Main/OneNote/OSD/Safety/DO-254 Summary.md

Simple and Complex hardware item:

Something is simple if a comprehensive combination of deterministic tests and analyses ensures correct functional performance under all foreseeable operating conditions with no anomalous behavior.

Everything else is a complex item.

• Simple hardware item: extensive documentation is unnecessary.
• Complex items: design assurance should be agreed to by the certification authority.
• Hierarchically analyse all levels for complexity. Include functions that are not testable such as unused modes or hidden states in sequential machines.

System Aspects of Hardware Design Assurance

1. System Aspects of Hardware Design Assurance

2. Allocate System functions to hardware (or software or combination of both)

3. Assign system development assurance levels

Overlaps are important: hardware function that contains safety requirements invokes safety assessment process and hardware design life cycle process.

• 3 Processes work in parallel:

  • System Development Process
  • Hardware Design Life Cycle Process
  • Software Life Cycle Process

• Design assurance level: defined by impact on passenger safety.

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• Objective with independance: another person must verify the item.

Questions

• What is our software assurance process

Todo:

• Define functions with associated requirements,
  failure conditions and design assurance level

Review:

• Chap2