Intel
®
81341 and 81342 I/O Processors
December 2007
Developer’s Manual
Order Number: 315037-002US
651
DDR SDRAM Memory Controller—Intel
®
81341 and 81342
7.8.23
Frequency Register — RFR
The Refresh Frequency Register is programmed for refreshing the DDR SDRAM
subsystem at the specified interval. Writing to the RFR programs the refresh counter
with the Refresh Interval. Reading from the RFR results in the value currently within the
refresh counter. Refer to
“Typical Refresh Frequency Register Values” on page 606
for
recommended programmed values.
Table 396. Refresh Frequency Register — RFR
Bit
Default
Description
31:13
0
Reserved
12:00
000H
Refresh Interval:
Programs number of clocks that trigger a request for a refresh cycle on DDR
SDRAM interface. When all zeroes, refresh cycles are disabled. See
.
Note:
When the memory interface is busy when the refresh counter expires, it is possible for
DMCU to generate more than one refresh cycle when the memory interface becomes
available.
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
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
+1870H