Re: [avr-chat] 32768 Hz clock

[Hugo González Monteverde]

> However, comparing to my wristwatch,  I find my clock falls behind about
> 1 minute every hour, so after 10 hrs, it's behind by 10 mins! My code
> above seems OK. Are there any hardware issues I need to address? Thanks
> for any help!
>

Totally.

This is realted to the capacitances you connect to the crystal.  I am 
not an expert at this, but check application notes for crystal 
considerations, such as the one from Dallas. They actually explain a bit:

"The frequency accuracy of a crystal-based oscillator circuit is mainly 
dependent upon the accuracy of the crystal and the accuracy of the match 
between the crystal and the oscillator capacitive load."

Take a look at it :

http://www.maxim-ic.com/appnotes.cfm/appnote_number/58


Hope that helps.

Hugo