Author Topic: Eagle Autorouter hate?  (Read 13089 times)

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Offline pyrohaz

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Eagle Autorouter hate?
« on: August 08, 2014, 04:18:00 pm »
I have to ask, I use Eagle for all of my PCB's and I have a pretty darned old version (Windows 98 styled buttons in Windows 7 old...) and yet, I'm only ever doing 2 layer PCB's with SMD and through hole components. One thing I wonder is that nearly every single person rips into the Autorouter. I'm really just wonder why tbh. I always hand route critical paths such as USB, capacitive sensors or anything >1MHz by hand (plus audio). Otherwise, I quite happily (with customised settings) use the autorouter and it always does an acceptable job for me! I rarely have to change many of the paths or anything like that.

Why the hate?  O0
« Last Edit: August 08, 2014, 11:38:38 pm by pyrohaz »
 

Offline zapta

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Re: Eagle Autorouter hate!
« Reply #1 on: August 08, 2014, 05:00:31 pm »
Otherwise, I quite happily (with customised settings) use the autorouter and it always does an acceptable job for me!

Same here. Critical nets by hand, rest (~80%) of the nets by the Eagle autorouter. I don't even bother to clean aesthetically.  Life is good.

Edit: I typically change the default autorouter settings,  5mil or 1mil grid, any angle routing on all layers. I rare occasion I also play with the optimization parameters, for example to increase the cost of routing in ground plan layers.
« Last Edit: August 08, 2014, 05:04:03 pm by zapta »
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Offline Precipice

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Re: Eagle Autorouter hate!
« Reply #2 on: August 08, 2014, 05:05:29 pm »
Would you be able to dump a screenshot of an autorouted board?
(I long ago abandoned autorouters, but you guys are making it sound like I might be missing out)
 

Offline Wilksey

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Re: Eagle Autorouter hate!
« Reply #3 on: August 08, 2014, 05:13:10 pm »
I would suggest a newbie in PCB routing tries hand routing a few simple projects just to get the practice in, nearly all of the books i've seen for Eagle (or <insert your favourite package name here> for that matter) guides you though many chapters on the autorouter.

For everyday practicality and time, router the critical paths by hand then let the autorouter rip is what I say!
 

Offline zapta

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Re: Eagle Autorouter hate!
« Reply #4 on: August 08, 2014, 07:52:53 pm »
Would you be able to dump a screenshot of an autorouted board?
(I long ago abandoned autorouters, but you guys are making it sound like I might be missing out)

Here is one

https://github.com/zapta/power-monitors/blob/master/pmon_3v8/eagle/pmon_3v8_board.pdf?raw=true

Crystal and critical power nets routed manually. Everything else auto. The blue bottom layer is ground plane (printed without the fill in).
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Offline Precipice

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Re: Eagle Autorouter hate!
« Reply #5 on: August 08, 2014, 08:17:24 pm »
OK, cool - thanks! (Was this Eagle?)
And I guess the second half of the question is - how long would that take you to hand route? (I assume the router takes essentially zero time?)
I'm also assuming that you still do the component placement entirely by hand, no autoplace to go with the autoroute, so placement time is the same for both approaches?

(I've just tried Altium's autorouter on a few boards I've done recently - it had a decent go at a couple, and I'm tempted to give it a try on a demo board I've got coming up, but the tighter boards, even simple ones, it just fails at. I could dig my Specctra license out, but I _know_ that's dimwitted)
 

Offline zapta

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Re: Eagle Autorouter hate!
« Reply #6 on: August 08, 2014, 08:46:58 pm »
OK, cool - thanks! (Was this Eagle?)
And I guess the second half of the question is - how long would that take you to hand route? (I assume the router takes essentially zero time?)
I'm also assuming that you still do the component placement entirely by hand, no autoplace to go with the autoroute, so placement time is the same for both approaches?

(I've just tried Altium's autorouter on a few boards I've done recently - it had a decent go at a couple, and I'm tempted to give it a try on a demo board I've got coming up, but the tighter boards, even simple ones, it just fails at. I could dig my Specctra license out, but I _know_ that's dimwitted)

Yes, that's eagle.

