Viewing Simulation Waveforms - 2023.2 English

Vitis High-Level Synthesis User Guide (UG1399)

Document ID
Release Date
2023.2 English

To view waveform data during RTL co-simulation, you must enable the following in the Config File Editor, or the config file:

  • Under tool select xsim as the RTL simulator, or set cosim.tool=xsim in the config file
  • Under trace_level select port or all, or set cosim.trace_level=port in the config file

Vivado simulator GUI opens and displays all the processes in the RTL design. Visualizing the active processes within the HLS design allows detailed profiling of process activity and duration within each activation of the top module. The visualization helps you to analyze individual process performance, as well as the overall concurrent execution of independent processes. Processes dominating the overall execution have the highest potential to improve performance, provided process execution time can be reduced.

This visualization is divided into two sections:

  • HLS process summary contains a hierarchical representation of the activity report for all processes.
    DUT name
    <function name>
  • Dataflow analysis provides detailed activity information about the tasks inside the dataflow region.
    DUT name
    <function name>
    Dataflow/Pipeline Activity
    Shows the number of parallel executions of the function when implemented as a dataflow process.
    Active Iterations
    Shows the currently active iterations of the dataflow. The number of rows is dynamically incremented to accommodate for the visualization of any concurrent execution.
    A stall signal that tells if there were any output stalls experienced by the dataflow processes (the function is done, but it has not received a continue from the adjacent dataflow process).
    RTL Signals
    The underlying RTL control signals that interpret the transaction view of the dataflow process.
Figure 1. Waveform Viewer

After C/RTL co-simulation completes, you can reopen the RTL waveforms in the Vivado IDE by selecting Wave Viewer under the REPORTS header for C/RTL COSIMULATION.

Important: When you open the Vivado IDE using this method, because the waveform was previously generated you can only use the waveform analysis features, such as zoom, pan, and waveform radix.