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Re: SPICE models and library symbols


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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