T i m i n g D i a g r a m s

SRAM WE burst write

WE* controlled, four word (3-2-2-2), burst write (wait = 2, BCYC = 01)

T1

BCLK

TA* (Note-4)

TEA*/LAST (Note-4)

6

A[27:0]

36

BE[3:0]* Note-2

CS[4:0]*

write D[31:0]

Async WE*

CS0WE*

12

RW*

TW T2

TW T2

30

30

27

9

29

 

 

29

19

 

 

19

 

 

 

 

TW T2

TW

T2

Note-1

T1

 

31

31

 

 

 

 

36

 

 

 

27

 

 

 

13

Notes:

1At least one null period occurs between memory transfers. More null periods can occur if the next transfer is DMA. Thirteen clock pulses are required for DMA context switching.

2Port size determines which byte enable signals are active:

8-bit port = BE3*

16-bit port = BE[3:0]

32-bit port = BE[3:0]

3The TW cycles are present when the WAIT field is set to 2 or more.

4The TA* and TEA*/LAST signals are for reference only.

2 8 0

N S 7 5 2 0 H a r d w a r e R e f e r e n c e , R e v . D 0 3 / 2 0 0 6

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Image 294
Digi NS7520 manual Sram WE burst write