set_clock_sense - 2024.1 English

Vivado Design Suite Tcl Command Reference Guide (UG835)

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2024.1 English

Set clock sense on ports or pins


set_clock_sense [‑positive] [‑negative] [‑stop_propagation]
    [‑clocks <args>] [‑quiet] [‑verbose] <pins>


Name Description
[-positive] Specify positive unate (non_inverting) clock sense
[-negative] Specify negative unate (inverting) clock sense
[-stop_propagation] Stop clock propagation from specified pins
[-clocks] List of clocks
[-quiet] Ignore command errors
[-verbose] Suspend message limits during command execution
<pins> List of port and/or pins




Sets clock sense at specified ports or pins. This is used to define the positive or negative unateness at the pin relative to a clock object. However, the specified unateness only applies at a non-unate point in the clock network, at a point where the clock signal cannot be determined. Since the clock signal is not determined, the defined clock sense propagates forward from the given pins.

Note: This command operates silently and does not return direct feedback of its operation.


-positive - (Optional) The unate clock sense is positive (non_inverting).

-negative - (Optional) The unate clock sense is negative (inverting).

-stop_propagation - (Optional) Stop the propagation of clocks in the -clocks argument from the specified pins or ports. Propagation of the clock as clock and data is stopped.

Note: -positive, -negative, and -stop_propagation are mutually exclusive.

-clocks <args> - (Optional) A list of clocks on which to apply the clock sense for the specified pins and ports. If the -clocks argument is not used, the clock sense will be applied to all clocks passing through the specified pins and ports.

-quiet - (Optional) Execute the command quietly, returning no messages from the command. The command also returns TCL_OK regardless of any errors encountered during execution.
Note: Any errors encountered on the command-line, while launching the command, will be returned. Only errors occurring inside the command will be trapped.
-verbose - (Optional) Temporarily override any message limits and return all messages from this command.
Note: Message limits can be defined with the set_msg_config command.

<pins> - (Required) List of ports and pins to propagate the clock sense to.


The following example specifies that only the positive unate paths will propagate through the output pin of the XOR gate as compared with the original clock.

set_clock_sense -positive [get_pins xor_a.z]