Jinx wrote:
>
> > I see no logical reason for the behaviour you are seeing
>
> That makes two of us. This is about as succinctly as I can put it
>
> http://home.clear.net.nz/pages/joecolquitt/SX_pins.html

> There seems to be no apparent consistency. I never know what
> to expect, which tends to cramp one's style. Some days the damn
> thing makes me feel like a complete muppet


And other times you feel like only half a muppet? ;o)

I've only had the quickest look at your link above, but
it does seem like a RMW fault;
* randomness indicates hardware (electrical) fault
* you are using clrb and setb (not movwf)

Try tackling it from an electrical side, change of
decoupling cap to a faster (lower ESR) type or
different size, or better located etc. Have you checked
distance (ie pF) of the driven lines?
Maybe a small series resistor on each line would allow
the SX output to rise faster and be less dependant on
line capacitance loading?

Dare I suggest it, have you considered writing to the
whole port using a shadow register as recommended by
all good muppets? :o)
-Roman

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