S9S12XS256J0CAL Datasheet, PDF (618/738 Pages) Freescale Semiconductor, Inc – Microcontrollers

64 KByte Flash Module (S12XFTMR64K1V1)
CAUTION
The FCLKDIV register should never be written while a Flash command is
executing (CCIF=0). The FCLKDIV register is writable during the Flash
reset sequence even though CCIF is clear.
S12XS Family Reference Manual, Rev. 1.13
618
Freescale Semiconductor