[dorkbotpdx-blabber] Eagle Board Layout

Scott Dixon scott at dixons.mailworks.org
Tue Sep 13 14:35:27 EDT 2011


On Sep 13, 2011, at 10:41 AM, Dave Edick wrote:

> Is this a double sided board?  It's quite common to have unrouted traces on single sided boards.  Sometimes a board just can't be laid out single sided without jumpers.  I haven't seen many double sided boards that require jumpers.  There it's more often a sign of bad routing.
> 
> IMHO, the Eagle autorouter is pretty mediocre.  The one at freerouting.net is a lot better, although more awkward to use.  You'll have to do an export of your board, then reimport it after routing.  One of the things I really like about it is that it allows tweaking the routing in-progress.  If I don't like the route of a particular trace, I can move it before it gets locked in place by additional traces.  I agree with Aaron that laying out by hand produces better results, but I don't think that's a good idea for your very first board.  If you do route by hand, make sure to do design rules checks periodically while routing.  Eagle doesn't do anything to enforce design rules compliance on manual routing.  If you're breaking the design rules, you want to know about it early so you don't repeat the mistake.

Yes, if you want to use an autorouter, I certainly recommend the freerouting.org one over the Eagle autorouter.  One other thing is that the freerouting router reroutes traces as you drag things around manually, if you want to do that.  And you can move components around at least a little and the routes adjust on the fly.  So even if you don't want to use the autorouter version, I find it is useful to play with the routing in freerouting because it gives some good ideas about how to lay out the routes that you might not have though of otherwise.  Sometimes, I find it best to manually route some of the important lines (power and maybe clocks or similar) and then run freerouting on the rest to see what happens.  You can also use keepout areas in freerouting to control some route placement.
One big thing to be aware of with the combo of Eagle and freerouting is that there is a problem with exporting ground pour polygons from Eagle.  I found that sometimes when you export a board design with ground pours in it, that they loose routed connections when they come back.  It seems to be a problem with either how Eagle handles ground pours or with the export script.  There is a thread on this on the freerouting forums but last time I looked, there wasn't any fix.  So what I do is to wait to add the ground pour polygons until after the routing has been done in freerouting and imported back into Eagle.
Scott
> 
> --
> /Dave Edick/  dave.edick at gmail.com or dave at solderslingers.com
> See http://solderslingers.com for Electronic Kits and Components.
> 
> 
> 
> On Tue, Sep 13, 2011 at 10:04 AM, <jameshensel at comcast.net> wrote:
> Having taken the Don's Dorkboard class, I have been inspired to design a companion board to add some relays, controls and such. 
>  
> I am using Eagle and have my schematic worked out.  I am struggling a bit with the board layout.  Maybe I am trying to be too frugal with board area but it seems almost impossible to get everything connected.  When I run the autorouter, it leaves several nets unrouted. 
>  
> I get it that I should place components near orther components that connect to each other.  Are there any other strategies I should consider?
> Thanks,  Jim Hensel
>  
> Trapdoor chicken plucker!
> 
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