There have been efforts in writing a formidable open source license aimed specifically at hardware in the absence of which, the open source hardware projects have to use the GPL and similar licenses which are primarily meant for software. The licenses for hardware have ported the fundamental principles of Open Source Software. A notable attempt at this is the Tucson Amateur Packet Radio (TAPR) Open Hardware License. Some organizations go for shared licenses like Opencores rallying for LGPL, FreeCores for GPL, Open Hardware Foundation voting for “copyleft” etc. It is a licensing agreement for electromechanical parts published under Open Hardware Licenses by the author(s) of the work which shall allow others to use that work for free, without any royalties or licensing fees. It has a certain constraints too, most importantly being the ‘share-alike’ and the ‘attribution requirements’. As mentioned before, an OSS relies on the capabilities of the copyright. But in case of hardware, things are a little tough and hence it has multiple layers available for licensing. These can be:
1. Mechanical Layer: This layer deals with the mechanical description of the project like the enclosure design, materials, units and dimensions, distributed in the form of CAD files (which might be from proprietary vendors like Autocad and Corel Draw). The drawing itself is copyrightable while the content is patentable published in well known formats like PDF, DWG, AI or DXF.
2. Schematic Layer: These are symbolic representations of electronic projects depicting the interconnections between parts. The image is copyrightable, but its content is not. The contents of the image include part lists and numbers and are generally distributed as easily readable graphics formats like BMP, PNG, JPG and PDF.
3. Layout Layer: PCB Layouts, which basically are derived from the schematic itself, further taking into consideration of the various layout requirements like trace widths and lengths, part placements etc. and are employed to create the physical circuit boards. These are distributed as copyrightable vector artwork formats like Gerber/Excellon.
4. Parts Lists and Datasheets: The part lists may be distributed as a part of the schematic (in the form of labeling)or as separate texts along with the datasheets of the components used. These components too should be freely available.
5. FPGA Code: Essentially the ‘software for silicon’, it is the text that defines the chip design. The code is copyrightable.
6. Firmware Code: It is copyrightable software that is burned into the memory to define the particular functions of the microprocessors or microcontrollers.
7. Software: Software that generally sits on top of the firmware for added functionality and is getting very common as embedded computers become commonplace.
The distribution terms of OSHW must comply with the criteria laid down in the license. The hardware release should be accompanied with complete documentation which shall include design files, and allow modifications and distribution of design files, and in case that is not possible, it should be available over well publicized means. It should explicitly show as to what part of the design is being released under the open source hardware license. If in case the hardware uses an embedded code or any software, then the necessary software should either be released under an Open Source Initiative approved open source license or the interfaces should be so documented that it is easy to write open source software for the purpose. The license allows modification of the works and hence, derived works from it along with permission to manufacture sell and distribute the products created from the design files. It shall not stop any party form selling or giving away the documentation and shall not require a royalty or any such fee for the sale. However, the derived documents and copyright notices associated with devices should provide attribution to the licensors and that this information should be accessible to the end-user as well. The license should not discriminate against any individual or group and must not be product specific which restricts hardware or software to a limited licensed works hence showing bias and discrimination. Most of these rules have been adapted or taken as it is from the open source software license.
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