I've had some pretty crazy problems with ICSP and the 877.  I never figured
out what caused it, but probably it was due to the wirewrap wire I used to
build the circuit with.  I found that a 12pf capacitor on the clock line to
ground fixed the problem (or a scope probe ... ).  The same problem occurred
with several different 877 chips in different configurations, and invariably
a little extra capacitance was needed.  Why?  No clue.  But it might be
worth a try.  I've not had the same problem with any other chips.


----- Original Message -----
From: "Matthew Brush" <matthewbrush@YAHOO.CA>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Friday, June 11, 2004 3:12 PM
Subject: Re: [PIC:] ICSP Problem, probably stupidity


> > your original message mentioned PGC and PGD being
> > connected, but nothing is said about /MCLR and PGM.
>
> Sorry, let me clarify.
>
> Vpp/MCLR is tied to Vdd with a 100k resistor and a
> diode in series to block the 12v from getting at the
> 5v (so to speak).
>
> There is no PGM pin on my programmer, so I just hooked
> it to GND/Vss.
>
> It seems like it's writing fine, but gets an error
> when verifying (reading) I think.  Initially I
> suspected it was noise or something messing up the
> PGD&PGC lines, that's why I wondered about maybe
> pulling them two to Vdd.
>
> The part was brand new when I installed it if that
> matters.
>
> Thanks for any other suggestions anyone has.
>
>
> =====
> MJ Brush
> LeftClick.ca Internet Media Services
> mbrush@[NOSPAM]leftclick.ca
>
> ______________________________________________________________________
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