Working with a Compiler Generated Junction Object on a Schematic Sheet in Altium Designer
Parent page: Schematic Objects
Summary
A junction is an electrical design primitive. It is a small circular object used to join intersecting wires (or buses, or signal harnesses) on a schematic sheet. A Compiler generated junction is a junction that is automatically placed by the Auto-junctioning feature when two wires/buses/signal harnesses are connected in a T-type fashion, or when a wire/bus/signal harness connects orthogonally to a pin, power port or other electrical object. This auto-junctioning capability allows you to create electrical connections at junction points without needing to manually define the connections through the placement of manual junctions.
Availability
This type of junction is placed automatically by the Schematic Editor's Auto-junctioning feature. As such, it is not a design object that can be accessed and placed by the user.
Placement
Compiler generated junctions are placed automatically whenever a T-junction occurs during wiring, such as 2 wires/buses/signal harnesses meeting in a T, or a wire/bus/signal harness orthogonally crossing the end of a component pin or another electrical object, such as a Power Port.
Defining a Junction at a Cross Over
When one wire/bus/signal harness crosses directly over another, no connection is created (a compiler generated junction is not automatically placed). If a connection is required in this situation, a Manual Junction must be placed.
Editing
A Compiler generated junction cannot be edited in the usual manner (via a dialog or graphically on the schematic sheet). The display properties of compiler generated junctions are configured on the Schematic - Compiler page of the Preferences dialog, as shown in the image below. Note that disabling the display of compiler generated junctions does not break the electrical connection at that junction point.
Indication of New Auto-Junction Creation
Depending on the affected wiring, performing a drag operation may result in the creation of auto-junctions at new locations. To provide visual feedback on where these new juntion instances will be, hotspots are used. Enable the use of these hotspots, and specify their color - for wires and buses - also as part of your preferences.
Visual Indication of Connectivity Change
While dragging a component, it is possible to inadvertently drag a little to far, or off-course, resulting in an unintended auto-junction, and a potentially fatal change to the connectivity of a circuit. To provide a timely and graphical indication of the status of connectivity while performing a drag, a couple of icons are used:
- OK - the drag operation is not altering the connectivity of the circuit.
- Alert - the drag operation is causing a change to the connectivity of the circuit.
The applicable icon is displayed near to the cursor as you drag.