Re: gEDA-user: Multiple pages

[al davis <ad252@xxxxxxxxxxxxxxxx>]

On Wednesday 18 August 2010, kai-martin knaak wrote:
> > You have said many times how much you love LTspice,
> 
> No I did not. I said, that I use it because using gnucap or
> ngspice with gschem is such a hassle. When I last looked into
> it, it took me much more time to get results with
> gschem/gnucap than with ltspice. And this is while schematic
> capture with ltspice is a bitch by itself. "Much more time"
> in this case translated to days rather than hours.

I agree that it is a hassle.  I have said it a few times.  What 
gets me most is that the translation is incomplete.  It seems I 
always need to hack the netlist.  The Verilog format (which the 
development branch of Gnucap ordinarily prefers) really doesn't 
work.  It doesn't do attributes at all.  Without attributes, you 
can't (for example) set the value of a resistor.  It has other 
problems too.

Since Gnucap has its own translator system, I would like to see 
a plugin for it to read the gschem format directly.  (and also 
one to read the PCB format).  That would have the side effect of 
being able to import date to gschem.  The same plugin could be 
used with gnucap's standalone translator, to provide file 
translations that could be used by other programs.


> This is the minimum set of features I feel necessary to
> actually use and recommend gnucap with gschem:
> 
> 1) a way to define a permanent group of symbols that shall
> participate in simulation.

check.

> 
> 2) predefined signal and probe symbols 

me too.

> 3) a fairly complete set of models for basic analog
> components

yes yes

> 4) a "simulate!" button to trigger the simulation and 
> yield output.

and how about the ability to augment the schematic by showing 
the DC voltages at the nets?

> The last two requirements are essential. Lack of immediately 
> available models is a show stopper for newbies. The models
> don't have to be elaborated and can be idealized. But they
> have to work with gnucap right away without manual tweaking.

Before we can consider that, we need to have a flawless 
translation of the netlist.  Those buttons are a waste if I need 
to manually edit the netlist.  

> The simulate-button requirement stands for a short round-trip
> time. For me, simulation is all about tweaking the circuit
> and watch out for the effect. It doesn't have to be an 
> actual button. Some kind of script or makefile run on the 
> *.sch file might do, too. 

It is for me too.  I usually save the netlist, then run gnucap 
interactively, usually doing stuff that spice won't let me do.  
Then when the circuit is finally tweeked, how do I propagate the 
changes back to the schematic?  (manually?)

> > Most gnucap users are not geda users.  The most active
> > Gnucap users look at it as an alternative to high priced
> > simulators like Spectre, Nanosim, BDA and Saber.  Not
> > (what they consider to be toys) like LTspice.
> 
> Well, I am talking about usability not accuracy, speed, or
> whatever the other simulators excel at. This might be a 
> different metric.

I know.  That is one of the reasons Qucs seems to be successful.  
The simulator engine is somewhat of a lightweight, and for big 
circuits it can be very slow, but people love it because it is 
easy for a beginner to use.  What we should have here is an 
upgrade path, so when they outgrow Qucs, we provide what they 
need.

> Do you you have some kind of vision on how gschem should 
> interact with gnucap?

Take a look at Qucs.  That's one way.  The manual way of getting 
a netlist and running it manually must be available too.

It seems you have a vision too.  Let's make it happen.



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