Contains material © Digilent, Inc. 20 pages Lab #2: Introduction to Computer Aided Design (Schematic Capture Entry) Revised 1_25_10 Overview Computer Aided Design (CAD) tools are an indispensable design resource used by engineers everywhere on a daily basis. Engineers with even basic computer resources can use CAD tools to create a picture-based or text-based definition of a circuit, simulate the circuit, and then implement the circuit in any one of a variety of different technologies. Many CAD tools have been in use for several generations, and are relatively stable and intuitive to use. Other CAD tools are emerging now, with still others just over the horizon. It is safe to say that practicing engineers will need to learn and apply many different CAD tools over their career. This lab exercise introduces the Xilinx ISE/WebPack Computer Aided Design (CAD) tools. These tools can be used to design and test virtually any digital circuit, and to automatically implement such circuits in programmable chips. The Xilinx tools allow circuits to be defined using several different methods - this exercise introduces a graphics-based program to create circuits, and a logic simulator program to verify the circuit’s performance. After design and verification, a chip configuration program can be used to download the circuit to the Digilent circuit board. Before beginning this module, you should… -Be familiar with reading and constructing basic logic circuits; -Understand logic equations, and how to implement a logic circuit from a logic equation; -Know how to operate Windows computers and Windows programs. After completing this module, you should… -Understand how basic CAD tools are used in basic circuit design; -Be able to implement any given combinational circuit using the Xilinx ISE schematic editor; -Be able to simulate any logic circuit using the Xilinx internal simulator; -Be able to examine the output of a logic simulator to verify whether a given circuit has been designed correctly. This module requires: -A Windows PC -The Xilinx ISE software -A Digilent BaSYS boardLab #2: Introduction to Computer Aided Design Contains material © Digilent, Inc. 2 The Design Process The availability of CAD tools has greatly eased the burden of the digital design process. Below is a diagram of the design process within a CAD system.Lab #2: Introduction to Computer Aided Design Contains material © Digilent, Inc. 3 Most CAD tools have the functionality to provide the designer the capability to do all of the above steps within one software package. Xilinx provides the designer the capability within its Project Navigator – this is the outer shell to the CAD tool, the part that allows the user to seamlessly bring all of these complex tasks together. Every design is developed as part of a project. The Project Navigator allows the designer to access any part of the project providing a shell and allowing many of the underlying details of the process to be hidden. This allows a beginning designer the capability to quickly learn about the design process without being burdened with all of the details. Two following procedures, Schematic capture and Test bench waveform simulation, will lead the reader through the development of a project using schematic capture as the design entry method. A. Creating a new Xilinx ISE Project using Schematic Capture a) Project Creation 1. Open the Xilinx ISE Program Navigator program by clicking on the ISE icon on the desktop window or from the Start button window. 2. Using the File pulldown menu, choose “New project”. Make certain to choose “New Project” and not just “New”Lab #2: Introduction to Computer Aided Design Contains material © Digilent, Inc. 4 Enter a name, (lab2 would be a good name) and location (C:\ece3714\labs\lab2) for your project. You may want to use separate directories for each project. Select the top level source as Schematic. Click Next> 3. Enter the Device Properties for the project like following figureLab #2: Introduction to Computer Aided Design Contains material © Digilent, Inc. 5 4. Click Next> at the bottom of the Device Properties window. b) Design Entry Once the project has been created, the design of the circuit can be added to the project. Design entry can be implemented using either Schematic capture or an HDL. Initially the design will be entered using schematic capture. 5. Click “New Source” in the Create New Source window. 6. Select “Schematic” as the Source type and 7. Type in a name (it can be the same or different than the project name) For BaSYS board Users Package: TK144 Speed: -5 Other options are the sameLab #2: Introduction to Computer Aided Design Contains material © Digilent, Inc. 6 8. Make certain that Add to Project is checked. 9. Click Next> or Finish> 10. You may get a window asking if you want to create the new directory. Click OK. You will then get the Select source type window again. Just click Next. 11. Click “Next” or “Finish” in the New Source Wizard Summary Window. 12. We will add the Constraints source that maps the names to the pin names, so click Add Source on the Add Existing Sources window. 13. . Make certain you have downloaded the “BaSYS_ECE3714.ucf” file from the lab webpage. Browse to the directory where it is located and double click to add it. 14. Notice that BaSYS2_3714.ucf is listed as copied to the project. Click Next> 15. Click Finish in the project summary for the project to be created.Lab #2: Introduction to Computer Aided Design Contains material © Digilent, Inc. 7 16. You should get a message concerning the Adding Source Files.. with BaSYS2_ECE3714.ucf listed. It should be listed as Synthesis/Implementation Only. Click OK. 17. You should now have the Design Summary on the ISE Window. 18. Note the location of the Sources, Processes, Transcript, and User Interface windows on the ISE screen. With the Design Summary open in the User Interface window, there are two additional rectangles for FPGA Design Summary and Project Properties. 19. These Sources, Processes, Transcript and User Interface windows can be moved on the screen, sizes changed or deleted. To get a deleted window back, use the ViewLab #2: Introduction to Computer Aided Design Contains material © Digilent, Inc. 8 button at