FuSa (Functional Safety) refers to the application of safety principles to ensure that systems, particularly in critical environments, operate correctly even when there are failures. FuSa is crucial in industries such as automotive, industrial automation, aerospace, and medical devices, where malfunctions could lead to catastrophic consequences, including harm to people or the environment.

Functional safety is governed by a set of standards, the most prominent being ISO 26262 for the automotive industry, IEC 61508 for industrial applications, and DO-178C for aerospace systems. These standards define the process for developing safety-critical systems, including risk assessment, hazard analysis, and the implementation of safety mechanisms to reduce risks to an acceptable level.

In the context of embedded systems and software development, FuSa involves designing systems with redundancy, fail-safes, and fault-tolerant mechanisms to handle hardware or software failures. This often includes the use of watchdogs, error-detecting codes (EDC), self-checks, and diagnostics to detect and respond to faults without compromising safety.
Safety Integrity Levels (SIL) or Automotive Safety Integrity Levels (ASIL) are used to classify the risk associated with system failures and determine the necessary safety measures. For example, ASIL ranges from A (lowest risk) to D (highest risk) in automotive standards. Developers are required to meet specific development processes and testing criteria based on the system’s safety classification.

FuSa systems typically integrate safety monitors, safe state mechanisms, and software elements that conform to specific coding standards (such as MISRA C) to ensure that failures are managed and do not escalate into hazardous situations. The focus is on both preventing failures and ensuring that, when failures occur, the system transitions to a controlled, safe state