EP7309 Просмотр технического описания (PDF) - Cirrus Logic

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EP7309

High-Performance, Low-Power System on Chip Enhanced Digital Audio Interface

Cirrus Logic 

Static Memory Burst Read Cycle

EP7309

High-Performance, Low-Power System on Chip

EXPCLK

nCS

A

nMWE

nMOE

HALF

WORD

WORD

D

EXPRDY

WRITE

tCSd

tAd

tAh

tAh

tAh

tCSh

tMOEd

tHWd

tMOEh

tWDd

tDs tDh

tDs tDh

tDs tDh

tDs tDh

tWRd

tEXs

tEXh

Figure 4. Static Memory Burst Read Cycle Timing Measurement

Note:

1. Four cycles are shown in the above diagram (minimum wait states, 1-0-0-0). This is the maximum number of consecutive

cycles that can be driven. The number of consecutive cycles can be programmed from 2 to 4, inclusively.

2. The cycle time can be extended by integer multiples of the clock period (27 ns at 36 MHz, 54 ns at 18.432 MHz, and

77 ns at 13 MHz), by either driving EXPRDY low and/or by programming a number of wait states. EXPRDY is sampled on

the falling edge of EXPCLK before the data transfer. If low at this point, the transfer is delayed by one clock period where

EXPRDY is sampled again. EXPCLK need not be referenced when driving EXPRDY, but is shown for clarity.

3. Consecutive reads with sequential access enabled are identical except that the sequential access wait state field is used to

determine the number of wait states, and no idle cycles are inserted between successive non-sequential ROM/expansion

cycles. This improves performance so the SQAEN bit should always be set where possible.

DS507PP1

Copyright 2001 Cirrus Logic (All Rights Reserved)

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