Physical Materials - Building Open Source Hardware - page 154

evant data sheets for each part. It can also include notes about each part as well as an indication of whether it
can be supplemented by a more generic part. Generally, this stack takes the format of a text file or a spread-
sheet, but it can also take the form of a recipe and list ingredients. 2
2 . View the recipe to make conductive dough from Squishy Circuits here: ht-
tp://courseweb.stthomas.edu/apthomas/SquishyCircuits/conductiveDough.htm .
4. Diagram of the physical layout of the electronic circuit: This is the layout dia-
gram, or board file, of the physical elements of the electronic circuitry. It includes
information about placement of the parts, paired with a schematic of the circuit dia-
gram, as well as information about how to make the PCB copper prints for the elec-
tronic schematics. Gerber files give information about the physical layout and gen-
erate the PCB electronics board.
5. Firmware for the microcontroller or processor: This stack documents the source
code and core firmware that runs on a microcontroller chip or the processor itself,
which acts as the brain of the entire system. This is often written in C or as Linux
utilities. Generally, the source code is released as a text file, and it can be down-
loaded directly, or from code repositories such as GitHub. 3 Precompiled executable
binary files are sometimes provided so users don't need to compile from source.
3 . www.github.com
6. Source code for the user interface software stack (e.g., APIs, drivers): If there
is a computer application layer with a graphical user interface (GUI), the source
code that communicates with a computer must be documented, as well as any
drivers necessary for running the software interface.
7. Assembly guide: This layer demonstrates how all pieces fit together. Complex
designs may require an assembly guide to make the hardware replicable.
Along with the just-mentioned layers, depending on the materials used in your hard-
ware, you may need other files as well. For example, in Chapter 16 , Joshua Pearce out-
lines scientific principles, equations, cultural context, and technical specifications as lay-
ers needed in reproducing scientific equipment and learning services. Because open
source hardware is new, layers may be missing for some materials. The most important
take-away message about layering open source principles is to ensure that every part of
your source design is replicable.
A designer can also choose to release additional design files that can help the user
make, use, or modify the device. This can include a handbook, photographs, drawings,
written instruction, use-case scenarios, or other explanations that can assist users.
Documentation for multiple types of design files can be hosted either directly on the
company/product website or on repositories that pertain to different physical elements.