Re: gEDA-user: Question regarding 1st LTSpice simulation
Andy Peters wrote: One obvious caveat is that the LTC switcher models are all proprietary and as such can't be used with any other spice. Are they hidden or licensed, or just a format that could be translated? John Griessen -- Ecosensory tinyOS devel on: ubuntu Linux; tinyOS v2.0.2; telosb ecosens1 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: Question regarding 1st LTSpice simulation
On Sep 18, 2007, at 11:40 AM, John Griessen wrote: Andy Peters wrote: One obvious caveat is that the LTC switcher models are all proprietary and as such can't be used with any other spice. Are they hidden or licensed, or just a format that could be translated? They are in a binary format. The program is smart enough to know which models are spice models and which are the proprietary binary models. The format is not published so far all calls to open it have been ignored. There's also some legalese about how the models are proprietary and cannot be reverse-engineered, etc etc. -a ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: Question regarding 1st LTSpice simulation
On Sep 17, 2007, at 4:23 PM, gene wrote: Honestly, I haven't even tried either gnucap nor ng-spice but use ltswitchercad quite a bit. I'm up for the change, but how's the learning curve? Anyone care to comment or compare the two? One obvious caveat is that the LTC switcher models are all proprietary and as such can't be used with any other spice. -a ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: Question regarding 1st LTSpice simulation
On Tuesday 18 September 2007, Andy Peters wrote: They are in a binary format. The program is smart enough to know which models are spice models and which are the proprietary binary models. The format is not published so far all calls to open it have been ignored. There's also some legalese about how the models are proprietary and cannot be reverse-engineered, etc etc. The dreaded proprietary lock-in. Our biggest enemy. It's a cover-crop... A while back, on another mailing list (Free Software Business, [EMAIL PROTECTED]), there was a posting about the concept of a cover crop in marketing. I will now take the liberty to repeat the posting, because it describes my feeling well... === begin quote For example, many companies are using what you might call a Cover Crop pattern. (Instead of borrowing military terms for marketing all the time, let's use one from agriculture.) http://www.sarep.ucdavis.edu/newsltr/v7n3/sa-8.htm You plant a cover crop not to harvest and eat it, but to add nitrogen and organic matter to the soil, encourage a population of beneficial insects, and to choke out weeds that would otherwise grow up to compete with your regular crop. Some examples of the cover crop pattern are: * MSFT Visual Studio 60-day license in C# books (beneficial insects: the ones that can code in C#; weeds choked out: the next Turbo Pascal * MSIE included with pre-installed MSFT Windows (nitrogen in the soil: MSIE-compatible web sites; weeds choked out...well, IANAL) * warez copies of Adobe Photoshop * academic discount programs * ubiquitous PHP and MySQL in every Linux distribution, and on every web hosting site Cover crops tend to be very cheap and easy to plant, compared to the main crop that you're protecting. (And they're not just for established fields -- a recommended part of clearing land is to plant a green manure crop to be plowed under before planting the real pasture or crop.) The benefits of a cover crop probably wouldn't be worth it if it cost much more. So part of Cover Crop as a business model design pattern would be that low cost distribution is more important than high-information-feedback distribution. end quote == So, for LT-spice What is the organic matter being added to the soil? What are the beneficial insects? And finally: What are the weeds they want to choke out? ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: Question regarding 1st LTSpice simulation
On Sep 18, 2007, at 12:07 PM, al davis wrote: So, for LT-spice What is the organic matter being added to the soil? What are the beneficial insects? And finally: What are the weeds they want to choke out? These are interesting questions. The answer is that LTC's business is selling chips, and by providing a tool that does very fast and very accurate simulations of their parts, they increase the chance that an engineer will choose an LTC part over a competitor's device. After all, switchmode power supplies can be tricky and an accurate simulation gives one a warm- fuzzy feeling that at least the topology and the component selection are correct. Their reason for not opening the format is simple: if one could use LTSpice to simulate a TI or National or whoever's part, then obviously the engineer could choose the competition as easily as choosing the LT part, and THAT is not in LT's interests. Linear Technology supports LTSpice as a means to an end. It would be nice if LT had standard spice models for their switchers that one could use in another program, even if these models were slower than the proprietary models. They DO provide spice models for their amplifiers, comparators and linear regulators, but clearly they think their switchers are the crown jewels. -a ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: Question regarding 1st LTSpice simulation
