Embedded Flash Memory; Table 22. Ram_Sm_6; Table 23. Flash_Sm_0 - ST STM32L4 Series User Manual

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
3.6.4

Embedded Flash memory

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
Table 22. RAM_SM_6
Read protection (RDP) and write protection (WRP)
ST
SRAM2 can be protected against illegal reads or erase/write by using these protection
features. The combination of these techniques and the related different protection level allows
End user to build an effective access protection policy.
Refer to functional documentation - in some cases a HardFault error is generated.
Refer to functional documentation
Systematic
SRAM2 size may vary depending on part number.
Not required
Continuous
Not applicable
Not required
Hardware random-failure detection capability for SRAM2 access policy is restricted to well-
selected marginal failure modes, mainly affecting program counter and SRAM2 interface
functions. The associated diagnostic coverage is therefore expected to be irrelevant in the
framework of STM32L4 and STM32L4+ Series safety concept.
Table 23. FLASH_SM_0
Periodic software test for Flash memory
End user or ST
Permanent faults affecting the system Flash memory interface address decoder are
addressed through a dedicated software test that checks the memory cells contents versus
the expected value, using signature-based techniques. According to IEC 61508:2 Table A.5,
the effective diagnostic coverage of such techniques depends on the width of the signature
in relation to the block length of the information to be protected - therefore the signature
computation method is to be carefully selected. Note that the simple signature method
(IEC 61508:7 - A.4.2 Modified checksum) is inadequate as it only achieves a low value of
coverage.
The information block does not need to be addressed with this test as it is not used during
normal operation (no data nor program fetch).
Depends on implementation
Depends on implementation
Permanent
Flash memory size changes according to the part number.
Memory signatures must be stored in Flash memory as well.
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 test is expected to have a relevant time duration – test integration must therefore
consider the impact on Application software execution.
Hardware and software diagnostics
RAM_SM_6
FLASH_SM_0
UM2305
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