Situs Routing Strategies

Parent page: PCB Dialogs

Summary

The Situs Routing Strategy dialog allows designers to view Routing setup report and define Routing Strategy before Auto Routing.

Access

Click Auto Route >> All or Auto Route >> All Setup to access this dialog.

Options/Controls

Routing Setup Report

The report lists potential problems that could affect router performance. Where possible, hints are provided in order to advise in the better preparation of the design for autorouting. Any errors/warnings/hints that are listed should be scrutinized and, if needed, the corresponding routing rules adjusted, before proceeding to route the design. It is essential that any routing-related rule violations are resolved before starting the autorouter. Not only can violations prevent routing at the location of the violation, they can also greatly slow the router as it continually attempts to route an unrouteable area.

• Edit Layer Directions - Layer routing direction is specified in the Layer Directions  dialog, which is accessed from the Situs Routing Strategies dialog. All enabled signal layers (defined in the layer stack) will be listed. Choose appropriate layer directions to suit the flow of the connection lines. Situs uses topological mapping to define routing paths, so it is not constrained to route horizontally and vertically. Typically it is best to have outer layers as horizontal and vertical. If, however, you have a multi-layer board with a large number of connections at a '2 O'clock' angle, then set one or more internal layers to have this as the preferred routing direction. The Layer Patterns pass in particular makes use of this information, and choosing the right direction can make a significant difference to routing performance in terms of both time and quality. Note that when you use angled layers you do not need to have a partner layer running at 90 degrees to this layer, since the router will typically route horizontally or vertically if it needs to avoid an obstacle on an angled layer. Avoid using the Any direction - the layer that is chosen to route a connection on is based on how closely the connection is aligned with the layer direction, so this layer becomes the layer of last resort. The Any direction is typically only used on single-sided boards
• Edit Rules - Click this button will pop up PCB Rules and Constraints Editor dialog where allows you add or edit design rules.
• Save Report As - Click this button to save Routing Setup Report.

Routing Strategy

• Available Routing Strategies- 

  Currently defined routing strategies are listed in the lower region of the Situs Routing Strategies  dialog. Click the Add button to access the Situs Strategy Editor  dialog, from where you can specify the passes to be included in a new strategy. The following routing passes are available. The passes can be used in any order, as a guide examine an existing strategy to see the order of passes.

  • Adjacent Memory - This is a connection-level routing pass. It is used to route adjacent same-net pins requiring fan-out, with a simple U pattern.
  • Clean Pad Entries - This is a connection level routing pass. It reroutes out from each pad centre along the longest axis of the pad.
  • Completion - This is a connection level routing pass. It is essentially the same as the Main pass, costed differently to resolve conflicts and complete difficult connections. Examples of costing differences include vias being cheaper and wrong-way routes being dearer.
  • Fan out Signal - This is a component level pass, based on the fanout settings defined by the Fanout Control. It checks for patterns in pads, considers clearance, routing width and via style, then selects a suitable fan out arrangement (inline row, staggered, etc) to meet the requirements defined in the design rule. Fanout is to signal layers only.
  • Fan out to Plane - This is a component level pass, based on the fanout settings defined by the Fanout Control. It checks for patterns in pads, considers clearance, routing width and via style, then selects a suitable fan out arrangement (inline row, staggered, etc) to meet the requirements defined in the design rule. Fanout is to an internal plane layer only.
  • Globally Optimized Main - This is a connection level routing pass. It provides optimal routing. It ignores contentions/violations on its first iteration. It then reroutes connections, with increased conflict costs, until there are no violations remaining. This pass, used in conjunction with the Orthogonal option enabled, can produce nicely routed patterns. Add a Recorner pass to the strategy to provide mitered cornering.
  • Hug - This is a connection level routing pass that reroutes each connection, following existing routing with the minimum clearance possible. The hug pass is used to maximize free routing space. Note that this pass is very slow.
  • Layer Patterns - This is a connection level routing pass. It only routes connections that match a layer direction (within a tolerance). It is costed to hug or follow existing routing to maximize free space.
  • Main - This is a connection level routing pass. It uses the topological map to find a routing path, then uses the push and shove router to convert the proposed path to actual routing.
  • Memory - This is a connection level routing pass. It checks for two pins on different components on the same layer that share X or Y coordinates.
  • Multilayer Main - This is a connection level routing pass. It is similar to the Main pass, but with costs optimized for multilayer boards.
  • Recorner - This is a connection level routing pass that is used to provide mitering of routed corners. This pass is used when the Orthogonal option is enabled for the strategy - essentially overriding it and mitering the corners of each route. If the Orthogonal option is disabled for the strategy being used, there is no need to include a Recorner pass as the autorouter will miter corners by default.
  • Spread - This is a connection level routing pass that reroutes each connection, attempting to spread the routing to use free space and equally space routing when it passes between fixed objects (such as component pads). Note that this pass is very slow.
  • Straighten - This is a connection level routing pass that attempts to reduce the number of corners. It does this by walking along the route to a corner, then from that corner performs a (horizontal/vertical/45up/45down) probe searching for another routed point on the net. If one is found, it then checks to see if this new path reduces the routed length.

• Name - Display the name of the Routing Strategy.

• Description - Display the description of the Routing Strategy.
   

• Add - Click to open Situs Strategy Editor dialog to add a new Routing Strategy.
• Remove - Remove an existing Routing Strategy.
• Edit - Editing a Routing Strategy.
• Duplicate - Duplicate a Routing Strategy.
• Lock All Pre-routes - Check this box will keep all the routes laid previously.
• Rip-up Violations After Routing - Check this box to automatically delete routings which violate design rule after Auto Routing.
• Route All - Click this button to start Auto Routing.