EAGLE Autorouter Exploration

RE: EAGLE Autorouter Exploration

jmsaltzman — Thu, 03 Oct 2013 18:01:52 GMT

Interesting post, DRC rule adjustment is definitely the key to getting usable results. This autorouted example shows a typically odd result: unevenly-spaced traces, vias where they shouldn't be, and a nonsensical mix of 45- and 90-degree corners.

I've found EAGLE's autorouter useful for guiding component placement: if it can autoroute, then I can route by hand easily. But its results remind me of monkeys mashing on typewriters: you might get an OK result sometimes, but do you want to develop monkey-wrangling skills or board-routing skills?!

For usable results, I'd recommend preparing more than just component placement before autorouting:

Add power polygons,
Hand-route short/obvious/important traces,
Set up net classes (eg. power vs. signal),
SAVE before autorouting so you don't rip up hand-routed prep with the autorouter results.

RE: EAGLE Autorouter Exploration

DAB — Tue, 01 Oct 2013 19:54:12 GMT

Hi Dave,

Good post. As I recall, most of the algorithms used for auto-routing have their origines in early AI research.

There are many ways to help the router out by learning how to plan your component layout so that there are clear short routes for your circuit lines.

There were many good layout artists in my day who could take a design and set it up to make the routing, done by hand in my day, so that the board layout was very clean.

I suspect that if you dig into the autorouting software you can find some "prefferences" tables where you can help the router in its decision process.

It is like any other good piece of software, you need to learn how to use it properly to get the most benefit from it.

If you let the defaults loose on your design, you will end up with some very creative solutions.

Makes good art though.

DAB

RE: EAGLE Autorouter Exploration

shabaz — Mon, 30 Sep 2013 22:44:18 GMT

Hi Dave,

Great article. Another suggestion for complex boards would be to use as few through-hole parts as possible, particularly dense connectors, because it is so much easier to route when the planes do not have component lead holes, so that traces can run under components too (assuming that is ok from a circuit design point of view).