Introduction to Digital Design / VHDL

Introduction to Digital Design - Richard E. Haskell & Darrin M. Hanna

This book uses 30 examples to show you how to create digital circuits in VHDL or Verilog and using block diagrams, simulate them, and quickly and download them to your Basys ™ or Nexys2 ™ board. Get up and running quickly - step-by-step, by example!

A major revolution in digital design has taken place over the past decade. Field programmable gate arrays (FPGAs) can now contain thousands of flip flops. Diagrams: The digital circuit has to contain thousands of gates. Reality The languages languages languages languages (HDLs). The most common HDLs used today are VHDL and Verilog. Both are in widespread use. When using logic equations. Boolean logic equations. Computer-aided design tools are used to simulate the VHDL or Verilog design and to synthesize the design to actual hardware.

This book assumes no previous knowledge of digital design. We will use Active-HDL from Aldec to design, simulate, synthesize, and implement our digital designs. A free student edition of Active-HDL simulator is available from Aldec Inc. ( www.aldec.com ). o synthesize your design to a Spartan3E FPGA, you will need to download the Free ISE WebPACK from Xilinx Inc. ( www.xilinx.com ). The XilinX synthesis tools are in the Aldec Active-HDL integrated GUI. We will use the ExPort utility to download your synthesized design to the Spartan3E FPGA. ExPort is part of the Adept software suite that you can download free from Digilent, Inc.




Important Notes on Software and Hardware Versions

This is a program a Basys2 or Nexys2 board, you must use a "front end", a tool to create a source file. Xilinx's free Webpack software contains all the necessary tools, including source file editors, a synthesizer, and downloader. Aldec also produces a free front-end tool that can be used to create source files. Called Active-HDL, this front-end design tool presents a more student-friendly design interface, and it can automatically route design files to Xilinx's back-end tools. The authors recommend Active-HDL due to its more intuitive interface.

If you are using a Basys board, you must use the user constraints file (.ucf) file for the Basys board (basys.ucf) available at http://www.lbebooks.com/downloads.htm

If you are using a Basys2 board, you must use the user constraints file (.ucf) file for the Basys2 board (basys2board.ucf) available at http://www.lbebooks.com/downloads.htm and you must download the Adept 2.1 (or above) software from the Adept Software page.

You can not use Adept 1.10 with the Basys2 board.

Table of Contents:

• Example 1 - Switches and LEDs
• Example 2 - 2-Input Gates
• Example 3 - Multiple-Input Gates
• Example 4 - Equality Detector
• Example 5 - 2-to-1 Multiplexer
• Example 6 - Quad 2-to-1 Multiplexer
• Example 7 - 4-to-1 Multiplexer
• Example 8 - Clocks and Counters
• Example 9 - 7-Segment Decoder
• Example 10 - 7-Segment Displays
• Example 11 - 2's Complement 4-Bit Saturator
• Example 12 - Full Adder
• Example 13 - 4-Bit Adder
• Example 14 - N-Bit Adder
• Example 15 - N-Bit Comparator
• Example 16 - Edge-Triggered D Flip-Flop
• Example 17 - D Flip-Flops
• Example 18 - Divide-by-2 Counter
• Example 19 - Registers
• Example 20 - N-Bit Register
• Example 21 - Shift Registers
• Example 22 - Ring Counters
• Example 23 - Johnson Counters
• Example 24 - Debounce Pushbuttons
• Example 25 - Clock Pulse
• Example 26 - Arbitrary Waveform
• Example 27 - Pulse-Width Modulation (PWM)
• Example 28 - Controlling the Position of a Servo
• Example 29 - Scrolling the 7-Segment Display
• Example 30 - Fibonacci Sequence
• Appendix A - Aldec Active-HDL Tutorial
• Appendix B - Number Systems
• Appendix C - Basic Logic Gates
• Appendix D - Boolean Algebra and Logic Equations
• Appendix E - VHDL / Verilog Quick Reference Guide

Manufacturer: Digilent
Code: 593-002