Xilinx 8.2i manual Data Sheet Report

Chapter 12: TRACE

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Data Sheet Report

The Data Sheet report summarizes the external timing parameters for your design. Only inputs, outputs and clocks that have constraints appear in the Data Sheet report for verbose and error reports. Tables shown in the Data Sheet report depend on the type of timing paths present in the design, as well as the applied timing constraints. Unconstrained path analysis can be used with a constraints file to increase the coverage of the report to include paths not explicitly specified in the constraints file. In he absence of a physical constraints file (PCF), all I/O timing is analyzed and reported (less the effects of any default path tracing controls). The Data Sheet report includes the source and destination PAD names, and either the propagation delay between the source and destination or the setup and hold requirements for the source relative to the destination.

There are four methods of running TRACE to obtain a complete Data Sheet report:

•Run with advanced analysis (–a)

•Run using default analysis (that is, with no constraints file and without advanced analysis)

•Construct constraints to cover all paths in the design

•Run using the unconstrained path report for constraints that only partially cover the design

Following are tables, including delay characteristics, that appear in the Data Sheet report:

•Input Setup and Hold Times

This table shows the setup and hold time for input signals with respect to an input clock at a source pad. It does not take into account any phase introduced by the DCM/DLL. If an input signal goes to two different destinations, the setup and hold are worst case for that signal. It might be the setup time for one destination and the hold time for another destination.

•Output Clock to Out Times

This table shows the clock-to-out signals with respect to an input clock at a source pad. It does not take into account any phase introduced by the DCM/DLL. If an output signal is a combinatorial result of different sources that are clocked by the same clock, the clock-to-out is the worst-case path.

•Clock Table

The clock table shows the relationship between different clocks. The Source Clock column shows all of the input clocks. The second column shows the delay between the rising edge of the source clock and the destination clock. The next column is the data delay between the falling edge of the source and the rising edge of the destination.

If there is one destination flip-flop for each source flip-flop the design is successful. If a source goes to different flip-flops of unrelated clocks, one flip-flop might get the data and another flip-flop might miss it because of different data delays.

You can quickly navigate to the Data Sheet report by clicking the corresponding item in the Hierarchical Report Browser.

•External Setup and Hold Requirements

Timing accounts for clock phase relationships and DCM phase shifting for all derivatives of a primary clock input, and report separate data sheet setup and hold requirements for each primary input. Relative to all derivatives of a primary clock input covered by a timing constraint.

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