Connecting a Net to a Free External Pin Using Post-Route ECO - 2020.2 English

UltraFast Design Methodology Guide for Xilinx FPGAs and SoCs

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2020.2 English

In some cases you might want to bring a net out to a free device pin for debug using external test equipment. This is possible if the device has a one or more free pins that can be utilized for this purpose.

  1. Launch the Vivado tools, and open the routed design checkpoint.
  2. Click Layout > ECO to switch to ECO mode.
  3. Click Create Port in the ECO Navigator. Select the appropriate IOSTANDARD, and fill in the Name.  In the Location dialog box enter the desired free package pin to be used for debugging. Click OK. A new I/O port appears in the netlist schematic viewer.
  4. Click Create Cell in the ECO Navigator, and select OBUF as the cell type. Give the cell a Name, and click OK.
  5. Hold the Ctrl key and select both the O port on the OBUF in the prior step and the port created in step 3. In the ECO Navigator, click Create Net. Fill in the field for a Name and click OK. This connects the OBUF to the I/O port.
  6. In the schematic viewer, locate the net in your design to be connected to the external port. Hold the Ctrl key, and select both the net from your design and the I pin on the OBUF created in the earlier step.
  7. Click Connect Net in the ECO Navigator to connect the net to the OBUF.

These steps can be repeated for as many nets as are desired. After all of the nets are connected to the desired pins, use the following instructions to launch incremental route and write a new bitstream containing the changes implemented in the previous steps.

  1. Click Route Design in the ECO Navigator. Select Incremental Route, and click OK.
  2. After routing is complete, a new bitstream can be written by selecting Generate Bitstream from the ECO Navigator. If the design contains any Vivado Debug Cores such as ILA or VIO, a new debug probes file should also be written by selecting Write Debug Probes.
    Note: If desired, this routed checkpoint can be saved by clicking Save Checkpoint As under Programing the ECO Navigator.
  3. The new bitstream contains the connection to the I/O ports.