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The Internet has changed the way EDA tools are evaluated and purchased

by Scott Augustinovich and Lonnie R. Cole, Senior Engineers, National Optical Astronomy Observatories (NOAO)

National Optical Astronomy Observatories (NOAO) is charged with designing three instruments for the SOLIS project, a new facility that will provide unique observations of the Sun for several decades. SOLIS will provide fundamental data necessary to understand the solar activity cycle, which has a profound effect on our weather, atmospheric conditions, communications, navigational systems and power distribution systems.

These instruments are the VectorSpectroMagnetograph (VSM), which will produce vector magnetic field maps of the sun at the rate of one map per 15 minutes; the Integrated Solar Spectrometer (ISS), providing data on the spectral content of the integrated light from the sun; and the Full Disk Patrol (FDP), which will produce images of the solar disk at selected wavelengths of light.

NOAO was using FPGAs for these instruments but we soon found that the simulator we were using didn't allow for stepping through the VHDL source code during simulation. The simulator was a block box approach: we knew the inputs but if the outputs were not what we wanted we had to change the

VHDL code and resimulate again and again until we stumbled across the correct solution. So we began to look for a more powerful tool.

We discovered that evaluating and buying EDA tools has become much simpler and faster through the Internet, with impressive services and support emerging in new forms that would not be feasible through any other medium. The time we saved was considerable.

Normally you have to obtain and read the company brochures, then talk to the sales dept. of each company to try to determine if their product will meet your needs. After you have narrowed it down to a few best choices, you talk to people using the product to cut through some of the marketing hoopla and get straight information on exactly what is possible and practical with the individual software package.

Even after all this you can't be sure you know about all the options available, and without being able to test a product before buying, it is possible that the product you choose might not be right for your current design environment.

Now you can use a Web search engine to look for the tool you want. We discovered that we could track down companies by visiting Electronics Design & Technology Network's (EDTN) EDA tool page at www.edtn.com/edatools. It offers a list of EDA tool companies organized by categories such as CAE, CAD, IC layout, and so on, with links to the companies' Web sites. You can also find EDA companies on the EE Design Center site (www.questlink.com). On each company's Web site you can get much more detailed information on a package, including technical papers.

Once the tool is located, many EDA toolmakers allow you to download a demo version or even a fully functional evaluation copy of the tool. A list of companies that offer downloads of demo versions or evaluation copies of EDA tools also can be found on EDTN's Web site at www.edtn.com/edatools/demos/.

One of our engineers had worked with the VHDL and Verilog tool ModelSim, a language- and platform-neutral simulator from Model Technology. He recommended it highly, so we downloaded an evaluation copy of the software from Model Technology's Web site (www.model.com).

We were able to test ModelSim directly on our project, and found that it allowed us to step through the VHDL source Code during simulation so we could see why an output behaves the way it does. If the output is not behaving in the desired way we know exactly what lines of code need to be modified to achieve the correct response. This gave us the confidence that this was indeed the right tool for our project. Most of the steps you normally have to follow to find the right package were eliminated.

When we were ready to buy, Model Technology, a subsidiary of Mentor Graphics Corporation (Wilsonville, Ore.), provided an order form over the Internet, further speeding up the process. Typically, getting a license takes only a day or two. Also, we received a five-percent discount for buying on-line. Such discounts can be significant when you consider purchases in the tens of thousands of dollars.

We used a credit card to buy ModelSim. Many companies like to buy using a credit card, and sometimes that is the only form of payment a vendor will accept for on-line purchases. Security is always a concern when using a credit card to buy over the Internet. However, almost all companies now have secure online purchasing. A variety of strategies are used. A common one is the digital certificate, which is an electronic "credit card" that establishes your credentials when doing business or other transactions on the Web. It is issued by a certification authority (CA), and contains your name, a serial number, expiration date, a copy of the certificate holder's public key used for encrypting and decrypting messages, and digital signatures.

On-line support varies greatly from one company to another, and can include data sheets, application notes, code libraries, and databases that can be searched for solutions to common problems. Model Technology, for example, offers numerous technical notes on design challenges, complete with sample code. They also post downloadable versions of their magazine, ModelUser; information and examples to aid users in customizing the ModelSim GUI (which is based on the Tcl/Tk standard); and a table of supported sign-off VITAL and Verilog libraries.

Traditional telephone support still exists, of course, but some vendors offer forms on their Web sites that you can fill out and submit, which eliminates long waits for a return call when no one is available to take your call. Most also offer e-mail support.

We have been impressed with how much more expedient technical support can be over the Internet, because if you can't make your problem clear to support personnel over the phone, you can zip your design and e-mail it in for the vendor's applications engineers to work with. Before this kind of support was available over the Internet, it was not practical to send a design to the vendor by mail since it wasn't possible to get all the libraries and configuration data on a disk. We usually were stuck with redoing the design until we found one that would simulate -- a trying process, especially since we had no way of knowing if the problem was in the design or in the software.

