PCB Auto Router
The PCB Auto Router is a feature of the CAD software that places traces automatically, often saving substantial time and effort. You can use the Auto Router to create your circuit initially or to modify a circuit at a later stage. For example, you might might place several footprints for a mini web server circuit, define nets and then run the Auto Router to create your circuit layout.
To route entire board:- Create nets if not already done.
- Click Tools | Route | All... The Auto Router dialog appears:
- Enter the desired parameters:
Nets to route
Number of nets to route. Click Change... to go to the edit nets dialog to choose nets to be routed.
Number of layers
Number of copper layers on which you want to auto-router to place traces - usually "Two sides".
Minimal gap
Minimum distance between conductors and between conductors and other copper objects. Smaller values improve the chance of fully routing your board.
Width of new traces
Width of traces created during the routing process. Smaller values improve the chance of fully routing your board. This parameter will not affect existing traces.
Use individual trace width for each net
Check to make auto-router use trace widths assigned for each net individually. Click the "Edit widths..." button to go to the Edit nets dialog to specify the trace widths. For a net that doesn't have a trace width specified, the value "Width of new traces" will be used.
Number of passes
The number of times the auto router will try to route your board. Higher values improve the chance of fully routing your board but take longer to complete.
Routing grid
Similar to the snap grid, the routing grid specifies the distance between imaginary grid lines along which the auto router will place conductors. Lower values improve the chance of fully routing your board but creates a higher density of traces and takes longer to run.
Obstacle closeness
Lower values usually improve the chance of fully routing your board but places traces closer to obstacles such as pads.
Trace bend Lower values usually improve the chance of fully routing your board but increases the number of bends in traces. Layer change Lower values usually improve the chance of fully routing your board but increases the number of vias. 45 deg trace
Lower values usually improve the chance of fully routing your board but increases the number of 45 degrees trace segments.
- Click Route.
- The Auto Router runs.
- Click OK to exit.
- Any connections the auto router fails to make will be displayed by unresolved Logical Connections lines (if enabled). Create those connections manually.
To route a footprint:- Create nets for the footprint if not already done.
- Click the footprint to select it.
- Click Tools | Route | Footprint... The Auto Router dialog appears.
- Enter the desired parameters.
- Click Route.
To route a logical connection:- Right click the logical connection.
- Choose "Auto route connection..." from the context menu.
- The Auto Router dialog appears.
- Enter the desired parameters.
- Click Route.
To "unroute", choose Edit | Undo.
Autoroute mode
When the autoroute mode is enabled Pad2Pad will automatically reroute a footprint after it's moved with either the mouse or the arrow keys. To turn the autoroute mode on/off please use the "Auto-route mode..." checkbox in Edit | Preferences | PCB Editor or just click the associated toolbar button. To change the routing settings choose Tools | Route | Settings.
