Altera SDC and TimeQuest API - Manual (Page 30)

2–20 Chapter 2: SDC and TimeQuest API Package and Commands
sdc
SDC and TimeQuest API Reference Manual © December 2009 Altera Corporation
remove_clock_uncertainty
Usage
remove_clock_uncertainty -from <from_clock> -to <to_clock>
Options
-from <from_clock>: Valid destinations (string patterns are matched using Tcl string
matching)
-to <to_clock>: Valid destinations (string patterns are matched using Tcl string
matching)
Description
Removes clock uncertainty from a collection of clocks to a collection of clocks. The source and destination
clocks can be any arbitrary collection of clocks. This command removes all uncertainty between two
clocks. If there does not exist uncertainty between two clocks specified in remove_clock_uncertainty, the
command does nothing for those two clocks but continues to attempt to remove uncertainty between other
clocks specified.
The values of the -from and -to options are either collections or a Tcl list of wildcards used to create
collections of appropriate types. The values used must follow standard Tcl or TimeQuest-extension
substitution rules. See the help for use_timequest_style_escaping for details.
Example
set_clock_uncertainty -setup -rise_from {clk1 clk2} -fall_to {clk3 clk4} \
200ps
set_clock_uncertainty -from {clk5 clk6} -to {clk7 clk8} 300ps
remove_clock_uncertainty -from {clk3 clk5} -to {clk4 clk7}