Chapter 7
Autorouting and Autoplacement
7-14
ni.com
4.
Edit one or both of the following fields in the
Optimization
area:
•
Change Direction Cost Factor
—A high direction cost factor
limits the number of trace corners the optimizer creates. A low
factor allows frequent changes in routing direction.
•
Equi-Space Trace Cost Factor
—A high value here indicates that
traces will be spread out more during optimization, with a
resultingly higher cost.
5.
If you wish to return the values to the default settings for Ultiboard,
click
Default
.
Caution
The
Default
button sets default values for all tabs in the
Routing Options
dialog
box.
Routing Options: Rip-Up Tab
Complete the following steps to set up rip-up parameters:
1.
Select the
Rip-Up
tab in the
Routing Options
dialog box.
2.
Edit one or more of the fields in the
Rip-up Trees
area:
•
Maximum Rip-Up Trees
—Sets the maximum number of traces
that can be ripped up during each rip-up cycle.
•
Maximum Rip-Up Depth
—Controls the persistence of the
rip-up process. The higher the value you set, the greater the
persistence each rip-up cycle has (that is, the more ways the
placement is analyzed before a final placement is made).
•
Maximum Rip-Up Retries
—Sets the maximum number of
rip-up retries for each trace. The higher the number of retries you
set, the greater the rip-up intensity in each trace.
Note
In general, high rip-up control values increase the persistence and intensity of the
rip-up and routing process. Thus, high values are especially useful for special tasks, such
as achieving 100 percent completion without intermediate router passes.
•
Distance-1 (0 or 1 Grid) Cost Factor
—Controls the use of
channels left by ripped-up traces in the near distance (0-1 grid
point, trace-to-trace). A high value results in infrequent use of
these channels, forcing relatively more local changes during
rip-up and retry routing. A low factor permits the router to use
these channels freely.
