MCF548x Reference Manual, Rev. 3
7-22 Freescale Semiconductor

7.10.2 Access Control Registers (ACR0–ACR3)

The ACRs, Figure 7-9, assign control attributes, such as cache mode and write protection, to specified
memory regions. ACR0 and ACR1 control data attributes; ACR2 and ACR3 control instruction attributes.
Registers are accessed with the MOVEC instruction with the Rc encodings in Figure 7-9.
For overlapping data regions, ACR0 takes priority; ACR2 takes priority for overlapping instruction
regions. Data transfers to and from these registers are longword transfers.
NOTE
The MBAR region should be mapped as cache-inhibited through an ACR or
the CACR.
NOTE
ACR0–ACR3 is read/write by the debug module.
Table 7-5 describes ACRn fields.
I
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
RBA ADMSK
W
Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Reg
Addr
ACR0: 0x004; ACR1: 0x005; ACR2: 0x006; ACR3: 0x007
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
RE S 0 0 AMM0 0 0 CM 0 SP W
100
W
Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Reg
Addr
ACR0: 0x004; ACR1: 0x005; ACR2: 0x006; ACR3: 0x007
1Reserved in ACR2 and ACR3.
Figure 7-9. Access Control Register Format (ACRn)
Table 7-5. ACRn Field Descriptions
Bits Name Description
31–24 BA Base address. Compared with address bits A[31:24]. Eligible addresses that match are assigned
the access control attributes of this register.
23–16 ADMSK Address mask. Setting a mask bit causes the corresponding address base bit to be ignored. The
low-order mask bits can be set to define contiguous regions larger than 16 Mbytes. The mask can
define multiple noncontiguous regions of memory.
15 E Enable. Enables or disables the other ACRn bits.
0 Access control attributes disabled
1 Access control attributes enabled