Ignore device during netlisting / simulation

  • gag2000

    gag2000 - 2014-05-22

    Dear all,

    Is there any way to ignore instance during netlisting ?
    I have testpoints that cause error during simulation (I like to have the same schematic for simulation and for fab...).

    If not, perhaps it would be a good idea to add a parameter which would allow to omit selected instances during ngspice netlisting.


  • Justin Fisher

    Justin Fisher - 2014-05-22

    Hi RG.

    I'm not sure what you're getting at. NGSPICE doesn't have a netlister. What schematic package are you using and how do you netlist?

    I wrote a netlister for gEDA gSchem that might work for you. Can't remember if it ignores devices that aren't connected, but I'm fairly sure it does.


    Kind regards,

    Justin Fisher.

  • gag2000

    gag2000 - 2014-05-23

    Hi Justin,

    OK, my question was not obvious : I use gnetlist with "-g spice-sdb" option for ngspice simulation.
    But sometimes, I want some device to be present (and connected) in the schematic, but omited by the netlister in case of simulation netlist (but not in case of e.g. PCB manufacturing).


    Last edit: gag2000 2014-05-23
  • marcel hendrix

    marcel hendrix - 2014-05-23

    You could put these conditionally used devices in a two separate libraries. In one
    of the libraries its subcircuit is empty. If you list all your libraries in a separate .inc file, a text editor can help you comment out the unwanted one.

    I normally add a parameter to a subckt which deactivates it (e.g. by multiplying the input by 0 or 1). This can result in inactive devices being netlisted, which is bad for speed reasons. However, it is very convenient if one can simulate a system's open loop and closed loop behavior from the same schematic.


  • gag2000

    gag2000 - 2014-05-23

    Thank you for the proposal Marcel.
    Just adding a property would be, in the way I use gEDA, more convenient for me (like the graphical property).


  • gag2000

    gag2000 - 2014-07-11

    Hi Marcel and Justin,

    I asked the question on the geda mailing list.
    John Doty has developed a backend to deal with such properties.
    Look at https://github.com/noqsi/gnet-spice-noqsi for further information and download.


  • marcel hendrix

    marcel hendrix - 2015-02-15

    Sorry for the (long) delay in answering.

    You can use .if(expr) .else .endif dotcard
    commands to conditionally add devices/instances
    to a netlist.

    I guess expr might be an evaluated environment
    variable ( e.g. $NETLIST ), but I didn't test



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