Placement and the manual routing of critical nets take most of the time (and may require iterations). I am also using the automatic router as a metric for quality of placement (do rough placement, do auto routing, examine the completion rate, number of vias, routs that do not make sense, undo the routing and improve the placement).

Auto routing may take some time (e.g. a minute or two), especially if you set fine auto router grid (default 50 is way too high, I use 5 or 1) but this is the fun part of all the layout process, you click a button and watch your work done. ;-)
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Offline zapta

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Re: Eagle Autorouter hate!
« Reply #7 on: August 08, 2014, 09:13:45 pm »
Change the title from '!' to '?' ?   (since you are asking, not stating hate).
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Offline FrankBuss

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Re: Eagle Autorouter hate!
« Reply #8 on: August 08, 2014, 09:14:09 pm »
Would you be able to dump a screenshot of an autorouted board?
(I long ago abandoned autorouters, but you guys are making it sound like I might be missing out)
A more complex example for which I used the autorouter: http://www.frank-buss.de/parallella/sampler/board.pdf Power lines routed by hand, then using the autorouter to do the rest. The board works fine. But I wouldn't use it for a production board, it just doesn't look as nice as a hand routed board, and Eagle can't route very dense boards, like this. But I do use it often the same way zapta says, as a metric for quality of placement. And the interactive "follow me" router mode in more modern Eagle versions is nice for manual routing.
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Offline pyrohaz

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Re: Eagle Autorouter hate!
« Reply #9 on: August 08, 2014, 11:41:22 pm »
Change the title from '!' to '?' ?   (since you are asking, not stating hate).

Have done! Sorry about that.

Would you be able to dump a screenshot of an autorouted board?
(I long ago abandoned autorouters, but you guys are making it sound like I might be missing out)
A more complex example for which I used the autorouter: http://www.frank-buss.de/parallella/sampler/board.pdf Power lines routed by hand, then using the autorouter to do the rest. The board works fine. But I wouldn't use it for a production board, it just doesn't look as nice as a hand routed board, and Eagle can't route very dense boards, like this. But I do use it often the same way zapta says, as a metric for quality of placement. And the interactive "follow me" router mode in more modern Eagle versions is nice for manual routing.

That board looks pretty complex in parts! Did you modify quite a few of the routes as I never get anything other than 45deg routes for corners and I can see in your board that there are a couple of different angles.

OK, cool - thanks! (Was this Eagle?)
And I guess the second half of the question is - how long would that take you to hand route? (I assume the router takes essentially zero time?)
I'm also assuming that you still do the component placement entirely by hand, no autoplace to go with the autoroute, so placement time is the same for both approaches?

(I've just tried Altium's autorouter on a few boards I've done recently - it had a decent go at a couple, and I'm tempted to give it a try on a demo board I've got coming up, but the tighter boards, even simple ones, it just fails at. I could dig my Specctra license out, but I _know_ that's dimwitted)

Yes, that's eagle.

Placement and the manual routing of critical nets take most of the time (and may require iterations). I am also using the automatic router as a metric for quality of placement (do rough placement, do auto routing, examine the completion rate, number of vias, routs that do not make sense, undo the routing and improve the placement).

Auto routing may take some time (e.g. a minute or two), especially if you set fine auto router grid (default 50 is way too high, I use 5 or 1) but this is the fun part of all the layout process, you click a button and watch your work done. ;-)

Thats a very good point actually, I really put a lot of effort into placing my components for ease of routing and highest efficiency, finding the best compromise can really take up a fair chunk of your time, then setting the autorouter to do the rest is normally only a negligible amount of time, especially on my i7!
 

Offline FrankBuss

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Re: Eagle Autorouter hate!
« Reply #10 on: August 08, 2014, 11:56:08 pm »
That board looks pretty complex in parts! Did you modify quite a few of the routes as I never get anything other than 45deg routes for corners and I can see in your board that there are a couple of different angles.
The thick power supply traces are all routed by hand, and IIRC I forgot some signals, which I quickly routed by hand, because I used a 1 mil routing grid, for which it needed an hour or so. The autorouter doesn't use other angles than 45deg and 90deg.
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Offline marshallh

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Re: Eagle Autorouter hate?
« Reply #11 on: August 09, 2014, 02:38:46 am »
Eagle's autorouter is absolutely terrible.

