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4 deactivation (dcab and deac), Command – Texas Instruments TMS320C6452 DSP User Manual

Page 16

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2.4.4

Deactivation (DCAB and DEAC)

DCAB

DDR_CLK
DDR_CLK

DDR_CS

DDR_CKE

DDR_RAS

DDR_WE

DDR_DQM[3:0]

DDR_CAS

DDR_BA[2:0]

DDR_A[13:11, 9:0]

DDR_A[10]

DEAC

DDR_CLK
DDR_CLK

DDR_CS

DDR_CKE

DDR_RAS

DDR_WE

DDR_DQM[3:0]

DDR_CAS

DDR_BA[2:0]

DDR_A[13:11, 9:0]

DDR_A[10]

Peripheral Architecture

The precharge all banks command (DCAB) is performed after a reset to the DDR2 memory controller or
following the initialization sequence. DDR2 SDRAMs also require this cycle prior to a refresh (REFR) and
mode set register commands (MRS and EMRS). During a DCAB command, DDR_A[10] is driven high to
ensure the deactivation of all banks.

Figure 6

shows the timing diagram for a DCAB command.

Figure 6. DCAB Command

The DEAC command closes a single bank of memory specified by the bank select signals.

Figure 7

shows

the timings diagram for a DEAC command.

Figure 7. DEAC Command

DSP DDR2 Memory Controller

16

SPRUF85 – October 2007

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