It turns out that the TX timers run about 1% too fast. I needed to set the timer to 6061 10ms (is 60,61s) steps to make the clock take accurate 1 minute steps.
Stefan Falk (12.5.2012, 17:32:32)
What ist “accurate”? What differing does still occur?
winijenh (13.5.2012, 20:53:12)
I didn’t test it extensively, but the clock runs accurate to a handful of seconds per 12 hours.