Derive_clocks, Derive_clocks –10 – Altera SDC and TimeQuest API User Manual

Page 20

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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 <period_value> [-waveform <edge_list>]

Options

-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

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

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