Any pcb layout programs allow you to import jpeg image as background?

[DarkMatter]

Funny, I could almost swear that somebody recently said...
snip

It is a silly concept."

It is a silly concept. Note how it is not a mainstream package.
You are a silly conceptualizer.

 

[DarkMatter]

Pardon my not being impressed, but, so what? They're still far bigger
than the one mil resolution of even cheap layout programs.

Dude. You are stupid. In order for an 0402 layout to work, the
parts have to be in the right place. That means that the software HAS
to be able to resolve that far if it can do accurate layouts of that
size part. Get a clue.

My original question was: what is different about that layout program
that makes it "more precise" to you?

Go take your meds.

 

[DarkMatter]

I assumed he would be pulling part footprints from the standard
library, and using the photo to help him manually run the traces to
the right pins. I see nothing impractical about it.

It is impractical because people that do layouts do them from
schematics. Also, it would be just as easy to get the part package,
and place it than it would be to get the overlay, then get the part,
then re-scale the overlay to match, then place the part because the
layout package requires it... etc etc etc... When all you should be
doing is grab the part from the library, and place the damned thing,
and then add wires to it (traces dufus).

It is impractical because it is a waste of time.

 

[DJ Delorie]

Dude. You are stupid. In order for an 0402 layout to work, the
parts have to be in the right place. That means that the software HAS
to be able to resolve that far if it can do accurate layouts of that
size part. Get a clue.

I've got plenty of clues. What I'm missing is an answer to my
question, which you seem to be unable to provide. The question is:
what does your layout package do differently, that makes it more
accurate? I know how to do layouts, and I know what a 0402 package
is, what I don't know is what your layout package does differently
that makes it "more accurate". Does it have better resolution than 1
mil? Does it allow for sub-mil positioning? Does it have a better
zoom feature?

Since I use PCB, and have the sources to it, if there's some feature
that makes it "more accurate" I might be able to add that feature to
PCB as well, if only you'd tell me what that feature is.

 

[John Larkin]

It is a silly concept. Note how it is not a mainstream package.
You are a silly conceptualizer.

We bring in DXFs all the time. It's often easier to do the mechanical
side of PC designs in Autocad, then bring them in and use that as a
placement template. This is especially useful when we have to, say,
mate up a PCB with an enclosure. PADS apparently won't import a BMP to
a PCB or a schematic, but it would be handy if it did... we could use
that for logos, cartoon characters, "comments" on schematics, stuff
like that. Most PCB programs are terrible drawing/drafting programs.

John

 

[Dana Raymond]

A fundamental scientific premis: You cannot prove a negative.

Dana Frank Raymond

 

[Dana Raymond]

The vast majority of layouts are done beginning with schematics - in fact it
is essential to ensure that the schematics agree with the wiring of the PCB.
The 'idea' of a circuit is first expressed in schematic form (unless from a
HDL, but thats a different story), hence thats were the PCB design process
begins.

However, there is a very small class of PCB layout package use where one
must copy a PCB. Sometimes this is done by product maintenance people, by
reverse-engineers, or to rescue the development path of a product originally
done in a defunct PCB package (anyone remember Orcad PCB? Yucckkk!).

Dana Frank Raymond

 

[joe]

Circad has a "reverse engineering" mode which lets you import a BMP file as
a background that you can trace over while doing your layout. There are
program features that let you scale the BMP image appropriately on both
axis.

Info is available at www.holophase.com

Wow, this program does exactly what I want. Thank you!!!

joe

 

[joe]

Would the whole PCB fit on your screen? If so, photocopy the image onto a
transparency and tape it to your screen.

Yes I actually tried that briefly before I posted the question, it was
just too cumbersome to work with. I would have to blow up the
transparency image like 8x to be useful, which means I would need to
switch between multiple transparencies.

Someone else suggested circad, which looks like it was custom made for
what I want to do, it has a reverse engineering mode which imports and
scales background images in its layout mode, awesome. I downloaded the
demo, the graphical interface is kinda unique and clunky, but typical
of layout programs.

 

[DarkMatter]

The vast majority of layouts are done beginning with schematics - in fact it
is essential to ensure that the schematics agree with the wiring of the PCB.
The 'idea' of a circuit is first expressed in schematic form (unless from a
HDL, but thats a different story), hence thats were the PCB design process
begins.

That's what I said... Twice now.

 

[DarkMatter]

However, there is a very small class of PCB layout package use where one
must copy a PCB. Sometimes this is done by product maintenance people, by
reverse-engineers, or to rescue the development path of a product originally
done in a defunct PCB package (anyone remember Orcad PCB? Yucckkk!).

Nope. I still see no benefit. A fresh layout with packages pulled
from libraries is easier. Pin spacings are standardized such that I
could use raw pads instead of library parts and do the job easier than
tracing would be as far as I'm concerned.

Layout from scratch is easier. Any physical nomenclature about the
board's application requisites would be maintained. It takes no more,
if not, hardly any more time, and the results are more reliable. We
have several old designs where the new design looks very similar.
They were STILL freshly done layouts. Many had the same schematics.
Of course, our part count is fairly low, because as I stated before,
four layers or less, and we do miniature stuff, so one only has so
much real estate to work with.

Get your application's workspace into the baseline grid resolve that
an early autocad package had or such. Then you'll be there.

Ask the Gerber baby what the tightest resolve the language allows
for is. I think it is one half the smallest aperture size on the
photoplotter.