Andy Peters wrote: On Sep 18, 2007, at 12:07 PM, al davis wrote: So, for LT-spice What is the organic matter being added to the soil? What are the beneficial insects? And finally: What are the weeds they want to choke out? These are interesting questions. Linear Technology supports LTSpice as a means to an end. It would be nice if LT had standard spice models for their switchers that one could use in another program, even if these models were slower than the proprietary models. They DO provide spice models for their amplifiers, comparators and linear regulators, [jg]Ah so, they're not cutting themselves out of widest consideration of simulation for generic parts, just the system-mostly-on-chip parts. The logic must be, If you have decided to pay for our system-mostly-on-chip parts, there's not much to design, so you can afford to be limited by using only switchercad. This implies the weeds from their perspective are other brands of system-mostly-on-chip parts, they don't contribute much organic matter and we are beneath being their beneficial insects even. but clearly they think their switchers are the crown jewels. John Griessen -- Ecosensory Austin TX ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: Question regarding 1st LTSpice simulation
Robert Butts wrote:
I tell my son the only dumb question is the one never asked. So with
that...
I'm doing an LTSpice simulation and following Stuart's howto. In the
Running LTSpice with gEDA designs step 5 is:
Create a link from your netlist output.net and a netlist in the
directory in which SwCADIII lives. Make the netlist suffix .cir. For
example: ln -s ${DESIGN_HOME}/output.net
${WINE_HOME}/.wine/fake_windows/Program Files/LTC/SwCADIII/MyDesign.cir
My questions are these:
1. Earlier in the howto I was directed to netlist my design and name it
design.cir. This is the netlist in my design directory and it ends in
.cir not .net. Should Stuart's howto read ${DESIGN_HOME}/output.cir and
not output.net http://output.net?
So far I've not come across a simulator which cared about the extension.
But I'm not an LTspice user.
BTW, why LTspice and not ng-spice or gnucap which are both open source?
With either of them, you can avoid tying yourself to a particular OS,
they both have mailing lists with not just users but program developers,
and you have more of an ability to influence the tools.
I've been down the path of closed source software with cheap or zero
cost to obtain before and at the end wished I hadn't. The particular
nameless tool ended up being a dead end road since I ultimately needed
to migrate to another OS and didn't want to shell out thousands for
something I was using as a hobby.
Just my 2 cents.
-Dan
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Re: gEDA-user: Question regarding 1st LTSpice simulation
Robert Butts wrote: When I'm creating the link how do you type the space in the directory Program Files? See below: /fake_windows/Program Files/LTC/SwCADIII/MyDesign.cir Maybe /fake_windows/Program\ Files/LTC/SwCADIII/MyDesign.cir JG -- Ecosensory Austin TX tinyOS devel on: ubuntu Linux; tinyOS v2.0.2; telosb ecosens1 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: Question regarding 1st LTSpice simulation
Dan McMahill wrote: Robert Butts w BTW, why LTspice and not ng-spice or gnucap which are both open source? With either of them, you can avoid tying yourself to a particular OS, they both have mailing lists with not just users but program developers, and you have more of an ability to influence the tools. I've been down the path of closed source software with cheap or zero cost to obtain before and at the end wished I hadn't. The particular nameless tool ended up being a dead end road since I ultimately needed to migrate to another OS and didn't want to shell out thousands for something I was using as a hobby. Honestly, I haven't even tried either gnucap nor ng-spice but use ltswitchercad quite a bit. I'm up for the change, but how's the learning curve? Anyone care to comment or compare the two? gene ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: Question regarding 1st LTSpice simulation
gene wrote: Dan McMahill wrote: Robert Butts w BTW, why LTspice and not ng-spice or gnucap which are both open source? With either of them, you can avoid tying yourself to a particular OS, they both have mailing lists with not just users but program developers, and you have more of an ability to influence the tools. I've been down the path of closed source software with cheap or zero cost to obtain before and at the end wished I hadn't. The particular nameless tool ended up being a dead end road since I ultimately needed to migrate to another OS and didn't want to shell out thousands for something I was using as a hobby. Honestly, I haven't even tried either gnucap nor ng-spice but use ltswitchercad quite a bit. I'm up for the change, but how's the learning curve? Anyone care to comment or compare the two? gene I'd comment, but I probably can't give a good measure of the learning curve. From my perspective, if you've used any circuit simulators, ngspice and gnucap are both pretty easy. But then again I first used spice nearly 2 decades ago and use circuit simulators daily so most of my learning curve memory is pretty distant. gnucap has some neat capabilities like being able to directly get at some internal components of device models (junction current vs charging current in a diode for example). gnucap also is quite a bit better than ng-spice for mixed mode sims since it was designed for that. I can't recall though if gnucap has small signal noise analysis at the moment. I'm a fan of learning about netlists and doing the first couple of sims by typing in a netlist by hand. Why? Because even with expensive commercial CAD systems, problems come up where you have to dig into the netlist to debug. Besides, it's one less thing to worry about when you're getting started. -Dan ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: Question regarding 1st LTSpice simulation
