> I am going to have to deal with this soon too.
> My plan is to assign the prescaler to the RTCC and spin waiting for it to
> equal zero.  With the prescaler, the count will be zero for several
> (possibly many) instruction cycles, so I shouldn't miss it.  I just need to
> have some logic to keep from detecting the same zero multiple times.
>
> Does anyone know of a better way to do this or have I hit it on the head?

In a project I'm working on at the moment, I don't need to know exactly
when the timer runs out (indeed, I might miss it having the value zero)
but I do want to act on every cycle it goes through, so that I don't lose
long-term accuracy.

For this, I can poll the most significant bit of the RTCC until I've seen
a one followed by a zero. I only have to poll, at worst, once per 128
increments to get the indication I need, which is much easier than polling
at least once every increment.

-adrian