Intel® Quartus® Prime Pro Edition User Guide: Scripting

ID 683432
Date 12/13/2021
Public

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3.1.24.3. create_relative_clock (::quartus::project)

The following table displays information for the create_relative_clock Tcl command:

Tcl Package and Version

Belongs to ::quartus::project

Syntax create_relative_clock [-h | -help] [-long_help] -base_clock <Base clock> [-comment <comment> ] [-disable] [-divide <integer> ] [-duty_cycle <integer> ] [-entity <entity> ] [-fall] [-invert] [-multiply <integer> ] [-no_target] [-offset <offset> ] [-phase_shift <integer> ] [-rise] [-tag <data> ] [-target <name> ] [-virtual] <clock_name>
Arguments -h | -help Short help
-long_help Long help with examples and possible return values
-base_clock <Base clock> Base clock name
-comment <comment> Comment
-disable Option to disable assignment
-divide <integer> Base clock division factor
-duty_cycle <integer> Duty cycle
-entity <entity> Entity to which to add clock assignment
-fall Option applies to falling edge
-invert Option to invert base clock
-multiply <integer> Base clock multiplication factor
-no_target Option to not assign clock to node
-offset <offset> Offset from base clock
-phase_shift <integer> Phase shift from base clock
-rise Option applies to rising edge
-tag <data> Option to tag data to this assignment
-target <name> Clock node name
-virtual Option to specify the clock as a virtual clock
<clock_name> Clock name
Description

Creates a relative clock that derived from the absolute clock. The "-offset" option can take the format: <floating point time value><time unit> For example, if the offset is 10.55ns, "10.55" is the <floating point time value> and "ns" is the <time unit>. The following table displays possible time units: Time Unit Description --------- -------------- s second(s) ms millisecond(s) us microsecond(s) ns nanosecond(s) ps picosecond(s) fs femtosecond(s) The "-phase_shift" option takes an integer that represents degrees of phase shift from the base clock period. For example, if a base clock has a period of 10ns and clk2 is a relative clock derived from the base clock. A phase shift value of 45 applies a 45 degree phase shift to clk2, producing an offset of 1.25ns from the base clock. For a given relative clock, you may specify a phase shift, an offset, or both. If both are specified, they are additive. If you specify the "-virtual" option, the relative clock is not assigned to any node in the timing netlist. You cannot specify the "-virtual" option and the "-target" option at the same time. For entity-specific assignments, use the "-entity" option to force the assignment to specified entity. If you do not specify the "-entity" option, the value for the FOCUS_ENTITY_NAME assignment is used. If the FOCUS_ENTITY_NAME value is not found, the revision name is used. 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.