4-6
MCF5272 User’s Manual
ROM Overview
4.4.2 ROM Programming Model
The MCF5272 implements the ROM base address register (ROMBAR), shown in
Figure 4-2 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 Table 4-4.
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)
Table 4-4. ROMBAR Field Description
Bits
Name
Description
31–14
BA
Base address. Defines the ROM module base address. ROM can reside on any 4-Kbyte boundary
in the 4-Gbyte address space.
13–6
—
Reserved, should be cleared.
5–1
C/I,
SC,
SD,
UC,
UD
Address space masks (ASn). Allows specific address spaces to be enabled or disabled, placing
internal modules in a specific address space. If an address space is disabled, an access to the
register in that address space becomes an external bus access, and the module resource is not
accessed. These bits are useful for power management as described in Section 4.4.2.2,
“Programming ROMBAR for Power Management.” In particular, C/I is typically set.
The address space mask bits are follows:
C/I = CPU space/interrupt acknowledge cycle mask. Note that C/I must be set if BA = 0.
SC = Supervisor code address space mask
SD = Supervisor data address space mask
UC = User code address space mask
UD = User data address space mask
For each ASn bit:
0 An access to the ROM module can occur for this address space
1 Disable this address space from the ROM module. References to this address space cannot
access the ROM module and are processed like other non-ROM references.
0
V
Valid. Indicates whether ROMBAR contents are valid. The BA value is not used and the ROM
module is not accessible until V is set.
0 Contents of ROMBAR are not valid.
1 Contents of ROMBAR are valid.
Содержание DigitalDNA ColdFire MCF5272
Страница 1: ...MCF5272UM D Rev 0 02 2001 MCF5272 ColdFire Integrated Microprocessor User s Manual ...
Страница 38: ...xxxviii MCF5272 User s Manual TABLES Table Number Title Page Number ...
Страница 58: ...1 10 MCF5272 User s Manual MCF5272 Specific Features ...
Страница 90: ...2 42 MCF5272 User s Manual Exception Processing Overview ...
Страница 96: ...3 6 MCF5272 User s Manual MAC Instruction Execution Timings ...
Страница 158: ...5 46 MCF5272 User s Manual Motorola Recommended BDM Pinout ...
Страница 184: ...7 12 MCF5272 User s Manual Interrupt Controller Registers ...
Страница 338: ...13 44 MCF5272 User s Manual Application Examples ...
Страница 414: ...18 6 MCF5272 User s Manual PWM Programming Model ...
Страница 452: ...19 38 MCF5272 User s Manual Power Supply Pins ...
Страница 482: ...20 30 MCF5272 User s Manual Reset Operation ...
Страница 492: ...21 10 MCF5272 User s Manual Non IEEE 1149 1 Operation ...
Страница 548: ...INDEX Index 12 MCF5272 User s Manual ...