By far the hottest thing in open hardware is the Arduino prototyping board and the various shield modules available for it. It is the platform for small electronics projects and kits. And it’s not just for hobbyists. There is a lot of sophisticated work being prototyped off Arduinos. Wired profiled the company behind the craze.
One thing the article mentions is that Arduino schematics are distributed under CC-By-SA:
Under the Creative Commons license, anyone is allowed to produce copies of the board, to redesign it, or even to sell boards that copy the design. You don’t need to pay a license fee to the Arduino team or even ask permission. However, if you republish the reference design, you have to credit the original Arduino group. And if you tweak or change the board, your new design must use the same or a similar Creative Commons license to ensure that new versions of the Arduino board will be equally free and open.
The article doesn’t mention it, but the company is actually using a combination of GPL, LGPL and CC-By-SA. Their FAQ says “the source code for the Java environment is released under the GPL, the C/C++ microcontroller libraries under the LGPL, and the schematics and CAD files under Creative Commons Attribution Share-Alike licenses.” The schematics are all CC-By-SA.
It’s not clear to me what criteria people consider when they chose between free licenses for hardware schematics. Conventional wisdom on the point is mixed. Some projects use GPL for hardware schematics and designs (e.g. the Open Telephony and RepRap projects). Other projects (like Arduino) go with CC, usually CC-By-SA. So how to choose?
There are a lot of differences between CC and GPL, and the choice depends on a project’s goals. There are definite advantages to each license, including one quite important difference that all hardware hackers should consider:
Source code.
GPL requires passing it on. CC doesn’t. For some hardware projects, the source code to the hardware is the schematic itself. For others (including Arduino and other CC-licensed projects), there is a different source code: the eagle file for the board. Without that file, reworking a design can be difficult or even impossible.
To whatever extent copyright law can guarantee sharing alike in hardware (and I’m somewhat skeptical on that point), people need those eagle files. None of the CC licenses require distribution of source code. If source code is important to your design, you should think carefully about how the GPL might apply to your project’s specific distribution model and whether downstream recipients have any meaningful right to modify if they don’t have source code.