On Monday 17 September 2007, Dan McMahill wrote: I'd comment, but I probably can't give a good measure of the learning curve. From my perspective, if you've used any circuit simulators, ngspice and gnucap are both pretty easy. But then again I first used spice nearly 2 decades ago and use circuit simulators daily so most of my learning curve memory is pretty distant. gnucap has some neat capabilities like being able to directly get at some internal components of device models (junction current vs charging current in a diode for example). gnucap also is quite a bit better than ng-spice for mixed mode sims since it was designed for that. I can't recall though if gnucap has small signal noise analysis at the moment. No. no small signal noise analysis. Use NG-spice for that. There is also no small signal distortion analysis. Again, use NG-spice for that. On the other hand, I have never found the small signal distortion analysis to be very useful, because it doesn't show large signal distortion at all. What I have found more useful is a real Fourier analysis. For this, gnucap wins. The Fourier analysis and time stepping work together to significantly lower the noise, so it is actually useful for measuring distortion. Gnucap is a lot faster for large circuits. I have one that runs in 8 hours in NG-spice, 40 seconds in gnucap. Quadratic time vs. linear time. As to the learning curve, it depends on where you are coming from. gnucap interactive commands are different from spice. As a teacher, I found that I could get students started faster on gnucap than any other, even the graphic ones. If you are starting cold, the command line is really the easiest way! The biggest trip point is the sequencing of attaching probes and doing an analysis. Batch spice doesn't care about sequencing. As a result, it doesn't let you play. Gnucap cares completely about sequencing. You need to attach the probes before you turn the power on (run the analysis), like you would with a GUI, or a real circuit. Gnucap is more like a breadboard metaphor. Spice is more like a declarative programming language metaphor. I'm a fan of learning about netlists and doing the first couple of sims by typing in a netlist by hand. Why? Because even with expensive commercial CAD systems, problems come up where you have to dig into the netlist to debug. Besides, it's one less thing to worry about when you're getting started. That's another thing I ran into in teaching. Other profs would teach only with a GUI, so they might not see a netlist ever, or until they hit a course I was teaching. I start them with a netlist, then let them learn a GUI later if they want to. With Spice, you need to make a file containing the netlist. Gnucap lets you type it in interactively, then make many cycles of change and simulate again, interactively. With Spice, every change and simulate again is another edit of a file. Too often, students are taught simulation as an afterthought. You do everything else, including actually build one, then simulate to appease the professor. They don't learn that a big reason for simulation is that it is easier than the many rebuild cycles on a real circuit. They also don't learn that simulation can give you data you can't measure, and can directly give you the numbers you want, as opposed to measuring what you can measure and calculating from there. gnucap is better in this respect, because lots more probes are available. You can directly probe things like the charge in a capacitor, the incremental capacitance of a junction, the transconductance of a transistor. The biggest problem I ran into is that many students can only use a GUI. They can't even type ls to get a file listing. For them any command line is incredibly confusing. They need a few weeks of lessons in how to use a real computer first. Many profs respond to this by only using a GUI, which at best only delays the awakening, at worst they never learn. If you are just starting with gnucap, get the stable release (0.35). When you have a need for something it doesn't do, the development version might do it. There is a big difference between the latest stable version and the latest development version. If you want to help us make a Free simulator that competes against the big bucks simulators, get the development version and dive in. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
gEDA-user: Question regarding 1st LTSpice simulation
I tell my son the only dumb question is the one never asked. So with
that...
