Using a systems description language for complete avionics systems

The specification and verification of large avionics systems is rapidly becoming intractable due to sheer size. We are coming to the point where even components of the system, such as Systems on Silicon (SoS), cannot be verified short of building prototypes, which is costly and slow. To deal with the SoS problem, the EDA Industry Council has formed the Systems Level Description Language (SLDL) committee. This paper describes the role of the proposed SLDL in the creation of avionics systems, which include digital, analog, microwave, and mechanical parts as well as software. More importantly for avionics systems, it addresses the use of legacy systems (both hardware and software) in the creation of those systems. The SLDL allows the specification of systems abstractly, without imposing an implementation domain (such as hardware or software) on the description. The user may then refine the description by decomposing the system into components, the components into subcomponents, and so on along the classical top-down hierarchical decomposition development path. Use of the SLDL stops when the components are sufficiently specified to allow an implementation specific language (such as VHDL, VHDL-AMS, or Ada) to “take over” and complete the systems design. Legacy systems, however, require a bottom-up approach. We show how the SLDL can be used in this approach to create a specification of a legacy system, integrate it into the overall avionics system, and (if necessary) reimplement the legacy system with newer technology (higher level software language, new hardware process, etc.)