Altera SDC and TimeQuest API - Manual (Page 20)

2–10 Chapter 2: SDC and TimeQuest API Package and Commands
sdc
SDC and TimeQuest API Reference Manual © December 2009 Altera Corporation
derive_clocks
Usage
derive_clocks -period [-waveform ]
Options
-period : Speed of the default clock in terms of clock period
-waveform : 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
# Automatically create a 10ns, 60% duty cycle clock on all
# unconstrained clock sources
derive_clocks -period 10 -waveform {0 6}