Matrix Color Coding - 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

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

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. To adjust background colors do one of the following:
    • 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, see 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
All paths between the source clock to the destination clock are excluded by user-defined false path or clock group constraints. If you run hold-only analysis (-delay_type min) and apply a set_max_delay -datapath_only constraint, the clock pair is classified as Ignored in the report and as Auto Generated False Path in the Inter-Clock Constraints column.
Light Blue: Partial False Path
Some paths between the source clock to the destination clock are ignored due to false path constraints, but the clocks are still synchronous.
Red: Timed (Unsafe)
The clocks are asynchronous. They do not share a common primary clock or they have an unexpandable period. See Vivado Design Suite User Guide: Using Constraints (UG903) for more on asynchronous clock groups.
Orange: Partial False Path (Unsafe)
Similar to Timed (Unsafe), but at least one crossing path is ignored by a false path exception.
Gray: Max Delay Datapath Only
All crossing paths are covered by a set_max_delay -datapath_only constraint.
Important: The matrix color shows the constraint relationship between clocks, not whether timing is met. A green tile means the clocks are properly timed and that they have a known phase relationship, not that the worst slack is positive.