1.8.4.5 Opening VCD File in ModelSim

To view the signals exported by the SmartDebug in the .vcd file, use the Modelsim Waveform window:

  1. Open ModelSim.
  2. Go to the Transcript window and convert VCD to WLF format using the following the vcd2wlf <file1.vcd> <file2.wlf> command as shown in the following figure.
    Figure 1-30. VCD to WLF Conversion
    Important: Conversion errors are most often caused by a nonexistent instance path. Ensure that the instance paths specified are correct.
  3. Open the WLF file created using File menu Open -> file2.wlf.
  4. Select window with wlf file name and add signals to the Waveform window, as shown in the following figure.
    Figure 1-31. Adding Signals
  5. Open the Wave window. Observe that the error signal is not asserted indicating data written and date read from DPSRAM is same, as shown in the following figure.
    Figure 1-32. Wave Window
Important: The Fabric_Debug block includes the match_out signal, which must always be high, indicating that the data expected from DPSRAM and the data read from DPSRAM matches. But the provided design has a bug due to which the match_out signal always toggles. Debug the match_data.v logic using the FHB feature and find the route cause. Add match_out and mem_out of count_chk_0 block to Active probe and export the signals. Observe when the match_out signal is asserted to 1'b0.