Home > Community > Forums > Custom IC Design > Accessing a net from top level

Email

* Required Fields

Recipients email * (separate multiple addresses with commas)

Your name *

Your email *

Message *

Contact Us

* Required Fields
First Name *

Last Name *

Email *

Company / Institution *

Comments: *

 Accessing a net from top level 

Last post Tue, Aug 28 2012 3:10 PM by swdesigner. 17 replies.
Started by Pramod 01 Jul 2009 03:36 AM. Topic has 17 replies and 5227 views
Page 1 of 2 (18 items) 1 2 Next >
Sort Posts:
  • Wed, Jul 1 2009 3:36 AM

    • Pramod
    • Not Ranked
    • Joined on Fri, Jul 18 2008
    • Posts 5
    • Points 70
    Accessing a net from top level Reply
    Hi All, I am using this forum for the first time though i have been using Cadence tools for sometime. I have a very basic question...(somebody might have already asked it) I have a GOLDENschematic for which I want to built a test bench in ADE.For this I built a schematic and instantiated the GOLDEN schematic in that.I added all the required stimuli for the pins available externally (through the GOLDEN symbol).Now my issue is that i need to add access a node(net) inside the GOLDEN schematic and want to put a current source on that.I don't want to change anything in GOLDEN.I tried to put the current source and label the net attached to it with . but this didn't work.While netlisting I could observe that the spectre was netlisting it like _. Can anybody guide me here,hope I am clear. Thanks, Pramod
    • Post Points: 20
  • Wed, Jul 1 2009 4:47 AM

    Re: Accessing a net from top level Reply

    Look at sourcelink solution 11017972 - this gives a component "deepprobe" which allows you to do this for spectre.

    Regards,

    Andrew.

    • Post Points: 65
  • Wed, Jul 1 2009 6:47 PM

    • Pramod
    • Not Ranked
    • Joined on Fri, Jul 18 2008
    • Posts 5
    • Points 70
    Re: Accessing a net from top level Reply
    Hi Andrew,

    Thanks for the quick reply!
    I will try the "deepprobe" component.

    Pramod
    LSI
    • Post Points: 5
  • Wed, Jul 1 2009 11:21 PM

    • Pramod
    • Not Ranked
    • Joined on Fri, Jul 18 2008
    • Posts 5
    • Points 70
    Re: Accessing a net from top level Reply
    Hi Andrew, I tried this and could see that this allows only probing. The original solution link also mentions it for probe. But i want to access it at top level and need to connect a voltage/current source.This i was not able to do with deepprobe. Whenever i connect a source with net name . it puts it as _ in netlist. Thanks, Pramod
    • Post Points: 20
  • Thu, Jul 2 2009 12:16 AM

    Re: Accessing a net from top level Reply
    Pramod,

    I think you're misunderstanding how to use it.

    Place an instance of the deepprobe in your top level schematic, and set the property on the instance to the hierarchical netlist path name to which you want to connect. For example "I1.I2.intnet1" . Make sure the name matches what's in the netlist in case it got mapped from the schematic name.

    Then connect your vsource or isource to the pin on the deepprobe instance.

    The deepprobe component instantiates an "iprobe" between the net connected to the pin and the internal net specified by the property. An iprobe is just like a zero volt source, so this is effectively a short through levels of hierarchy.

    If you just name a net in a schematic with a hierarchical name (as you've tried), then in Virtuoso it doesn't mean a hierarchical reference, so it would be quite wrong to netlist it as such in spectre. Otherwise you could easily simulate something different than you lay out or LVS. So the the spectre netlister maps the name to prevent this. Deepprobe however is deliberately a simulation-only component (it will fail to netlist in other netlisters) so that's then ok, provided it's used with care.

    Regards,

    Andrew
    • Post Points: 20
  • Thu, Jul 2 2009 2:18 AM

    • Pramod
    • Not Ranked
    • Joined on Fri, Jul 18 2008
    • Posts 5
    • Points 70
    Re: Accessing a net from top level Reply
    Hi Andrew, :-( Oh...my bad...I was trying the exactly same think which you were explaining. But due to my mistake i was labelling the instance as IO instead of I0 (Izero). This was causing me to fail the purpose.I could see it was working well with the test schematic (testit) provided with the sourcelink bundle. Anyway things are working fine for me now. Thanks a lot for the help! Looking forward for more. Pramod LSI Corp
    • Post Points: 5
  • Sat, Aug 21 2010 2:54 AM

    • N Venkat
    • Not Ranked
    • Joined on Sat, Aug 21 2010
    • Posts 1
    • Points 20
    Re: Accessing a net from top level Reply

    Hi Andrew,

    I am not able to find this sourcelink '11017972'. I am also not able to find any discussion thread explaining how to use this 'deepprobe'. Kindly help & direct me to the corresponding source of explanation.

