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Symbol Libraries (Schematic)

Symbol libraries define the electrical symbols used in schematic design. This page covers loading, structure, built-in symbols, and footprint linking.

Loading Symbol Libraries

From the Library panel when a schematic is active:

  1. Click Load Symbols…
  2. Select one or more KiCad symbol files (.kicad_sym).
  3. WireFrame parses the selected files immediately.
  4. Once complete, results are merged into the symbol library map.
  5. Available symbol names appear in a filterable list.

Symbol Loading

Symbol Structure

Each parsed symbol data includes:

Data Description
Pins Name, number, position, angle, length, electrical type (input/output/power), visibility
Graphics Rectangles, polylines, circles, arcs that form the symbol outline
Texts Reference ("R?"), Value, user-defined texts
Properties Footprint (default footprint name), BOM inclusion flags, parent symbol

Pin types

Electrical type Description
Input Signal input pin
Output Signal output pin
Bidirectional Can be input or output
Power Power pin (VCC, GND)
Passive Passive component pin (resistor, capacitor)
Open Collector Output that can only sink current

Symbol inheritance

  • Inheritance resolution merges properties from parent symbols before use.
  • Child symbols inherit graphics and pins from their parent, then override or add to them.

Virtual / Built-In Symbols

The built-in component library and the component manager provide simplified built-in components that don't require external library files:

Symbol Pins Purpose
NetLabel 1 pin at origin Net naming label
VCC 1 pin Positive power rail symbol
GND 1 pin Ground reference symbol
VDD 1 pin Alternative positive power symbol

These are used by the toolbar buttons for quick placement of power symbols and net labels.

Linking Footprints to Symbols

the footprint linking feature associates a default footprint with a symbol in the library:

How it works

  1. Select a symbol in the Library panel.
  2. Use the Link Footprint action (right-click menu or button).
  3. Choose a footprint from the loaded footprint libraries.
  4. The symbol's Footprint property is updated in the .kicad_sym file via an internal process.

Result

  • Future instances of that symbol automatically get the linked footprint in their properties.
  • Existing placed components are not retroactively updated — edit them individually if needed.

Importing Libraries from Other EDA Tools

Importing Altium symbol libraries

WireFrame can convert Altium schematic libraries for use in your projects:

  1. Go to File → Import → Altium Library…
  2. Select an Altium symbol library file (.SchLib or .IntLib).
  3. WireFrame converts the symbols and adds them to your library panel.
Altium format Support
.SchLib Full import — symbols, pins, graphics
.IntLib Extracted and converted (integrated libraries)

Post-import review

After importing Altium symbols, verify pin assignments and footprint links. Some Altium-specific properties may not have a direct equivalent in WireFrame.

Importing Eagle symbol libraries

Eagle library files (.lbr) contain both symbols and footprints. When importing:

  1. Go to File → Import → Eagle Library…
  2. Select an Eagle .lbr file.
  3. WireFrame extracts both symbols and footprints from the file.
  4. Symbols appear in the Library panel when a schematic is active.

Eagle version

Only Eagle XML format (version 6+) is supported for library import.

See Also