SDRAM Controller (SDRAMC)
Freescale Semiconductor
21-9
•
Use single series, single parallel termination (25
series, 50
parallel values are recommended,
but standard resistor packs with similar values can be substituted).
•
Series termination should be between the processor and memory, but closest to the processor.
•
The SD_CLK and SD_CLK signals can be terminated with a single termination resistor between
the two clock phases. A 100 – 120
resistor produces effective termination for the differential
SD_CLK. Placement of the terminator should be physically close to the input receiver on the
SDRAM(s).
If using a SDRAM DIMM, such as a 144-pin DDR2 SO-DIMM, termination on the CLK lines is
not recommended, as clock line termination is already populated on the DIMM module. Additional
termination on the motherboard (main board) may cause undersired effects.
•
0.1
F decoupling for every termination resistor pack.
21.3.3.1
Termination Example
shows the recommended termination circuitry for DDR SDRAM signals.
Figure 21-3. DDR SDRAM Termination Circuit
21.4
Memory Map/Register Definition
The SDRAM controller and its associated logic contain two sets of programming registers:
•
SDRAM controller’s control and configuration registers
•
Chip-select configuration control registers
NOTE
The slew rate for the SDRAM pins is controlled by a register in the pin
multiplexing and control module. See
Select Control Register (MSCR_SDRAM)
,
”
for more details.
shows the SDRAM controller control and configuration registers. Unspecified memory spaces
are reserved for future use. Access to reserved space is prohibited. It is recommended to write 0 to reserved
space. Reads from a write-only bit return 0.
DDR SDRAM
22
100
SD_CLK
SD_CLK
Address, Data
and Control
Processor
CLK
CLK
Address, Data
and Control
Note:
Place 100
resistor as
close as possible to the
Note:
Place series resistors as close
as possible to the processor
DDR’s clock receiver
51
V
REF
Summary of Contents for MCF54455
Page 33: ...xxviii Freescale Semiconductor ...
Page 67: ...Freescale Semiconductor 1 ...
Page 125: ...Freescale Semiconductor 1 ...
Page 145: ...Enhanced Multiply Accumulate Unit EMAC 5 21 Freescale Semiconductor ...
Page 173: ...Cache 6 28 Freescale Semiconductor ...
Page 179: ...Static RAM SRAM 7 6 Freescale Semiconductor ...
Page 207: ...Power Management 9 16 Freescale Semiconductor ...
Page 323: ...Reset Controller Module 13 8 Freescale Semiconductor ...
Page 389: ...Pin Multiplexing and Control 16 44 Freescale Semiconductor ...
Page 575: ...PCI Bus Controller 22 58 Freescale Semiconductor ...
Page 600: ...Advanced Technology Attachment ATA Freescale Semiconductor 23 25 ...
Page 601: ...Freescale Semiconductor 1 ...
Page 842: ...I2 C Interface Freescale Semiconductor 33 16 ...
Page 843: ...Freescale Semiconductor 1 ...
Page 921: ...Revision History A 6 Freescale Semiconductor ...