ST STM32L4 Series User Manual

SM CODE RAM_SM_3
Recommendations and known limitations
Implementation of this safety method shows a partial overlap with an already foreseen method
for Arm
®
Cortex
®
-M4 (CPU_SM_1); optimizations in implementing both methods are therefore
possible.
Table 20. RAM_SM_4
SM CODE RAM_SM_4
Description Control flow monitoring in Application software
Ownership End user
Detailed implementation
In case End user Application software is executed from SRAM, permanent and transient faults
affecting the memory (cells and address decoder) can interfere with the program execution.
The implementation of this method is required to address such failures.
For more details on the implementation, refer to CPU_SM_1 description.
Error reporting Depends on implementation
Fault detection time Depends on implementation. Higher value is fixed by watchdog timeout interval.
Addressed fault model Permanent/transient
Dependency on Device configuration None
Initialization Depends on implementation
Periodicity Continuous
Test for the diagnostic Not applicable
Multiple-fault protection CPU_SM_0: Periodic core self-test software
Recommendations and known limitations
Needed only in case of Application software execution from SRAM.
CPU_SM_1 correct implementation supersedes this requirement.
Table 21. RAM_SM_5
SM CODE RAM_SM_5
Description Periodic integrity test for Application software in RAM
Ownership End user
Detailed implementation
In case Application software or diagnostic libraries are executed in RAM, it is needed
to protect the integrity of the code itself against soft-error corruptions and related code
mutations. This method must check the integrity of the stored code by checksum computation
techniques, on a periodic basis. For implementation details, refer to similar method
FLASH_SM_0.
Error reporting Depends on implementation
Fault detection time Depends on implementation
Addressed fault model Permanent/transient
Dependency on Device configuration None
Initialization Depends on implementation
Periodicity Periodic
Test for the diagnostic
Self-diagnostic capabilities can be embedded in the software, according to the test
implementation design strategy chosen.
Multiple-fault protection
CPU_SM_0: Periodic core self-test software
CPU_SM_1: Control flow monitoring in Application software
Recommendations and known limitations
This method must only be implemented if Application software or diagnostic libraries are
executed from RAM.
UM2305
Hardware and software diagnostics
UM2305 - Rev 10
page 20/110

ST STM32L4 Series Specifications

General

Brand	ST
Model	STM32L4 Series
Category	Microcontrollers
Language	English