AC 2009-2462: VIRTUAL PROTOTYPING METHODOLOGY AS A REPLACEMENT FOR PHYSICAL DESIGN IN TEACHING EMBEDDED SYSTEMS

The application, versatility, and complexity of embedded systems are growing at the average rate of 14% annually. Such a growth requires acceleration in the time-to-market window while increasing yet their complexity. Due to their short design and production time the use of new and error-free design approaches that emphasize use of modern and high-level design tools and hardware/software tradeoffs are essential. These tools allow engineers to develop and test their designs before a single prototype is built. Virtual prototyping approach is relatively new methodology to permit such a design and virtual production in an integrated framework that is based on design principles that engineers perceive intuitively. It is a top down design approach for creating a virtual prototype for specification, design, simulation, and verification of hard(HW) and software (SW) concurrently. It allows simultaneous HW and SW development and provides means for capturing information at various design stages with higher accuracy, lower cost, better efficiency at a shorter time compared to the traditional practice of design. In this paper we address issues involved in using the methodology of virtual prototyping and its outcome in teaching embedded system design. This approach permits students to gain insight on the details of system level design, its performance, and its error free functionality without physically building one. Introduction Eembedded systems are special-purpose systems designed to perform a dedicated operation, often with real-time constraints. They are usually embedded as part of a complete system/device that includes HW, SW, and mechanical parts. These systems control many of the common devices in use today. Since these systems are dedicated for performing specific tasks and are produced in large quantities, it makes sense their design to be optimized. The optimization not only will reduce the size and cost of the product, it will also increase its reliability and performance. In the traditional design approach, on the onset, the system is portioned into HW unit, SW unit, and the interface unit, as shown in Fig. 1 [1-3]. Integration of these units takes place at the end when these units are developed. In this practice, the loop L2 corresponding to design of software depends on design of hardware and the loop L1 [1-3]. However, completion of loop L1 can be slow and expensive due to fabrication and verification cost of hardware. In addition, during the integration phase, the design flaws are exposed and since fixes in the hardware may not be easy, software is revised to make up for the hardware deficiencies. This will result in more time being spent for debugging the system which will result in slippage of the time to marker window, not considering expenses involved in the process. Furthermore, hardware designer may overlook the features that should be provided in the hardware to ease the programming process for the software designers/developers. In the traditional approach, design of the software is postponed until hardware is developed. However, development of HW can be slow and expensive due to verification and fabrication costs. Fig. 1. Current practice of design In a Virtual Prototyping course the design of HW and SW is coupled, eliminating the need for physical existence of hardware for the development of the software. In this methodology, students develop hardware and software concurrently, allowing them to: • Estimate benchmarks for running the software on a large system • Generate code for software models of the system. • Evaluate the trade-offs for architecture selection using performance models • Develop models that capture detailed requirements as the design moves forward. In addition students learn issues involved on: • Feasibility study • Exploration and design • Demonstration of design validity • System development and its maintenance. These steps are usually performed independent from each other with little continuity. The virtual prototyping approach is an ideal methodology for teaching design and performance issues for students, where cost and/or time may not permit their physical development. The methodology is a modeling and simulation-based approach that facilitates the concurrent design of HW and SW for gaining insight to the design of the three units HW, SW, and interface and interconnection between them. The benefits of such a practical approach for students in designing embedded systems are several folds, because through this approach they will be able to: • Detect the design errors early, which will result in shorter design cycle time. • Integrate smoothly HW, SW, and their interface. • Learn how this method can reduce significantly the number of prototypes and costs. • Learn to test and document the design features and the results more efficiently and logically. In addition, due to the advances in new technology, students can also include these advances in their model that will enable them to: • Exploit the latest advances in their models and observe their performance. Thus, permitting them to model and simulate the increasingly more complex systems. • Visualize immediate tactile feedback on the relation and interaction of various design modules. Embedded System Design and Building of Hardware Design of Interface Design and Coding of Software Integration of hardware and software units