> Does anyone have any strategies for placing components while still > in the ratsnest stage that will make for a really nice compact auto > routed board ? Or is it just trial and error ? I've always > wondered this...
I like to think in terms of important signals, and connectors. Place the connectors first, if they have a need to be at a specific location. Then think of the flow of signals, and place the key parts next (cpu, memory, interfaces, etc). I usualy hide all the power nets for this. The "nest" should be showing some form. Sometimes at this point I go back and rearrange pins to get a cleaner nest (less crossings, etc). Next is power. For a two-layer board, I put power on the bottom and signals (when possible) on the top. For a four layer board, signals are on the outside and power on the inside. I place and connect all the bypass caps, crystals, and other length-sensitive nets. Once power is done, I autoroute and see how bad it is. Sometimes I'll undo and manually route a few key nets (ones that should have been direct, but ended up all over the place) and try again. After I'm happy with the autoroute results, I optimize, then go through and manually "neaten" up the board. This means moving traces across pins/vias, making them land directly on pins, etc. I also double check footprints and hole sizes at this point, using a 1:1 printout of the board. Then I apply teardrops, often undoing and re-fixing traces that don't land centered on pads, and send it out to be made. _______________________________________________ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user