Detailed design of avionics control software

Avionics control systems are typical real time systems-automatic control algorithms are realized as periodic computations where strict requirements on the timing can be derived by a control analysis. The requirements are effectively end to end timing requirements on the computation-from sensory input to actuator output-and have to be transformed into a detailed control software design. This analysis, together with a resource and performance analysis, is required early in the development process-neither hardware nor prototypes of the software can be assumed to exist-in order to estimate the cost of development and the cost of hardware to meet customer requirements. The paper investigates the applicability of a method (the period calibration method) to transform the end to end requirements of an avionics control software, into a design consisting of a set of periodic tasks with buffered data flows. The experience is discussed and shortcomings of the method are analysed