New MCU functionalities in light of ISO 26262

May 03, 2013 // By Christopher Temple, Freescale
Functional safety is becoming more and more relevant for electrical and/or electronic systems (E/E systems) in the automotive domain through the ever increasing benefits of electronic control. This article explains how state-of-the-art MCUs support current safety standards.

Safety aspect are not only relevant for new automotive systems such as advanced driver assistance systems but also for established systems, such as power steering, and even seemingly simpler systems, such as various lighting controls, to name just a few examples. When looking at such systems it soon becomes evident that a malfunction of such an E/E system could be a source of harm in the form of physical injury or damage to the health of persons. In late 2011 the ISO 26262 standard was released as a sector specific functional safety standard for the automotive sector intended for - but not limited to - E/E systems in series production passenger cars. The objective of functional safety according to the ISO 26262 is to circumvent potential harm to persons that could be caused by malfunctioning E/E systems . In this sense the standard defines functional safety as the "absence of unreasonable risk due to hazards caused by malfunctioning behavior of E/E systems".

The ISO 26262 standard distinguishes between two main categories of failures that can lead to malfunctioning behavior of E/E systems. The one category focuses on systematic failures , which are defined as “ related in a deterministic way to a certain cause that can only be eliminated by a change of the design or of the manufacturing process, operational procedures, documentation or other relevant factors ”. Typical examples for systematic failures are failures such as those caused by SW bugs, manufacturing defects, flawed system design, or similar. Systematic failures can originate in HW as well as in SW. Due to their nature systematic failures will typically be evident across a broader scope of a mass produced product population. The other category focuses on random hardware failures , which are defined as occurring “unpredictably during the lifetime of a hardware element and that follows a probability distribution”. Typical examples for random hardware failures are failures such as those caused

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