Synthesized Design and Implemented Design - 2021.2 English

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

Document ID
Release Date
2021.2 English
  • Checks for DRCs related to the post synthesis netlist.
  • Checks for I/O, BUFG, and other placement.
  • Basic checks on the attributes wiring on MGTs, IODELAYs, and other primitives.
  • The same DRCs run taking into account any available placement and routing.
  • DRCs have four severities: Info, Warning, Critical Warning, and Error. Critical Warnings and Errors do not block the design flow at this point.

Steps of the implementation flow also run the DRCs, which can stop the flow at critical points. The placer and router check for issues that block placement. Certain messages have a lower severity depending on the stage. These are DRCs flagging conditions that do not stop opt_design, place_design , or route_design from completing, but which can lead to issues on the board.

For example, some DRCs check that the user has manually constrained the package pin location and the I/O standard for all design ports. If some of these constraints are missing, place_design and route_design issue critical warnings. However, these DRCs appear as an ERROR in write_bitstream. The tools will not program a part without these constraints.

The decreased severity earlier in the flow allows you to run the design through implementation iterations before the final pinout has been determined. You must run bitstream generation for a comprehensive DRC signoff.

The following figure shows the Vivado IDE graphical user interface form of Report DRC.

Figure 1. DRC Report

Click a DRC to open the properties for a detailed version of the message. Look in the Properties window to view the details. Most messages have a hyperlink for nets, cells, and ports referenced in the DRC.

Figure 2. Violation Properties Dialog Box

The DRC report is static. You must rerun Report DRC for the report to reflect design changes. The tool determines that the links are stale after certain design operations (such as deleting objects and moving objects), and invalidates the links.

Selecting an object from the hyperlink selects the object, but does not refresh the Properties window. To display the properties for the object, deselect and reselect it.

To create a DRC report in Tcl, run the command report_drc.

To write the results to a file, run the command report_drc -file myDRCs.txt.

Tip: For more information on report_drc, run report_drc -help.