set_clock_uncertainty (::quartus::project)
The following table displays information for the set_clock_uncertainty Tcl command:
Tcl Package and Version |
Belongs to ::quartus::project 4.0 |
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Syntax |
set_clock_uncertainty [-h | -help] [-long_help]
[-comment
<comment>
]
[-disable]
[-from
<src_clock_name>
]
[-hold]
[-remove]
[-setup]
-to
<dst_clock_name>
<value> |
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Arguments | -h | -help | Short help | ||
-long_help | Long help with examples and possible return values | |||
-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 | |||
-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: 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 Assignments created or modified by using this Tcl command are not saved to the Quartus Prime Settings File (.qsf) unless you explicitly call one of the following two Tcl commands: 1) export_assignments 2) project_close (unless "-dont_export_assignments" is specified) These two Tcl commands reside in the ::quartus::project Tcl package. You must save assignment changes before you run Quartus Prime command-line executables. Note, however, that the Tcl commands "execute_flow" and "execute_module" (part of the ::quartus::flow Tcl package) automatically call "export_assignments" before they run command-line executables. |
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Example Usage |
## Specify a simple setup uncertainty of .3ns ## and a simple hold uncertainty of .1ns set_clock_uncertainty 0.3ns -to clk -setup set_clock_uncertainty 0.1ns -to clk -hold ## Both of the following commands specify a ## simple setup and hold uncertainty of .3ns set_clock_uncertainty 0.3ns -to clk ## or set_clock_uncertainty 0.3ns -to clk -setup -hold ## Specify an interlock setup uncertainty of .3ns ## and an interlock hold uncertainty of .1ns set_clock_uncertainty 0.3ns -to clk -from src_clk -setup set_clock_uncertainty 0.1ns -to clk -from src_clk -hold |
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Return Value | Code Name | Code | String Return | |
TCL_OK | 0 | INFO: Operation successful | ||
TCL_ERROR | 1 | ERROR: Illegal value: <string> -- Specify a positive time value. | ||
TCL_ERROR | 1 | ERROR: You must open a project before you can use this command. |