Activation Actv, Actv Command | Texas Instruments TMS320C6455

Peripheral Architecture

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2.4.3Activation (ACTV)

The DDR2 memory controller automatically issues the activate (ACTV) command before a read or write to a closed row of memory. The ACTV command opens a row of memory, allowing future accesses (reads or writes) with minimum latency. The value of DBA[2:0] selects the bank and the value of A[12:0] selects the row. When the DDR2 memory controller issues an ACTV command, a delay of tRCD is incurred before a read or write command is issued. Figure 5 shows an example of an ACTV command. Reads or writes to the currently active row and bank of memory can achieve much higher throughput than reads or writes to random areas because every time a new row is accessed, the ACTV command must be issued and a delay of tRCD incurred.

Figure 5. ACTV Command

ACTV

DDR2CLKOUT

DDR2CLKOUT

DSDCKE
DCE0
DSDRAS
DSDCAS
DSDWE
DEA[13:0]	ROW
DBA[2:0]	BANK
DSDDQM[3:0]

16	C6455/C6454 DDR2 Memory Controller	SPRU970G – December 2005 – Revised June 2011
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Texas Instruments TMS320C6455 manual Activation Actv, Actv Command

Contents

Users Guide Submit Documentation Feedback Contents List of Figures List of Tables Submit Documentation Feedback Read This First Read This First Functional Block Diagram FeaturesPurpose of the Peripheral Industry Standards Compliance Statement Clock Control Signal DescriptionsMemory Map DDR2 Memory Controller Signal Descriptions Pin Description DDR2 Sdram Commands Truth Table for DDR2 Sdram CommandsCommand Function Protocol Descriptions Mode Register Set MRS and Emrs DDR2 MRS and Emrs Command Refresh Mode Refresh Command Actv Command Activation Actv Dcab Command Deactivation Dcab and Deac Deac Command Read Command DDR2 Read Command Write WRT Command Memory Width, Byte Alignment, and EndiannessAddressable Memory Ranges Address Type Generated by DDR2 Bank Configuration Register Fields for Address Mapping Address MappingBit Field Bit Value Bit Description Ibank Logical Address-to-DDR2 Sdram Address Map for 32-Bit Sdram Logical Address-to-DDR2 Sdram Address Map DDR2 Memory Controller Interface DDR2 Memory Controller Fifo Description DDR2 Memory Controller Fifo Block Diagram Command Ordering and Scheduling, Advanced Concept Command Starvation Refresh Scheduling Possible Race ConditionRefresh Urgency Levels Urgency Level Description Self-Refresh Mode Reset ConsiderationsDevice and DDR2 Memory Controller Reset Relationship DDR2 Memory Controller Reset Effect Initiated by 11.1 DDR2 Sdram Device Mode Register Configuration Values DDR2 Sdram Mode Register ConfigurationDDR2 Sdram Extended Mode Register 1 Configuration Mode Register Field 11.2 DDR2 Sdram Initialization After Reset 11.3 DDR2 Sdram Initialization After Register ConfigurationInterrupt Support Edma Event Support Using the DDR2 Memory Controller Connecting the DDR2 Memory Controller to DDR2 Sdram Connecting 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 Field DDR2 Memory Refresh Specification Sdrfc ConfigurationConfiguring Sdram Timing Registers SDTIM1 and SDTIM2 SDTIM1 Configuration SDTIM2 Configuration Dmcctl ConfigurationDDR2 Sdram Data Register Field Sheet Parameter Name Description Offset DDR2 Memory Controller RegistersRegister Description Module ID and Revision Register Midr Field Descriptions Module ID and Revision Register MidrBit Field Value Description DDR2 Memory Controller Status Register Dmcstat Ifrdy Sdram Configuration Register Sdcfg Sdram Configuration Register Sdcfg Field Descriptions Sequence. Values 4-7 are reserved for this field Sdram Refresh Control Register Sdrfc Sdram Refresh Control Register Sdrfc Field Descriptions Sdram Timing 1 Register SDTIM1 Sdram Timing 1 Register SDTIM1 Field DescriptionsTrfc TRP Trcd TWR Tras TRC Trrd Using this formula Sdram Timing 2 Register SDTIM2 Sdram Timing 2 Register SDTIM2 Field DescriptionsTodt Txsnr Txsrd Trtp Tcke Burst Priority Register Bprio Field Descriptions Burst Priority Register BprioPrioraise DDR2 Memory Controller Control Register Dmcctl DDR2 Memory Controller Control Register Dmcctl Revision History Products Applications DSPRfid TI E2E Community Home