68300

On Wed, May 22, 2002 at 10:46:57PM -0500, Scott Newell wrote:
> Just going through some old notes, and I noticed that at one time I
> calculated 22.118400 MHz as a nice number: it allows you to run the
> UARTs (SCI and TPU) at all the standard baud rates with no error.
> Using the PLL, it can be generated 38.400 kHz rock.  38.4 kHz also
> gives you a even 100 Hz PIT rate, something 32.768 kHz can't.

the next sweet point for baud rates after 22.118400 is 25.80480, which
is slightly above spec for the 25MHz part, isn't it?

with 32.768kHz you hit a similar spot at 22.020096, which gives < 1% for
all standard baud rates.

charles, what's the word on slightly overclocking these processors to
hit the sweet spots?

> So why does everyone seem to use 32.768 kHz?  Availability?

it's the one listed in the motorola literature, so it gets used by
default.  :)

-- 
  Aaron J. Grier  |   Frye Electronics, Tigard, OR   |  aaron@...