Re: gEDA-user: terminators

[DJ Delorie <dj@xxxxxxxxxxx>]

I think the only way to rotate the sdram chip and have nearly-equal
traces is to rotate 90 degrees and have the fpga pins nearest the
sdram go under the sdram to the furthest pins, so that the fpga pins
furthest from the sdram don't have to go as far.

You end up using more vias for power that way, though, and they take
up space as well.  If I build this at home, I can't put vias under
parts.

Alternately, have every other fpga pin connect to the far side, and
route traces between pins on the near side.  Again with the power
pins.

Another alternative is to rotate the fpga 45 degrees, and the sdram 90
degrees, to bring the furthest fpga pins closer.
http://www.delorie.com/electronics/sdram/rot9045.png

At the moment, though, I have the traces within half an inch of each
other, which I think is close enough for my purposes.

On a real board, the sdram and fpga would be BGA packages and you'd
just match up pin patterns on both to get equal traces.


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