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**Nicko** · 11-29-2002, 08:41 AM

Re: Question to all you Spice Guru's

Jan,

> I had a look at this Eagle package, but that
> would be a step backward compared to ULTICAP.

Why? I use Eagle a lot, and find it excellent. They have a "non-commercial" license that gives 4-layer Eurocard formats, and a zero-cost limited board size option. Support for Eagle is also *excellent* (not that I've had to use it often).

> Are there any Simulators that can handle
> Micro Processors like PIC's

I believe there are some that pretend to. However, there are some 400-odd PIC variants, and whilst there are "standard" modes of behaviour for certain port classes etc., even MPLAB will not emulate "simple" things like ADC interrupts. In short, use MPLAB/MPSIM/whatever to check your code - its far more reliable and more likely to work - at least the restrictions are known.

> How does one get the Spice Models for chips.
> E.g. Is there a spice model for the AD600 ?

Most manufacturers provide SPICE models in various formats for their products (they would be silly not to - just search for "SPICE MODEL" or "PSPICE" etc.). In Analog Devices' case (see link below) there are two AD600 variants listed with PSPICE models (SwitcherCAD can use most PSPICE models, its generally accepted to be a great & fast simulator, and ITS FREE).

> How often does it happen that you, yourself,
> could not simulate your design because you
> could not get one or more Spice models.

From time to time it happens that you can't find exactly what you are after, so you improvise. I had to make my own 1.5EK440CA TVS model using a couple of other close models, and I'm certainly NOT a SPICE expert. Use the newsgroup sci.electronics.cad for SPICE issues - The Google Groups search is a great resource. Making your own SPICE models is NOT for the faint of heart ;-)

HTH,

Nicko

Analog Devices' SPICE model home page

**Jan** · 11-29-2002, 04:30 PM

Re: Question to all you Spice Guru's

Hi Nicko,

Eagle is certainly a good product.
I have been playing aroud with it for a week or more and one can make nice PCB's with it.

Ulticap/Ultiboard is just more user-friendly.

For example:
One can copy devices, gates as well, using copy paste method.
One can search the device database on device numbers. While one types the individual devices, not "families", are shown.
One can rotate, mirror etc by using a Function key and while moving the component with the mouse.
Juctions are made automaticly... very handy.
It might not look like much difference, Eagle can do this all also, but only by first dropping the component and then using the mouse to click on the appropiate buttons.
Using Function keys halves the design time.

And I miss these "auto delete" of "open ended" traces.
This are traces, copper lines on PBC, that are connected to a component on one side but end somewhere on the board but not at a device.
So it "floats" ... and acts as an antenna.
With Ultiboard one can, with one button, remove these "floating" lines.
Very handy when one wants to remove a complete or part of a net.

But again, Eagle is a good product, specially for the price they ask.
My main concern is the speed with which I can design and draw.

There are some things I have not yet found out how to do in Eagle, but perhaps there might be a way to do it. E.g. How to preset the default trace thickness before starting to route the PCB
Also here, Ulticap can with one click of the F2 button switch from layer, adding a via automaticly.

Pity about the PIC simulation, would have been perfect.
But Ok, one cannot have everything.

I will play around with the AD600 model, thanks very much for the link.

It looks like I will use the free simulator to test small parts of my designs.... also very usefull.

Thanks for the info, Jan.

P.s. What does HTH mean ?
(Happily Transitorized Human ?)

**Nicko** · 11-29-2002, 05:32 PM

Re: Question to all you Spice Guru's

Hi Jan,

Have a look at the Eagle news groups - many of the points you raise can be solved easily - e.g. you can define your own keymapping so that you can make pretty much anything a single key/function key press.

Regarding the trace thicknesses etc. That is set using net classes - very simple - just look in the help for it. You can make the power traces thicker than signal etc. Also the DRC and autorouter are completely configurable, so they can be adjusted as you want.

