This page is about Eagle¹⁾ Cadsoft, a computer program which helps designing schematic diagrams (schematics) and circuit boards (pcb)²⁾.

During a design process it is sometimes necessary to add components which are not available in the ready supplied libraries. For this, components can be created manually and imported in the design. The method for this requires some fundamental understanding how components are organized in Eagle, both in the application itself as on disk. Guidelines about library design and recommendations how to use consistent nomenclature should help a user to successfully manage such collections of components, upgrade or extend them with other packages.

In the Control Panel within Eagle, one or more library folders may contain libraries with a long list of IC manufacturers, group of generic components or group specific symbols which can be browsed through.
When opening an existing library³⁾, one will observe that an item in such a library has for each device or device breed (i.e. equivalent components sharing the same functions but having different packages and/or symbols) primarily three entities:

• device: The real component, residing in a specific package with a specific symbol
• package: Footprint in the layout
• symbol: Drawing in the schematic

Each of these entities characterize a specific aspect of a component or component breed residing in a library.

The default libraries which come together with the other installation files, can be found when clicking on Options→Directories. On OSX, this is in $EAGLEDIR/lbr, where $EAGLEDIR represents the application installation directory from Eagle. It is important to keep this directory unchanged, as software updates may overwrite files in this folder.
A suitable location to put your own libraries in, would be in a subfolder within your Eagle projects folder like the following structure:

• $Home/Backup/eagle
  • eagle_custom_libraries
    • dev_mylibrary1
    • dev_mylibrary2
  • eagle_projects
    • Arduino
    • PowerSupply
    • etc.

In order to make Eagle aware of the main custom libraries folder, just add the directory in Options→Directories. Any subfolders within this folder will be automatically used as well. For example:

$EAGLEDIR/lbr:$HOME/Backup/eagle/eagle_custom_libraries

While we are configuring the libraries folder, one could do something similar for the projects folder:

$HOME/Backup/eagle/eagle_projects:$EAGLEDIR/projects/examples