MSC8144E Reference Manual, Rev. 3
12-16
Freescale
Semiconductor
DDR SDRAM Memory Controller
12.3.2
DDR SDRAM Mode-Set Command Timing
The DDR controller transfers the mode register set commands to the SDRAM array and it uses
the setting of TIMING_CFG_0[MRS_CYC] for the Mode Register Set cycle time. Figure 12-9
shows the timing of the mode-set command. The first transfer corresponds to the ESDMODE
code; the second corresponds to SDMODE. The Mode Register Set cycle time is set to 2 DRAM
cycles.
Figure 12-9. DDR SDRAM Mode-Set Command Timing
12.3.3
DDR SDRAM Write Timing Adjustments
The DDR memory controller facilitates system design flexibility by providing a write timing
adjustment parameter, WRITE DATA DELAY, configured in
TIMING_CFG_2[WRITE_DATA_DELAY] for data and
DQS
. The DDR SDRAM specification
requires that
DQS
be received no sooner than 75 percent and no later than 125 percent of an
SDRAM clock period from the capturing clock edge of the command/address at the SDRAM.
The TIMING_CFG_2[WRITE_DATA_DELAY] parameter can be used to meet this timing
requirement for a variety of system configurations, ranging from a system with one SDRAM
device to a fully populated system with ten memory devices. The
TIMING_CFG_2[WRITE_DATA_DELAY] field specifies how much to delay the launching of
DQS
and data from the first clock edge occurring one SDRAM clock cycle after the command is
launched. The delay increment step sizes are in 1/4 SDRAM clock periods starting with the
default value of 0. Figure 12-10 shows the use of the write data delay parameter.
Code
Code
SDRAM Clock
MCS
MCAS
MA[15–0]
MDQ[0–31]
MWE
MRAS
MDQS
0x4
0x0
MBA[2–0]
0
1
2
3
4
5
6
7
8
9
10
11
12
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 ...