Eagle CAD schematic to simulation - Page 1
Forum section: electronics / beginners

author: anishkgt
author_rank: Frequent Contributor
timestamp: December 03, 2016, 05:15:34 am
content: Could anybody please recommend me a simulation software that would work with Eagle. i hear there is LTSpice but which version. There are a bunch of the versions and not sure which to to go for. Are there any simpler ones than LTSpice ?

author: ataradov
author_rank: Super Contributor
timestamp: December 03, 2016, 05:41:56 am
content: Schematics for simulation and schematics for design are two very different things, I doubt you will find a good solution.Just use LTSpice for simulation.

author: anishkgt
author_rank: Frequent Contributor
timestamp: December 03, 2016, 06:06:06 am
content: Basically I need to simulate my schematic and LTspice has lot of versions. Is it LTSpice IV that I should go for ?

author: ataradov
author_rank: Super Contributor
timestamp: December 03, 2016, 06:07:20 am
content: Yes, LTSpice IV is the latest version, there is not reason not to use it.

author: anishkgt
author_rank: Frequent Contributor
timestamp: December 03, 2016, 06:17:38 am
content: Thanks Alex.Would this be rite forum to ask questions about ltspice ? Tried importing my schematic but errors were shown when exporting an LED. "Different quantities and spice order.....". Does it mean I have to create a new kit ray for led.

author: ataradov
author_rank: Super Contributor
timestamp: December 03, 2016, 06:20:43 am
content: Quote from: anishkgt on December 03, 2016, 06:17:38 amSure, why not?Quote from: anishkgt on December 03, 2016, 06:17:38 amImporting from where?It is highly likely that you will have to re-create the schematic in LTSpice from scratch. I doubt there is a reliable way to import from anything but other SPICE-type program. As I said, two different things with completely different approaches to schematic representation.

author: anishkgt
author_rank: Frequent Contributor
timestamp: December 03, 2016, 06:42:26 am
content: QuoteThat's is gonna be hard. Isn't there a easier way to do this. The eagle schematic has a link that says export. So probably there should be a way to do this but could not find a straight forward way to do it.How does the others do it ?

author: ataradov
author_rank: Super Contributor
timestamp: December 03, 2016, 06:44:48 am
content: Quote from: anishkgt on December 03, 2016, 06:42:26 amWhy?Quote from: anishkgt on December 03, 2016, 06:42:26 amThey don't. You can draw whatever you want in Eagle, but if there are no corresponding SPICE models, then you will be out of luck.Simulation schematic is VERY different from design schematic, for anything non-trivial there is no direct correspondence.

author: tatus1969
author_rank: Super Contributor
timestamp: December 03, 2016, 07:26:19 am
content: they have added an LT spice export function in Eagle, but i have never used it. your eagle design probably only contains geometrical data of your parts, so you will have to create all the necessary electrical data by yourself anyway. better start from scratch and concentrate on specific areas of your whole circuit only. LTspice is the simplest tool that i know, but your question suggests: are you aware that circuit simulation is a complex topic itself?

author: Karel
author_rank: Super Contributor
timestamp: December 03, 2016, 07:55:31 am
content: http://felicitas-ce.de/product/pcbsim/

author: anishkgt
author_rank: Frequent Contributor
timestamp: December 03, 2016, 09:01:55 am
content: Thanks guys. Will try all from scratch on spice and see how it goes.

author: anishkgt
author_rank: Frequent Contributor
timestamp: December 03, 2016, 02:22:02 pm
content: So i just tried out the LTSpice IV and suprisingly i could not find some devices in it. like the ATmega328P. is this version of the simulation limited to some components and the the versions of spice would be having.

author: ataradov
author_rank: Super Contributor
timestamp: December 03, 2016, 06:15:00 pm
content: Quote from: anishkgt on December 03, 2016, 02:22:02 pmThat's exactly what I wast talking about. It is impossible to do SPICE simulation on a micro controller. SPICE builds and solves a system of differential equations, so it does not support anything programmable. You typically use simulations to figure out details of reasonably small sub-circuits, not the whole thing.There are things like MultiSim that try to to this, but they fail real fast, so just forget that you can do a simulation like that and have reliable results.

author: anishkgt
author_rank: Frequent Contributor
timestamp: December 03, 2016, 07:25:55 pm
content: ah silly me, wasting time with simulation. but i am glad, i now know its simulators are not completely here to simulate a complete schematic. Then i guess its time to do it the age old way, print, Photoresist and finally etching.

author: ataradov
author_rank: Super Contributor
timestamp: December 03, 2016, 07:30:08 pm
content: Quote from: anishkgt on December 03, 2016, 07:25:55 pmAnd they never will be, because it is a pretty pointless exercise. Complete simulation of everything would be impossible, and trying to simulate every single MCU out there is a huge task, and there is no way anyone will get a return on investment on this.

author: tatus1969
author_rank: Super Contributor
timestamp: December 03, 2016, 08:14:54 pm
content: Quote from: anishkgt on December 03, 2016, 07:25:55 pmas I said, concentrate on specific aspects of your circuit. The first question should be: what specifically do I want to know about my circuit?

author: anishkgt
author_rank: Frequent Contributor
timestamp: December 04, 2016, 06:04:49 am
content: i was trying to test the whole circuit as etching process does take time since that would not work, specifically test if the 2 scr in back to back configuration would work as per the configuration on their datasheet.

author: ataradov
author_rank: Super Contributor
timestamp: December 04, 2016, 06:07:42 am
content: Quote from: anishkgt on December 04, 2016, 06:04:49 amWhat is "scr"? That specific part sounds exactly like something you would test in LTSpice. You don't need MCU for that. Unless "scr" is something programmable, in which case simulation is not likely to be accurate anyway.

author: anishkgt
author_rank: Frequent Contributor
timestamp: December 04, 2016, 06:58:02 am
content: Scr is silicon controlled rectifier or a thyristor. Hmm will have to see that then. What is spice XVII?

author: ataradov
author_rank: Super Contributor
timestamp: December 04, 2016, 06:58:13 am
content: Quote from: blueskull on December 04, 2016, 06:54:02 amI did not know it existedThere does not seem to be a whole lot of improvements compared to IV, but sure, I'll check that the next time I need to install LTSpice. For now, I don't see anything exiting to update immediately.

author: ataradov
author_rank: Super Contributor
timestamp: December 04, 2016, 07:01:03 am
content: Quote from: anishkgt on December 04, 2016, 06:58:02 amQuick search turns up thishttps://www.eevblog.com/forum/projects/ltspice-thyristorscr-library/How well those libraries are matched with real devices - who knows. For anything critical or unusual uses, I'd just assemble a real deal sub-circuit.Quote from: anishkgt on December 04, 2016, 06:58:02 amhttp://www.linear.com/designtools/software/