Intel
®
81341 and 81342—DDR SDRAM Memory Controller
Intel
®
81341 and 81342 I/O Processors
Developer’s Manual
December 2007
632
Order Number: 315037-002US
7.8.4
SDRAM Base Register — SDBR
This register indicates six bits of the beginning address (base address) of SDRAM
space. The SDRAM is addressed using a 36-bit address. This register is used in
conjunction with the
Section 7.8.5, SDRAM Upper Base Register — SDUBR
7.3.3.3, “DDR SDRAM Bank Sizes and Configurations” on page 578
for usage details.
There can be two contiguous physical banks defined by SBSR in the DDR SDRAM
subsystem starting at this address.
Note:
DDR2 SDRAM memory space must
never
cross a 4 Gbyte boundary.
Note:
This register should be read back after being written, before the Intel XScale
®
microarchitecture performs transactions which address the DDR SDRAM.
Warning:
The SDBR is internally used by the DDR MCU to create internal control signal. After
initializing the DDR MCU for normal operation, wehen the user decides to reconfigure
the DDR MCU at a later time by clearing SDBR, 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 377. SDRAM Base Register — SDBR
Bit
Default
Description
31:27
0
SDRAM Base Address:
These bits define part of the upper bits of the DDR SDRAM base address.
26:00
0
Reserved
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
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
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
+180CH