Allegro Front to Back User Guide

Allegro Front-to-Back User Guide Getting Logical Design Ready for Physical Layout October 2019 44 Product Version 17.4-2019 © 1999-2019 All Rights Reserved. You can choose the sequence in which the components of your design are annotated. The Annotation Sequence list contains three options that you can use to decide the sequence in which the objects on your design are annotated — Default, Left to Right, and Top to Bottom. ■ Designating Pins, Gates, or Packages for Swapping For PCB designs, a swap file is a text file containing old and new part references for use with the Backannotate command. Swap files are typically created by another application, such as PCB Editor. You can also create a swap (.SWP) file using any text editor that saves files in the ASCII format. When you are creating a swap file, include only the changes from the present state of the design to the state you want it to have. For example, you might place a part as U1 in the design, and change it in a PCB layout package first to U2, then to U3. The swap file should reflect the change from U1 to U3; do not include the intermediate step involving U2. For gate swaps, ensure that the gates being swapped are of the same type. If they are not, you may get incorrect results. For pin swaps, an additional element — the part reference — must be specified before the old and new values. Pin swap is limited to pins of the same type and shape on the same part. For example, you can swap data pins on U5B, but you cannot swap a pin on U5B with a pin on U5C. ■ Creating an update file The update file is used by the Update Properties tool to determine which objects to change, which of the objects' properties are affected, and what values those properties receive. You can create an update (.UPD) file using any text editor that saves files in ASCII format. The file can include comments; any text to the right of a semicolon is ignored by the Update Properties tool. Strings in the update file (except for comments) must be enclosed in quotation marks and cannot exceed 124 characters. You can use spaces and tab characters to format the update file in rows and columns, as shown in the example below. ■ Creating a Combined Swap and Update File You can create a file that combines the swap file and update file information. Run Backannotate to use a combined swap and update file. Swap and update files should have the same .SWP file extension as normal swap files.

• 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