For convenience, I created the following schematic symbol, and this subcircuit:
.subckt DIFFMETER a b out1 out2 BV1 out1 GND V=V(a,b) R1 out2 GND 1g .ends By putting the pins out1 and out2 in the same location, hiding out2, I could trick KiCad to consider any wire/label there connected. It would be nice if one could pass the actual expression (V value) as a subcircuit parameter, but my attempts at that failed. Not sure if it's possible, Holger? Cheers On Thu, Oct 31, 2019 at 11:14 AM Jonatan Liljedahl <[email protected]> wrote: > > On Wed, Oct 30, 2019 at 6:42 PM Holger Vogt <[email protected]> wrote: > > > > The current eeschema-ngspice interface is very limited. > > Are there any plans or roadmap for improving it? > > > > How would one plot, for example, the difference between two vectors? > > > I tried this in a text box: > > > > > > .save foo=(‘v(/input)-v(/output2)’) > > > .tran 10u 50m > > > > > > but "foo" does not show up in the list of vectors to display in the plot > > > window. > > > > Here you might have a look at > > https://forum.kicad.info/t/spice-plotting-difference-of-voltages/19545/2 > > Thanks! Also I found this way: I added a symbol and a dummy resistor, > setting the symbols Spice_Primitive and Value such that I get this in > the netlist: > > BV1 /diff GND V=V(/input,/output) > Rdummy1 NC_03 /diff 1g > > "V(/diff)" then shows up in the kicad plot menu. This also work for > other operations than diffing, for example > > BV2 /mul GND V=V(/input)*V(/output)/100 > > It would be nice if one could simply append stuff to the netlist in a > textblock, is this possible? > > > > Another thing, I found that one can use parameters for values, for > > > example {Rx} for a resistor value and then add a textbox with ".param > > > Rx=100k". Would it be possible to simultaneous get plots for a set of > > > different values of Rx? > > > > > > > Here you might try external ngspice. KiCad 5.1.x has a direct > > interface, where you generate a netlist from your circuit and then may > > call ngspice. This will offer the full ngspice capabilities and plotting > > via ngspice or gnuplot. I have described an example at > > http://ngspice.sourceforge.net/ngspice-eeschema.html#external . > > > > Unfortunately this interface has disappeared in KiCad 5.9.9 . I still > > will have to make a wish list bug report to get this back. > > Is this supposed to work on macOS as well? I downloaded the ngspice > package but the binary fails to run: > > $ ./ngspice > dyld: Library not loaded: /opt/X11/lib/libXaw.7.dylib > Referenced from: /Applications/ngspice/bin/./ngspice > Reason: image not found > Abort trap: 6 > > > -- > /Jonatan > http://kymatica.com -- /Jonatan http://kymatica.com
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