The FAA is realized on design level by one part that is intended to be application software and one part that will be
hardware. The realization also relies on a middleware abstraction which represents parts of basic software that cannot be
supressed on design level. Drivers and interfacing, mode managers, diagnostics services and voters are examples of basic
software that take an active part of the function. Other parts of basic software are invisible and need not be taken into
account on design level. Examples include communication and OS services.
In this task, a BSW function is decomposed into subfunctions and its internal behaviour is detailed or even formalized. The
detailing and formalization of the internal behaviour can for instance be done by providing an executable model of the
function, for instance by state machines and Simulink models.
During the decomposition and detailing of the BSW function, new information may emerge that calls for a change in the
interfaces of the design function. For that reason, it is allowed to modify also the interfaces of the function, although
it is not of primary concern for this task. This requires, however, close collaboration with the FDA architect.
In the decomposition and modeling process, certain assumptions and constraints on the environment and on the hardware
platform may be derived. This is also to be documented in a separate work product.
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