO]
>
>
>Regards,
>
>Steve
>
>--
>http://www.piclist.com hint: The PICList is archived three different
>ways.  See http://www.piclist.com/#archives for details.
>
>
>
>
>

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