Product Development at Component Level

In mechanics, there are Newton s laws in electronic we rely on Ohm s law until we have to use Maxwell s equation for high frequencies as a different description basis. 

If we now transfer logical elements to technical elements (compare Fig. 4.71), we realize that without finding a 1 to 1 allocation the number of interfaces could rise exponentially. 

All those interfaces need to be considered, since all characteristics and their possible failures at these interfaces and aU expected behaviors of the elements among each other can lead to failures, inconstancies or deviations towards the 

Drawings, circuit board layouts, parts lists, data sheets and design specifications describe the expected view at the realized product. In the context of product design, characteristics of the product should be documented as part of design specifications. The stmcture of the architecmre for the product determines the intersections for such considerations and lead to the structure of the design specification. For the product liability it is important to also indicate risks of the handling or usage of products in the product description, which is another aspect of safety than functional safety. 

The metrics, such as the risk priority index, indicate whether the design is assured by sufficient measures. System-FMEAs (seen as methodology) analyze mainly the architecture and consequently primarily the interfaces. This is why the Design-FMEA often goes to deeper level of abstraction. 

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Product Development at Component Level ESC SW-Architecture Basic Structure / including RTE data flow... 

Also for basic software or in AutoSar abstraction levels are addressed but in this case we don t mean horizontal abstraction levels but functional (perspectival) abstraction levels (e.g. hardware abstraction or microcontroller abstraction layer (MCAL)). Nevertheless, the interface between application software and microcontroller still play an important role in the definition of the abstraction level. In early revisions of ISO 26262 the hardware software interface (HSl) was implemented in part 5 (Product development at the hardware level) and 6 (Product development at the software level) and only after the CD version of ISO 26262 it moved into part 4 (Product development at the system level). What is special about this is that the microcontroller as a hardware element, similar to the electronics housing, predetermines essential design characteristics for the software. In order for these two components to interact properly, those characteristics and their potential flaws as well as the functions and their potential failure functions need to be considered. This obviously goes for all component interfaces. In the case of HSl we find a lot of relevant interface parameters. This means, that it is not only about the correct functions of the so-called low-level drivers, which provide information on microcontrollers to the software, the operating system, peripheral (DMA, I/O, bus etc.), internal communication, logic unit, memory or function libraries, which are provided by the computer, but also the systematic protection of potential failure or malftmction at this interface. 

In experimental serum sickness, a fall in serum complement level occurs at the time immune complexes form and inflammatory lesions develop (D6). However, levels of complement do not always reflect activation or consumption by immune complexes. The rate of synthesis of complement proteins may be sufficient to replace the amount being consumed, and several of the complement components are so-called acute-phase reactants, i.e., their levels rise with inflammation. Thus, activation may occur despite normal or even elevated levels in the serum. Turnover studies provide more direct evidence of complement utilization but are technically cumbersome (K4). A simpler approach is the detection of split products of complement components, which provides direct evidence of complement activation, or the examination of effusions for evidence of complement depletion (H31, N7, P7). 

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