I've been writing a few on-line calculators - you might like the one below if you are doing power traces - it calculates the width of trace you need to carry certain currents, and the associated power loss.

HTH = Hope That Helps

HTH

Nicko

Nick's trace width calculator

**Jan** · 11-29-2002, 07:06 PM

Re: Question to all you Spice Guru's

Hi Nicko,

I will have another look at the key mapping.
I did some of them, indeed quite easy, but I could not get the key to do its bit when I was still moving the part with the mouse. I have to release the part and then click on it again to for example rotate it, then click on the move button, then click on the part to move it to it final place.
As you see... quite a lot of mouse movements involved.
Perhaps I have to get a kind of "immediate" control in it.
Will have another look at the news groups again.

As I said, I think its a good tool, but sofar I found it lacking "userfriendliness" (Nice Scrabble word)

Nice calculator, will use it when I will design my motor control boards.
My guess is that I will need some 3-5 Amps (Pulsed) so I need some heavy duty traces.

YTH

Jan

**simeon webber** · 12-01-2002, 08:18 PM

Re: Question to all you Spice Guru's

if you want a sim thats good alround then use proteus {still has some bugs and runs slow}
b2 spice is very good for tape type sims {non RT but capture sims}

realtime multisim is good but has no libs no micro support{very poor} and there lcd isnt
there

as for the best this is the best of a good bunch of apps
so therefore i recomend visual spice b2 spice multisim proteus vsm

and stop there

or much better
is too wait 10 years then simulation will be easy stuff with all the new stuff then

but i can tell you i have designed stuff for 10 years
and any is better than none
there fore i use cheep easy to use abacom apps for drawing shareware proteus {although ill buy the full version soon to get reasonable code limits
and b2 spice full pro web version {there selling it cheep just now}

the libs are good anyway spice is easy too use and build new models
but coils are hard to model i use a resistor for the load this solves the problem
if you find it burns out use two

a light bulb 100w 240 v also makes a good load in spice for fet stages

as for the rest

you need to break designs into blocks

discrimination frontend rx tx etc

and test each part optimising as you go

you need to first take a step back and make a plan of action and procedures

as for micro simulate just the chip giving input where needed even if it takes using another micro to give signals you can definatly rely on for levels and output timing

i hope this helps

other than too add why ??? use one

all you seem to need is a new cad and pcb
infact why even that

i would start if you like good sims by buying protues but there isis and ares package about 1200 uk£ sterling

this will give rip and retry router autoplacers and all features although some libs are expensive

or look on the net for a poor mans "demo" version of proteus or b2 spice
i use the shareware cost .....300£ so far
you collect keys like a jailer

but for b2 ther eis no key or licence only install time
so for this reason it is very fast

the rest are rubbish unless you are prepaired to do most of the donkey work

i just hope i helped in any little way

it is such a complex subject to know
but the best is too test

and in small units

**Nicko** · 12-03-2002, 02:19 AM

Re: Question to all you Spice Guru's

Simeon,

I agree with some of what you say, but you can get a full simulation package and CAD for less than USD 100, not USD 300 or even USD 1200.

The Eagle non-commercial offer gives you a 4-layer Eurocard package with great libraries (its easy to add your own components), and excellent on-line support for free (on the news.cadsoft.de server) - also many board houses take Eagle files directly (e.g. Olimex) without going to the Gerber stage, and this saves a huge amount of time. Eagle also runs on Linux, which appeals to some...

SwitcherCADII is FREE, full featured, and very quick to work with. Its also very fast and ACCURATE, which many SPICE products based on the public domain SPICE 3 codebase are not. SWCAD has been completely re-written, and is used by Linear Technology in-house. There are many 10s of 1000s of users, mostly professional. Mike Englehart (sp?) the main author gives a lot of support on sci.electronics.cad and is fanatical about making SWCAD simply the best. It can use most PSPICE models as well...

