Texas Instruments TMS320C642x DSP Memory Width and Byte Alignment, Addressable Memory Ranges

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Peripheral Architecture

2.5Memory Width and Byte Alignment

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 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

20	DDR2 Memory Controller	SPRUEM4A–November 2007
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Contents Users Guide Submit Documentation Feedback Contents List of Figures List of Tables Read This First Features Purpose of the PeripheralIndustry Standards Compliance Statement Functional Block DiagramSupported Use Case Statement Clock Control Clock SourceClock Configuration PLLC2 ConfigurationMemory Map 3 DDR2 Memory Controller Internal Clock DomainsSignal Descriptions DDR2 Memory Controller Signal DescriptionsClock enable Active high Pin Type DescriptionDDR2 Sdram Commands Truth Table for DDR2 Sdram CommandsCommand Function Protocol DescriptionsRefresh Mode Refresh CommandDcab Command Deactivation Dcab and DeacDeac Command Actv Command Activation ActvRead Command DDR2 Read CommandWrite WRT Command DDR2 WRT CommandMode Register Set MRS and Emrs DDR2 MRS and Emrs CommandMemory Width and Byte Alignment Addressable Memory RangesEndianness Support Bit External MemoryBit Field Bit Value Bit Description Bank Configuration Register Fields for Address MappingAddress Mapping Logical Address-to-DDR2 Sdram Address Map for 32-Bit Sdram Logical Address-to-DDR2 Sdram Address Map for 16-bit SdramLogical Address-to-DDR2 Sdram Address Map DDR2 Sdram Column, Row, and Bank Access DDR2 Memory Controller Interface DDR2 Memory Controller Fifo DescriptionCommand Ordering and Scheduling, Advanced Concept Command Starvation Possible Race ConditionSelf-Refresh Mode Refresh SchedulingRefresh Urgency Levels Urgency Level DescriptionReset Signal Reset Source Reset ConsiderationsReset Sources VTP IO Buffer Calibration Auto-Initialization SequenceDDR2 Sdram Configuration by MRS Command DDR2 Sdram Configuration by EMRS1 CommandInitializing Configuration Registers DDR2 Memory ControllerPeripheral Architecture DMA Event Support Power ManagementInterrupt Support Emulation Considerations Connecting the DDR2 Memory Controller to DDR2 Memory Supported Use CasesConnecting DDR2 Memory Controller for 32-Bit Connection Configuring Sdram Bank Configuration Register Sdbcr Sdram Bank Configuration Register Sdbcr ConfigurationConfiguring Sdram Refresh Control Register Sdrcr DDR2 Memory Refresh SpecificationConfiguring Sdram Timing Registers Sdtimr and SDTIMR2 Sdram Timing Register Sdtimr ConfigurationSdram Timing Register 2 SDTIMR2 Configuration DDR2 Data Register Field Manual Data Manual FormulaRegister Field Name Description Configuring DDR PHY Control Register DdrphycrDDR PHY Control Register Ddrphycr Configuration Mode D63-32 D31-0Acronym Register Description DDR VTP RegisterBit Field Sdram Status Register SdrstatSdram Status Register Sdrstat Field Descriptions Bit Field Value Description Sdram Bank Configuration Register SdbcrSdram Bank Configuration Register Sdbcr Field Descriptions Reserved Reserved. Always write a 0 to this bit Sdram Refresh Control Register Sdrcr Sdram Refresh Control Register Sdrcr Field DescriptionsSdram Timing Register Sdtimr Sdram Timing Register Sdtimr Field DescriptionsSdram Timing Register 2 SDTIMR2 Sdram Timing Register 2 SDTIMR2 Field DescriptionsPeripheral Bus Burst Priority Register Pbbpr Peripheral Bus Burst Priority Register PbbprInterrupt Raw Register IRR Interrupt Raw Register IRR Field DescriptionsInterrupt Masked Register IMR Interrupt Masked Register IMR Field DescriptionsInterrupt Mask Set Register Imsr Interrupt Mask Set Register Imsr Field DescriptionsInterrupt Mask Clear Register Imcr Interrupt Mask Clear Register Imcr Field DescriptionsDDR PHY Control Register Ddrphycr DDR PHY Control Register Ddrphycr Field DescriptionsVTP IO Control Register Vtpiocr VTP IO Control Register Vtpiocr Field DescriptionsDDR VTP Enable Register Ddrvtper DDR VTP Enable Register Ddrvtper Field DescriptionsDDR VTP Register Ddrvtpr DDR VTP Register Ddrvtpr Field DescriptionsTable A-1. Document Revision History Additions/Modifications/DeletionsImportant Notice