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Table 26.
FLASH_SM_3
SM CODE
FLASH_SM_3
Description
Option byte write protection
Ownership
ST
Detailed implementation
This safety mechanism prevents unintended writes on the option byte. The use of this method
is encouraged to enhance end application robustness for systematic faults.
Error reporting
Write protection exception
Fault detection time
Not applicable
Addressed fault model
None (systematic only)
Dependency on
Device
configuration
None
Initialization
None (always enabled)
Periodicity
Continuous
Test for the diagnostic
Not applicable
Multiple-fault protection
CPU_SM_0: Periodic core self-test software
Recommendations and known limitations
This method addresses systematic faults in software application and it have zero efficiency in
addressing hardware random faults affecting the option byte value during running time. No DC
value is therefore associated.
Table 27.
FLASH_SM_4
SM CODE
FLASH_SM_4
Description
Static data encapsulation
Ownership
End user
Detailed implementation
If static data are stored in Flash memory, encapsulation by a checksum field with encoding
capability (such as
CRC
) must be implemented.
Checksum validity is checked by
Application software
before static data consuming.
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
On demand
Test for the diagnostic
Not applicable
Multiple-fault protection
CPU_SM_0: Periodic core self-test software
Recommendations and known limitations
None
Table 28.
FLASH_SM_5
SM CODE
FLASH_SM_5
Description
Option byte redundancy with load verification
Ownership
ST
Detailed implementation
During option byte loading after each power-on reset, the bit-wise complementarity of the
option byte and its corresponding complemented option byte is verified. Mismatches are
reported as an error.
Error reporting
Option byte error (OPTVERR) generation
UM2305
Hardware and software diagnostics
UM2305
-
Rev 10
page 23/110