Most importantly, don't blindly beleive the results of a SPICE simulation. SPICE is tricky stuff, whichever one you use. Many models, even manufacturers models, are either just sometimes inaccurate (especially on boundary condtitions) or plain WRONG. You must be very sceptical, and rely heavily on experience for what you believe...

I've been a professional engineer for 22 years (26 if you include the time doing the degree), and its easier now to get going, as the design tools are so much better. However there are a huge number of areas that are really open for grabs in PI design - I was looking at some late 1970's designs recently, and their input stages are substantially the same as those commonly used now, whilst in the last 20 years the design of low-noise amplifiers has changed radically, as has the availability of new monolithic amplifier designs.

Its time that PI detectors moved on a bit... and that doesn't just mean using a PIC/AVR or whatever - the basic analogue techniques are still vital.

Nicko

**simeon webber** · 12-04-2002, 01:40 PM

Re: Question to all you Spice Guru's

i have a proteus model for the 7660
if others need it ill post on vsm.libs site later....... tonight
i also have some irf XXX models for proteus vsm

that the ones in the package dont work very well {infact some irf mentioned in default lib set have no models
these are fixed and a full rage
will be avalible later.... on vsm.libs

i will happily make {within reason} any model
even some dll's types i can handle ...
let me know by email {other than coils this is easy stuff}

Click Here

**simeon webber** · 12-08-2002, 02:32 PM

Re: Question to all you Spice Guru's

i too agree with your views
esp on cad for analogue simualtion

if you want too spend money

its gota still be proteus {v6 due in 1 month} or multisim {also very good mixed mode but crap for cpu}

although b2 spice and virtual spice are very good at mixed mode
with virual spice having better instuments

but b2 has the best set of libs i could find
there pro demo had everything most with spice {usual spice for mixed mode}

try simulating a pic runing with an opamp on any other cad but proteus
and hahaha no chance.....

i think anything thats free and works has got too be a good.... app to install and use
for anything thats free and works

i have never tried it {but ill download it too view it}
becouse i work out most values of stuff as i go
or as i debug
from experience and books./.. on opamps rf and linear design
{use a calculator too long then your in deep trouble mentaly i know professional guys cant add three 4 digit numbers without one or a bit of paper and 5 mins .... so called degree students.....}

but for any serious micro processor stuff where the odd opamp is needed also digtal logic or bipolar ;fet etc....
or for pure opamp design then i think quite definatly proteus cant be beaten .....

yes 100 $ is a good price
for 100$ of functions

i would personaly rather have 100 features that 96 work with adiquate precision
then no real features and it is accurate for the ones it has
even although the libs are good

the real truth behind librarys is this
it is realy quite simple

most cad makers when they make an app
just lift the lib files from one of there other products
they write there libs file architecture in such a way as too make convertion apps that splice spice cad files like mod's and cir file etc... on to each lib as it converts
as you can imagine this makes the whole lib process much easier

however
some manufatures of cad use a different approch
this is too rebuild an app each major build from the bottom up
this includes the lib sets so this takes too long each time and so for this reason and resorcs limits imposed by changing platforms

the libs are basicaly hand built also from the bottom up each time

this does allow for errors to creap in
with the need for my lib site as a prime example

but in the end makes an "engineer's" lib set varified by the company but mostly constructed and relyed on by the users themself's
stimulating people to make there own adjustemnts and libs {its tooooo easy so dont moan if it isnt there ask someone or make it yourself gaining valuble knowlage of how they work into the process

for a cheep solution to analoge stuff only i will try switchercad to see how it runs on xp... etc....

?do you know is it a multithreaded app {i use multicpu machines ??? and the manufacturers never tell you....}

{my spelling is bad becouse i dont do enough crosswords my own "calculator type" senario}

never let your mind go stail too maths....

just remember

infinity is a ball the geometry of infinity is a cube fits in the ball and inside the cube lives trig as an eq pymarid or parts of the maths as expressions in the form of shapes that make each "master shape"

with algibra and arithmatic our way to describe and compute the shapes

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