Clock, Reset, and Power Control (CRP)
MPC5510 Microcontroller Family Reference Manual, Rev. 1
Freescale Semiconductor
5-7
Preliminary
Table 5-3. CRP_RTCSC Field Descriptions
Field
Description
CNTEN
Counter Enable. The CNTEN bit enable the RTC counter. CNTEN asserted has the effect of asynchronous
resetting (synchronous reset negation) all the RTC logic. This allows for the RTC configuration and clock
source selection to be updated without causing synchronization issues.
0 Counter disabled
1 Counter enabled
RTCIE
RTC Interrupt Enable. The RTCIE bit enables interrupts requests to the system if RTCF is asserted.
0 RTC interrupts disabled
1 RTC interrupts enabled
RTCF
RTC Interrupt Flag. The RTCF bit indicates that the RTC counter has reached the counter value matching
RTCVAL. RTCF is cleared by writing a 1 to RTCF. Writing a 0 to RTCF has no effect. Note that the RTCF bit
must be cleared before entering SLEEP or STOP mode, if the RTC is to be used as the wakeup source.
0 No RTC interrupt
1 RTC interrupt
ROVRF
Counter Roll Over Interrupt Flag. The ROVRF bit indicates that the RTC has rolled over from 0xFFFF_FFFF
to 0x0000_0000. ROVRF is cleared by writing a 1 to ROVRF. Writing a 0 to ROVRF has no effect. Note that
the ROVRF bit must be cleared before entering SLEEP or STOP mode, if the RTC rollover is to be used as
the wakeup source.
0) RTC has not rolled over
1) RTC has rolled over
RTCVAL
RTC Compare Value. The RTCVAL bits are compared to bits 10–21 of the RTC counter and if match sets
RTCF. RTCVAL may only be updated when CNTEN is 0.
APIEN
Autonomous Periodic Interrupt Enable. The APIEN bit enables the autonomous periodic interrupt function.
0 API disabled
1 API enabled
APIIE
API Interrupt Enable. The APIIE bit enables interrupts requests to the system if APIF is asserted.
0 API interrupts disabled
1 API interrupts enabled
APIF
API Interrupt Flag. The APIF bit indicates that the RTC counter has reached the counter value matching API
offset value. APIF is cleared by writing a 1 to APIF. Writing a 0 to APIF has no effect. Note that the APIF bit
must be cleared before entering SLEEP or STOP mode, if the API is to be used as the wakeup source.
0 No API interrupt
1 API interrupt.
CLKSEL
Clock Select. The CLKSEL bits select the clock source for the RTC. CLKSEL may be updated when CNTEN
is 0 only.
Note: The 32 kHz IRC or 32 kHz OSC are not automatically enabled if selected; therefore, they must be
enabled before either one is selected for use.
00 32 kHz IRC
01 32 kHz OSC
10 16 MHz IRC with 512 prescaler divide
11 16 MHz IRC without 512 prescaler divide