> > Humm, I seem to recall a discussion through this list a while back on
> > Interrupt
> > on Change, and someone demonstrated that a write to a port fouls up the
> > interrupt detection the same as a read/modify/write on the port. The
>write

I learned long ago NOT to use the port for anything except interrupt on
change, if you want that feature.  Even if it could be worked around, the
code would be so ugly it might not even be worthwhile.

From the 16C71 datasheet:

"The interrupt on change feature is recommended for
wake-up on key depression operation and operations
where PORTB is only used for the interrupt on change
feature. Polling of PORTB is not recommended while
using the interrupt on change feature."

I don't think they make as big of a deal out of this as they should.  One
small paragraph at the end of the I/O section can easily be overlooked.
Besides, they just say "not recommended"... I've *never* gotten it to work
with any reliability (i.e. >99% accuracy) without fouling everything up in
the ISR.

--Andrew
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