MC9S12HY64 Datasheet, PDF (253/792 Pages) Freescale Semiconductor, Inc – S12 Microcontrollers

S12 Clock, Reset and Power Management Unit (S12CPMU) Block Description
Figure 7-19. Waveform selected on API_EXTCLK pin (APIEA=1, APIFE=1)
API min period / 2
APIES=0
API period
APIES=1
MC9S12HY/HA-Family Reference Manual, Rev. 1.04
Freescale Semiconductor
253