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. _______________________________________________ geda-user mailing list [email protected] http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
