Datasheet

Chapter 17 Periodic Interrupt Timer (S12PIT24B8CV2)
MC9S12XE-Family Reference Manual Rev. 1.25
Freescale Semiconductor 675
MOVB #$01,PITINTE ; enable interupt channel 0
MOVB #$80,PITCFLMT ; enable PIT
CLI ; clear Interupt disable Mask bit
;******************** Main Program *************************************************************
MAIN: BRA * ; loop until interrupt
;******************** Channel 0 Interupt Routine ***************************************************
CH0_ISR: LDAA PITTF ; 8 bit read of PIT time out flags
MOVB #$01,PITTF ; clear PIT channel 0 time out flag
RTI ; return to MAIN