The only reason it'd be worth using is because the handrouting system is also a complete joke.

After using an interactive push/shove router (or hell, even one that simply lets you adjust existing routes without horribly breaking things) you'll be able to bang out basically any board in short order by hand, and it'll be superior.
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Offline zapta

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Re: Eagle Autorouter hate?
« Reply #12 on: August 09, 2014, 02:47:39 am »
Eagle's autorouter is absolutely terrible.

Can you explain why you consider it to be terrible?
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Offline Wilksey

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Re: Eagle Autorouter hate?
« Reply #13 on: August 09, 2014, 10:04:50 pm »
Interactive push and shove would be a great benefit, but I wouldn't say it was terrible, and manual routing is quite easy, I can't really see why people have issues with it, I can only think that people just prefer their existing tools, which is fair enough as you have spent so long with them.
 

Offline c4757p

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Re: Eagle Autorouter hate!
« Reply #14 on: August 09, 2014, 10:07:47 pm »
Eagle's autorouter is absolutely terrible.

Can you explain why you consider it to be terrible?

Because:

Eagle can't route very dense boards, like this.

That's a dense board, not a complicated board. It looks rather trivial to me, actually. If it can't do that, what good is it?
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Offline FrankBuss

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Re: Eagle Autorouter hate?
« Reply #15 on: August 09, 2014, 10:16:38 pm »
That's a dense board, not a complicated board. It looks rather trivial to me, actually. If it can't do that, what good is it?
The Eagle files are here:

https://github.com/FrankBuss/kerberos/tree/master/eagle

The problem is the bus. Maybe I'm using the autorouter wrong, but Eagle doesn't route nice parallel traces for buses, but uses lots of vias instead and a very chaotic routing, and it can't finish it then in the end. Maybe some Eagle user could try it, I've read that the autorouter was improved in version 7 (I'm still using version 6). But don't cheat and don't let Eagle route signals on the ground and power planes (it's a 4 layer board) :)
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Offline c4757p

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Re: Eagle Autorouter hate?
« Reply #16 on: August 09, 2014, 10:29:42 pm »
Autorouters are for large circuits with big buses. This is like a car that's only capable of driving on the living room floor - okay, cute toy, but do you really expect me to use it?
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Offline zapta

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Re: Eagle Autorouter hate?
« Reply #17 on: August 10, 2014, 01:52:38 am »
Autorouters are for large circuits with big buses. This is like a car that's only capable of driving on the living room floor - okay, cute toy, but do you really expect me to use it?

There are many products that I wouldn't use but it doesn't mean they are not useful for other people and other use cases.  It's not an all our l or nothing thing.
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Offline zapta

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Re: Eagle Autorouter hate?
« Reply #18 on: August 10, 2014, 06:24:55 am »
The Eagle files are here:

https://github.com/FrankBuss/kerberos/tree/master/eagle

The problem is the bus. Maybe I'm using the autorouter wrong, but Eagle doesn't route nice parallel traces for buses, but uses lots of vias instead and a very chaotic routing, and it can't finish it then in the end. Maybe some Eagle user could try it, I've read that the autorouter was improved in version 7 (I'm still using version 6). But don't cheat and don't let Eagle route signals on the ground and power planes (it's a 4 layer board) :)

Is it midi.brd?  It is fully routed. Do you have the version after the manual routing of critical nets and before final auto routing?
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Offline FrankBuss

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Re: Eagle Autorouter hate?
« Reply #19 on: August 10, 2014, 09:45:01 am »
Is it midi.brd?  It is fully routed. Do you have the version after the manual routing of critical nets and before final auto routing?
Yes, midi.brd. Disable all layers, enable just 1 and 16, then select all and ripup group will leave only the routing in layers 2 and 3 for the power supply. Then try to autoroute with just layer 1 and 16 enabled for the router. With routing grid 1 mil it manages 95%.
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Offline FrankBuss

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Re: Eagle Autorouter hate?
« Reply #20 on: August 10, 2014, 05:47:22 pm »
Autorouters are for large circuits with big buses. This is like a car that's only capable of driving on the living room floor - okay, cute toy, but do you really expect me to use it?
I'm using Eagle since DOS time, so I'm familiar with all the quirks. But it is very good where it matters: a stable program, which didn't crashed once since I used it, unlike when I tried Altium Designer, which crashed twice the weekend I tried it. How can I trust a program which crashes? What if it silently changes some traces instead of crashing? And digital rule check worked all the time reliable, too in Eagle. I can create a board in a few minutes, create the gerber files and send it to the PCB manufacturer and can be sure that it comes back as I drew it (not necessarly working as I planned it :) ).

