Reference Safety Architecture; Safety Architecture Introduction; Compliant Item; Definition Of Compliant Item - ST STM32L4 Series User Manual

3

Reference safety architecture

This section reports details of the STM32L4 and STM32L4+ Series safety architecture.
3.1

Safety architecture introduction

Device(s) analyzed in this document can be used as Compliant item(s) within different safety applications.
The aim of this section is to identify such Compliant item(s), that is, to define the context of the analysis with
respect to a reference concept definition. The concept definition contains reference safety requirements, including
design aspects external to the defined Compliant item.
As a consequence of Compliant item approach, the goal is to list the system-related information considered
during the analysis, rather than to provide an exhaustive hazard and risk analysis of the system around
Device. Such information includes, among others, application-related assumptions for danger factors, frequency
of failures and diagnostic coverage already guaranteed by the application.
3.2

Compliant item

This section defines the Compliant item term and provides information on its usage in different safety architecture
schemes.
3.2.1

Definition of Compliant item

According to IEC 61508:1 clause 8.2.12, Compliant item is any item (for example an element) on which a claim is
being made with respect to the clauses of IEC 61508 series. Any mature Compliant item must be described in a
safety manual available to End user.
In this document, Compliant item is defined as a system including one or two STM32 devices (see
communication bus is directly or indirectly connected to sensors and actuators.
Other components might be related to Compliant item, like the external HW components needed to guarantee
either the functionality of Device (external memory, clock quartz and so on) or its safety (for example, the external
watchdog or voltage supervisors).
A defined Compliant item can be classified as element according to IEC61508-4, 3.4.5.
3.2.2

Safety functions performed by Compliant item

In essence, Compliant item architecture encompasses the following processes performing the safety function or a
part of it:
• input processing elements (PEi) reading safety related data from the remote controller connected to the
sensor(s) and transferring them to the following computation elements
• computation processing elements (PEc) performing the algorithm required by the safety function and
transferring the results to the following output elements
UM2305 - Rev 10
Figure 2.
Sensor
Remote
S
controller
Remote
S
controller
STM32 as Compliant item
Processing element
STM32
device(s)
Compliant item
UM2305
Reference safety architecture
Figure
Actuator
Remote
A
controller
Remote
A
controller
2). The
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