Intel
®
81341 and 81342 I/O Processors
December 2007
Developer’s Manual
Order Number: 315037-002US
653
DDR SDRAM Memory Controller—Intel
®
81341 and 81342
02:01
01
2
50 Ohm Adjust Control
: This field provides control to further adjust the value for all the 50 ohm drive
strength selection made using
“RCOMP Pad Drive Strength Select — RPDSR” on page 654
00
2
45.6 ohm
01
2
50 ohm
10
2
55 ohm
11
2
Reserved.
00
1
2
RCOMP State Machine Enable
: Enables the RCOMP state machine. The RCOMP state machine
monitors and controls the drive strength as opposed to the manually programming the values. An
external calibration resistor is referenced via the MCAL[1:0] pins to dynamically adjust the slew rate and
drive strength in order to compensate for temperature and voltage variations.
Table 397. DDR RCOMP Control Register — DRCR (Sheet 2 of 2)
Bit
Default
Description
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
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 offset
+2000H