But I'm willing to change, if there is a better program, and not too expensive (my main profession is programming, not PCB design). The manual routing capabilities, the autorouter and the Eagle GUI in general is indeed from stone age. What program can you recommend?
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Offline zapta

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Re: Eagle Autorouter hate?
« Reply #21 on: August 10, 2014, 08:48:45 pm »
Is it midi.brd?  It is fully routed. Do you have the version after the manual routing of critical nets and before final auto routing?
Yes, midi.brd. Disable all layers, enable just 1 and 16, then select all and ripup group will leave only the routing in layers 2 and 3 for the power supply. Then try to autoroute with just layer 1 and 16 enabled for the router. With routing grid 1 mil it manages 95%.

I think I know what the problem is. The eagle router needs special consideration when you allow it to add traces in a filled polygon because the traces can break the polygon ('collapse' as eagle calls it). This is exactly what happened here, the top layer has filled ground polygon and can have auto traces which results in non routed GND air wires due to the collapsed polygons.  What I typically do is to manually route the ground as a critical net which guarantees that the GND polygon will not collapse (all islands are connected).  Otherwise the auto router did pretty good in this case (I used top='/', bottom='\', grid=1) and achieved 100% and consistently decreases the via count as it went through the optimization process.

MY boards are typically two layers with bottom layer having ground plane + traces. As mentioned earlier I manually route the ground and sometimes I also increase the cost of traces in the ground plan layer to encouraging shorter traces there to improve plane connectivity. When autorouting is done I spot check the routing by highlighting nets using the 'eye' button and estimating the actual-length/ideal-length ration. So far it never disappointed me.

Edit: ia ma using eagle 6.5.0 on Mac OSX 10.9.4.
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Offline pyrohaz

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Re: Eagle Autorouter hate?
« Reply #22 on: August 11, 2014, 01:05:46 pm »
Autorouters are for large circuits with big buses. This is like a car that's only capable of driving on the living room floor - okay, cute toy, but do you really expect me to use it?
I'm using Eagle since DOS time, so I'm familiar with all the quirks. But it is very good where it matters: a stable program, which didn't crashed once since I used it, unlike when I tried Altium Designer, which crashed twice the weekend I tried it. How can I trust a program which crashes? What if it silently changes some traces instead of crashing? And digital rule check worked all the time reliable, too in Eagle. I can create a board in a few minutes, create the gerber files and send it to the PCB manufacturer and can be sure that it comes back as I drew it (not necessarly working as I planned it :) ).

But I'm willing to change, if there is a better program, and not too expensive (my main profession is programming, not PCB design). The manual routing capabilities, the autorouter and the Eagle GUI in general is indeed from stone age. What program can you recommend?

I agree here, I've not had the opportunity to use Altium (considering it cost a ton) though I'd always be willing to learn. The main thing that attracts me to eagle is the general simplicity of using it. Once you get around some of its quirks (like using route instead of wire - not a particularly intuitive thing IMO), its really simple and you just create your schematic, place components and go!

I find that Altium just looks really complex!
 

Offline FrankBuss

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Re: Eagle Autorouter hate?
« Reply #23 on: August 11, 2014, 02:59:18 pm »
I tried Altium once (http://www.frank-buss.de/altium/). They offered a 60 day free trial some time ago. Maybe if you ask them, they will offer it again, or ask Dave if they don't want :) . But right, Altium is much more complex, would need some time to get used to it. It is used a lot in big companies for big projects, so maybe they can live with the crashes and it doesn't do any other bad things to your schematic. But too expensive for me as well.
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