Freescale Semiconductor MCF54455 Reference Manual page 735

Real-Time Clock
Figure 28-15. Flow Chart of Alarm and Time-of-Day Programming
28-14
Disable the alarm interrupt
(clear RTC_IER[ALM])
Program the alarm or time-of-day registers
Clear any incidental alarm interrupt
during programming
(write 1 to RTC_ISR[ALM])
Enable the alarm interrupt
(set RTC_IER[ALM]
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