Task: Specify BSWFunction Details
This task decomposes a top-level abstraction of software-implemented platform software, such as drivers and services and specifies it in more detail.
Disciplines: Core Tasks
Purpose
The purpose of the task is to specify the internals of an abstraction of platform software that makes it possible to define the complete end-to-end path from plant to controller function and back to plant.
Relationships
Main Description
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.
Steps
Specify BSW function
This step decomposes the BSW function into subfunctions. The specification involves structuring and decomposition of functions to meet needs on allocation, sourcing, re-use, criticality, performance, etc.
Modify interfaces if necessary
This step may modify the interfaces specified by the top-level design, if new needs or findings are discovered during the detailed design of the function. However, this requires close cooperation with the FDA architect.
Identify design constraints
Assumptions and constraints that have been derived during the detailing process are identified and documented in a separate work product.