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geda:gschem_ug:pins_nets_buses [2011/12/15 15:16] peterb [Pins, nets and buses] |
geda:gschem_ug:pins_nets_buses [2014/04/24 01:41] vzh <key> formatting |
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+ | | << [[Components]] | **[[geda:gschem_ug|gEDA gschem User Guide]]** | [[Graphics]] >> | | ||
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+ | ===== 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 [[geda:gnetlist_ug|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. | ||
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+ | <note tip>If you are designing a symbol, see also the [[geda:gschem_symbol_creation|Symbol Creation Guide]].</note> | ||
+ | |||
+ | 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 [[selecting|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. | ||
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+ | 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 <key>Ctrl</key> 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 ==== | ||
+ | |||
+ | <note important>Since buses are not currently fully supported by [[geda:gnetlist_ug|gnetlist]], buses are commonly used only for documentation purposes.</note> | ||
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+ | 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 <key>Ctrl</key> 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. | ||