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Re: SPICE models and library symbols


Hi Nhat,

There are fields dedicated to Spice model definitions, try to set a
model with the Spice Model editor dialog (in the Component Properties
dialog [1]) and notice that new fields will appear.


1. http://docs.kicad-pcb.org/5.0.0/en/eeschema.html#_assigning_models

On 08/13/2018 10:31 PM, Nhat Khai wrote:
> Sorry to a long email and my english. But here is my though. I can be
> wrong, so please don't be angry.
> Here is my case of use:
>   I have a lot of SUBCKT models (100+), and modified/customized SUBCKT
> models with parameters. In KiCad4, I using the default value of
> symbol/component to refer to default model. Later on in project, I can
> change that value point to my own SUBCKT model with some parameter
> specified for special case of simulation. It doable in KiCad4, but text in
> component's value some time look long and ugly. So it would be nice to have
> keep it compatible and following:
>   a. KiCad understand SUBCKT parameter and allow user to set these values
> -- Give KiCad a gateway to support ~90% of most simulation needed without
> understand resistor, voltage, current model ... etc.
>   b. KiCad give user option to stick with value (backward compatible) or
> use alternative field (one or more) for specifications the spice model.
>   c. These alternative field can be hide or visible just like any other
> normal field.
>   d. Using fields, all the model parameters can be just be export as BOM.
> Allow user to ensure they don't make mistake. Great visibility over 100+
> model all at one.
>   e. The .cir file allow user option to how to managing their spice library
> that fit there own workflow. (Using normal editor, look at 100+ model all
> at one in one file, source control in the spice language, no need to learn
> another KiCad language to look at the git diff,...etc).
> I think, embedding spice model into symbol is nice but is have issues:
> 1. Visibility of the model is hard to access (one by one). It is trouble
> some to verify 100 spice model all at once.
> 2. User tent to not trust spice model where I don't know about it, or where
> it comes from. (they will refer to download directly form manufacture, or
> their customized version.
> Also, embedding spice model into the component is nice in eeschema, but is
> have similar issue:
> 1. Visibility of the model have is one by one.
> 2. Here is one of my resistor value for simulation: "{2k*0.9026} tc1=4.21m
> tc2=4.427u dtemp=27". Current KiCad5 don't understand this. However, I
> don't expect it understand it like KiCad4 did. But if it understand the
> simple SUBCKT then I can use it and pass in parameters, and help it more
> readable, and my life easier :-).
> KiCad simulation seem to missing a generic mode for the unexpected
> simulation types. Which again, in my case is temperature sweep or can be
> multi-parameter sweeps. It think the effort to have it recognize are
> beautiful. But generic simulation should be the most importance one to
> cover first. Meaning, it don't event need to understand the simulation type
> and still able to plot the result. My case, I use spice directive to
> specify my unusual simulation, and no matter how I specify it, current
> simulation tool should able to plot result after simulation finished (is
> the best I can dream of). Current it is not, if it don't understand what
> type of simulation I'm doing (witch again I think it don't have to).
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