Cross Probing Between Parent and Child Designs - 2024.1 English

Vivado Design Suite User Guide: Design Analysis and Closure Techniques (UG906)

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2024.1 English

It is necessary to cross probe between designs from the Dataflow Design, to the parent design for various reasons. For example, it might be required to:

  • Cross probe to the parent netlist to see detail that has been trimmed out of the dataflow netlist. This is performed to observe items such as:
    • Cells that are trimmed away
    • Number of pipeline stages between key placement cells
    • To look at placement of cells that are not available in the dataflow netlist
  • Run an analysis that is not available in the dataflow viewer such as:
    • A timing report
    • Congestion analysis using report_design_analysis

Cell cross probing is the most effective way to cross probe. This is done by selecting a cell object in one design and then cross probe by switching the design. When creating the netlist, many nets are renamed so there is no correlation typically between a net in one design and one in the dataflow design.

When cross probing from the dataflow design to the original netlist, all leaf cells in the dataflow viewer are in the parent netlist as the dataflow netlist is a subset of the parent netlist. This results in a successful cross probe. However, going from the parent netlist to the dataflow design is less likely to be successful as this is a subset. Avoid trying to cross probe from leaf cells such as registers or LUTs and instead cross probe using cells that are kept in the dataflow netlist such as Block RAMs, UltraRAMs, DSPs and hard IPs.

The simplest way to switch between designs is to use the Design Switch icon at the top of the screen. This allows a rapid switch to the parent design or the previously used dataflow design. This icon is only available after the dataflow design is created. The icon changes depending on whether the switch is to or from a dataflow design.

The following denote the Switch Design Icons:

  • denotes cross probing to the DFV.
  • denotes cross probing from the DFV.