Memory Controller Programming Model
MSC8144E Reference Manual, Rev. 3
Freescale Semiconductor
12-45
DDR_SDRAM_CFG_2 provides control configuration for the DDR controller in addition to that
provided by DDR_SDRAM_CFG.
Table 12-23. DDR_SDRAM_CFG_2 Field Descriptions
Bit Reset
Description
FRC_SR
31
0
Force Self Refresh
0
Normal operating mode.
1
Self Refresh mode.
—
30
0
Reserved. Write to zero for future compatibility.
DLL_RST_
DIS
29
0
DLL Reset Disable
The DDR controller typically issues a DLL reset to the
DRAMs when it exists self refresh. However, you can
disable this function by setting this bit during
initialization.
0
DDR controller issues a DLL
reset when exiting self refresh.
1
DDR controller does not issue a
DLL reset when exiting self
refresh.
—
28
0
Reserved. Write to zero for future compatibility.
DQS_CFG
27–26
0
DQS Configuration
Defines the DQS mode - single ended or differential.
Should be cleared for DDR1.
00
Only true DQS signals are
used.
01
Differential DQS signals are
used for DDR2 support.
10
Reserved.
11
Reserved.
—
25–23
0
Reserved. Write to zero for future compatibility.
ODT_CFG
22–21
0
ODT Configuration
Defines how ODT is driven to the on-chip I/O.
See Table 12-49 for the definition of the impedance
value that will be used.
00
Never assert ODT to
internal I/O.
01
Assert ODT to internal I/O
only during writes to DRAM.
10
Assert ODT to internal I/O
only during reads to DRAM.
11
Always keep ODT asserted
to internal I/O.
—
20–16
0
Reserved. Write to zero for future compatibility.
NUM_PR
15–12
0
Number of Posted Refreshes
Determines how many posted refreshes, if any, can be
issued at one time. If posted refreshes are used, this
field, along with SICFG[REFINT], must be
programmed so that the maximum t
ras
specification
cannot be violated. For example, some DDR1
SDRAMs cannot use more than three posted
refreshes because the required refresh interval can
exceed the maximum constraint for t
ras
.
0000
Reserved.
0001
1 refresh at a time.
0010
2 refreshes at a time.
0011
3 refreshes at a time.
...
1000
8 refreshes at a time.
1001–1111Reserved.
—
11–5
0
Reserved. Write to zero for future compatibility.
Summary of Contents for MSC8144E
Page 1: ...MSC8144E Reference Manual Quad Core Media Signal Processor MSC8144ERM Rev 3 July 2009 ...
Page 48: ...MSC8144E Reference Manual Rev 3 xlviii Freescale Semiconductor ...
Page 86: ...MSC8144E Reference Manual Rev 3 1 38 Freescale Semiconductor Overview ...
Page 168: ...MSC8144E Reference Manual Rev 3 3 60 Freescale Semiconductor External Signals ...
Page 242: ...MSC8144E Reference Manual Rev 3 5 26 Freescale Semiconductor Reset ...
Page 314: ...MSC8144E Reference Manual Rev 3 8 24 Freescale Semiconductor General Configuration Registers ...
Page 414: ...MSC8144E Reference Manual Rev 3 10 14 Freescale Semiconductor MSC8144E SC3400 DSP Subsystem ...
Page 452: ...MSC8144E Reference Manual Rev 3 11 38 Freescale Semiconductor Internal Memory Subsystem ...
Page 520: ...MSC8144E Reference Manual Rev 3 12 68 Freescale Semiconductor DDR SDRAM Memory Controller ...
Page 1070: ...MSC8144E Reference Manual Rev 3 21 28 Freescale Semiconductor Timers ...