Information

System Configuration
MPC8308 PowerQUICC II Pro Processor Reference Manual, Rev. 1
5-46 Freescale Semiconductor
Figure 5-34. Real Time Clock Module Functional Block Diagram
5.4.7.2 RTC Operational Modes
The RTC unit can operate in the following modes:
• RTC enable/disable mode
RTCNR[CLEN] enables the RTC timer. It should be set by software, after an RTC reset, to enable
the RTC timer.
— RTC disable mode (RTCNR[CLEN] = 0)
When the RTC’s clock is disabled, counter maintains its old value (default).
— RTC enable mode (RTCNR[CLEN] = 1)
When the counter’s clock is enabled, it continues counting using the previous value.
• RTC every-second interrupt enable/disable mode
— RTC every-second interrupt enable mode (RTCNR[SIM] = 1)
In this mode, RTC sets the RTEVR[SIF] flag and generate an interrupt after the RTC’s 32-bit
counter reaches zero.
— RTC every-second interrupt disable mode (RTCNR[SIM] = 0)
In this mode, the RTC sets the RTEVR[SIF] flag but does not generate an interrupt after the
RTC’s 32-bit counter reaches zero.
• RTC alarm interrupt enable/disable mode
— RTC alarm interrupt enable mode (RTCNR[AIM] = 1)
In this mode, the RTC sets the RTEVR[AIF] flag and generates an interrupt each time when the
RTC’s 32-bit counter reaches the RTALR[ALR] value.
— RTC alarm interrupt disable mode (RTCNR[AIM] = 0)
In this mode, the RTC sets the RTEVR[AIF] flag but does not generate an interrupt when the
RTC’s 32-bit counter reaches the RTALR[ALR] value.
• RTC internal/external input clock mode
The input clock to the RTC may be the CSB clock or an external RTC_PIT_CLOCK.
Clock
Disable
RTC
Input
System
Bus Clock
32-bit
Prescaler
32-bit
Counter
RTPSR[PRSC]
RTCNR[CLEN]
RTLDR[CLDV]
RTEVR[SIF]
RTCTR[CNTV]
RTEVR[AIF]
RTCNR[AIM]
RTCNR[SIM]
Second
Interrupt
Alarm
Interrupt
RTCNR[CLIN]
RTALR[ALRM]
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