Published January 2000

THE FOUNDATION ENVIRONMENT

by Ingo Cyliax

Start • Design Flow • Sources and PDF

In this installment, I want to take a look at the design tools you will need to start designing with FPGAs and CPLDs. This is actually a pretty complicated topic, possibly even more involved than the architecture overview I covered last time.

DESIGN TOOLS

FPGA/CPLD vendors are primarily interested in developing what is called the back end. It's the pieces of software you'd need to take a design that has been captured either in schematics or high-level description language (HDL) into a form that can be used to program a part.

However, because the EDA tool industry is fairly dynamic and FPGA/CPLD parts keep evolving, the software developers for back-end tools fight a battle on two fronts. They not only have to develop libraries for different EDA tools and simulators, they have to come up with better fitters and routers for new parts that have more resources and complex architectures. All while maintaining an image that it's "easy."

Evolving interchange standards like EDIFand Verilog/VHDL help standardize interfaces to CAD tools and simulators. For example, a CAD vendor can now provide an EDIF-compatible library of design elements that use Verilog or VHDL to implement the models necessary for simulation environments. Of course, there are still some glitches, but things are getting better.

Realizing that there is a potentially large learning curve, FPGA/CPLD vendors are also offering cost-effective, entry-level design environments. These are complete packages with design entry, simulators, libraries, and the back end. Later, I will show you one of these packages.

These design environments are certainly good for learning FPGA/CPLD development and, in many cases, actually designing fairly large designs. However, if your organization already standardizes on one CAD environment, these packages may not be of much help, and you're back to the integration game. If you're one of these organizations, you probably have the resources to handle the integration to a specific FPGA/CPLD back end.

For the rest, going with a FPGA/CPLD design environment from the FPGA/CPLD vendor is probably one of the best ways to go. There’s a lot of support on the vendor's web site for these packages, because if you get good at designing for their parts, they hope to sell a large quantity of them.

The particular package I want to look at with you this month is Xilinx's Foundation environment. Foundation is a representative of other environments. It's also very complete. Finally, if you're a student or someone that just wants to learn this stuff, Xilinx has a student edition of this package, which sells for under $100 and includes a good tutorial style text book that will work you through the tool.

The student edition is not a crippled version of Foundation, except that it only supports some of the small/medium-sized devices. After you come up to speed and want to try a commercial design, you should go ahead and purchase the production version. It comes with a support contract, where the student version doesn't.

Let's get started.

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