
Memory Map/Register Definition
MCF5271 Reference Manual, Rev. 2
Freescale Semiconductor
18-9
18.3.3 DRAM Controller Mask Registers (DMR0/DMR1)
The DMRn,
Figure 18-4, includes mask bits for the base address and for address attributes.
18.3.4 General Synchronous Operation Guidelines
To reduce system logic and to support a variety of SDRAM sizes, the DRAM controller provides
SDRAM control signals as well as a multiplexed row address and column address to the SDRAM.
18.3.4.1 Address Multiplexing
Table 18-7 shows the generic address multiplexing scheme for SDRAM configurations. All
possible address connection configurations can be derived from this table.
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
R
BAM
0
W
Reset
——————————————
0
15
14
13
12
11
10
987
6543210
R
0000000
WP
0000000
V
W
Reset
0000000000000000
Address
IPSBAR + 0x00_004C (DMR0); 0x00_0054 (DMR1)
Figure 18-4. DRAM Controller Mask Registers (DMRn)
Table 18-6. DMRn Field Descriptions
Bits
Name
Description
31–18
BAM
Base address mask. Masks the associated DACRn[BA]. Lets the DRAM controller connect
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 Prohibit write accesses. The DRAM controller deasserts the external DRAMW (Write
Enable) signal and an access error exception occurs.
7-1
—
Reserved, should be cleared.
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.