Design & Architecture Phase

 

The Design & Architecture Phase uses the outputs of the Requirements Phase to develop the Low Level Requirements. These Low Level Requirements include details on the design and architecture that can be used to implement Source Code, ref. DO-178B Section 5.2.

 

The inputs to the Design & Architecture Phase are as follows:

 

• Software High Level Requirements Document (SHLRD)
• Software High Level Signal Dictionary (SHLSD)
• Software Development Plan
• Software Requirements, Design, and Coding Standards (SRDCS)

 

The outputs of the Design & Architecture Phase are as follows:

 

• Software Low Level Requirements Document (SLLRD)
• Software Low Level Signal Dictionary (SLLDD)

 

Software Low Level Requirements Document (SLLRD)

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The Software Low level requirements document identifies how the requirements are partitioned and lists the Low Level requirements of the Software item. Low level requirements may contain implementation specific details of how the software will implement the functionality and behavior described in the high level requirements. Derived low level requirements should be provided to the system safety assessment process. The V&V phase activities should commence as soon as a baseline of the SHLRD can be established in CM, including reviews for clarity, consistency, and most important testability.

 

Software Low Level Data Dictionary (SLLDD)

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The low level data dictionary contains a list of the input and output signals used in the SLLRD. This document also describes the attributes of the signals. This includes: the signal names, signal data types, operational ranges (min/max), memory map addresses, units, etc. Ideally, this data dictionary would be directly traceable to the Software High Level Signal Dictionary (SHLSD) with a standardized naming convention for all data.