Mail Archives: geda-user/2016/01/04/17:19:15
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Peter, have you looked at https://github.com/noqsi/gnet-spice-noqsi?
On Jan 4, 2016, at 7:12 AM, Peter Clifton =
(petercjclifton AT googlemail DOT com) [via geda-user AT delorie DOT com] =
<geda-user AT delorie DOT com> wrote:
>=20
> On 4 Jan 2016 14:00, "Roland Lutz" <rlutz AT hedmen DOT org> wrote:
>=20
> > Thinking about it, I'm not even sure if this behavior (treating the =
slots of a package as individual SPICE objects) is even necessary. The =
other SPICE backends don't seem to be using it.
>=20
The history of this is complicated. There was a time years ago when a =
broken libgeda wound up in distribution because of a failed attempt to =
make slotting work =93right=94 for both layout and SPICE. But what=92s =
right for SPICE depends on context. Can you ignore crosstalk within a =
package (maybe it=92s the most important thing you=92re modeling)? If =
you can, and the SPICE model you have is for one slot (a very common =
scenario), you may want to accommodate that. Otherwise, you probably =
want to have one object per package.
This issue was my most important motivation for writing =
gnet-spice-noqsi, which allows the user to control the connections of =
model instances to nets through the spice-prototype attribute. This =
works at the symbol level, or even the instance level, with defaults =
that imitate gnet-spice-sdb.
Is the current behavior of gnet-spice-sdb for slotted devices documented =
anywhere?
> An alternative option would be to have a (schematic or netlist based) =
sub-model which maps the connections of the actual part, to 'n' internal =
instances of the cell model.
>=20
>=20
Gnet-spice-noqsi makes this a user choice.
> It really depends on whether you are viewing the schematic and spice =
simulation as that of the design with actual parts, or at a more =
abstracted level where actual embodiment of the opamp cells means =
picking what chip they go in.
>=20
>=20
Yes. And in the process of turning an idea into a finished design, you =
may go through intermediate states that mix abstract and concrete. Even =
when you have a finished design, the SPICE =93test fixture=94 is usually =
a rather abstract piece of circuitry. That=92s why the back end needs to =
allow the user to control the expression of a device in the SPICE =
netlist. It also needs good defaults, of course, so you don=92t need to =
hold its hand about every resistor.
John Doty Noqsi Aerospace, Ltd.
http://www.noqsi.com/
jpd AT noqsi DOT com
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<html><head><meta http-equiv=3D"Content-Type" content=3D"text/html =
charset=3Dwindows-1252"><meta http-equiv=3D"Content-Type" =
content=3D"text/html charset=3Dwindows-1252"><meta =
http-equiv=3D"Content-Type" content=3D"text/html =
charset=3Dwindows-1252"></head><body style=3D"word-wrap: break-word; =
-webkit-nbsp-mode: space; -webkit-line-break: after-white-space;">Peter, =
have you looked at <a =
href=3D"https://github.com/noqsi/gnet-spice-noqsi">https://github.com/noqs=
i/gnet-spice-noqsi</a>?<div><br><div><div>On Jan 4, 2016, at 7:12 AM, =
Peter Clifton (<a =
href=3D"mailto:petercjclifton AT googlemail DOT com">petercjclifton AT googlemail DOT co=
m</a>) [via <a =
href=3D"mailto:geda-user AT delorie DOT com">geda-user AT delorie DOT com</a>] <<a =
href=3D"mailto:geda-user AT delorie DOT com">geda-user AT delorie DOT com</a>> =
wrote:</div><br class=3D"Apple-interchange-newline"><blockquote =
type=3D"cite"><p dir=3D"ltr"><br>
On 4 Jan 2016 14:00, "Roland Lutz" <<a =
href=3D"mailto:rlutz AT hedmen DOT org">rlutz AT hedmen DOT org</a>> wrote:</p><p =
dir=3D"ltr">> Thinking about it, I'm not even sure if this behavior =
(treating the slots of a package as individual SPICE objects) is even =
necessary. The other SPICE backends don't seem to be using =
it.<br></p></blockquote><div>The history of this is complicated. There =
was a time years ago when a broken libgeda wound up in distribution =
because of a failed attempt to make slotting work =93right=94 for both =
layout and SPICE. But what=92s right for SPICE depends on context. Can =
you ignore crosstalk within a package (maybe it=92s the most important =
thing you=92re modeling)? If you can, and the SPICE model you have is =
for one slot (a very common scenario), you may want to accommodate that. =
Otherwise, you probably want to have one object per package.<br><br>This =
issue was my most important motivation for writing gnet-spice-noqsi, =
which allows the user to control the connections of model instances to =
nets through the spice-prototype attribute. This works at the symbol =
level, or even the instance level, with defaults that imitate =
gnet-spice-sdb.<br><br>Is the current behavior of gnet-spice-sdb for =
slotted devices documented anywhere?<br></div><blockquote type=3D"cite"><p=
dir=3D"ltr">An alternative option would be to have a (schematic or =
netlist based) sub-model which maps the connections of the actual part, =
to 'n' internal instances of the cell =
model.</p><div><br></div></blockquote><div><br></div>Gnet-spice-noqsi =
makes this a user choice.<br><blockquote type=3D"cite"><p dir=3D"ltr">It =
really depends on whether you are viewing the schematic and spice =
simulation as that of the design with actual parts, or at a more =
abstracted level where actual embodiment of the opamp cells means =
picking what chip they go =
in.</p><div><br></div></blockquote><div><br></div>Yes. And in the =
process of turning an idea into a finished design, you may go through =
intermediate states that mix abstract and concrete. Even when you have a =
finished design, the SPICE =93test fixture=94 is usually a rather =
abstract piece of circuitry. That=92s why the back end needs to allow =
the user to control the expression of a device in the SPICE netlist. It =
also needs good defaults, of course, so you don=92t need to hold its =
hand about every resistor.<br></div><br><div =
apple-content-edited=3D"true">
<span class=3D"Apple-style-span" style=3D"border-collapse: separate; =
border-spacing: 0px;"><p style=3D"margin: 0.0px 0.0px 0.0px 0.0px"><font =
face=3D"Helvetica" size=3D"3" style=3D"font: 12.0px Helvetica">John =
Doty<span class=3D"Apple-converted-space"> =
<span class=3D"Apple-converted-space"> </span><span =
class=3D"Apple-converted-tab"> <span =
class=3D"Apple-converted-space"> </span></span></span>Noqsi =
Aerospace, Ltd.</font></p><p style=3D"margin: 0.0px 0.0px 0.0px =
0.0px"><a href=3D"http://www.noqsi.com/">http://www.noqsi.com/</a></p><p =
style=3D"margin: 0.0px 0.0px 0.0px 0.0px"><font face=3D"Helvetica" =
size=3D"3" style=3D"font: 12.0px Helvetica"><a =
href=3D"mailto:jpd AT noqsi DOT com">jpd AT noqsi DOT com</a></font></p><br =
class=3D"Apple-interchange-newline"></span>
</div>
<br></div></body></html>=
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