Dave King wrote:

> Just to kill this beast stone dead ;-] Any idea of how long any/all ports will
> safely stay stable or can you assume that they will as long as adequate
> power is available to the system?  Hours months days etc?


I believe it is good practice to refresh port outputs
when you can. Ports (and ram too) are cmos flip flops
and only stay in their existing state until something
changes them. Unfortunately that something can be psu
spikes, or spikes from the output pin itself. Which DO
happen.

It depends on how long your circuit would tolerate the
port being in the wrong state. Something like a relay
driver may tolerate wrong-state for 50mS or so, so you
only need to refresh it every 50mS. But some outputs are
more critical... Or you can set the port once and just
leave it up to fate. :o)
-Roman

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