Re: gEDA-user: Using 60Hz mains frequency for timing?

[Larry Doolittle <ldoolitt@xxxxxxxxxxxxxxx>]

Randall -

On Fri, May 02, 2008 at 12:33:03PM -0400, Randall Nortman wrote:
> Just a quick non-gEDA design question -- I have the choice between
> using the zero crossings of the 60Hz mains voltage or my MCU clock
> (generated from an 18.432MHz quartz crystal producing a 48MHz CPU
> clock via PLL built into the MCU) for low-resolution timing.

60 Hz mains timing is terrible.  Use the crystal.  The only
thing mains can be used for is long-term (more than 1 day)
absolute accuracy, and then only if you are really careful
with both hardware and software design to avoid noise spikes,
and your customer doesn't decide to run it from a generator
or inverter.

   - Larry


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