Running Report Clock Domain Crossings - 2025.2 English - UG906

Vivado Design Suite User Guide: Design Analysis and Closure Techniques (UG906)
Document ID
UG906
Release Date
2025-12-10
Version
2025.2 English
Figure 1. Report CDC Dialog Box

You can run the Report CDC command from either the Vivado IDE or the Tcl Console. When you run Report CDC from the Vivado IDE, it provides all the details for the CDC paths between the specified clocks by default.

  1. Select Reports > Timing > Report CDC or use the report_cdc -name cdc_1 in the Tcl Console.
  2. In the Report CDC dialog box, fill in the following fields:
    Results Name
    Enter a name for the report. This name appears in the Timing window or in the file output.
    Equivalent Tcl option: -name <windowName>
    Clocks (From/To)
    Use the Clocks From and To fields to optionally specify the source and/or destination clocks for the CDC analysis. This narrows the scope to specific clocks and creates a more readable report. Click the Browse button to search for clock objects.
    Equivalent Tcl options: -from <clockNames> and -to <clockNames>
    File Output
    Specify a file to write the results. You can choose whether to overwrite the file or append to it.
    Equivalent Tcl options: -file <fileName> and -append
    Options
    Set additional behaviors for the report:
    • Suspend message limits during execution

      Equivalent Tcl option:-verbose

    • Ignore command errors

      Equivalent Tcl option:-quiet

Note: By default, the Tcl version only prints the Summary by Clock Pairs table. To include full CDC path details, add the -details option:
report_cdc -details
Note: Enabling the -details option can generate large reports or log files depending on the design size. Use it only when detailed analysis is needed.