Matrix Color Coding - Matrix Color Coding - 2026.1 English - UG906

Vivado Design Suite User Guide: Design Analysis and Closure Techniques (UG906)
Document ID
UG906
Release Date
2026-06-23
Version
2026.1 English

The matrix in the Clock Interaction report uses color-coded tiles to show the relationship between source and destination clocks.

Use the following steps to view and customize the color coding in the Clock Interaction matrix:

  1. Open the Clock Interaction report.
  2. Locate the color-coded matrix showing source clocks (vertical) and destination clocks (horizontal).
  3. Use one of the following options to adjust background colors:
    • Go to Tools > Settings > Colors > Clock Interaction Chart.
    • Click the gear icon on the Clock Interaction tab to access color settings directly.
    For more information, refer to Specifying Colors in the Vivado Design Suite User Guide: Using the Vivado IDE (UG893).
  4. To hide the color legend, click the question mark icon on the left side of the matrix toolbar.

Color Meanings

Black: No Path
No timing paths exist between the source and destination clocks. There is no clock interaction to report.
Green: Timed
The clocks are synchronous. The timing engine confirms they share a common primary clock and have a simple period ratio.
Dark Blue: User Ignored Paths
User-defined false path or clock group constraints exclude all paths between the source and destination clocks. If you run hold-only analysis with -delay_type min and apply set_max_delay -datapath_only, Vivado classifies the clock pair as Ignored. In that case, the Inter-Clock Constraints column shows Auto Generated False Path.
Light Blue: Partial False Path
False path constraints ignore some paths between the source and destination clocks. The clocks still remain synchronous.
Red: Timed (Unsafe)
The clocks are asynchronous. They do not share a common primary clock or they have an unexpandable period. For more details on asynchronous clock groups, refer to Vivado Design Suite User Guide: Using Constraints (UG903).
Orange: Partial False Path (Unsafe)
This classification is similar to Timed (Unsafe). At least one crossing path is ignored by a false path exception.
Gray: Max Delay Datapath Only
set_max_delay -datapath_only constraint covers all crossing paths.
Important: The matrix color shows the constraint relationship between clocks. It does not show whether timing is met. A green tile means the clocks are properly timed and have a known phase relationship. It does not mean the worst slack is positive.