Texas Instruments TMS320DM647, DM648 DSP manual Burst Priority Register Bprio, Prioraise

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DDR2 Memory Controller Registers

4.7Burst Priority Register (BPRIO)

The Burst Priority Register (BPRIO) helps prevent command starvation within the DDR2 memory controller. To avoid command starvation, the DDR2 memory controller momentarily raises the priority of the oldest command in the command FIFO after a set number of transfers have been made. The PRIO_RAISE bit sets the number of transfers that must be made before the DDR2 memory controller raises the priority of the oldest command. The BPRIO is shown in Figure 26 and described in Table 24. See Section 2.7.2 for more details on command starvation.

Figure 26. Burst Priority Register (BPRIO)

31			16
	Reserved
		R-0
15	8	7	0
Reserved			PRIO_RAISE
R-0			R/W-0xFF

LEGEND: R/W = Read/Write; R = Read only; -n= value after reset

Table 24. Burst Priority Register (BPRIO) Field Descriptions

Bit	Field	Value	Description
31-8	Reserved		Reserved. The reserved bit location is always read as 0. A value written to this field has no effect.
7-0	PRIO_RAISE		Number of memory transfers after which the DDR2 memory controller will elevate the priority of the
			oldest command in the command FIFO. Setting this field to FFh disables this feature, thereby
			allowing old commands to stay in the FIFO indefinitely.
		0	1 memory transfer
		1	2 memory transfers
		2	3 memory transfers
		3-FEh	4-FFh memory transfers
		FFh	Feature disabled, commands can stay in command FIFO indefinitely

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DSP DDR2 Memory Controller

SPRUEK5A –October 2007

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Contents Users Guide Submit Documentation Feedback Contents List of Figures List of Tables Read This First Related Documentation From Texas Instruments Trademarks Purpose of the Peripheral FeaturesFunctional Block Diagram Industry Standards Compliance Statement Memory Map Signal DescriptionsClock Control DDR2 Memory Controller Signal Descriptions Pin DescriptionDDR2 Sdram Commands Truth Table for DDR2 Sdram CommandsCommand Function Protocol DescriptionsMode Register Set MRS and Emrs Refresh ModeDdrclk MRS/EMRS Ddrcke Ddrcs Ddrras Ddrcas Ddrwe COLActivation Actv Ddrcs Ddrras Ddrcas DdrweDcab Command Deactivation Dcab and DeacRead Command DDR2 Read CommandWrite WRT Command Memory Width and Byte AlignmentAddressable Memory Ranges Memory Width Maximum Addressable BytesBank Configuration Register Fields for Address Mapping Address MappingBit Field Bit Value Bit Description IbankLogical Address-to-DDR2 Sdram Address Map for 16-bit Sdram Logical Address-to-DDR2 Sdram Address Map DDR2 Memory Controller Interface DDR2 Memory Controller Fifo DescriptionDDR2 Memory Controller Fifo Block Diagram Command Ordering and Scheduling, Advanced ConceptCommand Starvation Refresh Scheduling Possible Race ConditionRefresh Urgency Levels Urgency Level DescriptionReset Sources Self-Refresh ModeReset Considerations 11.1 DDR2 Sdram Device Mode Register Configuration Values DDR2 Sdram Mode Register ConfigurationDDR2 Sdram Extended Mode Register 1 Configuration 11 DDR2 Sdram Memory Initialization11.2 DDR2 Sdram Initialization After Reset 11.3 DDR2 Sdram Initialization After Register ConfigurationInterrupt Support Edma Event SupportUsing the DDR2 Memory Controller Connecting the DDR2 Memory Controller to DDR2 SdramConnecting to Two 16-Bit DDR2 Sdram Devices Connecting to a Single 16-Bit DDR2 Sdram Device Connecting to Two 8-Bit DDR2 Sdram Devices Programming the Sdram Configuration Register Sdcfg Sdcfg ConfigurationProgramming the Sdram Refresh Control Register Sdrfc Function SelectionDDR2 Memory Refresh Specification Sdrfc ConfigurationConfiguring Sdram Timing Registers SDTIM1 and SDTIM2 SDTIM1 ConfigurationSDTIM2 Configuration Dmcctl ConfigurationDDR2 Sdram Data Register Field Sheet Parameter Name DescriptionDDR2 Memory Controller Registers Offset Acronym Register DescriptionModule ID and Revision Register Midr DDR2 Memory Controller Status Register DmcstatModule ID and Revision Register Midr Field Descriptions Bit Field Value DescriptionSdram Configuration Register Sdcfg Sdram Configuration Register Sdcfg Field DescriptionsSdram Configuration Register Sdcfg Field Descriptions Sdram Refresh Control Register Sdrfc Sdram Refresh Control Register Sdrfc Field DescriptionsSdram Timing 1 Register SDTIM1 Sdram Timing 1 Register SDTIM1 Field DescriptionsTrfc TRP Trcd TWR Tras TRC TrrdDDR2 memory data sheet. Calculate using this formula Sdram Timing 2 Register SDTIM2 Sdram Timing 2 Register SDTIM2 Field DescriptionsTodt Tsxnr Tsxrd Trtp TckePrioraise Burst Priority Register BprioBurst Priority Register Bprio Field Descriptions DDR2 Memory Controller Control Register Dmcctl ReseTable A-1. Document Revision History Additions/Modifications/DeletionsRfid Products ApplicationsDSP