**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

![FAR/JAR and Advisory Material 
Systems 
Safety 
Assessment 
Safety/ 
Hardware 
Hardware 
Safety/ 
Software 
Safety/ 
Hardware/ 
Software 
Software 
Hardware 
Software 
Figure 2-1 Relationships Among Airborne Systems, Safety Assessment, 
Hardware and Software Processes ](Exported%20image%2020231126172017-0.png)

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](https://en.wikipedia.org/wiki/DO-178C) by impact on passenger safety.
-   
    
- ![Level 
    A 
    B 
    C 
    D 
    E 
    Failure condition 
    Catastrophic 
    Hazardous 
    Major 
    Minor 
    No Safety Effect 
    [11] 
    Objectives 
    71 
    69 
    62 
    26 
    With independence 
    30 
    18 
    5 
    2 ](Exported%20image%2020231126172017-1.png)
- 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