There are other benefits of shopping on the Internet. Free EDA software is beginning to appear. Electric Editor, Incorporated (Los Gatos, Calif.) offers the source code for their Electric VLSI Design System free, downloadable from their Web site (www.electriceditor.com). Electric Editor reasons that giving Electric away will result in sales of their supporting products and services: add-on modules, documentation and training, and consulting.

The FreeHDL Project is developing a free, open source, VHDL simulator for Linux under the Free Software Foundation's GNU Public License (www.freehdl.seul.org/simulator.html). VAUL, a VHDL-93 parser, is available now. gEDA (www.geda.seul.org) is a collection of free tools for electrical circuit design, simulation and prototyping/production, also under the GNU Public license.

Some major companies are also offering freebies to their customers. Viewlogic (Marlborough, Mass.), for example, gives away StateCAD Lite, which allows you to generate VHDL and Verilog state machines of up to eight states from graphical state diagrams. Download from www.viewlogic.com/eval/statecad_eval.html. Cadence (San Jose, Calif.) gives away the Allegro Viewer for viewing and plotting Allegro PCB design databases and Advanced Package Designer databases. It can be downloaded from www.cadence.com/software/pcb_info/ pcb_software/allegro.html. A variety of auxiliary tools are offered by some of the major EDA software companies.

Opinions vary as to whether free EDA software is feasible or even useful. Some object on the grounds that if it's free, it can't be any good. But many, like Electric Editor, Inc. think that free software will generate sales of add-on tools and other products.

We don't agree with the idea that that free software is no good just because it's free. We tried Viewlogic's free StateCAD Lite software and although it could be more intuitive to use, it is very powerful tool. It gave several options for the output language, VHDL, Verilog, C, ABEL, and Altera, which we found extremely helpful. This could be an effective teaching tool for someone who knows one language and needs to learn one of the others, or as a comparison of how different languages are implemented. StateCAD Lite seems to be very flexible allowing the user a variety of languages, implementation platforms, and implementation options, which give a user nearly unlimited potential. It's not as powerful a simulator as it might be, but you can't expect free software to be as powerful as a fully developed commercial product, after all.

Hardware companies would be smart to give design tools away for the hardware they sell. One plan would be to give tools to college students so that they are already familiar with it when they enter the workforce. This would boost chip sales because once a user is familiar with a tool they are unlikely to try to learn a new one as long as the one they are using works. Chip companies could give their tools to designers and offer free training, which also would boost sales of their products. But many companies sell their chips and then sell the tools to use them, making users feel that they are paying at both ends for one complete product.

We believe the wave of the future may be Web-based EDA tools that will be accessed on a time-lease basis. Time-leasing EDA tools on the Web will benefit small companies and startups by allowing them access to sophisticated tools they could not afford to buy. It may also benefit companies where a large team of people needs to use the tools and the cost of multiple licenses may be prohibitive. And it's another way to evaluate software before buying it.

The movement has already started. Power Design Tools (www.pdt.com), for example, has developed a Web-based simulation service software called WebSIM. WebSIM allows users to perform complex analog circuit simulations over the Web. The product is targeted at IC vendors and merchant power supply manufacturers, and will allow them to include actual product simulation on their Web sites, giving the vendor's customers real-time product behavior modeling over the Internet.

PDT offers free use of a demonstration version of the tool on its Web site (www.pdt.com/national_sim/nsc_sim.html). We tried it and found the tool so intuitive and user-friendly that even someone unfamiliar with it can simulate a design easily. Some simulators we have seen only allow you to do a couple of simulations and then force you to reload the simulator, but WebSIM allows you to change component values again and again. The ability to see the output waveform is extremely well done. For this particular installation we'd like to see all component characteristics editable, and a library of parts to place in the simulation, but in general we think PDT's WebSIM demonstrates very well how valuable a Web-based simulation service can be.

But a number of problems have to be solved before such services are widely offered, and many companies are adopting a wait-and-see attitude. It's not all that certain that such services will be profitable. And pipelines are a problem. T1 lines, with their throughputs of 1.544 megabits per second, will have to be more widely deployed than they are now to handle files that may be many megabytes in size, even when compressed.

Here, too, security is an issue. Companies will not be willing to send IP over the Internet unless they know that invulnerable security measures are in place.

We'd like to see more VHDL libraries on parts vendors' Web sites in the future. If parts suppliers furnish the model the engineer's job is made a lot easier, and engineers are likely to buy those parts for which models are available.

The ability to use purchase orders for on-line purchasing would be a welcome advance, since high-priced tools exceed the credit card limit of many companies. One way this can work is that customers who apply for and are approved for on-line credit are given secure passwords they use to make on-line purchases. When an order is placed, the customer enters the password and the order is assigned a P.O. number for tracking purposes. When the product is shipped, the customer receives an invoice.

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