Converting Layouts in the Postscript format

I decided to use Postscript as input format for a number of reasons:

Every layout program should be able to produce postscript
In difference to the Gerber format no aperture table is needed
Using pstoedit it is easily possible, to extract all neccessary data out of a postscript file

Usage

Generate one file for the top side and one for the bottom side. The bottom side must not be mirrored! Both sides must have the same position!
Execute pstoedit (see below how to compile it with the "pcb" driver):
```
~/cnc/pstoedit_3.21/src > ./pstoedit -f pcb 8085b.ps 8085b.dat 
```
"8085b.ps" is the layout and the output file is "8085b.dat".
Check the file "pcberror.dat". Normally it should only contain:
```
Sample header 
Opening page: 1
Closing page: 1
Sample trailer 
```
If some items could not be converted, they will be written into "pcberror.dat"
Use "test_drvpcb" to verify the conversion:
```
~/cnc/pstoedit_3.21/src > test_drvpcb 8085b.dat 8085bv.ps
```
"8085bv.ps" is the data from "8085b.dat" converted back to postscript. The original layout can be compared with this file by using any Postscript viewer.

Restrictions

This program is intended for typical Layout data. There may be lines, rectangles and circles.

By inspecting "pcberror.dat" one can see what items have not been converted.

Output Format

The output format is quite simple, here is an example:

L 289 3855 289 169
R 1844 628 1899 682
F 1871 748 1871 748 55
F 1871 842 1871 842 55
F 1871 935 1871 935 55
.
.
.

Every line of the file contains one Line, Rectangle or Filled line. The syntax is:

L x1 y1 x2 y2
F x1 y1 x2 y2 w
R x1 y1 x2 y2

With (x1/y1) and (x2/y2) as end or corner points and w as the line width. The units are mil (1/1000 inch).

Support for Drill data

If one assumes that every circle or rectangle is a pad with a hole in its center, it is possible to use the layout to get the drill data. With the restriction however that the diameter is not known and that all holes are looked upon as being centered, also it will not work for SMD.

If the used layout-program supports the printing of holes only, then this can always be used to get the drill data (with diameter).

To generate the drill data out of a postscript layout, "pstoedit" with the environment variable

pcbdrv_drill

set to any value different to "no" is used. If the value is a positive number, it will be used as the hole diameter. If the value is anything else (that can not be converted to a number), the diameter is taken from the input file (circle diameter) and only circles are converted.

The output format is then:

D x1 y1 d

"pcb_error.dat" will not be empty if a complete layout is used as input, it contains the lines in this case.

Internals

The following files have been modified / added to the pstoedit distribution:
Makefile.in
drvpcb.h
drvpcb.cpp

After adding these files "pstoedit" can then be compiled as described in the distribution.

See the "pstoedit" Documentation to see how it works. The drivers, in this case "drvpcb" get single paths that must be converted to the output format. "drvpcb" was created by modifying "drvsample". "drvpcb" tries to convert each path into a line, filled line, rectangle or circle. If this fails the original output from "drvsample" is written in "pcberror.dat". See "drvpcb.cpp" for the details. It should be easy to add support for further objects if necessary.

Download

download drvpcb

Hans-Jürgen Jahn 4.09.02