Intel
®
81341 and 81342 I/O Processors
December 2007
Developer’s Manual
Order Number: 315037-002US
593
DDR SDRAM Memory Controller—Intel
®
81341 and 81342
7.3.3.6
DDR SDRAM Commands
The DMCU issues specific commands to the DDR SDRAM devices by encoding them on
the
CS[1:0]#
,
RAS#
,
CAS#
, and
WE#
inputs.
lists all of the DDR SDRAM
commands understood by DDR SDRAM devices. The DMCU supports a subset of these
commands.
DDR SDRAM commands are synchronous to the clock so the DMCU sets up the above
conditions prior to the
M_CK[2:0]
rising edge.
Table 364. DDR SDRAM Commands
Command
,a
,
b
a. Shaded boxes indicate commands not supported by 81341 and 81342. They are included for completeness.
b. 512 Mbit DDR2 technologies uses
BA[1:0]
,
whereas 1 Gbit/2 Gbit DDR2 technologies use
BA[2:0]
.
Conditions
Comments
SCE# RAS# CAS# SWE#
Other
NOP
0
1
1
1
No Operation
Load Mode
0
0
0
0
BA[1:0]
= Sel
c
c. Selects which mode register is programmed. 00
2
selects Mode Register, 01
2
selects Extended Mode Register,
10
2
selects Extended Mode Register 2, and 11
2
selects Extended Mode Register 3.
Load the (Extended) Mode
Register from
MA[13:0]
Row Activate
0
0
1
1
BA[1:0]
= Leaf Activate a row specified on
MA[13:0]
Read
0
1
0
1
BA[1:0]
= Leaf
MA[10]
= 0
Column burst read
Column address on
MA[13:0]
Read w/
Auto-Precharge
0
1
0
1
BA[1:0]
= Leaf
MA[10]
= 1
Column burst read with row
precharge at the end of the
transfer
Write
0
1
0
0
BA[1:0]
= Leaf
MA[10]
= 0
Column burst write
Column address on
MA[13:0]
Write w/
Auto-Precharge
0
1
0
0
BA[1:0]
= Leaf
MA[10]
= 1
Column burst write with row
precharge at the end of the
transfer
Precharge
0
0
1
0
BA[1:0]
= Leaf
MA[10]
= 0
Precharge a single leaf
Precharge All
0
0
1
0
MA[10]
= 1
Precharge all leaves
Auto-Refresh
0
0
0
1
Refresh both banks from on-chip
refresh counter
Self-Refresh
0
0
0
1
CKE
= 0
Refresh autonomously while
CKE
= 0
Power Down
X
X
X
X
CKE
= 0
Power down when both banks
precharged when
CKE
= 0
Stop
0
1
1
0
Interrupt a read or write burst.