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Trial Route & Detail Route

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Advanced Member level 3
Sep 22, 2004
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global route icc

How do you know whether the design is trail routed or detail routed?.

If 90% of wires are detail routed then consider the design as detail routed. This therefore allows for a small percentage of wires that failed to route, but are still not trialRoutes.

Is the above definition is correct?.

trial route

hi kumar,
I know global route and detail route,, wht is this trail route...?

route values

Trial Route performs quick global and detailed routing for estimating routing-related congestion and capacitance values. It also incorporates any changes made during placement, such as scan reorder.
You can use Trial Route results to estimate and view routing congestion, and to estimate parasitic values for optimization and timing analysis. When used during prototyping, Trial Route creates actual wires, so you can get a good representation of RC and coupling for timing optimization at an early stage in the flow. Trial Route also produces a congestion map you can view to get early feedback on whether the design is routable.
Trial Route results can also be used for pin assignment when you commit partitions.

For more info, please refer cadence SOC Encounter User Guide.

scanreorder means

If I'm not mistaken, Cadence's SoC Encounter uses the term Trial Route while Synopsys' Astro uses the term Global Route.
Although SoC Encounter says it creates "actual sign-off wires", if you look closely, you may find some very obvious shorts!

It only means that actual wire routes have been created. Of course you can stream out the data & ship it to the foundry but manufacturing it will probably be a disaster.
One mistake you might make is if you accidentally hit the Trial Route button after doing some iterations of Detail Route... :cry:

So in short, Trial Route vs Detail Route doesn't depend on %. One is considered routing with careful consideration of routing constraints (Detail Route) while the other is just a quick, rough routing for estimation purposes.


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how to add routing blockage in astro

may be, I haven't used Synopsys tools..

I agree with your point. But if the user commits this kind of mistakes, you should have some quality routine procedure which will check the design before the tape out.

Each net/wire routed by trial route have some attribute, you make sure that this attribute count is 0 on the final database.

after route pin assignment encounter

Trail route in CDN tools and similar is virtual route in Snps world
both are used as estimates for the RC values for the non routed nets only, if it is routed then it will calculate the actual RC values.


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trial route .com

yeah.. this trial route is used to estimate the parasitic values & according to that the tool will do logic optimization to meet the timing requirements.

This will avoid the more iteration...

in trial route the nets are not trimmed, mostly you can check connections to IO pins which wont be exact as it would be in detail routing.

not only the i/o pin paths i think, the other signal nets also may not be in the exact what detail route would do,

The trial route nets will be used to extract the RC & based on that info, the tool will do the timing optimization. This is just for optimization & efficient placement purpose. This will allow the tools to add the buffers/inverters.

Moreover if there is any routing blockage present in the design, the router may forced to use long nets. These kind of info you can get in the early stage of the design & accordingly you can modify your floorplan/placement.

This depends on how trial route values match with detail route values.

Add on point, Trial route does not fix DRC's. (Takes less time)
Trial Route will give idea on routing congestion at early stage so that one can avoid iterations and save timing. This takes very less time than Global routing and Detail routing. Detail routing will take time to fix DRC's.

This option (Trial route) is available in SOC encounter (cadence terminology)
The other tools may have other name as their own terminology

yes, this will not fix any DRC violations.. This terminology is used in SOC Encounter only as far my knowledge...

in snps , it is called virtual route,
There is some thing diff i found between two routers,,, i,e nano route & ICC route,
nano route will do the routing in two phases ,,global route & detail route, but in ICC there is one more phase called track assignment,, i think,, in nano route,, this phase in included in detail route

Hi all,

By default timing analysis is based on a "Virtual Route" Which is an estimation of Resistance, Capacitance values of all metal layers

Thanks & Regards,

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