MSC8144E Reference Manual, Rev. 3
12-6
Freescale
Semiconductor
DDR SDRAM Memory Controller
When ECC is enabled, all memory accesses are performed on word boundaries (that is, all
DQM
signals are set simultaneously). However, when ECC is disabled, the memory system uses the
DQM
signals for byte lane selection. Table 12-1 and Table 12-2 show how DDR SDRAM
memories are used with x8 or x16 devices for 32 or 16 bit memory interfaces.
12.1.2
DDR SDRAM Organization
Although the DDR memory controller multiplexes row and column address bits onto 16 memory
address signals and 3 logical bank select signals, individual physical banks can contain memory
devices with fewer than 31 address bits. Each physical bank can be individually configured to
provide from 12 to 16 row address bits plus 2 or 3 logical bank-select bits and from 8–11 column
address bits. Table 12-3 lists the DDR SDRAM device configurations supported by the DDR
memory controller.
Note:
DDR SDRAM is limited to 30 total address bits.
Table 12-1. Byte Lane to Data Relationship for a 32-Bit Memory Interface
Data Byte Lane
Data Bus Mask
Data Bus Strobe
Data Bus 32-Bit Mode
0 (MSB)
MDM0
MDQS0
MDQ[0–7]
1
MDM1
MDQS1
MDQ[8–15]
2
MDM2
MDQS2
MDQ[16–23]
3 (LSB)
MDM3
MDQS3
MDQ[24–31]
Table 12-2. Byte Lane to Data Relationship16-Bit Memory Interface
Data Byte Lane
Data Bus Mask
Data Bus Strobe
Data Bus 16-Bit Mode
0 (MSB)
MDM0
MDQS0
MDQ[0–7]
1 (LSB)
MDM1
MDQS1
MDQ[8–15]
Table 12-3. DDR SDRAM Device Configurations
SDRAM Device
Device Configuration
Row x Column x
Sub-bank Bits
32-Bit Bank Size
Two Banks of Memory
64 Mb
8 Mb
×
8
12
×
9
×
2
32 MB
64 MB
64 Mb
4 Mb
×
16
12
×
8
×
2
16 MB
32 MB
128 Mb
16 Mb
×
8
12
×
10
×
2
64 MB
128 MB
128 Mb
8 Mb
×
16
12
×
9
×
2
32 MB
64 MB
256 Mb
32 Mb
×
8
13
×
10
×
2
128 MB
256 MB
256 Mb
16 Mb
×
16
13
×
9
×
2
64 MB
128 MB
512 Mb
64 Mb
×
8
13
×
11
×
2
256 MB
512 MB
512 Mb
32 Mb
×
16
13
×
10
×
2
128 MB
256 MB
1 Gb
128 Mb
×
8
14
×
11
×
2
512 MB
1 GB
1 Gb
64 Mb
×
16
14
×
10
×
2
256 MB
512 MB
2 Gb
256 Mb
×
8
15
×
11
×
2
1 GB
2 GB
2 Gb
128 Mb
×
16
15
×
10
×
2
512 MB
1 GB
4 Gb
512 Mb
×
8
16
×
11
×
2
2 GB
4 GB
4 Gb
256 Mb
×
16
16
×
10
×
2
512 MB
2 GB
Содержание MSC8144E
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Страница 40: ...MSC8144E Reference Manual Rev 3 xl Freescale Semiconductor Contents 26 5 12 8 RNG Output FIFO 26 186 ...
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Страница 242: ...MSC8144E Reference Manual Rev 3 5 26 Freescale Semiconductor Reset ...
Страница 314: ...MSC8144E Reference Manual Rev 3 8 24 Freescale Semiconductor General Configuration Registers ...
Страница 414: ...MSC8144E Reference Manual Rev 3 10 14 Freescale Semiconductor MSC8144E SC3400 DSP Subsystem ...
Страница 452: ...MSC8144E Reference Manual Rev 3 11 38 Freescale Semiconductor Internal Memory Subsystem ...
Страница 520: ...MSC8144E Reference Manual Rev 3 12 68 Freescale Semiconductor DDR SDRAM Memory Controller ...
Страница 884: ...MSC8144E Reference Manual Rev 3 17 44 Freescale Semiconductor RapidIO Interface Dedicated DMA Controller ...
Страница 1070: ...MSC8144E Reference Manual Rev 3 21 28 Freescale Semiconductor Timers ...