kicad-developers team mailing list archive

[Dick Hollenbeck <dick@...>]

Igor and others:

Ok, the specctra interface is now solid enough for some early adopters 
to play with. Why would you want to do that? Well because of the 
outstanding http://freerouting.net router.

This is not only an autorouter, but also an *outstanding*, world class, 
push and shove manual router.

I am using it to route a 400 part board now and the push and shove 
capability leads to at least a 5 fold increase in productivity. It 
will take you at least a full day to learn the manual aspect of the 
router. If your board it hobbyist in nature, skip that, just use the 
autorouter, it can be as little as 5 seconds to learn the autorouter, 
simply load the board and click *autoroute*. Otherwise learning the 
push and shove manual router is well worth your time.

To be honest, my board is complicated enough that I am doing mostly push 
and shove manual routing. However when I see a clear path for a route, 
I can do incremental autorouting in the freerouter, simply by selecting 
a pad or two ahead of time. You can also do incremental "fanout" 
before you do autorouting. It is a cost based router so you can give 
strong hints on which layers to use for which nets.

I am saying all this here on this list before I say anything on the 
users list so that if there are issues that popup there is a smaller 
audience at first.

Let me say in no uncertain terms that if your board is complicated, it 
will be well worth a day for you to spend on learning the freerouter. 
Even the manual aspect of it is wonderful. Let me also say that it will 
take a full day, nothing short of that to get used to it.

I hope to get a better write up than this sometime, but that will happen 
later. Here is a start for now:


1) Establish your default via and track sizes and save your board 
normally in pcbnew. These defaults will be what is used in the 
freerouter, as defaults only.


2) Load the kicad *.brd file into a text editor and edit the lines which 
start with "Layer[n]". These are the layer names and types. You can 
use only two "layer types" with freerouter: signal or power. If you 
have a power plane on most of a layer, identify that layer as a power 
layer. Change the layer names if you want, but use no spaces in layer 
names, underscore is ok. The layer name must be <= 20 characters. Save 
the board file to disk in your text editor.


3) load the board back into pcbnew, verify that the layer names "took".


4) Make sure all your zones have zone boarders. Only zone boarders are 
used, not zone fills in freerouter.


5) Export the file to Specctra DSN. <boardname>.dsn


6) Launch the freerouter from http://freerouting.net, it is java based 
and the UI can be sluggish but trust me, this loss in time will be 
overcome many many times over.


7) Load your own design. Pick the <boardname>.dsn file. If you have 
less than a simple polygon for your board edges, go back into pcbnew and 
clean the board perimeter up, make it simple, contiguous, and 
re-export. If the board does not load, it means there is a parsing 
error in freerouter, go to the freerouter support forum and report it. 
I will watch that forum for problems which could be related to *.DSN 
file format problems.


In theory at this point, you can do the entire layout in freerouter, 
saving your work using the "File | Save As" option to back up your work 
as you quit for the day. You can always go back and load this 
<boardname>.DSN file from freerouter. You can add via_rules and track 
widths according to net classes so that as you route a new net, the via 
dimensions, track widths, and clearances, are picked for you 
automatically and on a per net basis. "Net class" basis, actually.


Note that if you have power zones, freerouter will route only into the 
zone, and will not connect power pins to each other if a zone is 
nearby. So later you will have unconnected tracks in Kicad, but that 
is a problem in Kicad, not freerouter and may someday go away. :-D 
The copper is where it needs to be if there is a zone connecting the 
power. I would ignore the problem for now unless you manually want to 
route a few power tracks just to quiet down pcbnew.


7) When your board is done in freerouter, simply chose "File | Export 
Specctra Session File", and choose a filename like <boardname>.ses. 
The *.ses extension is what you should use for session files, they are 
different than *.dsn files, and they may not be reloaded into 
freerouter. They are the pathway back into Kicad, and only if you also 
have the original *.brd file loaded before importing the *.ses file.


8) From pcbnew with your board loaded, import the *.ses file. The 
components are moved, and all the tracks and vias are deleted before 
creating all new tracks and vias from the session file. Never save 
this imported board unless you are happy with the results, and 
especially not if the import fails. This is because the original 
tracks and vias are all deleted before the import. So if the import 
fails and you save, you will not have any original tracks and vias that 
you might have routed in pcbnew before doing the export.


Let's go back to the export to *.DSN:


When tracks and vias are exported they are put into a "protected" status 
as they enter freerouter. You must first "un fix" them to modify 
them. Do this by selecting the objects you want to unfix, then press 
the 'u' key. So can immediately select any number of objects by drawing 
a box around them so this is very easy. You can also delete tracks from 
an area and autoroute them back.

You can intermix incremental autorouting with manual routing. You can 
do incremental (not a complete board), part specific "fan outs", rather 
than fanning out all parts on a board.

I think you will find that spending a day in freerouter will be worth 
it. The push and shove routing in freerouter's manual mode is a gem, 
truly a gem. And by having this capability in Kicad, you now have the 
capability to turbocharge your productivity in a way never before 
imagined. 

And lastly, the manual routing within freerouter may give us ideas for 
features that we can eventually start to build into Kicad. I'm telling 
you now, if you it give it a day, you will get hooked on the manual 
routing within freerouter. I was ready to give up until I really 
started to understand it. One final tip, leave open the subwindow 
called "Rules | Net" while you are routing. It will let you highlight 
any net by name, subset the ratsnest, etc.

Hopefully you will get as much benefit out of this as I have put effort 
into making the bridge possible!

Happy routing,

Dick