STMP3XXX_RTC_PERSISTENT0_XTAL24MHZ_PWRUP
pers0_clr = STMP3XXX_RTC_PERSISTENT0_XTAL24MHZ_PWRUP;
pers0_clr = STMP3XXX_RTC_PERSISTENT0_XTAL24MHZ_PWRUP |
pers0_set = STMP3XXX_RTC_PERSISTENT0_XTAL24MHZ_PWRUP;