mc9s12xd256 Freescale Semiconductor, Inc, mc9s12xd256 Datasheet - Page 640

• Manufacturer Part Number: mc9s12xd256
• Description: Hcs12x Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Chapter 17 Memory Mapping Control (S12XMMCV2)
17.4.3
17.4.3.1
A possible access error is flagged by the MMC and signalled to XGATE under the following conditions:
For further details refer to the XGATE Block Guide.
17.4.3.2
After programming the protection mechanism registers (see
Figure
module:
If the RWPE bit is set the CPU write accesses into the XGATE RAM region are blocked. If the CPU tries
to write the XGATE RAM region the AVIF bit is set and an interrupt is generated if enabled. Furthermore
if the XGATE tries to write to outside of the XGATE RAM or shared regions and the RWPE bit is set, the
write access is suppressed and the access error will be flagged to the XGATE module (see
“Illegal XGATE Accesses”
The bottom address of the XGATE RAM region always starts at the lowest implemented RAM address.
The values stored in the boundary registers define the boundary addresses in 256 byte steps. The 256 byte
block selected by any of the registers is always included in the respective region. For example setting the
shared region lower boundary register (RAMSHL) to $C1 and the shared region upper boundary register
(RAMSHU) to $E0 defines the shared region from address $0F_C100 to address $0F_E0FF in the global
memory space (see
The interrupt requests generated by the MMC are listed in
the related interrupt vector address and interrupt priority.
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1. XGATE RAM region
2. CPU RAM region
3. Shared Region (XGATE AND CPU)
1-20) and setting the RWPE bit (see
XGATE performs misaligned word (in case of load-store or opcode or vector fetch accesses).
XGATE accesses the register space (in case of opcode or vector fetch).
XGATE performs a write to Flash in any modes (in case of load-store access).
XGATE performs an access to a secured Flash in expanded modes (in case of load-store or opcode
or vector fetch accesses).
XGATE performs a write to non-XGATE region in RAM (RAM protection mechanism) (in case
of load-store access).
Chip Access Restrictions
Illegal XGATE Accesses
Illegal CPU Accesses
Figure
1-25).
and the XGATE Block Guide).
MC9S12XDP512 Data Sheet, Rev. 2.17
Figure
1-17) there are 3 regions recognized by the MMC
Table
Figure
1-23. Refer to the Device User Guide for
1-17,
Figure
1-18,
Freescale Semiconductor
Figure
Section 1.4.3.1,
1-19, and