12.1. Overview

12.1. Overview

A component consist of the following elements

• A graphical representation (geometrical shapes, texts).
• Pins.
• Fields or associated text used by the post processors: netlist, components list.

Two fields are to be initialized: reference and value. The name of the design associated with the component, and the name of the associated footprint, the other fields are the free fields, they can generally remain empty, and could be filled during schematic capture.

However, managing the documentation associated with any component facilitates the research, use and maintenance of libraries. The associated documentation consists of

• A line of comment.
• A line of key words such as TTL CMOS NAND2, separated by spaces.

• An attached file name (for example an application note or a pdf file).

  The default directory for attached files:

  kicad/share/library/doc

  If not found:

  kicad/library/doc

  Under linux:

  /usr/local/kicad/share/library/doc

  /usr/share/kicad/library/doc

  /usr/local/share/kicad/library/doc

Key words allow you to selectively search for a component according to various selection criteria. Comments and key words are displayed in various menus, and particularly when you select a component from the library.

The component also has an anchoring point. A rotation or a mirror is made relative to this anchor point and during a placement this point is used as a reference position. It is thus useful to position this anchor accurately.

A component can have aliases, i.e. equivalent names. This allows you to considerably reduce the number of components that need to be created (for example, a 74LS00 can have aliases such as 74000, 74HC00, 74HCT00…).

Finally, the components are distributed in libraries (classified by topics, or manufacturer) in order to facilitate their management.