    Regards,

    Venkat 


     

    • Post Points: 20
  • Mon, Aug 23 2010 1:47 AM

    • Frank Wiedmann
    • Top 75 Contributor
    • Joined on Thu, Jul 17 2008
    • Muenchen, Bavaria
    • Posts 96
    • Points 1,575
    Re: Accessing a net from top level Reply

    Log in to support.cadence.com and search for deepprobe.

    • Post Points: 5
  • Wed, Nov 17 2010 3:10 PM

    Re: Accessing a net from top level Reply

     How do we handle arrays? We get an array when we try to access a node within an instance like

     

    Xtop.Xnest.Xcell<3>

     

    Thanks!

    • Post Points: 20
  • Fri, Nov 19 2010 1:58 AM

    Re: Accessing a net from top level Reply

    I presume you are saying you are getting an "error" (not "array") when you are trying to use deepprobe with such a net? First of all, you need to find out what that net is called in the netlist, becaue the parameter for deepprobe is the name in the netlist. If in IC61, you may have the net shown as Xcell\<3\>, in which case you might have to enter (I think) Xtop.Xnest.Xcell\\<3\\> (i.e. two backslashes) because otherwise one will get escaped. Not 100% certain (and I'm afraid I don't have time to make the experiment). Anyway, experiment around this and see what happens.

    Regards,

    Andrew.

    • Post Points: 20
  • Fri, Nov 19 2010 9:02 AM

    Re: Accessing a net from top level Reply

     Right on both counts. Thanks.

     xand\<1\>.A\<0\>

     is how you handle a bussed net within an arrayed instance.

    • Post Points: 5
  • Mon, Nov 29 2010 10:23 PM

    Re: Accessing a net from top level Reply

    Would this work with AMS or, as the doc says (currently), only for spectre?

    What would the workaround be to get it to work with AMS-APS?

     

    Thanks

    • Post Points: 20
  • Tue, Aug 28 2012 2:26 PM

    • jjcan
    • Not Ranked
    • Joined on Tue, Aug 28 2012
    • Posts 2
    • Points 40
    Re: Accessing a net from top level Reply

    I'm using IC5141ISR20110503, MMSIM11.1.0.341.isr6, and INCISIV12.10.3

    I have been able to get deepprobe to work with AMS(APS) using OSS through the ADE, however it requires modifying the resulting netlist.vams located in the simulation's "netlist" directory.  The toplevel netlist located in the netlist/ihnl/cds* directory has an iprobe line:

     _ANALOG_BEGIN
    x1 (x0.n0 n1) iprobe
    _ANALOG_END

    However when this makes it into the netlist.vams file, which is what AMS uses when running, it looks like:

     iprobe x1 (\x0.n0 , n1);

    The hierarchical name has a \ placed at the beginning of the name which causes it not to work.  Deleting this \ and rerunning without renetlisting allows the net to be accessed hierarchically.  There may be an option to stop this \ from being added, but I don't know what it is.  Until then, hand editting is a reasonable approach.

     Josh

    • Post Points: 20
  • Tue, Aug 28 2012 2:36 PM

    Re: Accessing a net from top level Reply

    Hand editing is to be deprecated as much as possible.

    Cadence gave me a solution a couple years back. You can place a deepprobe whose property form has 2 fields - one the hierarchical pathname for AMS and one for Spectre. It works good..

    • Post Points: 20
  • Tue, Aug 28 2012 2:50 PM

    • jjcan
    • Not Ranked
    • Joined on Tue, Aug 28 2012
    • Posts 2
    • Points 40
    Re: Accessing a net from top level Reply

    I've searched for "deepprobe" and I haven't found this solution.  I don't know where to start since I haven't found anything that describes how a hierarchical pathname for AMS differs from Spectre.  I've found hints that this may be the case, but not what it may be.  So, what is the difference?

     Thanks!

    • Post Points: 20
Page 1 of 2 (18 items) 1 2 Next >
Sort Posts:
Started by Pramod at 01 Jul 2009 03:36 AM. Topic has 17 replies.