Table 20. Ram_Sm_4; Table 21. Ram_Sm_5 - ST STM32L4 Series User Manual

SM CODE
Recommendations and known limitations
SM CODE
Description
Ownership
Detailed implementation
Error reporting
Fault detection time
Addressed fault model
Dependency on Device configuration
Initialization
Periodicity
Test for the diagnostic
Multiple-fault protection
Recommendations and known limitations
SM CODE
Description
Ownership
Detailed implementation
Error reporting
Fault detection time
Addressed fault model
Dependency on Device configuration
Initialization
Periodicity
Test for the diagnostic
Multiple-fault protection
Recommendations and known limitations
UM2305 - Rev 10
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
Control flow monitoring in Application software
End user
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.
Depends on implementation
Depends on implementation. Higher value is fixed by watchdog timeout interval.
Permanent/transient
None
Depends on implementation
Continuous
Not applicable
CPU_SM_0: Periodic core self-test software
Needed only in case of Application software execution from SRAM.
CPU_SM_1 correct implementation supersedes this requirement.
Table 21. RAM_SM_5
Periodic integrity test for Application software in RAM
End user
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.
Depends on implementation
Depends on implementation
Permanent/transient
None
Depends on implementation
Periodic
Self-diagnostic capabilities can be embedded in the software, according to the test
implementation design strategy chosen.
CPU_SM_0: Periodic core self-test software
CPU_SM_1: Control flow monitoring in Application software
This method must only be implemented if Application software or diagnostic libraries are
executed from RAM.
Hardware and software diagnostics
RAM_SM_3
RAM_SM_4
RAM_SM_5
UM2305
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