Microcontroller User's Manual

15-8 MCF5282 User’s Manual MOTOROLA
SDRAM Controller Operation
15.2.2.3 DRAM Controller Mask Registers (DMR0/DMR1)
The DMRn, Figure 15-4, includes mask bits for the base address and for address attributes.
Table 15-6 describes DMRn fields.
31 1817 9876543210
Field BAM — WP — C/I AM SC SD UC UD V
Reset Uninitialized 0
R/W R/W
Addr IPSBAR + 0x04C (DMR0), 0x054 (DMR1)
Figure 15-4. DRAM Controller Mask Registers (DMRn)
Table 15-6. DMRn Field Descriptions
Bits Name Description
31–18 BAM Base address mask. Masks the associated DACRn[BA]. Lets the DRAM controller connect to various DRAM
sizes. Mask bits need not be contiguous (see Section 15.3, “SDRAM Example.”)
0 The associated address bit is used in decoding the DRAM hit to a memory block.
1 The associated address bit is not used in the DRAM hit decode.
17–9 — Reserved, should be cleared.
8 WP Write protect. Determines whether the associated block of DRAM is write protected.
0 Allow write accesses
1 Ignore write accesses. The DRAM controller ignores write accesses to the memory block and an address
exception occurs. Write accesses to a write-protected DRAM region are compared in the chip select module for
a hit. If no hit occurs, an external bus cycle is generated. If this external bus cycle is not acknowledged, an access
exception occurs.
7 — Reserved, should be cleared.
6–1 AMx Address modifier masks. Determine which accesses can occur in a given DRAM block.
0 Allow access type to hit in DRAM
1 Do not allow access type to hit in DRAM
Bit Associated Access Type Access Definition
C/I CPU space/interrupt acknowledge MOVEC instruction or interrupt acknowledge cycle
AM Alternate master DMA master
SC Supervisor code Any supervisor-only instruction access
SD Supervisor data Any data fetched during the instruction access
UC User code Any user instruction
UD User data Any user data
0 V Valid. Cleared at reset to ensure that the DRAM block is not erroneously decoded.
0 Do not decode DRAM accesses.
1 Registers controlling the DRAM block are initialized; DRAM accesses can be decoded.