Intel
®
81341 and 81342 I/O Processors
December 2007
Developer’s Manual
Order Number: 315037-002US
633
DDR SDRAM Memory Controller—Intel
®
81341 and 81342
7.8.5
SDRAM Upper Base Register — SDUBR
This register indicates the upper four 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 7.8.4, SDRAM Base Register — SDBR
. Refer to See
Section 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:
DDR 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 SDUBR is internally used by the DDR MCU to create internal control signal. After
initializing the DDR MCU for normal operation, when the user decides to reconfigure the
DDR MCU at a later time by clearing SDUBR, 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 378. SDRAM Upper Base Register — SDUBR
Bit
Default
Description
31:04
0
Reserved
03:00
0
SDRAM Upper Base Address:
Define part of the upper bits of the DDR SDRAM base address.
PCI
IOP
Attributes
Attributes
28
24
20
16
12
8
4
0
31
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
rv
na
rw
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
+1810H