NXP Semiconductors MC9S12G - Page 377

S12 Clock, Reset and Power Management Unit (S12CPMU)
MC9S12G Family Reference Manual Rev.1.27
NXP Semiconductors 379
Write: Anytime
Figure 10-18. Waveform selected on API_EXTCLK pin (APIEA=1, APIFE=1)
Table 10-16. CPMUAPICTL Field Descriptions
Field Description
7
APICLK
Autonomous Periodical Interrupt Clock Select Bit — Selects the clock source for the API. Writable only if
APIFE = 0. APICLK cannot be changed if APIFE is set by the same write operation.
0 Autonomous Clock (ACLK) used as source.
1 Bus Clock used as source.
4
APIES
Autonomous Periodical Interrupt External Select Bit — Selects the waveform at the external pin
API_EXTCLK as shown in Figure 10-18. See device level specification for connectivity of API_EXTCLK pin.
0 If APIEA and APIFE are set, at the external pin API_EXTCLK periodic high pulses are visible at the end of
every selected period with the size of half of the minimum period (APIR=0x0000 in Table 10-20).
1 If APIEA and APIFE are set, at the external pin API_EXTCLK a clock is visible with 2 times the selected API
Period.
3
APIEA
Autonomous Periodical Interrupt External Access Enable Bit — If set, the waveform selected by bit APIES
can be accessed externally. See device level specification for connectivity.
0 Waveform selected by APIES can not be accessed externally.
1 Waveform selected by APIES can be accessed externally, if APIFE is set.
2
APIFE
Autonomous Periodical Interrupt Feature Enable Bit — Enables the API feature and starts the API timer
when set.
0 Autonomous periodical interrupt is disabled.
1 Autonomous periodical interrupt is enabled and timer starts running.
1
APIE
Autonomous Periodical Interrupt Enable Bit
0 API interrupt request is disabled.
1 API interrupt will be requested whenever APIF is set.
0
APIF
Autonomous Periodical Interrupt Flag — After each time-out of the API (time-out rate is configured in the
CPMUAPIRH/L registers) the interrupt flag APIF is set to 1. This flag can only be cleared by writing a 1. Writing
a 0 has no effect. If enabled (APIE = 1), APIF causes an interrupt request.
0 API time-out has not yet occurred.
1 API time-out has occurred.
APIES=0
APIES=1
API period
API min. period / 2