gEDA/PCB Stuff

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gEDA/PCB Stuff

This page exists so that I can post random notes, ideas, and other pages related to the open source PCB layout editor and other gEDA-related programs.

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Projects

Blue Sky Ideas

Solving the heavy symbol problem - component databases with an attribute lookup API
Pin Mapping - a better way to do gate and pin swapping
Bus Pins - busses in gschem that actually mean multiple signals.
New PCB File Format - High level design doc for a new file/data format.
Layers, Shapes, and Multiboards

Plug-Ins for PCB

Polygon Stitcher - for use with pstoedit, and for cutting holes in polygons.
"Ben Mode" photos for the PNG hid
FindRat
BoardFlip
RenumberBlock
Teardrops

Compile like this:

gcc -I$HOME/geda/pcb-build/src -I$HOME/geda/pcb-build -O2 -shared plugin.c -o plugin.so

Other PCB Stuff

Toner Transfer using Transparencies - some experiments
pbm2escp2.zip - prints 2880 dpi PBM film files to Espon printers.
Spirals Challenge boards
Inkjet notes and experiments
UV LED exposure box
Neck-down example (*.pcb)
Liquid Tin
Dremel Stand
Brass Etching
Hot Plate Experiments
Schmartboard sample

Tips and Techniques

HID

Lesstif HID Sample

What is the HID project? HID stands for Human Interface Device. The idea is to split the PCB sources into the "core" which manages the data structures for the board itself, and the "hids", which includes all GUI, printing, and exporting code. This way, the core doesn't need to know anything about the GUI, for example. There are two primary purposes for doing this: first, it allows us to support multiple GUIs in the same source set, and second, it makes developing new core or gui functionality much easier (for example, the core always uses board coordinates, whereas before, board and GUI coordinates were mixed together).

Goodies

The new PS exporter supports a "bloat" setting where you can compensate for any inaccuracies in the thickness of traces and pads, either because of your printer or your etching process. Positive bloat values make traces and pads slightly thicker, negative values make them slightly thinner. You can download a sample circuit board (looks like this, also gerber and pdf) that has traces of various widths and spacings to help you calibrate your process. Simply print and etch the sample board, and inspect it. The top half has line/space patterns with various bloat settings (-150..150), just find the row that is actually correct (line width same as space width), and use that bloat setting. The bottom half shows different trace widths on various grids so you can judge how well your process handles tiny details. There's also a set of pins for drill sizes 50..80 with 5, 10, 15, and 20 mil annuli.

There's an EPS exporter now, that can be used to create illustrations for documentation, and for converting board layers (manually) to other bitmap formats with ghostview.

The new Postscript exporter emits a single file with multiple pages in it, and supports both fill-page and color options. Samples:

Mono, actual size: PDF 287k PS 500k
Color, fill page: PDF 300k PS 500k

CVS

Since we moved to git.gpleda.org, my local cvs mirror is no longer useful.

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