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Overview of KiCAD – free electronics design program.

Categories: KiCAD, Software
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Published on: 13/06/2012

KiCAD is a program for electronics design. It includes schematic editor, PCB editor, Gerber files viewer and some utilities. It has a 3D modelling capability as well, but the render quality is lower than of competitors. Nevertheless it is more than enough for visual design check and enclosure allocation. There are Windows and Linux versions of the program. Also, a Mac OS version exists but it is not stable yet.

The main benefits of the program are its price (free!) and functionality which is not limited compared to free versions of Eagle or DipTrace. KiCAD can work with up to 16 layer PCB and has no limits of its size. There are quite a lot of element and footprint libraries for KiCAD. Also it has well designed editors to quickly make your own ones. The main part of KiCAD concept is separate libraries for elements and footprints. From one side it requires additional step in design to allocate a footprint to an element, but from other hand it adds a lot of flexibility. For instance, we have one schematic symbol for a resistor and we linked a 0805 SMD footprint to it. But during the PCB design we changed our mind and decided to use a 0603 SMD instead. In this case we don’t need to go back and change a schematic. We just change the link. Such a concept allows to have only one footprint of a type (i.e., 0805 or SOT-23) and just link it to a component avoiding to keep and create copies for each. At the first glance I thought that such a concept is not too convenient but I changed my opinion after I had completed the full project cycle from schematic design to Gerber files – it is actually good.

The user interface can be considered as a disadvantage of the program. It is not intuitive enough and requires a manual to do some stuff. But I believe that Eagle has the same issue. This problem appears at the start and almost goes away after one or two projects completed in KiCAD. Good manuals for it can be found here: http://www.kicad-pcb.org/display/KICAD/KiCad+Documentation. Reading them significantly reduces the time to learn the program. Also they have a lot of useful tips.

Generally, the development cycle in KiCAD starts from creating a schematic in “Eeschema” program. Then footprints are allocated in “Cvpcb” program. The next step is to design PCB and prepare Gerber files for production in “PCBNew” program. It is possible to make step back on each stage, make changes and pass them forward. Because there are several programs involved in the design, the understanding of their links is quite important for effective work.

Also, a netlist can be saved in “Spice” and used for a circuit simulation in any program that supports this popular format. It is very easy to create Bills of Materials for its order. It has big list of different options and formats for the output file. “Bitmap2Component” is included into the package which allows creating logos on a silkscreen layer or touching buttons on copper layers. Very useful and convenient “Pcb Calculator” is also included to the package.

Quite big components, footprints and 3D models library is located here: www.kicadlib.org. To create multipin components for schematic I use this great online utility: http://kicad.rohrbacher.net/quicklib.php. It allows to quickly create different types of components for which I use pin names from data copied from a datasheet edited in Excel.

I considered 3D PCB rendering function as a toy at a first glance, but I changed my mind later after I made myself familiar with it and tried to use it. It helped me to find a couple mistakes in my design, so now I use for each design that requires enclosure allocation or just have tight components placement. KiCAD already has most basic 3D models. A lot more can be downloaded from the abovementioned library. Also, most manufactures have 3D models of their components on Internet sites. Unfortunately, they usually use “iges” or “step” formats that are not recognised by KiCAD. It requires “.wrl” format made by “Wings3D” program. It is also a free program but it doesn’t recognise “iges” and “step” formats ether. By the way, it is quite easy to make your own 3D model of a component in this program, especially if you don’t need to highly detail it. I’ll show how to do it quickly in one of my future posts. “Wings3D” can be downloaded here: www.wings3d.com. it is free and can be launched under Windows, Linux or Mac OS. Very good manual for the program can be found here: www.vrspace.org/sdk/vrml/tools/wings3d/wings3d_manual1.6.1.pdf. I highly recommend making familiar with it and understanding the main principles of it before starting to use it. It will save a lot of time.

KiCAD is very good documented, so I don’t see any point to describe its work in further details. But the topic about 3D models preparation for isn’t covered enough, so in the next post I’ll show you how to quickly prepare such a models for it.

I’ve decided to use this program as a main for my hobby projects.

All my posts about KiCAD that exist at the moment can be found here.

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