Cache Register Definition
MCF548x Reference Manual, Rev. 3
Freescale Semiconductor 7-19

7.10 Cache Register Definition

This section describes the MCF548x implementation of the Version 4e cache registers.

7.10.1 Cache Control Register (CACR)

The CACR in Figure 7-8 contains bits for configuring the cache. It can be written by the MOVEC register
instruction and can be read or written from the debug facility. A hardware reset clears CACR, which
disables the cache; however, reset does not affect the tags, state information, or data in the cache.
NOTE
CACR is read/write by the debug module.
Table 7-4 describes CACR fields. Note that some implementations may include fields not defined here;
consult the part-specific documentation.
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
R DEC DW DESB DDPI DHLCK DDCM DCINVA DDSP 0 0 0 BEC BCINVA 0 0
W
Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
R IEC 0 DNFB IDPI IHLCK IDCM 0 ICINVA IDSP 0 EUSP DF 0 0 0 0
W
Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Reg
Addr
0x002
Figure 7-8. Cache Control Register (CACR)
Table 7-4. CACR Field Descriptions
Bits Name Description
31 DEC Enable data cache.
0 Cache disabled. The data cache is not operational, but data and tags are preserved.
1 Cache enabled.
30 DW Data default write-protect. For normal operations that do not hit in the RAMBARs or ACRs, this field
defines write-protection. See Section 7.9.1, “Caching Modes.”
0 Not write protected.
1 Write protected. Write operations cause an access error exception.
29 DESB Enable data store buffer. Affects the precision of transfers.
0 Imprecise-mode, write-through or cache-inhibited writes bypass the store buffer and generate
bus cycles directly. Section 7.9.4.2.1, “Push and Store Buffers,” describes the associated
performance penalty.
1 The four-entry FIFO store buffer is enabled; to maximize performance, this buffer defers pending
imprecise-mode, write-through or cache-inhibited writes.
Precise-mode, cache-inhibited accesses always bypass the store buffer. Precise and imprecise
modes are described in Section 7.9.1.2, “Cache-Inhibited Accesses.”