Re: [avr-chat] AVR-chat Digest, Vol 96, Issue 5

[Robert Rolf]

   1. Re: XMEGA clocking questions (Graham Davies)

Having taken the position that the crystal is not necessary, I should
probably qualify that by saying that I also agree with
David Kelly and Anthony Andriano and I do exactly what David suggests by
including a footprint for a 32.768 kHz crystal and then not populating it.
Partly this is in case the internal oscillator does turn out to be too far
off (hasn't happened yet) but also partly in case I (or my client) discover
a need to keep accurate wall-clock time in firmware.

Graham.

If you want 'accurate' clock time, don't forget the needed timmer cap for the 32kHz crystal.

Simpler to trim to exact frequency than to do software correction for the inevitable error.