Intel® Quartus® Prime Pro Edition User Guide: Timing Analyzer

ID 683243
Date 4/03/2023
Public
Document Table of Contents

3.5.1.7. Report Clock Transfers

The Timing Analyzer's Reports > Clock Domain Crossings > Report Clock Transfers command reports all clock-to-clock transfers in the design. The equivalent scripting command is report_clock_transfers.

Report Clock Transfers generates the Setup Transfers report and the Hold Transfers report that display data about the clock-to-clock transfers.

Figure 53. Setup Transfers Report Shows Clock-to-Clock Transfers

The Setup Transfers report and Hold Transfers report display all possible transfers, including rising clock edge to rising clock edge (RR), falling clock edge to rising clock edge (FR), rising clock edge to falling clock edge (RF), and falling clock edge to falling clock edge (FF) paths.

  • If a path exists in the design, the report column cell is white and lists the number of paths.
  • If a path is a false path, the report column cell is light gray and contains the text "false path."
  • If a path does not exist in the design, then the report column cell is dark gray.

The Setup Transfers report and Hold Transfers report also lists the Worst-Case Slack for setup, the Worst-Case Operating Conditions, and the Clock Pair Classification for each clock path. The Clock Pair Classification includes the following:

Table 9.  Clock Pair Classifications
Clock Pair Classification Definition
Intra-Clock (Timed Safe)
  • From Clock and To Clock are the same.
  • No timing constraint required.
Inter-Clock Synchronous (Timed Safe)
  • From Clock and To Clock relate synchronously, and have a known phase and frequency relationship.
  • Multicycle path constraint may or may not exist.
Asynchronous (Timed Unsafe)
  • From Clock and To Clock are asynchronous.
  • Timing constraints (false path, clock groups, set_max_skew) do not exist.
Ignored (Not Timed)
  • From Clock and To Clock are asynchronous.
  • Timing constraints (false path, clock groups, set_max_skew) exist and setup and hold slack are not applicable.

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