The hardware portion of a design
begins an understanding of the project definition. Components must be
chosen and arranged in manner to achieve the design goal. A schematic is a
pictorial of these decisions. It not only helps in understanding how all
the parts work together but also leads to the development of both a BOM and PCB
layout.
The BOM or 'Bill of Material' identifies each component
with its ID, value, device type, and a number of optional parameters like,
manufacturer, distributor, and pricing info. Once physical parts
have been designated, their physical attributes are known and a PCB or 'Printed
Circuit Board' can be designed.
At this stage packaging must be considered. The
dimensions (shape and material) of the PCB are determined by the packaging it
will go into. The PCB contains the physical placement of each part and the
interconnects (traces) between these components.
The last stage of the hardware design
process is to have the PCBs fabricated. Although any PCB
manufacturer can do this, there are companies that specialize in small prototype
runs. A prototype may consist of only the basic processes to achieve a low
cost testable PCB with no special coatings or nomenclature layers. This
allows a preliminary design to be tested prior to finalizing the design.
It also gives the designer a platform to use for prototyping first
software. Special software may be written to exercise the hardware design
to its fullest extent. If any changes to the design are necessary the
schematics are altered and the whole process is repeated.