
Cache
MCF5282 Coldfire Microcontroller Reference Manual, Rev. 2.2
4-8
Freescale Semiconductor
23
DISI
Disable instruction caching. When set, this bit disables instruction caching. This bit, along with
the CENB (cache enable) and DISD (disable data caching) bits, control the cache
configuration. See the CENB definition for a detailed description.
0 Do not disable instruction caching
1 Disable instruction caching
invalidate all bit.
22
DISD
Disable data caching. When set, this bit disables data caching. This bit, along with the CENB
(cache enable) and DISI (disable instruction caching) bits, control the cache configuration.
See the CENB definition for a detailed description.
0 Do not disable data caching
1 Disable data caching
invalidate all bit.
21
INVI
CINV instruction cache only. This bit can not be set unless the cache configuration is split
(both DISI and DISD cleared). For instruction or data cache configurations this bit is a
don’t-care. For the split cache configuration, this bit is part of the control for the invalidate all
operation. See the CINV definition for a detailed description
Table 4-6 describes how to set the cache invalidate all bit.
20
INVD
CINV data cache only. This bit can not be set unless the cache configuration is split (both DISI
and DISD cleared). For instruction or data cache configurations this bit is a don’t-care. For the
split cache configuration, this bit is part of the control for the invalidate all operation. See the
CINV definition for a detailed description
Table 4-6 describes how to set the cache invalidate all bit.
19–11
—
Reserved, should be cleared.
10
CEIB
Cache enable noncacheable instruction bursting. Setting this bit enables the line-fill buffer to
be loaded with burst transfers under control of CLNF[1:0] for noncacheable accesses.
Noncacheable accesses are never written into the memory array.
0 Disable burst fetches on noncacheable accesses
1 Enable burst fetches on noncacheable accesses
9
DCM
Default cache mode. This bit defines the default cache mode: 0 is cacheable, 1 is
noncacheable. For more information on the selection of the effective memory attributes, see
0 Caching enabled
1 Caching disabled
8
DBWE
Default buffered write enable. This bit defines the default value for enabling buffered writes. If
DBWE = 0, the termination of an operand write cycle on the processor's local bus is delayed
until the external bus cycle is completed. If DBWE = 1, the write cycle on the local bus is
terminated immediately and the operation buffered in the bus controller. In this mode, operand
write cycles are effectively decoupled between the processor's local bus and the external bus.
Generally, enabled buffered writes provide higher system performance but recovery from
access errors can be more difficult. For the ColdFire CPU, reporting access errors on operand
writes is always imprecise and enabling buffered writes further decouples the write instruction
and the signaling of the fault
0 Disable buffered writes
1 Enable buffered writes
7–6
—
Reserved, should be cleared.
Table 4-4. CACR Field Descriptions (continued)
Bits
Name
Description