Hello Phil,

>Phil said
However, the PIC18FXX2 datasheet say if the
Background Debugger is disabled, then RB6 and
RB7 can be used as general purpose IO pins.

BUT - can RB6 and RB7 still then be used as
SCLK and SDAT for ICSP?

>walt comments
I turn off the background 'debugger' for my 
18F252 (same as 452 only less pins) 
production boards and use RB6 & RB7 for 
ICSP, as well as driving logic inputs. 
There are some gotchas which
you need address. For one don't hang 
capacitors on either of these lines unless 
you use Berg jumper/switches to the isolate lines 
during program time. As I recall there are 
couple of other things to watch out 
for as well, -don't drive these lines from 
gates or transistors, especially 'low', 
during programming. There was something 
about diodes as well? As long as you are 
talking about stuff like this, I discovered 
that adding a pullup resistor to Vdd 
on the Vpp/MCLR* (pin 1) line is 
good thing to do also, solved random  
program operation faults. I use 5.1k Ohm.

Good Luck,

best wishes,
walt williams

================================

Date: Sun, 23 Jan 2005 14:33:15 +0000
From: "Phil Cross" <pj_cross@hotmail.com> To:
piclist@mit.edu Subject: Re: [PIC] Newbie -
18F452 ICSP Message-ID:
<BAY102-F27C7ED20B4EDDE20260005F4840@phx.gbl>
Content-Type: text/plain; format=flowed
MIME-Version: 1.0 Precedence: list Reply-To:
"Microcontroller discussion list - Public."
<piclist@mit.edu> Message: 30

Thanks to John J McDonough for the
information - it has clarified things for me.

I have one further question before the mists
totally clear (I hope).

In the CONFIG4L word there is a bit called
!DEBUG, which enables and disables the
Background Debugger. I don't want this
feature (I don't really understand what it
is) so I have disabled it.

However, the PIC18FXX2 datasheet say if the
Background Debugger is disabled, then RB6 and
RB7 can be used as general purpose IO pins.

BUT - can RB6 and RB7 still then be used as
SCLK and SDAT for ICSP?

Thanks again for the help,
Regards, Phil.


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