Software development is the critical link in the development of today's embedded wireless applications. Some estimates place software creation at 50% to 70% of overall product-development costs. To remain competitive, wireless designers must be able to write and test out their new software code as the hardware is being developed. Such an approach is now possible through the use of a virtual prototype that can accurately model processor, bus, and peripheral behaviors.

When designing at the electronic systems level (ESL), a well-constructed virtual-prototype model will provide a platform upon which real embedded software can be executed. It also allows the designer to accurately predict the system's behavior, which is mandatory for high-level, architectural tradeoff analysis (see figure).

One of the more promising startups to offer an ESL virtual-prototyping platform is VaST Systems Technology. Its platform comprises the CoMET, METeor, and Metrix products. CoMet is the primary design environment for the concurrent development of embedded hardware and software systems. It enables the specification, modeling, design, and verification of executable virtual prototypes. The end result is a fast and cycle-accurate design of a system's virtual hardware platform. VaST has developed a library of nearly 25 common processors.

Additional processor models are in the works. For example, the company recently announced its collaboration with StarCore LLC. The two companies partnered to create a cycle-accurate model of the StarCore SC1200 processor core.

By combining these processor models with bus and peripheral models that are supplied by the company or other sources, designers can analyze many alternative hardware systems. Bus models, such as PCI, Ethernet, CAN, and others, can be created at the transaction level or even the lower signal level. Peripheral devices and bus bridges can be designed at the level that is demanded by functional and timing accuracy. For processors, simulation speeds range from 20 to 200 MIPS. Bus simulation speeds reach up to 2 million transactions per second.

Once the virtual prototype has been created, embedded software designers can start writing code. Using the virtual hardware platform that is generated by CoMET, METeor enables the creation of real-time embedded software. The developers who use METeor can run their code—in binary-image form—as if it were being executed on a single-board computer. Software engineers can therefore develop an operating system and associated device drivers within a target virtual prototype. In addition, they can port existing operating systems.

For virtual prototypes to be useful to embedded software and device drivers, they must represent cycle-accurate models of the architected system. Device-driver developers need that accuracy to know how many instruction cycles are being consumed by various subroutines. This understanding, in turn, helps them to optimize their code.

Foremost on the minds of most embedded wireless developers is the power utilization of their designs. This requirement is especially critical when evaluating alternative ESL algorithms. Metrix, the latest member of VaST's tool suite, permits designers to evaluate their algorithms in terms of energy usage and performance. To select the optimal design architecture, it's crucial to have an early understanding of the effects of talk time or digital-picture processing on the power consumption of a wireless handset.

Together, these three products help to create a usable ESL platform. Within this environment, embedded software developers can start the time-consuming task of code generation on a stable reference model. Meanwhile, hardware designers can continue to work on the register-transfer-level (RTL) code.

CoMET, which includes Metrix, costs $80,000. METeor with Metrix is priced at $35,000. All are now available.

VaST Systems Technology
1270 Oakmead Pkwy., Suite 310, Sunnyvale, CA 94085-4004; (408) 328-0909, FAX: (408) 328-0945, www.vastsystems.com.