Embedded Sram; Table 22. Ram_Sm_0; Table 23. Ram_Sm_2 - ST STM32F2 Series User Manual

3.6.3

Embedded SRAM

SM CODE
Description
Ownership
Detailed implementation
Error reporting
Fault detection time
Addressed fault model
Dependency on MCU
configuration
Initialization
Periodicity
Test for the diagnostic
Multiple faults protection
Recommendations and known
limitations
SM CODE
Description
Ownership
Detailed implementation
Error reporting
Fault detection time
Addressed fault model
Dependency on MCU configuration
Initialization
Periodicity
Test for the diagnostic
UM1845 - Rev 4
Table 22.
RAM_SM_0
Periodical software test for SRAM memory
End user or ST
To enhance the coverage on SRAM data cells and to ensure adequate coverage for permanent faults
affecting the address decoder it is required to execute a periodical software test on the system RAM
memory. The selection of the algorithm must ensure the target SFF coverage for both the RAM cells and
the address decoder. Evidences of the effectiveness of the coverage of the selected method must be also
collected
Depends on implementation
Depends on implementation
Permanent
RAM size can change according to the part number
Depends on implementation
Periodic
Self-diagnostic capabilities can be embedded in the software, according the test implementation design
strategy chosen
CPU_SM_0: periodical core self-test software
Usage of a March test C- is recommended.
Because the nature of this test can be destructive, RAM contents restore must be implemented. Possible
interferences with interrupt-serving routines fired during test execution must be also considered (such
routines can access to RAM invalid contents).
Note: unused RAM section can be excluded by the testing, under end user responsibility on actual RAM
usage by final application software
Table 23.
RAM_SM_2
Stack hardening for application software
End user
The stack hardening method is used to enhance the application software robustness to SRAM
faults that affect the address decoder. The method is based on source code modification,
introducing information redundancy in the stack-passed information to the called functions. Method
contribution is relevant in case the combination between the final application software structure and
the compiler settings requires a significant use of the stack for passing function parameters.
Implementation is the same as method CPU_SM_4
Refer to CPU_SM_4
Refer to CPU_SM_4
Refer to CPU_SM_4
Refer to CPU_SM_4
Refer to CPU_SM_4
Refer to CPU_SM_4
Refer to CPU_SM_4
Description of hardware and software diagnostics
RAM_SM_0
RAM_SM_2
UM1845
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