At 09:10 AM 08/03/2005 -0500, you wrote:
>Hey, Roland!
>
>You MAY find the problem with pin 10 (RB4/PGM) of the '628. Although I'm 
>not familiar with the AN589 programmer, I hit the same problem with my 
>old programmer, where I could program 'F84 chips all day long and failed 
>to program 'F628 chips. Turned out you need to pull pin 10 low before 
>you program an 'F628 chip. I just inserted a resistor from pin 10 to GND 
>and my problems went away. Now I can reliably program the '628s all day 
>long.
>

Hi Dennis

RB4 is applicable to low voltage programming only. The AN589 cct uses high
voltage programming.

As it says on most of the data sheets;

"
Note 1: The High Voltage Programming mode is
always available, regardless of the state
of the LVP bit, by applying VIHH to the
MCLR pin.
"

I've just tested it on my jig, and it programs fine in both states of RB4.
A problem that does crop up however, is like one of my cct's where RB6 and
RB7 are part of a keyboard scanning routine. The programmer(software)
battles to initiate the sequence, and I'd have to depress a key to halt the
scanning and allow programming to start.


Regards
Roland Jollivet

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