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Subject: Auto routing in Allegro16.0

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angelj
Posts: 6
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7/10/2008 9:01 PM
hiii all, Can anyone help me in autoruoting in allegro16.0 I have routed PCB's manually only. So i am not familiar with the constraint settings which are to be given while auto routing the board.presently i'm working on motherboard. it needs to meet with several constraints like etch length,impedence etc.

bluecad
Posts: 16
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7/11/2008 12:07 AM
Hi, You must read Allegro PCB Router (Specctra) tutorials. Below link can help you. http://www.eautoroute.com/makedo.html If you are not familiar to autorouting (with Specctra), it will be more difficult. Regards, FERHAT YALDIZ

angelj
Posts: 6
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7/11/2008 3:21 AM
thanks ferhat, but shall i get some tutorials ya manuals which helps me for auto routing.. i'm not familiar with spectra. how it is done in spectra.what are the do.files? nw am trying to autoroute by setting the constraints in allegro PCB editor. i hav two BGA's in my board is it possible to route it by autorouting. expecting reply soon.

andrewjw
Posts: 46
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7/11/2008 4:08 AM
Specctra reads in a dsn file (either directly or in the background like from Allegro) which contains all the physical database info (nets, components, padstacks, placement), then it also uses do files to set up things like rules, routing etc. When you go to Specctra from Allegro it automatically creates a dsn file and do files so that all the rules set in Allegro are transfered to Specctra. Do files are also used to set up additional; rules and different types of routing, for example you may want to run a set of routing passes that does the following:- selects all clocks bus routing fanout main route clean second main route final clean mitre So basically a do file is just a sequence of commands that Specctra carries out - they can be simple or complex.

angelj
Posts: 6
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7/11/2008 4:18 AM
thanks andrew, can u tell me how the settings are given for autorouting in allegro.

andrewjw
Posts: 46
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7/11/2008 7:08 AM
there's many, many setting that can be used in the auto-router - too many to go over here. The best way to learn the tool is to start using it, go through the tutorials, get some training from Cadence, use the web.... If you are using Allegro PCB as a front end set as many constraints as possible there, then these will be pushed through to Specctra - try not to set constraints in Specctra if you can avoid it, these do not get pushed back to Allegro. If you do need to set constraints make sure you capture them in a do file so you can use them again in a future Specctra session. There's a quick utility called SmartRoute which will run a default set of routing passes over your design - this should give you an indication if the design is routable or not (AutoRoute->Route). All SmartRoute does is run an internal algorithm to try and route the design, depending on the design it may or may not succed - each design is different so there's no one setup that will work for every design, normally you need to change your routing strategy depending on the type of design to get the best results. Lastly, don't expect Specctra to route every design 100% - this is not going to happen but depending on the effort put into the setup the results will typically reflect the amount of effort.

angelj
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7/13/2008 10:01 PM
from where shall i get these tutorials... if anyone have some pls help me.

redwire
Posts: 73
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7/15/2008 11:33 PM
They're included with licensed installs. Contact Cadence if you can not find them.

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