The Report CDC details can be viewed by looking at the CDC Details section in the report. You can use the detailed report to view the schematic of the selected path (by pressing the F4 key), view the timing report, or generate a new timing report by right-clicking on the individual entry.
You can use the timing reports and schematics to review unexpected CDC paths in the design, to identify incorrect or missing timing exceptions, and to find missing
ASYNC_REG properties. An example of the CDC Detailed Report is shown in the following figure.
Figure 1. CDC Detailed Report
The CDC Detailed Report table includes the following columns:
- Severity: Reports the severity of the CDC Rule as Info, Warning, or Critical.
- ID: The unique identification number of the CDC Rule, as listed in Table 1.
- Description: A short description of the CDC Rule.
- Depth: The number of synchronizer stages found (only applies to synchronizer topologies).
- Exception: The timing exception applied to the CDC path.
- Source (From): The CDC timing path startpoint.
- Destination (To): The CDC timing path endpoint.
- Category: Displays Safe, Unsafe, Unknown, etc.
- Source Clock (From): The name of the source clock.
Note: This column displays only when you click CDC Details (left column of Timing-Report CDC window)
- Destination Clock (To): The name of the destination clock.
Note: This column displays only when you click CDC Details (left column of Timing-Report CDC window)Important: The CDC report can flag issues in some of the Xilinx IPs because the CDC engine does not recognize all possible CDC topologies and does not provide a built-in waiver mechanism. More information can be found in each Xilinx IP Product Guide.