MC9S12T64 Datasheet, PDF (134/608 Pages) Motorola, Inc – Specification

Freescale Semiconductor, Inc.
Module Mapping Control (MMC)
Select Priority
Although internal resources such as control registers and on-chip
memory have default addresses, each can be relocated by changing the
default values in control registers. Normally, I/O addresses, control
registers, vector spaces, expansion windows, and on-chip memory are
mapped so that their address ranges do not overlap. The MMC will make
only one select signal active at any given time. This activation is based
upon the priority outlined in Table 26 below. If two or more blocks share
the same address space, only the select signal for the block with the
highest priority will become active. An example of this is if the registers
and the RAM are mapped to the same space, the registers will have
priority over the RAM and the portion of RAM mapped in this shared
space will not be accessible. The expansion windows have the lowest
priority. This means that registers, vectors, and on-chip memory are
always visible to a program regardless of the values in the page select
registers.
Table 26 Mapping Precedence
Precedence
Highest
...
...
...
...
Lowest
Resource
BDM space (Internal) when BDM is active this 256 byte block of
registers and ROM appear at $FF00 – $FFFF
Register Space – 1K bytes fully blocked for registers
RAM (internal) – 2K bytes
CALRAM – 2K bytes
On-Chip Flash EEPROM – 64K bytes
Remaining external
In expanded modes, the data registers and data directions registers for
Ports A and B are removed from the on-chip memory map and become
external accesses. If the EME bit in the MODE register is set, the data
and data direction registers for Port E are also removed from the on-chip
memory map and become external accesses.
In emulation modes, if the EMK bit in the MODE register is set, the data
and data direction registers for Port K are removed from the on-chip
memory map and become external accesses.
External Memory
Accesses
All address space not used by internal resources is by default external
memory space in expanded modes. In MC9S12T64, internal memory
resources have to be disabled so that external memory can be
accessed. The Flash EEPROM can be disabled by clearing the ROMON
MC9S12T64Revision 1.1.1
Module Mapping Control (MMC)
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