On 2010-08-06 15:25, alan.b.pearce@stfc.ac.uk wrote:
>> I am driving a 44780 LCD display 4 bit data mode with an 18F1320 with
> in
>> the common way, the 4 data signals are driven by RB4 - RB7. Using a
>> PICKIT2 to program and debug the board. RB7 and RB6 are dual function
>> also as PGC and PGD. I get an error when trying to program or debug
> with
>> this setup. The error goes away  if I unplug the display ribbon cable.
>
> These displays have internal weak pull up resistors, but I wouldn't
> think they would be enough. It may be the total capacitive load that
> ends up on the programming pins upsetting the clock and data rise&  fall
> times.

Or that the RW pin (currently unknown circuit) floating
so that the LCD is in "read" mode and actively driving
the data-pins.
--=20
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