Texas Instruments TMS320C642x DSP manual Configuring DDR PHY Control Register Ddrphycr

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Supported Use Cases

3.2.4Configuring DDR PHY Control Register (DDRPHYCR)

The DDR PHY control register (DDRPHYCR) contains a read latency (READLAT) field that helps the DDR2 memory controller determine when to sample read data. The READLAT field should be programmed to a value equal to CAS latency plus round trip board delay minus 1. The minimum READLAT value is CAS latency plus 1 and the maximum READLAT value is CAS latency plus 3 (again, the READLAT field would be programmed to these values minus 1).

When calculating round trip board delay the signals of primary concern are the differential clock signals (DDR_CLK and DDR_CLK) and data strobe signals (DDR_DQS). For these signals, calculate the round trip board delay from the DDR2 memory controller to the memory and then choose the maximum delay to determine the READLAT value. In this example we will assume the round trip board delay is 1 DDR_CLK cycle, therefore READLAT can be calculated as follows:

READLAT = CAS latency + round trip board delay – 1 = 4 + 1 – 1 = 4

Table 21. DDR PHY Control Register (DDRPHYCR) Configuration

Register Field Name	Description	Register Value
DLLRESET	Programmed to remove the DDR2 memory controller DLL from	0
	reset.
DLLPWRDN	Programmed to power up the DDR2 memory controller DLL.	0
READLAT	Read latency is equal to CAS latency plus round trip board delay	4
	for data minus 1.

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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 PeripheralSupported Use Case Statement Functional Block DiagramIndustry Standards Compliance 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 MemoryAddress Mapping Bank Configuration Register Fields for Address MappingBit Field Bit Value Bit Description 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 Sources Reset ConsiderationsReset Signal Reset Source VTP IO Buffer Calibration Auto-Initialization SequenceDDR2 Sdram Configuration by MRS Command DDR2 Sdram Configuration by EMRS1 CommandInitializing Configuration Registers DDR2 Memory ControllerPeripheral Architecture Interrupt Support Power ManagementDMA Event 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 FormulaDDR PHY Control Register Ddrphycr Configuration Configuring DDR PHY Control Register DdrphycrRegister Field Name Description Mode D63-32 D31-0Acronym Register Description DDR VTP RegisterSdram Status Register Sdrstat Field Descriptions Sdram Status Register SdrstatBit Field Sdram Bank Configuration Register Sdbcr Field Descriptions Sdram Bank Configuration Register SdbcrBit Field Value Description 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