derive_clocks

derive_clocks

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The following table displays information for the derive_clocks Tcl command:

Tcl Package and Version

Belongs to ::quartus::sdc 1.5

Syntax

derive_clocks [-h | -help] [-long_help] -period <period_value> [-waveform <edge_list>]

Arguments

-h | -help	Short help
-long_help	Long help with examples and possible return values
-period <period_value>	Speed of the default clock in terms of clock period
-waveform <edge_list>	List of edge values

Description

Creates a clock on sources of clock pins in the design that do not
already have at least one clock sourcing the clock pin. This command
is equivalent to calling create_clock on each clock source in the
design that does not already have a clock assigned to it.

See the help for create_clock for more information.

Altera does not recommend using this command during final sign-off
analysis of a design. derive_clocks should only be used early in the
design phase when the clocks are not completely known. When possible,
create_clock and create_generated_clock should be used instead.

Example Usage

# Automatically create a 10ns, 60% duty cycle clock on all
# unconstrained clock sources
derive_clocks -period 10 -waveform {0 6}

Return Value

Code Name	Code	String Return
TCL_OK	0	INFO: Operation successful

 

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