32kHz Crystal driving QE128 RTC

Discussion created by Metis_Steve on Dec 6, 2011
Latest reply on Dec 8, 2011 by Metis_Steve



I'm trying to get a 32768 crystal to drive the RTC module for the QE128 while getting regular interrupts about every ms.

Right now, I have things working correctly using the internal oscillator, but I'd like to improve long term RTC accuracy.


First of all, is this even possible? When I set the prescale value to 0, it appears to disable the RTC clock source (the interrupt vector never runs).  So given that it appears I HAVE to use the prescaler, it's not possible for me to set the prescaler to a low value when using an external clock source.


Second, while I'm certain that the crystal and trim capacitors are installed correctly, I cannot get the RTC to use this crystal with any prescale value.  Does anyone have any suggestions?


Thank you.