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 find out net corresponding constraint set 

Last post Tue, Jan 7 2014 5:28 AM by fxffxf. 1 replies.
Started by cc jiun 06 Jan 2014 09:57 PM. Topic has 1 replies and 4902 views
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  • Mon, Jan 6 2014 9:57 PM

    • cc jiun
    • Not Ranked
    • Joined on Thu, Apr 28 2011
    • Posts 1
    • Points 20
    find out net corresponding constraint set Reply

    Hi, Sir

     I would like to find what netname is corresponding to constraint set by skill.

    for example. net: VSS 's constraint set is default, net: LVDD 's constraint set is GSSG100_ohm...etc.  

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    • Post Points: 20
  • Tue, Jan 7 2014 5:28 AM

    • fxffxf
    • Top 25 Contributor
    • Joined on Thu, Jul 17 2008
    • ., AK
    • Posts 298
    • Points 4,735
    Re: find out net corresponding constraint set Reply

    Constraints sets (csets) are not assigned at the net level except in the simplest use model.

    Electrical constraints (ECsets), which have the simplest use model, could be assigned at the net level by an ECset. You need to remmeber that an ECset is just a grouping of electrical constraints so while a net might have a ECset assigned it also may have an override constraint such as IMPEDANCE assigned directly. In the case of directly assigned Ecsets if you have the net dbid (net) then the ecset name is obtained via:

         net->prop->ELECTRICAL_CONSTRAINT_SET

    Alternatively, the net may have an ECset without an IMPEDANCE constraint but it is a member of BUS which is asssigned a different ECSET with an IMPEDANCE rule. When Allegro resolves, for impedance on the net it will obtain the value off the ECSET on the Bus. A Skill API can be used to obtain the electrical rule that impacts a net via:

          axlCNSNetFlattented

    Physical, spacing and same net csets have a more complex use model. Constraint regions, layers,netclasses and in some cases most conservative impact the constraint resolution for these domains. If you are directly assigning csets to nets then just like with ecsets you can obtain the cset on the net via the property method. Example if a net has a physical cset assigned then given a net dbid the pcset name is

          net->prop->PHSYICAL_CONSTRAINT_SET

    Spacing and same net use can be obtained the same way via their properties.

     

    • Post Points: 5
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Started by cc jiun at 06 Jan 2014 09:57 PM. Topic has 1 replies.