![Intel IXP45X Developer'S Manual Download Page 600](http://html1.mh-extra.com/html/intel/ixp45x/ixp45x_developers-manual_2073092600.webp)
Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors—Memory Controller
Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors
Developer’s Manual
August 2006
600
Order Number: 306262-004US
11. After waiting T
mrd
cycles, software issues a
mode-register-set
command by writing
0001
2
to the SDIR to program the DDRI SDRAM parameters and to
reset
the DLL.
The MCU supports the following DDRI SDRAM mode parameters:
a. CAS Latency (tCAS) = two or two and one-half for DDRI, or three or
four for DDRII based on the programmed setting in
“DDRI SDRAM Control Register 0 SDCR0”
b. Burst Type = Sequential
c. Burst Length (BL) = four
12. After waiting T
mrd
cycles, software issues a
precharge-all
command to the DDRI
SDRAM interface by setting the SDIR to 0010
2
.
13. After waiting T
rp
cycles, software provides two
auto-refresh
cycles. An
auto-refresh
cycle is accomplished by setting the SDIR to 0110
2
. Software must ensure at least
T
rfc
cycles between each
auto-refresh
command.
14. Following the second
auto-refresh
cycle, software must wait T
rfc
cycles. Then,
software issues a
mode-register-set
command by writing to the SDIR to program the
DDRI SDRAM parameters without resetting the DLL by writing 0000
2
to the SDIR.
Figure 107. Supported DDRII SDRAM Extended Mode Register Settings
Note:
DDRI_BA[1:0] must be 01
2
to select the Extended Mode Register.
A12 doesn’t exist for 128 Mbit Technology
B4213-001
0
0
0
A0
A12
The DDR SDRAM Extended
A3
A6
0
Additive Latency
OCD is programmed
through the DDR
Calibration Unit (DCAL)
Mode Register resides in the
DDR SDRAM devices.
DLL Enable:
0: Enable
1: Disable
0
0
0
Figure 108. Supported DDRI SDRAM Mode Register Settings
Note:
DDRI_BA[1:0] must be 00
2
to select the Mode Register.
A12 doesn’t exist for 128 Mbit Technology
B4214-001
0
0
0
CAS Latency :
010: 2 (DDR only)
011: 3 (DDR-II only)
100: 4 (DDR-II only)
110: 2.5 (DDR only)
Other: X
Burst Type:
0: Sequential
Burst Length:
010: 4
A0
A12
Operating Mode (A8:A7):
00: Normal Operation
(Do not Reset DLL)
10: Normal Operation
(In DLL Reset)
Other: X
A3
A6
0
The DDR SDRAM mode register resides
in the DDR SDRAM devices.