Set-Up and Initialization
MSC8144E Reference Manual, Rev. 3
Freescale Semiconductor
12-29
12.6.2
DDR SDRAM Initialization Sequence
After all parameters are configured, system software must set CSx_CONFIG[MEMEN] to enable
the memory interface. 200
μ
s must elapse after DRAM clocks are stable
(DDR_SDRAM_CLK_CNTL[CLK_ADJUST] is set and any chip select is enabled) before
MEMEN can be set. Therefore, a delay loop in the initialization code may be necessary if
software is enabling the memory controller. If DDR_SDRAM_CFG[BI] bit is not set to bypass
initialization, the DDR memory controller conducts an automatic initialization sequence to the
memory, which follows the memory specifications. If the bypass initialization mode is used,
software can initialize the memory through the DDR_SDRAM_MD_CNTL register.
RD_TO_PRE
Read-to-Precharge
Interval
DDR1
Configure to 010.
DDR2
Configure according to the specifications for
the memory used (A t
rtp
).
CKE_PLS
Minimum CKE Pulse
Width
DDR1
Can be set to 001.
DDR2
Configure according to the specifications for
the memory used (t
cke
).
FOUR_ACT
Window for Four
Activates
DDR1
Configure to 0001.
DDR2
Configure according to the specifications for
the memory used (t
faw
). Applicable for 8
logical banks.
2T_EN
2T Timing Enable
DDR1
In heavily loaded systems, this bit can be set
to 1 to gain extra timing margin on the
interface at the cost of address/command
bandwidth.
DDR2
DLL_RST_DIS
DLL Reset DIsable
DDR1
Typically 0, unless you want to bypass the
DLL reset when exiting self refresh.
DDR2
DQS_CFG
DQS Configuration
DDR1
Configure to 00.
DDR2
Can be either 00 or 01, depending upon
whether differential strobes are used.
ODT_CFG
ODT Configuration
DDR1
Configure to 00.
DDR2
Can be set for termination at the I/Os
according to system topology. Typically, if
ODT is enabled, the internal I/Os are set up
for termination only during reads to DRAM.
BSTOPRE
Burst To Precharge
Interval
DDR1
Can be set to any value, depending upon the
application. To enable auto precharge, clear
this field to all 0s.
DDR2
Table 12-14. Programming Differences Between Memory Types (Continued)
Parameter
Description
Differences
Page
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 ...