Intel
®
81341 and 81342—DDR SDRAM Memory Controller
Intel
®
81341 and 81342 I/O Processors
Developer’s Manual
December 2007
630
Order Number: 315037-002US
7.8.3
SDRAM Control Register 1 — SDCR1
The SDRAM Control Registers (SDCR[1:0]) are responsible for programming the
operation of the DDR SDRAM state machines as defined in
and
“DDR SDRAM Mode Programming” on page 601
. The SDCR1 specifies
the remaining SDRAM timing parameters required by the DDR SDRAM state machine
not specified in SDCR0.
Warning:
SPD values read must be converted into MCLK Periods.
Table 376. DDR SDRAM Control Register 1 - SDCR1 (Sheet 1 of 2)
Bit
Default
Description
31
0
2
DQS# Disable: Controls the behavior of the strobes.
0 = DQS# Enabled for Differential operation.
1 = DQS# Disabled for Singled-ended operation.
30:27
0000
2
RTCMD
: Read to Command (non-Read) turnaround period in MCLK periods.
Equation 24.RTCMD = tRTP = X
where tRTP is from SPD, and X equals:
• 2 (for 400 MHz and 533 MHz)
• 3 (for 667 MHz)
26:23
0000
2
WTCMD
: Write to Command (non-Read) turnaround period in MCLK periods.
Equation 25. WTCMD = tCAS - 1 + (BL/2) + tWR
where BL = 4, tCAS and tWR are from SPD.
22:19
0000
2
RTW:
Read to Write turnaround period in MCLK periods This parameter is not used for
read-modify-write.
Equation 26. RTW = (BL/2) + 2
where BL = 4.
PCI
IOP
Attributes
Attributes
28
24
20
16
12
8
4
0
31
rw
na
rw
na
rw
na
rw
na
rw
na
rw
na
rw
na
rw
na
rw
na
rw
na
rw
na
rw
na
rw
na
rv
na
rw
na
rw
na
rw
na
rw
na
rw
na
rw
na
rw
na
rw
na
rw
na
rw
na
rw
na
rw
na
rw
na
rw
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
+1808H