Intel
®
81341 and 81342 I/O Processors
December 2007
Developer’s Manual
Order Number: 315037-002US
579
DDR SDRAM Memory Controller—Intel
®
81341 and 81342
512 Mbit DDR2 SDRAM devices comprise four internal leaves. The DMCU controls the
leaf selects within 512 Mbit DDR2 SDRAM by toggling
BA[0]
and
BA[1]
.
1 Gbit and 2 Gbit DDR2 SDRAM devices comprise eight internal leaves. The DMCU
controls the leaf selects within 1 Gbit and 2 Gbit DDR2 SDRAM by toggling
BA[0]
,
BA[1]
and
BA[2]
.
The two DDR SDRAM chip enables (
CS[1:0]#
) support a DDR SDRAM memory
subsystem consisting of up to two banks. The base address for the two contiguous
banks are programmed in the DDR SDRAM Base Register (SDBR) and DDR SDRAM
Upper Base Address Register (SDUBR) and must be aligned to the size of supported
memory. For example, when the amount of DDR memory supported is 4 GBytes, the
base address registers boundary must be programmed to align on a 4 Gbyte boundary.
Similarly, when the amount of DDR memory supported is 256 MBytes, the base address
registers boundary must programmed to align on a 256 Mbyte boundary. The bank size
of the DDR SDRAM bank is programmed in the DDR SDRAM Bank Size registers
(SBSR). Bank 0 is also configurable into multiple regions. By default bank 0 is a single
64-bit region. For higher core data processing performance, a 32-bit region can be
defined within Bank 0 with the DDR SDRAM 32-bit Region Size Register (S32SR).
Note:
The Base Address registers (SDBR and SDUBR) must be programmed to align on
boundaries that are based on the total size of DDR memory supported. For example,
when only 4Gbytes of DDR memory is supported, then the base address registers must
be aligned on a 4-Gbyte boundary.
Note:
The DDR SDRAM Bank Size register (SBSR) provides the size of one DDR memory
bank. All banks must be of the same size and type. Otherwise, the SBSR is
programmed with the smallest bank size.
Note:
DDR SDRAM memory space must be aligned to a 128 Mbyte boundary and must
never
cross a 4 Gbyte boundary.
Table 359. DDR SDRAM Address Register Summary
DDR SDRAM Address Register
Definition
DDR SDRAM Base Register (SDBR)
Provides lower part of the base address for DDR SDRAM
memory space. Smallest address alignment supported is
128 Mbyte boundary. This register is used in conjunction
with SDUBR to provide the entire base address.
DDR SDRAM Upper Base Register (SDUBR)
Upper part of the base address for DDR SDRAM memory
space. This register is used in conjunction with SDBR to
provide the entire base address.
DDR SDRAM Size Register (SBSR)
Provides size of a single bank. Smallest size is128 Mbytes.
DDR SDRAM 32-Bit Size Register (S32SR)
The size for the memory space to operate as 32-bit
memory region (in MBs). S32SR must be less than, or
equal to 1/2 of bank 0 size. Ignored with a 32-bit data bus
width.