pin swap in SDRAM

Jan 30, 2007 7 Replies
T

Hi,



to ease the routing of my PCB, I'd like to swap some data lines on a SDRAM. I'd like to be 100% sure that the swapping will not create problems once the PCB is built. I use a SDRAM MT48LC8M16A2 from Micron. The only documentation that I found is:

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about DDR, and they say "Pin-swap within a given byte lane to optimize the data bus routes further. Caution: Do not swap individual data bits across different byte lanes."



Is there any other recommendation ? Any positive experience ?



Thanks



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L

The datasheet's advice is good. Swap within bytelanes as you wish. Do not swap between bytelanes. What further information do you need?

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T

larwe ha scritto:

I am trying to understand if there is any side-effect of pin-swapping. As an example, I was thinking to pin swap data lines of a Flash memory; but I realized that these devices have special commands sent on the data bus, so commands would get screwed-up (and myself too :)

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L

Well, yes - but this is easily handled with macros in your program. This sort of thing is very common.

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L

Because you lose the ability to address individual bytelanes uniquely if you mix them up like this.

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I

Of course, I'm sorry, for some reason I misread your previous answer, I thought you ment to swapy *between* bytelanes, not *within*. My wrong.

:wq ^X^Cy^K^X^C^C^C^C
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A

"tullio.grassi" ...

Nope, not the data bus but the address bus - DO NO swap those lines...

Regards, Arie de Muynck

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