« Components | gEDA gschem User Guide | Graphics »

## Pins, nets and buses

Connectivity in gEDA schematics and symbols is shown using pins, nets and buses.

- Pins are used in symbols, and represent either a physical pin on an electronic component, or a logical connection to a subcircuit schematic.
- Nets are used in schematics. They represent individual wires, and are used to connect together the pins of components.
- Buses are also used in schematics, and represent “bundles” of multiple nets.

Nets, pins and buses can have attributes attached to them to control how they are interpreted by gnetlist.

### Adding and editing pins

Pins have a connectible end, which is highlighted with a colored swatch, and a static end. Nets can only be connected at the highlighted end.

If you are designing a symbol, see also the Symbol Creation Guide.

To begin adding pins, use Add→Pin. Left-click once to position the connectible end of the new pin, and left-click again for the other end. To finish placing pins, right-click.

If you select a pin, handles will appear for each of its endpoints. You can left-click and drag these with the mouse to change the position of the pin's endpoints.

### Adding and editing nets

Nets are made up of straight net segments, and net connections are formed either where two net segment ends meet, or where a net segment end meets a net segment midpoint. If two net segments cross, they do not form a connection. A net connection is marked by a circular cue, and a disconnected (or “floating”) net end with a square cue.

To add a net segment, use Add→Net. There are two modes for adding nets: normal mode, and magnetic mode (the default). To switch between them, use Options→Toggle Magnetic Net.

- In magnetic mode, new nets snap onto nearby connectible points on pins and nets. The target location that the next net point will snap to is highlighted with a circle.
- In normal mode, new nets snap to the grid like other newly-created objects.

Nets will be added using only combinations of horizontal and vertical segments, unless you hold down the <Ctrl> key, in which case segments at any angle will be used.

Selected nets can be modified by dragging the handles on their endpoints in the same way as pins.

### Adding and editing buses

Since buses are not currently fully supported by gnetlist, buses are commonly used only for documentation purposes.

Like nets, buses are made up of bus segments, follow similar connectivity rules, and can be edited in the same way.

To add buses, use Add→Bus. When adding buses, each new bus segment is constrained to be either horizontal or vertical, unless you hold down the <Ctrl> key. Buses do not support magnetic mode.

When you connect a net to a bus, a “bus ripper” symbol is automatically inserted. This allows two nets to be attached to the same point on a bus from opposite sides without shorting together.