Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronic Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

altium gerbers and the gerbv free viewer

Status
Not open for further replies.

buenos

Advanced Member level 3
Joined
Oct 24, 2005
Messages
956
Helped
40
Reputation
82
Reaction score
21
Trophy points
1,298
Location
Sunnyvale, California, USA
Activity points
9,073
gerbv

hi

i have extracted some gerber files from the altium designer, and opened with the opensource gerberviewer program, the GERBV. ( http://gerbv.sourceforge.net/ )
the problem is, if i open a signal layer, some of the via pads are bigger than they really are in the design. actually i have observed that these pads connect to the plane layers, and they have bigger pad diameters on plane layers, but the gerbv shows the pad diameter from the plane on the signal layers. If i open the gerbers with the viewmate, the pads have correct size.

why is it?
 

cyberrat

Advanced Member level 3
Joined
Jun 19, 2001
Messages
898
Helped
86
Reputation
172
Reaction score
41
Trophy points
1,308
Location
In the sewers of the U.K.
Activity points
5,824
@ltium gerbers and the gerbv free viewer

It could be that the apeture is being misread or there is an error converting from imperial to metric (thou/mm) ?

have you tried adjusting the aperture that is in error to the correct size in the Gerber viewer to see the effect?
 

buenos

Advanced Member level 3
Joined
Oct 24, 2005
Messages
956
Helped
40
Reputation
82
Reaction score
21
Trophy points
1,298
Location
Sunnyvale, California, USA
Activity points
9,073
@ltium gerbers and the gerbv free viewer

hi

i dont really understand.

some pads are bigger, some other pads are not. interestingly those are bigger, which have bigegr pads on other layers. but gerber files should contain only one layer / file. i think
 

House_Cat

Advanced Member level 4
Joined
Feb 21, 2002
Messages
1,371
Helped
406
Reputation
812
Reaction score
98
Trophy points
1,328
Location
USA
Activity points
16,422
I would just stay away from Gerbv. Viewmate is a solid product from a big company (Pentalogix) and Gerbv is an open-source program with questionable accuracy.

I can tell you from personal experience that you can trust Viewmate. It is used by many fabs in its full paid form (Viewmaster). I've never heard of anyone having a problem with either Viewmate or Viewmaster. Open source programs are works in progress, and can have many odd problems until they've been widely used and tested for several years.
 

buenos

Advanced Member level 3
Joined
Oct 24, 2005
Messages
956
Helped
40
Reputation
82
Reaction score
21
Trophy points
1,298
Location
Sunnyvale, California, USA
Activity points
9,073
@ltium gerbers and the gerbv free viewer

ok.
the point is, i would like to reuse their opensource code, as a front end in viewing gerber files. i want to try to write my code to that, which would extract spice netlist from the PCB parasitics, for power integrity (later signal integrity too) simulation with an also opensource and free spice program. there is a little chance that i will succed, because i am hardware guy, not a software guy, although i wrote some DOS and DSP related programs in the past.
 

House_Cat

Advanced Member level 4
Joined
Feb 21, 2002
Messages
1,371
Helped
406
Reputation
812
Reaction score
98
Trophy points
1,328
Location
USA
Activity points
16,422
OK then, back to GerbV. Yes, the Gerber files output from Altium contain only one layer per file, unless you opt to include one of the mechanical layers with every file in the "Layers" tab of the Gerber Setup dialog.

Do you see the abnormal pads when you load only one layer into GerbV? Have you tried loading one layer at a time instead of a batch import?

My guess would be that Gerbv is doing something wrong when building the aperture table that causes apertures to be overwritten or merged in batch imports. Bringing the layers in one at a time would allow you to check for differences in Gerbv behaviour between the two different ways of loading the files.
 

buenos

Advanced Member level 3
Joined
Oct 24, 2005
Messages
956
Helped
40
Reputation
82
Reaction score
21
Trophy points
1,298
Location
Sunnyvale, California, USA
Activity points
9,073
@ltium gerbers and the gerbv free viewer

>Do you see the abnormal pads when you load only one layer into GerbV
yes. i have tried even to copy a single layer file into a separate folder, rename it, then open it. it was still bad.
maybe something anaomaly is already in the gerbers but better programs can compensate it.
 

House_Cat

Advanced Member level 4
Joined
Feb 21, 2002
Messages
1,371
Helped
406
Reputation
812
Reaction score
98
Trophy points
1,328
Location
USA
Activity points
16,422
Re: @ltium gerbers and the gerbv free viewer

maybe something anaomaly is already in the gerbers but better programs can compensate it.

That's unlikely. A Gerber file is a simple ASCII file. If it's RS-274X, there's a Dcode table at the beginning of the file, and the data is listed following that table. If it's RS-274D, it's exactly the same only the Dcodes are defined in a separate aperture file. The plot data is grouped separately under each Dcode in either case.

For what you are seeing, either the data for a given Dcode would have to be split into other Dcode areas, or the Dcode table would have to have two different entries for the same aperture. Nethier of those things could exist in the original file and still read OK into a different CAM editor.

The problem has to be in GerbV itself. The first thing I would do is find out what Dcode Gerbv thinks the wrong sized pads are. Using a text editor, I would then look at that pad in the Gerber file itself. You can locate it by using the X,Y coordinates from Gerbv, and then scanning for one or both coordinates in the text editor under the Dcode that I got from Gerbv. Compare that entry to the others that properly plot.

If you want me to take a look at it, zip up the Gerber layer that is screwed up and PM it to me. I won't try to write code for Gerbv, but maybe I can see what's going wrong.
 

buenos

Advanced Member level 3
Joined
Oct 24, 2005
Messages
956
Helped
40
Reputation
82
Reaction score
21
Trophy points
1,298
Location
Sunnyvale, California, USA
Activity points
9,073
@ltium gerbers and the gerbv free viewer

ok thanx.
the guys at gerbv fixed it with the new version 2.1, just it wasnt on the website yet.
 

Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top