Spehro's alternate timing intervals would be an easy and
pretty accurate solution

> Using a 16MHz crystal and timing of 4545/4546

This would give a mark:space of 1136.25us : 1136.5us

440Hz = period of 2272.73us

1136.25 + 1136.5 = 2272.75 = 439.9956Hz = 0.0001% low

> ...other "standards" .... other than the A4=440 Hz.

> http://www.boulder.nist.gov/timefreq/general/glossary.htm

You'll notice that the page also mentions how other notes in a
particular scale are derived from the root. What this means is that
the "A" in the key of C is not the same frequency as the "A" in the
key of Eb. According to purists, music becomes discordant if there
is a key change. Ideally all instruments should change their tuning
to the root of the key moved into. Possible with an electronic k/b, a
bit tricky with tubular bells

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads