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Eagle Autorouter

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Pommie

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I'm using the autorouter in Eagle to route a board (attached) and it works fine except for the ground plane (top layer). For some reason the autorouter isn't connecting the various ground plane orphans. In the attached board I've hand routed the tracks that have square vias. As you can see some of the tracks are simply a via then a straight track then another via. Why doesn't the autorouter do this? Is there anything I can do to fix this? FYI, the bottom layer is Vdd.

Thanks,

Mike.
board.png
 

ronsimpson

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Auto routers do not work well, even the very pricey ones.
Auto routers are often used by people who do not know how. They do a bad part layout and think the auto router will fix all.
You do have "orphans". In Eagle, some where where you set up ground fill there is a check box to kill orphans.
OR
You can attach each orphan on red to a ground in blue. (also blue orphans connect to ground in red) Must be done by hand with a via.
 

Pommie

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In Eagle, some where where you set up ground fill there is a check box to kill orphans.
OR
You can attach each orphan on red to a ground in blue. (also blue orphans connect to ground in red) Must be done by hand with a via.
I have orphans turned on but these are orphans that connect to pins and need connecting to the actual ground plane. Placing a via on an orphan makes the fill go around the via so the via isn't connected to anything.

Mike.
 

ronsimpson

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Name the via. Use "gnd". When the via has the same net name as the polygon area fill they will connect.

Here is a corner of a board. (4 layers but only two showing) Blue = local ground for the regulators and is used as a heat sink.
The inside layers, not shown, are ground and mostly power(s).
The blue ground connects with vias to the inside ground layer. The vias also pull heat to the ground layer.
Each via was renamed to "gnd".
upload_2016-6-20_0-0-56.png
 
Last edited:

Pommie

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Thanks Ron, hadn't though of that. I still don't understand why the autorouter doesn't do it.

Mike.
 

ronsimpson

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why the autorouter doesn't do it
I think if you did not have a poly fill on it would have put traces in and then if you added the "polygon gnd" over the top.......
I think because it started with ground everywhere it assumed that ground could be reached easy.

If I connect a orphan, and there is current flow, I use more than one via to make a good connection. A real orphan with no current is not so important but in my example there is real current flow.
 

Pommie

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I tried removing the polygons yesterday and it routed fine. Looks like in future the poly pour will be the last thing before sending to the board house.

Thanks Ron,

Mike.
 

Pommie

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Attached are the before and after fill images. I've made it bigger to accommodate 3 AAA battery holders on the reverse.

Edit, just noticed I haven't added the inter battery connections to the power class so they're too thin.

Mike.
before.png after.png
 

DerStrom8

Super Moderator
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Autorouters are rubbish. It's definitely worth learning to route and doing the routing yourself. I'm seeing some potential problems with your autorouted board. Tracks coming off pads that leave an acute angle could trap etchant, which will eat away at the copper over time, potentially leading to connection problems down the road. Also, tracks that go off at some odd angle other than 45 degrees just look terrible. I'm also concerned about some of your clearances, though I don't know what voltages are present on this board or what sort of environment it will be used in. Furthermore, I see some illogical routing (unnecessarily long tracks, ugly branches, etc) that could be fixed if you did it yourself.

I cannot express how much I recommend just routing this board by hand. It's small and simple, and the autorouter is just making a mess (and will always just make a mess).
 

Pommie

Well-Known Member
Most Helpful Member
I agree, autorouters are rubbish and in the past I've almost always routed by hand. However, as this is nearly all surface mount and will be made by a board house, I thought I'd let the autorouter have a go. I'm not worried about the clearances as the board house supplies a drc file and it passed with flying colours. I't's also only at 3.3V. The board in the initial post had strange angles due to me having to bodge tracks after the autorouter. However, in post #9 there are only 45 degree angles.

Mike.
 
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