Datasheet

S12 Clock, Reset and Power Management Unit (S12CPMU)
MC9S12G Family Reference Manual, Rev.1.23
392 Freescale Semiconductor
Figure 10-18. Waveform selected on API_EXTCLK pin (APIEA=1, APIFE=1)
APIES=0
APIES=1
API period
API min. period / 2