Intel
®
81341 and 81342 I/O Processors
December 2007
Developer’s Manual
Order Number: 315037-002US
635
DDR SDRAM Memory Controller—Intel
®
81341 and 81342
7.8.7
SDRAM Bank Size Register — SBSR
This register indicates size and number of DDR SDRAM banks. These parameters are
used to calculate total DDR SDRAM memory size supported. The total DDR SDRAM size
calculated is then used to program the Base Address Registers. For example, the Base
address Registers must align to the total size of DDR memory supported. This register
is also used to indicate the bank boundaries for address decoding and bank select
signals generation. Bit[0] of this register also provides the DDR technology type.
Note:
DDR SDRAM memory space must
never
cross a 4 Gbyte boundary.
Note:
This register is read back after being written, before the Intel XScale
®
microarchitecture performs transactions which address the DDR SDRAM.
Warning:
SPD values read must be converted into MCLK Periods.
Warning:
SDRAM Bank Size and Number of DDR Banks fields are internally used by DDR MCU to
create internal control signals. After initializing DDR MCU for normal operation, when
the user decides to reconfigure DDR MCU at a later time by clearing any of these fields,
the user must wait for a period of inactivity on both the north and south internal buses
before accessing the DDR MCU again to allow ample time for the new values to settle.
Table 380. SDRAM Bank Size Register — SBSR (Sheet 1 of 2)
Bit
Default
Description
31:27
00000
2
SDRAM Bank Size:
Defines the size of a single DDR SDRAM bank.
00000
2
= Empty 00001
2
= 128 MB 00010
2
= 256 MB 00100
2
= 512 MB 01000
2
= 1 GB
all other values are reserved.
Note:
128 MBytes memory size is only possible on 81341 and 81342 when supporting a 32-bit data
bus. For example, minimum memory size supported with a 64-bit data bus is 256 MBytes.
26:12
000_0H
Reserved
21:16
00_0000
2
Secondary SDRAM Bank Size:
Defines the size of the Secondary DDR SDRAM window addressed by
the Secondary SDRAM Base Register.
00 0000
2
= Secondary window disabled
00 0001
2
= 64 MB
00 0010
2
= 128 MB
00 0100
2
= 256 MB
00 1000
2
= 512 MB
01 0000
2
= 1 GB
10 0000
2
= 2 GB
all other values are reserved.
15:12
0H
Reserved
11:08
0000
2
RMW:
Read to Write turnaround period in MCLK periods for Read-Modify-Write.
Equation 31. RMW = tCAS + (BL/2) + tEDP
where BL = 4, tEDP = (Refer to SDCR0[18:16]), and tCAS is from SPD.
PCI
IOP
Attributes
Attributes
28
24
20
16
12
8
4
0
31
rw
na
rw
na
rw
na
rw
na
rw
na
rv
na
rv
na
rv
na
rv
na
rv
na
rw
na
rw
na
rw
na
rw
na
rw
na
rw
na
rv
na
rv
na
rv
na
rv
na
rw
na
rw
na
rw
na
rw
na
rv
na
rv
na
rv
na
rv
na
rv
na
rw
na
rw
na
rw
na
Attribute Legend:
RV = Reserved
PR = Preserved
RS = Read/Set
RW = Read/Write
RC = Read Clear
RO = Read Only
NA = Not Accessible
Intel XScale
®
microarchitecture Local
Bus Address offset
+1814H