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Local Memory
MCF5272 ColdFire
®
Integrated Microprocessor User’s Manual, Rev. 3
Freescale Semiconductor
4-5
ROMBAR can be configured similarly, as described in
Section 4.4.2.2, “Programming ROMBAR for
.”
4.4
ROM Overview
The ROM modules has the following features:
•
16-Kbyte ROM, organized as 4K x 32 bits
•
Contains data tables for soft HDLC (high-level data link control)
•
The ROM contents are not customizeable
•
Single-cycle access
•
Physically located on ColdFire
core's high-speed local bus
•
Byte, word, longword address capabilities
•
Programmable memory mapping
4.4.1
ROM Operation
The ROM module contains tabular data that the ColdFire core can access in a single cycle. The ROM can
be located on any 16-Kbyte address boundary in the 4-Gbyte address space.
,” describes priorities when a fetch address hits multiple local memory
resources.
4.4.2
ROM Programming Model
The MCF5272 implements the ROM base address register (ROMBAR), shown in
and
described in the following section.
4.4.2.1
ROM Base Address Register (ROMBAR)
ROMBAR determines the base address location of the internal ROM module, as well as the definition of
the allowable access types. ROMBAR can be accessed in supervisor mode using the MOVEC instruction
with an Rc value of 0xC00. It can also be read when the processor is in background debug mode (BDM).
To access the ROM module, ROMBAR should be initialized with the appropriate base address.
ROMBAR fields are described in
.
31
14
13
8
7
6
5
4
3
2
1
0
Field
BA
—
—
C/I SC SD UC UD
V
Reset
—
00
—
—
—
—
—
0
R/W
W for CPU; R/W for debug
Address
CPU space + 0xC00
Figure 4-2. ROM Base Address Register (ROMBAR)
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