CPLD Schematic Design Guide

Preface

About This Manual

This CPLD Schematic Design Guide provides information on using the CPLD fitter and supported CAE interfaces to create designs for Xilinx CPLD devices. It focuses on schematic design techniques, including making the best use of library components in schematics. For more detailed information about using CPLD with CAE tool interfaces, refer to the following:

Libraries Guide

For related information about CPLD design entry, refer also to the following:

CPLD Synthesis Design Guide

Manual Contents

This manual covers the following topics:

• “Getting Started with Schematic Design” chapter, presents an overview of schematic design for CPLD devices, including a simple example design.
  
  
• “Design Entry Techniques” chapter, describes the fundamental techniques for expressing logic in a schematic design for a CPLD device.
  
  
• “Controlling Design Implementation” chapter, discusses techniques for controlling how various parts of your design are implemented into a CPLD device.
  
  
• “Design Applications” chapter, describes useful techniques for expressing efficient CPLD designs.
  
  
• “Attributes” appendix lists and describes CPLD schematic attributes, which allow access to CPLD architectural features.
  
  
• “CPLD Library Selection Guide” appendix lists all the symbols that may be used in CPLD schematic designs.
  
  
• “Fitter Command and Option Summary” appendix summarizes implementation options of the Design Manager, and lists parameters for the the cpld command.
  
  
• “Simulation Summary” appendix shows how to sumulate from the Design Manager and command line.
  
  
• “Technical Support” appendix lists sources of support Xilinx offers.
  
  

Conventions

This manual uses the following conventions. An example illustrates each convention.

• Courier font indicates messages, prompts, and program files that the system displays.
  
  speed grade: -100
  
  
• Courier bold indicates literal commands that you enter in a syntactical statement.
  
  rpt_del_net=
  
  Courier bold also indicates commands that you select from a menu.
  
  File Open
  
  
• Italic font denotes the following items.
  
  
  • Variables in a syntax statement for which you must supply values
    
    edif2ngd 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 “[ ]” indicate an optional entry or parameter. However, in bus specifications, such as bus [7:0], they are required.
  
  edif2ngd [option_name] design_name
  
  Square brackets also enclose footnotes in tables that are printed out as hardcopy in DynaText^®.
  
  
• Braces “{ }” enclose a list of items from which you choose one or more.
  
  lowpwr ={on|off}
  
  
• A vertical bar “|” separates items in a list of choices.
  
  symbol editor_name [bus|pins]
  
  
• A vertical ellipsis indicates repetitive material that has been omitted.
  
  IOB #1: Name = QOUT'
  IOB #2: Name = CLKIN'
  .
  .
  .
  
  
• A horizontal ellipsis “. . .” indicates that an item can be repeated one or more times.
  
  allow block block_name loc1 loc2 ... locn;
  
  

In addition, Xilinx has created several conventions for use within the DynaText online documents.

• Red-underlined text indicates an interbook link, which is a cross-reference to another book. Click on the red-underlined text to open the specified cross-reference.
  
  
• Blue-underlined text indicates an intrabook link, which is a cross-reference within a book. Click on the blue-underlined text to open the specified cross-reference.
  
  
• There are several types of icons.
  
  Iconized figures are identified by the figure icon.
  
  
  
  Iconized tables are identified by the table icon.
  
  
  
  The Copyright icon displays in the upper left corner on the first page of every Xilinx online document.
  
  
  
  The DynaText footnote icon displays next to the footnoted text.
  
  
  
  Double-click on these icons to display figures, tables, copyright information, or footnotes in a separate window.
  
  
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