MC9S12P128_10 Datasheet, PDF (224/566 Pages) Freescale Semiconductor, Inc – S12 Microcontrollers

S12 Clock, Reset and Power Management Unit (S12CPMU)
Figure 7-19. Waveform selected on API_EXTCLK pin (APIEA=1, APIFE=1)
API min period / 2
APIES=0
API period
APIES=1
S12P-Family Reference Manual, Rev. 1.13
224
Freescale Semiconductor