Feature request .step command in Simulator

[ModuloFS]

Hello,

i created a feature request for the .step functionality of the simulator as it is available in LTSpice:

[Feature Request] add .step command functionality to simulator (#20508) ·...

This was also requested here:

SPICE .STEP Command

The spice .step directive isn’t supported by the KiCAD spice engine and simulating it with a .command routine fails with a viewport access error. Is there any practical way to run a series of simulations whilst varying a parameter? I’ve been using LTSpice for years and second only to the ability to plot a fourier series, the .step directive is probably the most useful tool in the arsenal when dealing with audio/radio designs.

[lucas]

ngspice currently doesn’t have a step command. I remember that @holger mentioned at some point that it is on his tentative feature list and might be implemented at some point in the future. You can use ngspice’s control language to emulate step commands, which works very nice. It’s a little bit more cumbersome, but it actually gives you more flexibility (since it is a real scripting language). Currently the problem is that kicad’s frontend doesn’t really facilitate displaying all the result. Kicad only shows the last run. So what you can do is write the results to disk with an ngspice command.

Attached you find a small example project that does that. To look at the simulation results, you have to open the plot_1.svg file in project folder afterwards.

BC817_characterization_v9.zip (9.2 KB)

The following image shows what the result looks like.

[m852]

The simulator itself in the assemblies is not updated for a very long time on the windows platforms, as well as fixes for other libraries, although this platform is in 1st place in popularity. In order not to wait for half a year, you can try GitHub - ra3xdh/qucs_s: Qucs-S is a circuit simulation program with Qt-based GUI submit a feature request

[lucas]

@m852

The simulator itself in the assemblies is not updated for a very long time

Kicad 9 comes on windows with ngspice44 which is the newest major release from this year. Qucs-S is also a great tool, but they use the same ngspice version (afaik).

[m852]

the newest release is 44.2 which was released more than two months ago at the time the transition from 43 to 44 took 5 months) in this board the assembly of flat pack packages is much faster this concerns all libraries not only the simulator the reason is unknown
qucs_s has a library that can be connected without building a new package and it is not the only one
https://ra3xdh.github.io/

[lucas]

I think we have a different notion of what constitutes a “very long time”. ngspice44 is barely a month older than ngspice44-2. In any case, is there anything in 44-2 that is relevant to step functions and the ngspice control language?

[ModuloFS]

Yes i know this way. But i think it is not very intuitive and it would be nice if it would be possible to display the results directly in KiCad. Because of that a implementation of the functionality in KiCad would be nice i think.

[lucas]

Yes, absolutely agree. Just wanted to show that a lot already exists, however isn’t exposed in a nice way to the user. I actually started implementing some of the stuff on the kicad side (very far off from being merged). So, hopefully it will be ready for kicad v10. For the step command itself we have to see what the ngspice team will do. I am optimistic that they will implement it at some point, but my impression was that it is not on their immediate road map.

[m852]

You didn’t understand that updating all libraries is extremely slow, not from the library side, but from the Kicad side, for example, for Ubuntu ppa it’s still 43