rtc configure register
XTAL32K_RETURN_WAIT | cycles to wait to return noral xtal 32k |
XTAL32K_RESTART_WAIT | cycles to wait to repower on xtal 32k |
XTAL32K_WDT_TIMEOUT | If no clock detected for this amount of time |
XTAL32K_STABLE_THRES | if restarted xtal32k period is smaller than this |