PXD10RM Datasheet, PDF (1091/1332 Pages) Freescale Semiconductor, Inc – PXD10 Microcontroller

31.8 API functional description
Setting RTCC[APIEN] bit enables the autonomous interrupt function. The 10-bit RTCC[APIVAL] field
selects the time interval for triggering an interrupt and/or wakeup event. Since the RTC is a free running
counter, the APIVAL is added to the current count to calculate an offset. When the counter reaches
(offset count + 1), a interrupt and/or wakeup request is generated. Then the offset value is recalculated and
again retriggers a new request when the new value is reached. APIVAL may only be updated when APIEN
is disabled. When a compare is reached, the RTCS[APIF] interrupt flag bit is set (after proper clock
synchronization). If the RTCC[APIIE] interrupt enable bit is set, then the API interrupt request is
generated. If there is a match while in low power mode, then the API will first generate a wakeup request
to force a wakeup into normal operation, then the APIF flag will be set.
Freescale Semiconductor
PXD10 Microcontroller Reference Manual, Rev. 1
Preliminary—Subject to Change Without Notice
31-9