4.1.34.1. derive_clock_uncertainty (::quartus::sdc

Intel® Quartus® Prime Pro Edition User Guide: Scripting

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ID 683432

Date 4/03/2023

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Visible to Intel only — GUID: reference_TCL_tcl_pkg_sdc_ext_ver_2_0_cmd_derive_clock_uncertainty

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4.1.34.1. derive_clock_uncertainty (::quartus::sdc_ext)

The following table displays information for the derive_clock_uncertainty Tcl command:

Tcl Package and Version	Belongs to ::quartus::sdc_ext
Syntax	`derive_clock_uncertainty [-h \| -help] [-long_help]` `[-add]` `[-overwrite]`
Arguments	`-h \| -help`		Short help
	`-long_help`		Long help with examples and possible return values
	`-add`		Adds results to user-defined clock uncertainty assignments
	`-overwrite`		Overwrites user-defined clock uncertainty assignments
Description	Applies inter-clock, intra-clock and I/O interface uncertainties based on timing model characterization. This command calculates and applies setup and hold clock uncertainties for each clock-to-clock transfer found in the design. The calculation of the uncertainties is delayed until the next update_timing_netlist call. To get I/O interface uncertainty in addition to inter-clock and intra-clock uncertainties, create a virtual clock to represent an off-chip clock for input or output delay specification and assign delays to input/output ports with set_input_delay and set_output_delay commands that specify the virtual clock. If set_input_delay and set_output_delay commands specifying a non- virtual clock are called, derive_clock_uncertainty applies either inter-clock or intra-clock uncertainty for that clock transfer since those transfers represent a clock-to-clock domain rather than an I/O-to-register clock domain. The set_clock_uncertainty calls will override the derived values for a source clock and destination clock pair unless either the set_clock_uncertainty command or the derive_clock_uncertainty command specified the -add option, in which case the values are added. Specifying the -overwrite option will instead cause all set_clock_uncertainty commands to be ignored. Previous set_clock_uncertainty assignments can also be manually removed by using the remove_clock_uncertainty command. Note that this command is called automatically and the user only needs to manually call it to specify the -add or -overwrite options.
Example Usage	# create a virtual clock create_clock -name virtual -period 1 # apply input/output delays with the virtual clock to get # I/O interface uncertainties set_input_delay -clock virtual -add_delay 0 [all_inputs] set_output_delay -clock virtual -add_delay 0 [all_outputs] # call derive_clock_uncertainty. results will be calculated # at the next update_timing_netlist call derive_clock_uncertainty update_timing_netlist
Return Value	Code Name	Code	String Return
	TCL_OK	0	INFO: Operation successful

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Intel® Quartus® Prime Pro Edition User Guide: Scripting

4.1.34.1. derive_clock_uncertainty (::quartus::sdc_ext)