CHAPTER 5

CASE STUDIES

The purpose of this chapter is to:

• Illustrate the stages in transforming a problem definition into a working solution
• Provide illustrations of typical design tools
• Show the usefulness of hierarchy

We have deliberately chosen elementary examples, which for the most part only use a small portion of a field-programmable gate array (FPGA) chip, apart from the final example of the videostore controller. The problems have been carried out with Xilinx and Algotronix FPGAs, using CAD tools obtained from these companies and ViewLogic Inc. Since CAD software is regularly improved, and command sequences change, any detailed information on particular CAD tools would probably be out of date by the time this book is published. We recommend that you obtain the latest editions of data books, user guides, and so forth, from the companies or their local distributors. At the end of the chapter there are suggestions for projects you might like to try for yourself.

The Xilinx examples have been developed for a generally available demonstration board, which is shown in Figure 5–1. It has eight switches for input, eight individual light-emitting diode (LED) displays for output, and a 7-segment numerical LED display. Some of the examples have been devised to fit this restricted set of circumstances.

Figure 5–1. Xilinx demonstration board. Photograph courtesy of Xilinx, Inc. © Xilinx, Inc. 1991. All rights reserved. (Photograph by P. Crockett)