Texas Instruments TMS320DM646X DMSOC manual Timing Waveform of an Asram Read with PCB Delays

Models: TMS320DM646X DMSOC

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Use Cases

Figure 14. Timing Waveform of an ASRAM Read with PCB Delays

Setup 2

1

Hold

Strobe 4

3

EM_CS

tCS

EM_CS (ASRAM)

EM_A[21:0]/

EM_BA[1:0]

tCS

tEM_A

EM_A[21:0]/

EM_BA[1:0] (ASRAM)

tEM_A

tRC(m)

EM_OE

tEM_OE tEM_OE

EM_OE (ASRAM)

tSU

tEM_D

tH

tEM_D

EM_D[15:0]

tACC(m) tCOD(m) tOH(m)

EM_D[15:0] (ASRAM)

From Figure 15, the following equations may be derived. tcyc is the period at which the EMIF operates. The W_SETUP, W_STROBE, and W_HOLD fields are programmed in terms of EMIF cycles where as the data sheet specifications are typically given is nano seconds. This is explains the presence of tcyc in the denominator of the following equations. A minus 1 is included in the equations because each field in ACFGn is programmed in terms of EMIF clock cycles, minus 1 cycle. For example, W_SETUP is equal to W_SETUP width in EMIF clock cycles minus 1 cycle.

SPRUEQ7C –February 2010

Asynchronous External Memory Interface (EMIF)

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Image 35
Texas Instruments TMS320DM646X DMSOC manual Timing Waveform of an Asram Read with PCB Delays