set_load - 2024.1 English

Vivado Design Suite Tcl Command Reference Guide (UG835)

Document ID
UG835
Release Date
2024-05-30
Version
2024.1 English

Set capacitance on output ports and output pins

Syntax

set_load [‑rise] [‑fall] [‑max] [‑min] [‑quiet] [‑verbose] <capacitance>
    <objects>

Usage

Name Description
[-rise] Specify the rise capacitance value (for ports only)
[-fall] Specify the fall capacitance value (for ports only)
[-max] Specify the maximum capacitance value
[-min] Specify the minimum capacitance value
[-quiet] Ignore command errors
[-verbose] Suspend message limits during command execution
<capacitance> Capacitance value
<objects> List of output ports and output pins

Categories

SDC, XDC

Description

Sets the load capacitance on output ports to the specified value. The load capacitance is used during power analysis when running the report_power command, but is not used during timing analysis.

Tip: The default unit of capacitance is picofarads (pF), but can be changed using the set_units command.

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

Arguments

-max - (Optional) Provided for SDC compatibility. Ignored by the Vivado™ tools.

-min - (Optional) Provided for SDC compatibility. Ignored by the Vivado tools.

-rise - (Optional) Provided for SDC compatibility. Ignored by the Vivado tools.

-fall - (Optional) Provided for SDC compatibility. Ignored by the Vivado tools.

-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.

<capacitance> - (Required) The value of the load capacitance. The value is specified as a floating point value >= 0. The default is 0.

<objects> - (Required) A list of output port objects to assign the capacitance load to. All outputs in the design may be obtained using the all_outputs command.

Examples

The following example sets the specified load capacitance value for all ports:

set_load 5.5 [all_outputs]

The following example sets the rising and falling edge load capacitance for the specified output ports:

set_load -rise -fall 8 [get_ports wbOutput*]