The general library guidelines apply to all library elements (symbols / footprints / models / templates / 3D models). However, these guidelines may be overridden in some cases by specific exceptions described in further sections.
Generic symbols can be used with multiple footprints. They do not have a default footprint assigned. Generic symbols allow flexibility in the design workflow. For this workflow the symbol placed into the schematic is typically selected to fit the intended function instead of fitting a particular part. The footprint assignment happens later when the exact part number is selected. Using generic symbols allows a small number of library symbol elements to represent a very large number of possible component combinations.
An example of the use of generic symbols are the Resistor and Capacitor symbols available in the KiCad library. These symbols do not have an assigned default footprint, as there are many possible compatible footprints.
Many symbols have corresponding footprints where multiple physical pins are connected to a single logical net. It is desirable that in such cases the user only has to connect a single pin in the schematic, and it will automatically route to all the physical pins on the PCB.(This is not only done to reduce clutter in the schematic drawing. The main reason is to move some responsibility for correct connections from the circuit designer over to the library.)
KiCad has separate windows for drawing the schematic ("Schematic Editor"),laying out the board ("PCB Editor"), and editing symbols and footprints ("SymbolEditor" and "Footprint Editor"). KiCad comes with a large library of highquality, user contributed symbols and footprints, but it is also simple to createnew symbols and footprints or modify existing symbols and footprints.
The Choose Symbol dialog lists the available symbol libraries and the componentsymbols contained within them. Basic devices like passive components, diodes,and other generic symbols are found in the Device library. Specific devices,such as a particular LED, may be found in other libraries.
A number of power and ground symbols are available in the Power symbol library.However, there is a shortcut for adding these symbols: click the Add a PowerPort button or use the P hotkey. Thisbrings up the Choose a Symbol dialog, but only displays symbol librariesthat contain power port symbols.
In addition to global symbol and footprint library tables, there are alsoproject library tables for symbols and footprints. Symbols and footprints thatare added to the global tables are available in all projects, while symbols andfootprints in the project-specific tables are available only for that specificproject. Users can add their own libraries to the global library tables or toproject-specific tables.
To maintain high-quality symbol and footprint libraries, KiCad has aKiCad Library Conventions document, which is a set ofguidelines for symbols and footprints. It is not necessary to follow theseconventions for personal libraries, but they are a good starting point.Footprints and symbols in the officiallibrary are required to follow KLC. KLC is used as a basis for the symbol andfootprint in this guide. 2b1af7f3a8