
Chapter 3 Memory Mapping Control (S12XMMCV4)
MC9S12XE-Family Reference Manual Rev. 1.21
Freescale Semiconductor
189
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Simultaneous accesses to different resources1 (internal, external, and peripherals) (see Figure 3-1 ) Resolution of target bus access collision
MCU operation mode control
MCU security control
Separate memory map schemes for each master CPU, BDM and XGATE
ROM control bits to enable the on-chip FLASH or ROM selection
Port replacement registers access control
Generation of system reset when CPU accesses an unimplemented address (i.e., an address which
does not belong to any of the on-chip modules) in single-chip modes
3.1.3
S12X Memory Mapping
The S12X architecture implements a number of memory mapping schemes including
a CPU 8 MByte global map, dened using a global page (GPAGE) register and dedicated 23-bit
address load/store instructions.
a BDM 8 MByte global map, dened using a global page (BDMGPR) register and dedicated 23-
bit address load/store instructions.
a (CPU or BDM) 64 KByte local map, dened using specic resource page (RPAGE, EPAGE and
PPAGE) registers and the default instruction set. The 64 KBytes visible at any instant can be
considered as the local map accessed by the 16-bit (CPU or BDM) address.
The XGATE 64 Kbyte local map.
The MMC module performs translation of the different memory mapping schemes to the specic global
(physical) memory implementation.
3.1.4
Modes of Operation
This subsection lists and briey describes all operating modes supported by the MMC.
3.1.4.1
Power Saving Modes
Run mode
MMC is functional during normal run mode.
Wait mode
MMC is functional during wait mode.
Stop mode
MMC is inactive during stop mode.
3.1.4.2
Functional Modes
Single chip modes
In normal and special single chip mode the internal memory is used. External bus is not active.
1. Resources are also called targets.