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Timing
Constraints
User Guide
UG612 (v 11.1.1) April 29, 2009
www.xilinx.com
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Preface
About the Timing Constraints User
Guide
This chapter provides general information about this Guide, and includes:
• “Timing Constraints User Guide Contents”
• “Additional Resources”
• “Conventions”
Timing Constraints User Guide Contents
The Timing Constraints User Guide contains the following chapters:
• Chapter 1, “Introduction to the Timing Constraints User Guide”
• Chapter 2, “Timing Constraint Methodology”
• Chapter 3, “Timing Constraint Principles”
• Chapter 4, “Specifying Timing Constraints in XST”
• Chapter 5, “Specifying Timing Constraints in Synplify”
• Chapter 6, “Timing Constraint Analysis”
Additional Resources
For additional documentation, see the Xilinx
®
website at:
http://www.xilinx.com/support/documentation/index.htm
To search the Answer Database of silicon, software, and IP questions and answers, or to
create a technical support WebCase, see the Xilinx website at:
http://www.xilinx.com/support/mysupport.htm
Conventions
This document uses the following conventions. An example illustrates each convention.
• “Typographical”
• “Online Document”
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Preface: About the Timing Constraints User Guide
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Typographical
The following typographical conventions are used in this document:
Online Document
The following conventions are used in this document:
Convention Meaning or Use Example
Courier font
Messages, prompts, and
program files that the system
displays
speed grade: - 100
Courier bold
Literal commands that you enter
in a syntactical statement
ngdbuild design_name
Helvetica bold
Commands that you select from
a menu
File > Open
Keyboard shortcuts Ctrl+C
Italic font
Variables in a syntax statement
for which you must supply
values
ngdbuild design_name
References to other manuals
See the Development System
Reference Guide for more
information.
Emphasis in text
If a wire is drawn so that it
overlaps the pin of a symbol, the
two nets are not connected.
Square brackets [ ]
An optional entry or parameter.
They are required in bus
specifications, such as
bus[7:0],
ngdbuild [option_name]
design_name
Braces { }
A list of items from which you
must choose one or more
lowpwr ={on|off}
Vertical bar |
Separates items in a list of
choices
lowpwr ={on|off}
Vertical ellipsis
.
.
.
Repetitive material that has
been omitted
IOB #1: Name = QOUT’
IOB #2: Name = CLKIN’
.
.
.
Horizontal ellipsis . . .
Repetitive material that has
been omitted
allow block block_name
loc1 loc2 ... locn;
Convention Meaning or Use Example
Blue text
Cross-reference link to a location
in the current file or in another
file in the current document
See the section “Additional
Resources” for details.
Refer to “Title Formats” in
Chapter 1 for details.
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Conventions
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Red text
Cross-reference link to a location
in another document
See Figure 2-5 in the Virtex-II
Platform FPGA User Guide.
Blue, underlined text
Hyperlink to a website (URL)
Go to http://www.xilinx.com
for the latest speed files.
Convention Meaning or Use Example
