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2.5
Memory Width and Byte Alignment
DDR2 memory controller data bus
DDR_D[31:24]
DDR_D[23:16]
DDR_D[15:8]
DDR_D[7:0]
32-bit memory device
16-bit memory device
Peripheral Architecture
The DDR2 memory controller supports memory widths of 16 bits and 32 bits.
Table 5
summarizes the
addressable memory ranges on the DDR2 memory controller. See the device-specific data manual for the
memory widths that are supported. Both big-endian and little-endian formats are supported.
Figure 11
shows the byte lanes used on the DDR2 memory controller. The external memory is always
right-aligned on the data bus.
Table 5. Addressable Memory Ranges
Memory Width
Maximum addressable bytes per CS space
Description
×
16
128 Mbytes
Halfword address
×
32
256 Mbytes
Word address
Figure 11. Byte Alignment (Little-Endian Mode)
DDR2 Memory Controller
20
SPRUEM4A – November 2007
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