Intel
®
81341 and 81342—DDR SDRAM Memory Controller
Intel
®
81341 and 81342 I/O Processors
Developer’s Manual
December 2007
654
Order Number: 315037-002US
7.8.25
RCOMP Pad Drive Strength Select Register — RPDSR
This register provides the drive strength values for various pad groups. The selected
drive strength values are used by the RCOMP state machine to dynamically adjust the
drive strength and the slew rate in order to compensate for temperature and voltage
variations. The selected values are further adjusted by using the
Table 398. RCOMP Pad Drive Strength Select — RPDSR
Bit Default
Description
31:12 00000H Reserved
11:09 000
2
Drive Strength Select
: Drive strength for CKE[1:0] and CS[1:0]# pads used by RCOMP state machine. Value
can be further adjusted using
“DDR RCOMP Control Register — DRCR” on page 652
.
000
2
50 ohm Drive strength
001
2
35 ohm Drive strength
010
2
25 ohm Drive strength
011
2
17.9 ohm Drive strength (
Recommended value for Unbuffered DIMMs
)
100
2
15 ohm Drive strength
All other values are reserved
08:06 000
2
Drive Strength Select
: Drive strength for M_CK[2:0] and M_CK[2:0]# pads used by RCOMP state machine.
Value can be further adjusted using
“DDR RCOMP Control Register — DRCR” on page 652
000
2
50 ohm Drive strength
001
2
35 ohm Drive strength
010
2
25 ohm Drive strength
011
2
17.9 ohm Drive strength
100
2
15 ohm Drive strength
All other values are reserved
05:03 000
2
Drive Strength Select
: Drive strength for BA[2:0], MA[13:0], WE#, RAS#, CAS#, ODT[1:0] pads used by
RCOMP state machine. Value can be further adjusted using
“DDR RCOMP Control Register — DRCR” on
000
2
50 ohm Drive strength
001
2
35 ohm Drive strength
010
2
25 ohm Drive strength
011
2
17.9 ohm Drive strength (
Recommended value for Unbuffered DIMMs
)
100
2
15 ohm Drive strength
All other values are reserved
02:00 000
2
Drive Strength Select
: Select drive strength for DQ[63:0] pads used by RCOMP state machine. Value can be
further adjusted using the
“DDR RCOMP Control Register — DRCR” on page 652
000
2
50 ohm Drive strength
001
2
35 ohm Drive strength
010
2
25 ohm Drive strength
011
2
17.9 ohm Drive strength
100
2
15 ohm Drive strength
All other values are reserved
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
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 offset
+2004H