Altera Quartus II Scripting - Manual (Page 622)

3–492 Chapter 3: Tcl Packages & Commands
timing_assignment
Quartus II Scripting Reference Manual © July 2013 Altera Corporation
set_clock_uncertainty
Usage
set_clock_uncertainty [-comment <comment>] [-disable] [-from <src_clock_name>] [-hold]
[-remove] [-setup] [-tag <data>] -to <dst_clock_name> <value>
Options
-comment <comment>: Comment
-disable: Option to disable assignment
-from <src_clock_name>: Source clock name
-hold: Option to specify hold time uncertainty
-remove: Option to remove assignment
-setup: Option to specify setup time uncertainty
-tag <data>: Option to tag data to this assignment
-to <dst_clock_name>: Destination clock name
<value>: Amount of expected clock jitter
Description
Specifies simple or interlock clock uncertainty (or clock jitter) used during setup and/or hold time
analysis. The optional source clock <src_clock_name> is specified for interlock uncertainty and is not
specified for simple uncertainty.
You may specify the -setup option, the -hold option, or neither. If neither is specified, then the command
applies to both setup and hold.
The <value> is the expected amount of clock jitter. The format of <value> is "<numerical value><time
unit>", for example, "0.5ns".
The following table displays available time units:
Assignments created or modified by using this Tcl command are not saved to the Quartus II Settings File
(.qsf) unless you explicitly call one of the following two Tcl commands:
■ export_assignments
■ project_close (unless "-dont_export_assignments" is specified)
Time Unit Description
s second(s)
ms millisecond(s)
us microsecond(s)
ns nanosecond(s)
ps picosecond(s)
fs femtosecond(s)
Hz hertz
KHz kilohertz
MHz megahertz
GHz gigahertz