Teaching HW/SW Co-Design With a Public Key Cryptography Application

This paper describes a lab session-based course on hardware/software (HW/SW) co-design. Real problems often need to combine the speed of an HW solution with the flexibility of an SW solution. The goals of this course are to show that there are many alternative solutions in the design space and to teach the fundamental concepts of HW/SW co-design. The sample application for the course project is a basic public key (RSA) application. This application is attractive for pedagogic purposes because its complex arithmetic and large word lengths make it difficult to realize in SW on an embedded microcontroller. However, the alternative of a pure application-specific integrated circuit (ASIC) application is also not a satisfactory solution, as this lacks the flexibility to support multiple public key applications. The project follows a stepwise approach, with assignments that build on each other. Students are required to make their own decisions as to the partitioning between HW and SW, the interface design, and the optimizations goals. Besides imparting hard skills in HW design and embedded SW design, the course inculcates several soft skills-in particular, decision making, presentation skills, teamwork, and design creativity-generally overlooked in engineering.