Hard and Soft Spacing Rules
Hard rules must be followed, soft rules are preferred. You will typically prefer to route with soft rules but if routing fails to converge or detours excessively, hard rules can be applied to relax the requirements. Use set_soft_rule_adherence to choose what level of effort should be applied by the router to satisfy preferred spacing rules. The effort levels are described in the following table.
Soft Spacing Rule Adherence Effort Levels
|
Effort
|
Description
|
Global Router
|
Conduit Router
|
Detail Router
|
|
Maximum
|
Router attempts to apply the soft rule, only abandoning the attempt if it fails to make the connection.
|
Use soft rule.
|
Use soft rule if space is available.
|
Use soft rule, but use hard rule if the point-to-point router fails with the soft rule.
|
|
High
|
Router attempts to make room for soft rules until several passes in detail route.
|
Use hard/soft heuristic algorithm to select where each rule can be applied.
|
Use soft rule if space is available.
|
Use the soft rule check in earlier passes and the hard rule in later passes.
|
|
Medium
|
Router attempts to make room for soft rules at earlier stages but abandons the attempt in detail route.
|
Use hard/soft heuristic algorithm to select where each rule can be applied.
|
Use soft rule if space is available.
|
Collect violations and route to the hard rule.
|
|
Low
|
Router makes little effort to make space for soft rules, but it may use them if there is space available.
|
Use hard rule.
|
Use soft rule if space is available.
|
Collect violations and route to the hard rule.
|
To determine the current router effort level, use get_soft_rule_adherence. To check soft spacing rule adherence by layer and net, use check_route_quality -checks softSpace.
Related Topics
Preparing the Routing Environment
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