> That all makes sense.  But what I don't understand is how you integrate
> that ISR with other things that may be happening on the chip.  For
> example, if I have a time-sensitive asynchronous serial routine, I would
> expect that I would have to disable interrupts so that I didn't mess
> that up.  And if I disable interrupts, won't it throw the clock off?

As long as you disable interrupts around short sections of code that are
much shorter than the interrupt period, no problem.  The interrupt
condition may get set during the time interrupts are off, so the interrupt
will be taken immediately after they are re-enabled.

Temporarily disabling interrupts is common for atomically accessing a
collection of state that can be altered by an interrupt routine.


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