kicad-developers team mailing list archive

[Andy Peters <devel@xxxxxxxxx>]

> On Nov 4, 2015, at 1:02 PM, xarx@xxxxxx wrote:
> 
> Hello Andy,
> 
> what you are saying really interests me. 
> 
>> Regarding integrating any kind of simulation tool into the mainline PCB
> design
>> package, I suggest the following: DONT BOTHER.
> 
> I'm not an EE professional, I'm an EE hobbyist. And my ideal tool would allow
> me to draw a schema and allow me to copy it to a document or to publish it to
> internet. And then by extending it a little bit I could use the same schema
> for simulations (which may then force me to modify the schema and publish it
> again). And when I'm satisfied, then I would amend the schema with new
> information (without the necessity to draw and maintain another copy of it)
> and use it for Pcb creation. I don't know whether there are any quirks when
> performing this workflow in large scale, but in an amateur scale I see no
> problems with that. KiCad allows one to omit selected components from netlist
> exports, or from Pcb creation, or from both.

Well, you say “use the same schema for simulations (which may then force me to modify the schema …” which sounds like you’re basically creating two different schematics. And that’s fine. What I argue against is attempting to use the _same_ schematic for both SPICE (or other) simulation and PCB layout.

What I think happens with most designs is that there is only a small part which needs to be simulated. Consider a mostly-digital design with DAC on it, and you want to simulate the DAC output filter. It’s easiest to pull out the filter and simulate it separately, and when you’re happy, copy that design (with proper component values) back to the main design. Yes, there is some amount of self-discipline involved.

For documentation, I use OS X, so the Print command enables PDF output for free. On Windows you can install something like CutePDF which creates a virtual printer that outputs to PDF files.


> Concerning LTSpiceIV, I found it an excelent simulator with a terrible editor.
> That's why I wouldn't mind editing netlists for LTSpice somewhere else - in
> KiCad :-) But for now I'm happily using KiCad + NgSpice.

No doubt — the schematic capture for LTSpice is rather dreadful, with non-obvious commands for everything. (It makes EAGLE look user-friendly and standard.) I printed out the cheat sheet with the key commands because I can never remember them. But LTSpice beats other tools is that you can click on a net and it plots the voltage waveform for that net. Click on a component, and it plots the current through that component. I honestly don’t know if the KiCad/NgSpice combination does that.

> So, perhaps your way and purpose of using the tools is different from mine?

Oh, yes, certainly years of working in a production environment ingrains some habits that are impossible to shake. Thankfully, Kicad easily accommodates those habits, and I think that’s because the guys who started the project and continue to maintain it need to do PCB design in a production environment. Much of what is needed for production is overkill for the hobbyist, but I honestly think that if Kicad didn’t appeal to the professionals it would be yet another half-baked open-source CAD program and not the useful tool it has become. 

-a