mc9s12xf512 Freescale Semiconductor, Inc, mc9s12xf512 Datasheet - Page 427

• Manufacturer Part Number: mc9s12xf512
• Description: S12x Microcontrollers 16-bit Automotive Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

Chapter 11 Memory Mapping Control (S12XMMCV4) SUPPORTING FLEXRAY
When the device is operating in expanded modes except emulation single-chip mode, accesses to global
addresses which are not occupied by the on-chip resources (unimplemented areas or external memory
space) result in accesses to the external bus (see
Figure
).
In emulation single-chip mode, accesses to global addresses which are not occupied by the on-chip
resources (unimplemented areas) result in accesses to the external bus. CPU accesses to global addresses
which are occupied by external memory space result in an illegal access reset (system reset) in case of no
MPU error. BDM accesses to the external space are performed but the data will be undefined.
In single-chip modes accesses by the CPU (except for firmware commands) to any of the unimplemented
areas (see
Figure
) will result in an illegal access reset (system reset) in case of no MPU error. BDM
accesses to the unimplemented areas are allowed but the data will be undefined.No misaligned word access
from the BDM module will occur; these accesses are blocked in the BDM module (Refer to BDM Block
Guide).
Misaligned word access to the last location of RAM is performed but the data will be undefined.
Misaligned word access to the last location of any global page (64KB) by any global instruction, is
performed by accessing the last byte of the page and the first byte of the same page, considering the above
mentioned misaligned access cases.
The non-internal resources (unimplemented areas or external space) are used to generate the chip selects
(CS0,CS1,CS2 and CS3) (see
Figure
), which are only active in normal expanded, emulation expanded
(see
Section 11.3.2.1, “MMC Control Register
(MMCCTL0)).
MC9S12XF - Family Reference Manual, Rev.1.19
Freescale Semiconductor
427