 

[DarkMatter]

I've got plenty of clues. What I'm missing is an answer to my
question, which you seem to be unable to provide. The question is:
what does your layout package do differently, that makes it more
accurate? I know how to do layouts, and I know what a 0402 package
is, what I don't know is what your layout package does differently
that makes it "more accurate". Does it have better resolution than 1
mil? Does it allow for sub-mil positioning? Does it have a better
zoom feature?

Since I use PCB, and have the sources to it, if there's some feature
that makes it "more accurate" I might be able to add that feature to
PCB as well, if only you'd tell me what that feature is.

It is probably the base level grid that the workspace uses. Some
packages are 2D and layers. Some are 3D environments.

The resolve in the package I described must be sub mil, because the
coordinate display resolves to sub mil accuracy. The minimum grid
step is only one mil, however. For sub mil, the grid would have to be
unsnapped. It shouldn't matter for four layers or less, as I
indicted, it would all one needs. If you need sub mil accuracy, then
even standard PCB manufacturing won't get you there from what I can
tell. Now hybridized articles, and specialized substrates can be more
resolved, sure. Run-o-the-mill PCB runs have a maximum resolve as the
"hairys" will get ya if ya run stuff to close to each other.
Copper dendrites from hell.

 

[DarkMatter]

We bring in DXFs all the time.

Depends on the layout package as to that capability.

It's often easier to do the mechanical
side of PC designs in Autocad, then bring them in and use that as a
placement template.

Actually, many layout packages have fine editors that allow all the
nomenclature required for a package to be rendered. From silk screen
to hidden pin descriptions. It has to be done anyway.

This is especially useful when we have to, say,
mate up a PCB with an enclosure.

Sounds like the lack of a good mech eng, and layout personage.
Hell we can do it from a glance practically.

PADS apparently won't import a BMP to
a PCB or a schematic, but it would be handy if it did... we could use
that for logos, cartoon characters, "comments" on schematics, stuff
like that. Most PCB programs are terrible drawing/drafting programs.

Our time is devoted to turning product and quick time-to-market
stuff, we don't have time for logos anywhere but on the labeling...
so far. Especially in these lean times.

 

[DJ Delorie]

Ok, it sounds like your package is no more accurate than PCB, which
does everything you claim your package does. Or at least, I'm not
going to get any useful information from you about it. In either
case, there's no point in asking you about this any more.

If you are the programmer, I am surprised at your entire line of
questioning, from the get go.

I'm not surprised you're too stupid to realize what the question was.
You obviously don't understand enough about pcb layout packages (or
software development) to realize what I was asking.

PCB is at http://pcb.sourceforge.net/

PCB has 1 mil accuracy, both in element sizing and placement, and an
8x zoom (8 pixels = 1 mil). It supports up to 8 layers and a 30x30
inch board. The zoom limits and number of layers are compile-time
constants, so if you need more, it only takes a few minutes to change
them. Also included is autoplace, a gridless autorouter, and a trace
optimizer. Output formats are Postscript and RS-274X, including full
support for masks, paste, and silk on both sides.

 

[DJ Delorie]

The resolve in the package I described must be sub mil, because the
coordinate display resolves to sub mil accuracy. The minimum grid
step is only one mil, however. For sub mil, the grid would have to be
unsnapped.

Ok, this is useful information. No, PCB doesn't have sub-mil spacing,
even off-grid.

 

[Terry]

DarkMatter threw some tea leaves on the floor

Dude. You are stupid.

Moronic accusation of the *century*.

In order for an 0402 layout to work, the
parts have to be in the right place. That means that the software HAS
to be able to resolve that far if it can do accurate layouts of that
size part. Get a clue.

How about answering DJ's question ?

Its simple, do you need it repeated ?

Go take your meds.

In other words, you don't *comprehend* DJ's question ?

Be polite to DJ, he's a well respected software author. Who knows, if you
answer his questions, *you* might learn something

 

[John Larkin]

PCB is at http://pcb.sourceforge.net/

PCB has 1 mil accuracy, both in element sizing and placement, and an
8x zoom (8 pixels = 1 mil). It supports up to 8 layers and a 30x30
inch board. The zoom limits and number of layers are compile-time
constants, so if you need more, it only takes a few minutes to change
them. Also included is autoplace, a gridless autorouter, and a trace
optimizer. Output formats are Postscript and RS-274X, including full
support for masks, paste, and silk on both sides.

Sounds like you're storing all coordinates as 16-bit integers. Why not
just use floats? They're about as fast on a modern CPU.

John

 

[DJ Delorie]

Sounds like you're storing all coordinates as 16-bit integers. Why not
just use floats? They're about as fast on a modern CPU.

Historical. The protocol unit for X coordinates is a 16 bit integer.
If anything, we'd change to 32 bit ints measuring 0.0001 inch, but so
far, nobody has needed a board bigger than 30 inches, so there's not
much point in changing it yet.

Plus, floats suck. You can't always store exact decimal values with
them. It's almost always better to use scaled integers instead.
Given that gcc supports 64 bit integers on nearly all platforms,
there's little reason to use floats to hold large integers any more.

 

[nospam]

Sounds like you're storing all coordinates as 16-bit integers. Why not
just use floats? They're about as fast on a modern CPU.

Probably not with all the trouble of almost equal comparisons and having to
convert and round to ints all the time anyway.

The most appropriate unit is probably 1/1270000 inch in 32 bits. That
allows dimensions with 0.1mil and 0.01mm precision to have integer
representations.

 

[Sir Charles W. Shults III]

You assume that his layout package, or that all layout packages have
such features available to them.

He didn't assume anything- he asked a question.

Cheers!

Chip Shults
My robotics, space and CGI web page - http://home.cfl.rr.com/aichip