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Xilinx Constraints Guide

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TPSYNC (Timing Point Synchronization)<br />

The TPSYNC (Timing Point Synchronization) constraint:<br />

• Is a grouping constraint.<br />

Architecture Support<br />

Applicable Elements<br />

Chapter 4: <strong>Xilinx</strong> <strong>Constraints</strong><br />

• Flags a particular point or a set of points with an identifier for use in subsequent<br />

timing specifications. If you use the same identifier on several points, timing<br />

analysis treats the points as a group<br />

Applies to FPGA devices. Does not apply to CPLD devices.<br />

• Nets<br />

• Instances<br />

• Pins<br />

Propagation Rules<br />

When the timing of a design must be designed from or to a point that is not a<br />

synchronous element or I/O pad, the following rules apply if a TPSYNC timing point is<br />

attached to any of the following.<br />

• Net<br />

The source of the net is identified as a potential source or destination for timing<br />

specifications.<br />

• Macro pin<br />

All of the sources inside the macro that drive the pin to which the constraint is<br />

attached are identified as potential sources or destinations for timing specifications.<br />

If the macro pin is an input pin (that is, if there are no sources for the pin in the<br />

macro), then all of the load pins in the macro are flagged as synchronous points.<br />

• The output pin of a primitive<br />

The output is flagged as a potential source or destination for timing specifications.<br />

• The input pin of a primitive<br />

The input of the primitive is flagged as a potential source or destination for timing<br />

specifications.<br />

• An instance<br />

The output of that element is identified as a potential source or destination for<br />

timing specifications.<br />

• A primitive symbol<br />

Attached to a primitive symbol, TPSYNC identifies the outputs of that element as a<br />

potential source or destination for timing specifications. See the following figure.<br />

<strong>Constraints</strong> <strong>Guide</strong><br />

UG625 (v. 13.2) July 6, 2011 www.xilinx.com 297

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