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I know that lots of people out there feel that autoroute results are not useable.

I find that the autorouter is a good way to get a good placement. I use eagle. I do a basic placement, autoroute everything and look where my wire crossings are. Where I can reduce wire length. ripup, repeat.

The thing is, the eagle router really isn't that good. I often get routes that should be doable with a straight shot, yet eagle insists on adding jogs.

I feel that given a good placement, many routes should be obvious. I don't want to click them all by hand.

So I'm looking for something better. toporouter is intriguing. The problem there is I don't know how to write an output from eagle that it reads.

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closed as primarily opinion-based by Olin Lathrop, pipe, dim, duskwuff, old_timer Jan 16 '18 at 1:23

Many good questions generate some degree of opinion based on expert experience, but answers to this question will tend to be almost entirely based on opinions, rather than facts, references, or specific expertise. If this question can be reworded to fit the rules in the help center, please edit the question.

  • 10
    \$\begingroup\$ Wow, I do the exact opposite. I spend the great majority of my design time on placement. \$\endgroup\$ – Connor Wolf Sep 21 '10 at 8:28
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    \$\begingroup\$ I spend time on my placement also. The process allows me to find issues with what pins I am using. Many times I am able to switch some pins around on the micro-controller in order for the layout to be cleaner. I can really only see this by constantly looking back and forth between my schematic and layout. \$\endgroup\$ – Kellenjb Sep 21 '10 at 13:37
  • \$\begingroup\$ I agree that placement is the most important aspect of getting a good board. I've route that autorouting is a good way to evaluation the placement \$\endgroup\$ – mmccoo Sep 30 '10 at 4:29
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    \$\begingroup\$ I manually route everything. It's an art if you can do it, but it's only worth it if you're going to make a very small board or something with high speed stuff involved. \$\endgroup\$ – Thomas O Oct 26 '10 at 14:23
  • \$\begingroup\$ TopoR (according to its datasheet) supports Electra format for import/export; Eagle also supports that (youtube.com/watch?v=Rb9XzsfeELQ), I'd go in that direction to make them talk. \$\endgroup\$ – fceconel Dec 3 '12 at 15:10
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The one between your ears.

Seriously, PCB software autorouters leave a lot to be desired, especially the cheap ones.

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  • 2
    \$\begingroup\$ I was just thinking I would give this answer. Damn, beaten... \$\endgroup\$ – Connor Wolf Oct 27 '10 at 5:53
  • \$\begingroup\$ mee too, I'm not an expert (3 years doing PCBs, 5 months professionally) and in a couple of hours I can get a decently routed, sub 128 nets, sub 20MHz board. \$\endgroup\$ – J.P.Wack Oct 28 '10 at 3:06
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Freerouting has an improved autorouter for Eagle.

http://jeelabs.org/2009/05/17/better-pcb-auto-routing/

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  • \$\begingroup\$ I love freerouting.....it is the best software in the world!!!!!!! \$\endgroup\$ – DarthRubik Jul 4 '16 at 15:44
  • \$\begingroup\$ I am using it currently to route a 1,500 pin board, and it finished in 10 minutes.....I am glad I do not have route up all of those pins \$\endgroup\$ – DarthRubik Jul 4 '16 at 15:45
  • \$\begingroup\$ The supplied example doesn't look good for Freerouting, it left numerous rat's nest connections hanging around while Eagle fit everything in. If via limit was set in Eagle, it would produce the same result most likely, but objectively it did a more complete job. The board itself is a tough cookie though, i would fail at manually routing it too. \$\endgroup\$ – Siana Feb 27 '17 at 13:16
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Pulsonix uses the Electra autorouter, as do several other packages; it's very good. It can be used with Eagle.

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  • \$\begingroup\$ I bought the 4-layer version of Electra. It takes a long time to play around with its settings but it does very well on a "clean" config file. It was able to route the vast majority of my board very well, and left me with a dozen traces that I spent about 16 hours on. It doesn't (yet) do balanced traces or length matching, but both are on the todo list. \$\endgroup\$ – akohlsmith Sep 21 '10 at 14:14
  • \$\begingroup\$ I don't use it much, but I find that it usually routes to completion, or close to it. \$\endgroup\$ – Leon Heller Sep 21 '10 at 14:56
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Altium ostensibly now uses topological routing, though I haven't had much of a chance to play with it yet.

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  • 3
    \$\begingroup\$ I've been using Altium for about 10 years. In my experience, their autorouting hasn't improved to the level that's worth using for complex boards, which is when it would be useful. The boards it generates usually have the traces that are routed early on along direct paths, but the last few traces it routes are insane-- long and changing layers a lot, which is bad for high speed signals. \$\endgroup\$ – pingswept Sep 21 '10 at 12:31
  • \$\begingroup\$ I think the trick is that you shouldn't just let the auto-router do all the work. They have a Smart Wire that auto-routes a single trace pretty effectively. Their auto-router can also do one bus at a time. Let it do the grunt work, and then you can tweak the results. Use Smart Wire for the last few traces. \$\endgroup\$ – ajs410 Sep 21 '10 at 17:41
  • \$\begingroup\$ Well, ostensibly they redesigned the autorouter at some point recently (I went from 6.0 to 9.0 in one leap). The old one did suck. I haven't had a chance to play with the situs one yet. \$\endgroup\$ – Connor Wolf Sep 22 '10 at 9:18
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Well, I'm one of those people that don't use autorouter, but, if you want to use it, I would recommend FreeROUTE and, to keep everything free, use KiCAD for schematics and everything else!

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I've used Sunstone Circuits PCB123 V3's auto-router with great success. The previous version of their software were pretty buggy, but as of version 3 it seems stable. For a point of reference, I had a 6"x4" board with about 1000 nets and it was able to successfully route all but 40 of them. Their auto-router even has options to fanout traces, relax routing, or set the desired trace tolerances. The software itself is a pretty full feature (for being free) PCB design too, boasting 3D modeling, the ability to read in netlists in a variety of formats, as well as output mechanical drawings. I'm not sure of it's ability to inter-operate with Eagle, but it might be worth a try.

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I've used an autorouter (admittedly, a high-end one - Mentor Graphics Expedition) on every board I've done (10 years+). If you have constraints like

  • "only on this layer"
  • "These two signals form a differential pair"
  • "must match lengths with these nets"
  • "The time delay from 'here to here' must be the same as 'from somewhere else to a fourth place +100ps'"

then you must tell it about them. The autorouter will attempt to respect those constraints (or tell you where it failed). Once you have an autoroute setup which completes well it allows you to experiment with placement, via sizes, removing layers, etc. very quickly to get an idea as to how much slack is in your board design.

The places I don't autoroute tend to be power supplies, as it's easier just to put the copper shapes around the pins that need it than flag all the nets which need to be "chunkier".

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  • \$\begingroup\$ The question is What autorouter do you use/like?, not Do you like to use an autorouter?. If you like your "high-end" autorouter, please tell us it's name, so maybe we can look into it, or even start using it! \$\endgroup\$ – Connor Wolf Mar 14 '13 at 9:24
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    \$\begingroup\$ @ConnorWolf: fair comment - updated \$\endgroup\$ – Martin Thompson Mar 14 '13 at 11:19

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