Allegro Front to Back User Guide

Allegro Front-to-Back User Guide Capturing Physical Constraints October 2019 61 Product Version 17.4-2019 © 1999-2019 All Rights Reserved. Using Constraint Manager with PCB Editor Constraint Manager is a spreadsheet-based application with an easy-to-use interface for entering constraints. Another advantage of using Constraint Manager is that it allows you to create generic constraints that you can apply to multiple nets or Xnets at the same time. These reusable constraints are called CSets (Constraint Sets). At a later point in time, if your design requirements change, you can edit the generic rule. The updated rule will be automatically applied to the nets or Xnets that refer to the rule.The existing routes will not modify, but may show DRCs. Sharing Constraint Details with Schematic Design Tools If you have made changes to the design in physical layout tool, the logical design needs to be updated with these changes, to ensure that the designs are synchronized. This flow of constraints and other data from Allegro PCB Editor to logic design tools is referred to as back- to-front flow. To update the logical design with the modifications in the physical layout of the design, use Import Physical command from the logic design tools. The files that are read by the logic design tools, while importing changes communicate component, part, function, pin, and electrical constraint information. For more information on the files used in the back-to-front flow, see the section Back to Front Constraint Flow in Allegro Constraint Manager User Guide. Constraint Manager provides the following functionality: ■ Creating topology files to use with electrical constraint sets ■ Importing electrical constraint sets ■ Assigning electrical constraint sets to buses, differential pairs, and XNets The layout editor designs begin with default constraint sets (named DEFAULT) for spacing and physical constraints. However, electrical constraint sets do not have a default. You can edit the spacing and physical default constraint sets and specify where and to what elements each constraint applies. You can also assign height information to package symbol files (.dra) and to package keepin and package keepout areas of a board file (.brd) or substrate design file (.mcm). For more information about constraints in PCB Editor, Allegro Constraint Manager User Guide for Constraint Manager connected to Allegro PCB Design.

• Cover
• c contents - Contents
• Preface
• About the Front-to-Back Flow
• How This Book is Organized
• Creating and Managing Libraries
• Allegro Front-end Tools Libraries
• Library Structure
• Creating and Managing Libraries
• OrCAD Libraries
• Capturing Logical Design
• Creating Project Using Allegro Tools
• System Capture
• You can also perform other page manipulation operations, such as creating a new page or deleting an existing page from the Project viewer. You can drag and move the pages up and down to change their order in the Project viewer.
• Allegro Design Entry HDL
• Creating Project Using OrCAD Capture
• Creating a Schematic
• Designing Schematic Using System Capture
• Creating Schematic Using OrCAD Capture
• Capturing Logical Designs using DE-HDL
• Capturing Logical Design Constraints
• Why Constraint Manager?
• Using Constraint Manager with Design Capture Tools
• All the constraints are stored in the Constraint Manager Database (CMDB) and saved in the dictionary and constraints file designname.dcf.
• Constraints in System Capture
• Capturing Constraints in Design Entry HDL
• Capturing Constraints in OrCAD Capture
• Creating Variants of Your Design
• Managing Variants in System Capture
• Creating Variants using Variant Editor
• Getting Logical Design Ready for Physical Layout
• Preparing a System Capture Design for Physical Layout
• Preparing a DE-HDL Design for Physical Layout
• Exporting a DE-HDL Design
• Forward Mode
• Preparing an OrCAD Capture Design for Physical Layout
• Exporting an OrCAD Capture
• Annotating the Design
• Packaging Your Design (Advanced)
• Generating a Bill of Materials
• Updating the Schematic With the Changes in the Board
• Passing Properties from the Layout to Schematic
• Designing Layout
• Physical Layout using OrCAD PCB Editor
• Creating a Board Outline
• Creating Symbols and Padstacks
• Importing Logic
• Defining Layers
• Defining Constraints
• Placement
• Routing
• Design Synchronization
• Physical Layout using OrCAD Capture
• Preparing the Schematic for Layout
• Property Flow from Capture to PCB Editor
• Generating Initial Board File
• Backannotation from PCB Editor
• Running Design Rules Check - Physical Rules
• Capturing Physical Constraints
• Using Constraint Manager with PCB Editor
• Synchronizing Schematics and Boards
• Need for Synchronization
• Design Synchronization Tasks
• Feedback Mode