add_condition - 2023.2 English

Vivado Design Suite Tcl Command Reference Guide (UG835)

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2023.2 English

Conditionally execute Tcl commands


add_condition [‑name <arg>] [‑radix <arg>] [‑notrace] [‑quiet] [‑verbose]
    <condition_expression> <commands>


The condition object created.


Name Description
[-name] Assign a unique name (label) to a condition. Multiple conditions cannot be assigned the same name. If no name is specified, then a default label named as condition<id> is automatically created
[-radix] Specifies which radix to use. Allowed values are: default, dec, bin, oct, hex, unsigned, ascii, smag.
[-notrace] Turn off the logging of condition commands
[-quiet] Ignore command errors
[-verbose] Suspend message limits during command execution
<condition_expression> The condition expression when true executes the given commands
<commands> Commands to execute upon condition



Add a condition that is evaluated by a specified condition, <condition_expression>, and runs a series of simulation Tcl commands when the condition is TRUE.

Conditions can be defined prior to starting the simulation. When a condition is added, the simulator evaluates the condition expression anytime a signal change is detected. When a specified condition expression becomes TRUE, the condition commands are run.

The add_condition command returns a condition identifier for the added condition, or returns an error if the command fails.


-name <arg> - (Optional) Provide a unique name for the condition. If no name is specified, then a default named is automatically created.

-radix <arg> - (Optional) Specifies the radix to use for the value of the condition. Allowed values are: default, dec, bin, oct, hex, unsigned, ascii, or smag (signed-magnitude).

Note: The radix dec indicates a signed decimal. Specify the radix unsigned when dealing with unsigned data.

-notrace - (Optional) Disable the logging of condition <commands> that are run when the condition is TRUE.

-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.

<condition_expression> - (Required) Specify an expression for the condition. If the condition evaluates to true, the simulation will run the specified <commands>. Specific operators that can be used in condition expressions are "equal" (==), and "not-equal" (!=). Numeric comparison operators <, >, <=, and >= can also be used. Multiple filter expressions can be joined by AND and OR (&& and ||).

<commands> - (Required) Specify the Tcl commands or Tcl procedure to run when the <condition_expression> is true. This command is surrounded by {} (braces). The command can include standard Tcl commands and simulation Tcl commands, except run, restart, and step. Tcl variables used in the condition expression are surrounded by quotes "" instead of {} so variable substitution can be performed. Refer to the Vivado Design Suite User Guide: Using Tcl Scripting (UG894) for more information on variable substitution.


The following example defines a condition named resetLow, that becomes true when the reset signal is low, and then puts a message to the standard output, and stops the current simulation:

add_condition -name resetLow {/testbench/reset == 0 } {
puts "Condition Reset was encountered at [current_time]. Stopping simulation."
stop }

This next example defines a Tcl procedure, called myProc, that uses the add_force command to define clk and reset signal values, and print a standard message when it completes. A condition is then added that calls myProc when reset is low:

proc myProc {} {
  add_force clk {0 1} { 1 2} -repeat_every 4 -cancel_after 500
  add_force reset 1
  run 10 ns
  remove_force force2
  puts "Reached end of myProc"
add_condition -radix unsigned /top/reset==0 myproc