I'm doing an LTSpice simulation and following Stuart's howto. In the
Running LTSpice with gEDA designs step 5 is:
Create a link from your netlist output.net and a netlist in the directory
in which SwCADIII lives. Make the netlist suffix .cir. For example: ln -s
${DESIGN_HOME}/output.net ${WINE_HOME}/.wine/fake_windows/Program
Files/LTC/SwCADIII/MyDesign.cir
My questions are these:
1. Earlier in the howto I was directed to netlist my design and name it
design.cir. This is the netlist in my design directory and it ends in .cir
not .net. Should Stuart's howto read ${DESIGN_HOME}/output.cir and not
output.net?
2. Did I miss something and I was supposed to copy the netlist to the
directory in which SwCADIII lives or does the link create a phantom netlist?
Thanks,
Rob
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Re: gEDA-user: Question regarding 1st LTSpice simulation
On Sep 16, 2007, at 12:49 PM, Robert Butts wrote:
I'm doing an LTSpice simulation and following Stuart's howto. In the
Running LTSpice with gEDA designs step 5 is:
Create a link from your netlist output.net and a netlist in the
directory
in which SwCADIII lives. Make the netlist suffix .cir. For example:
ln -s
${DESIGN_HOME}/output.net ${WINE_HOME}/.wine/fake_windows/Program
Files/LTC/SwCADIII/MyDesign.cir
My questions are these:
1. Earlier in the howto I was directed to netlist my design and
name it
design.cir. This is the netlist in my design directory and it ends
in .cir
not .net. Should Stuart's howto read ${DESIGN_HOME}/output.cir and
not
output.net?
LTSpice doesn't care whether the netlist is called .net or .cir.
2. Did I miss something and I was supposed to copy the netlist to the
directory in which SwCADIII lives or does the link create a phantom
netlist?
you can open the file from anywhere; it does not have to be in the
SwCAD III directory. However, SwCADIII has a ridiculous hard-coded
library directory structure ...
-a
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Re: gEDA-user: Question regarding 1st LTSpice simulation
When I'm creating the link how do you type the space in the directory
Program Files? See below:
/fake_windows/Program Files/LTC/SwCADIII/MyDesign.cir
On 9/16/07, Andy Peters [EMAIL PROTECTED] wrote:
On Sep 16, 2007, at 12:49 PM, Robert Butts wrote:
I'm doing an LTSpice simulation and following Stuart's howto. In the
Running LTSpice with gEDA designs step 5 is:
Create a link from your netlist output.net and a netlist in the
directory
in which SwCADIII lives. Make the netlist suffix .cir. For example:
ln -s
${DESIGN_HOME}/output.net ${WINE_HOME}/.wine/fake_windows/Program
Files/LTC/SwCADIII/MyDesign.cir
My questions are these:
1. Earlier in the howto I was directed to netlist my design and
name it
design.cir. This is the netlist in my design directory and it ends
in .cir
not .net. Should Stuart's howto read ${DESIGN_HOME}/output.cir and
not
output.net?
LTSpice doesn't care whether the netlist is called .net or .cir.
2. Did I miss something and I was supposed to copy the netlist to the
directory in which SwCADIII lives or does the link create a phantom
netlist?
you can open the file from anywhere; it does not have to be in the
SwCAD III directory. However, SwCADIII has a ridiculous hard-coded
library directory structure ...
-a
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