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Xilinx Synthesis Technology User Guide

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Contents<br />

About This Manual<br />

Conventions<br />

XST <strong>User</strong> <strong>Guide</strong><br />

Manual Contents ...........................................................................iii<br />

Additional Resources ....................................................................iv<br />

Typographical ................................................................................vii<br />

Online Document ..........................................................................viii<br />

Chapter 1 Introduction<br />

Architecture Support .....................................................................1-1<br />

XST Flow .......................................................................................1-1<br />

Chapter 2 HDL Coding Techniques<br />

Introduction ...................................................................................2-2<br />

Signed/Unsigned Support .............................................................2-13<br />

Registers .......................................................................................2-13<br />

Log File ....................................................................................2-14<br />

Related Constraints .................................................................2-14<br />

Flip-flop with Positive-Edge Clock ............................................2-15<br />

VHDL Code .........................................................................2-15<br />

Verilog Code .......................................................................2-16<br />

Flip-flop with Negative-Edge Clock and Asynchronous Clear ..2-16<br />

VHDL Code .........................................................................2-17<br />

Verilog Code .......................................................................2-18<br />

Flip-flop with Positive-Edge Clock and Synchronous Set ........2-18<br />

VHDL Code .........................................................................2-19<br />

Verilog Code .......................................................................2-20<br />

Flip-flop with Positive-Edge Clock and Clock Enable ..............2-20<br />

VHDL Code .........................................................................2-21<br />

Verilog Code .......................................................................2-22<br />

4-bit Register with Positive-Edge Clock, Asynchronous Set and Clock<br />

Enable ......................................................................................2-22<br />

VHDL Code .........................................................................2-23<br />

Verilog Code .......................................................................2-24<br />

Latches ....................................................................................2-24

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