Replacing Debug Probes on a Placed and Routed Design Checkpoint - 2023.2 English

Vivado Design Suite User Guide: Programming and Debugging (UG908)

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2023.2 English

When using the Vivado Hardware Manager to debug a design that has been programmed on a device, the nets being probed for debug sometimes need to be swapped for other alternative nets. Instead of going back and changing your RTL code, or changing the nets being probed in the inserted debug cores, you can use the ECO flow to replace the debug nets.

To use the ECO flow, open the placed and routed design checkpoint (DCP), in the Vivado IDE, and change the layout to ECO.

Figure 1. Selecting the ECO Layout

The Flow Navigator now changes to ECO Navigator with a different set of options

Figure 2. ECO Navigator

In the ECO Navigator, click Replace Debug Probes to bring up the Replace Debug Probes dialog box.

Figure 3. Replace Debug Probes Dialog Box

In the Replace Debug Probes dialog box, highlight the probes whose nets you want to change, and click the Edit Probes button. Use the Edit Probes button to the right of each probe to change individual nets. Alternatively, you can use the Edit Probes button on the left edge of the window to change the nets for multiple probes.

Figure 4. Edit Probes Button

Click the Edit Probes button to bring up the Choose Nets dialog box, where you can choose nets to replace the existing ones.

Enter the Find criterion to select the nets you want to replace the existing nets. If the Find criterion returns more than 10000 nets, refine your criterion and try again. Select the preferred nets on the Find Results on the left and click the arrow (->) to add those nets to the Selected Names column on the right. Ensure the nets in the Selected Names column on the right correspond to the number of nets being replaced. Click OK to continue.

Figure 5. Choose Nets Dialog Box

Important: Once you have completed replacing all the debug probes necessary, rerouted them, and regenerated the bitstream, you must regenerate the debug probes file (.ltx).
Tip: You can also choose multiple nets or a bus by clicking on the Edit Probes button on the left in the Replace Debug Probes dialog box.

After you replace all the desired nets on the debug cores, click OK to bring up a confirmation dialog box to confirm the changes about to be made.

Important: Check the Tcl Console to ensure that there are no Warnings/Errors.
Figure 6. Modify Debug Probe Tcl Messages

Deleting any net segment on the path of a net being probed could have an impact on the probe names displayed in the Hardware Manager. Vivado IDE picks the net segment closest to the net being probed with a MARK_DEBUG attribute on it. If there is no net segment with a MARK_DEBUG attribute, the top level net is picked. If there is more than one net segment with a MARK_DEBUG attribute, the tool randomly selects one of those nets.

After you have replaced all the debug probe ports, you can save your modifications to a new checkpoint using the Save Checkpoint As option in the ECO Navigator. The Replace Debug Probes command in the ECO Navigator needs to be run to generate a new .ltx file for the debug probes. You should generate a new bit file to program the device. You can connect to the Vivado Hardware Manager to debug the design with the new changes.