An introduction to the open source electronic design (automation) suite.
The purpose of this article is to introduce you to the gEDA design suite - a very powerful and comprehensive set of design tools. Let me assure you, gEDA does work - it is our only tool for generating Gerber files.
A brief background is in order. We are a small design and manufacturing shop with several specialized electronic products. We needed PCBs to be made but did not have the commercial packages that are currently available. We were lured into the “free” solution - vendor specific proprietary software packages - but this locked us into a specific vendor which imposed certain limits on us. As our product line and volume expanded, we knew we had to have more choices available. Since we were already using open source software, we decided to try gEDA. It was a painful start. The unresolved dependencies seemed to be limitless. We finally tracked down everything we needed to get a functioning system and a two-and-a-half-year journey began. Our intention here is to get you going by benefiting from our mistakes.
Your Goal:
You will use the gEDA suite to lay out your schematic and then design a PWB conforming to that schematic and components. The files generated for use by the gEDA suite are in clear text, which is a major advantage when things are not working properly. I will show you how to go into a file and manually fix problems. The final product will generate the Gerber files which are needed by your board vendor.
The first thing you have to do is get the system installed. Here is a brief list of the packages which make up the suite:
gnetlist (1) - gEDA/gaf Netlist extraction/generation
gschem (1) - gEDA/gaf Schematic Capture
gsymcheck (1) - gEDA/gaf Symbol Checker
xgsch2pcb (1) - gEDA/gaf gschem -> PCB workflow GUI
gattrib -creates a BOM in spreadsheet format
Gerbv - Gerber file viewer
PCB - The PCB layout tool GUI
The home page of the gEDA project is http://geda.seul.org/wiki/. Here you can download source codes as well as RPMs for supported systems.
Now, we don’t really wish to participate in the discussions over which distribution to use or which desktop GUI is best. Lets just say that we have tried several different platforms (and desktops) and some play nicer with gEDA than others. When we started this project, we were using SuSe with KDE, and with the assistance of http://rpm.pbone.net/, we were able to get the dependencies resolved. We did get the suite to work well enough for us in this way to get our production boards made.
As our requirements grew we started seeing problems, so to understand the system better we wrote a tutorial as a point of reference. It helped a lot.
The first program you will run is gschem - start it from the command line in a terminal. You will be presented with a nice GUI that is largely intuitive.
You will add schematic symbols to the drawing area, then connect the circuits with lines to represent the wires and/or traces of a PWB. Start gschem to see what it looks like. Don’t get too far along here, as the default schematic representations are not exactly what you will need. When you elect to place a schematic symbol, you will be presented with a library of symbols. The “add component” button is in about the middle of the window, and looks like a two-prong plug. The component selector window opens and presents “folders” with drop down menus. Take some time navigating through the different levels of symbol folders to see what is available. Unfortunately, the menu folders are not a duplicate of the folders that are on the drive, so finding a particular symbol can sometimes be rather frustrating. When you select a symbol, the preview window shows you what will be placed in the drawing area.
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