GPIOs: Critical IP For Functional Safety Applications

The prevalence and complexity of electronics and software (EE systems) in automotive applications are increasing with every new generation of car. The critical functions within the system on a chip (SoC) involve hardware and software that perform automotive-related signal communication at high data rates to and from the components off-chip. Every SoC includes general purpose IOs (GPIOs) on its periphery. GPIO IP blocks facilitate the communication between on-chip logic and the off-chip components.

For automotive SoCs, GPIO IP blocks are typically developed as Safety Element out of Context (SEooC) and delivered with a set of Assumptions of Use (AoUs). Any risk due to failure of the EE components within the SoC due to systematic failures, random failures, and dependent failures between the hardware and/or software components can potentially involve the GPIO cells as well. It is thus important that the GPIO blocks are treated as a safety related logic. In this role, GPIOs need safety analysis to mitigate any faults occurring in them before the result of fault occurrence causes a system-wide failure. the integrity level of any safety related logic must include GPIO cells. Standards like ISO 26262 have provided a framework of risk classification by defining Automotive Safety Integrity Levels (ASILs). Designers meet their system ASIL requirements through analysis within work products like Failure Modes Effects and Diagnostics Analysis (FMEDA). FMEDA captures the details of various failure modes, its effects, its distribution, the associated suitable safety mechanisms, and the diagnostic coverage of safety mechanism.

This white paper describes some of the commonly used safety mechanisms in an automotive-ready GPIO library suite, and system integrators can implement safety mechanisms to detect the faults in GPIO cells. Finally, the paper will describe how safety related deliverables are helpful to SoC integrators in their design of the safe SoCs.

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