SM CODE
BUS_SM_0
Detailed implementation
The intra-chip connection resources (Bus Matrix, AHB or APB bridges) needs to be
periodically tested for permanent faults detection. Note that STM32L4 and
Series devices have no hardware safety mechanism to protect these structures. The test
executes a connectivity test of these shared resources, including the testing of the arbitration
mechanisms between peripherals.
According to IEC 61508:2 Table A.8, A.7.4 the method is considered able to achieve high
levels of coverage.
Error reporting
Depends on implementation
Fault detection time
Depends on implementation
Addressed fault model
Permanent
Dependency on
Device
configuration
None
Initialization
Depends on implementation
Periodicity
Periodic
Test for the diagnostic
Not applicable
Multiple-fault protection
CPU_SM_0: Periodic core self-test software
Recommendations and known limitations
Implementation can be considered in large part as overlapping with the widely used
Periodic
read-back of configuration registers
required for several peripherals.
Table 15.
BUS_SM_1
SM CODE
BUS_SM_1
Description
Information redundancy in intra-chip data exchanges
Ownership
End user
Detailed implementation
This method requires to add some kind of redundancy (for example a
CRC
checksum at
packet level) to each data message exchanged inside
Device
.
Message integrity is verified using the checksum by
Application software
, before consuming
data.
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
Implementation can be in large part overlapping with other safety mechanisms requiring
information redundancy on data messages for communication peripherals. Optimizations are
therefore possible.
3.6.3
Embedded SRAM
Table 16.
RAM_SM_0
SM CODE
RAM_SM_0
Description
Periodic software test for static random access memory (SRAM)
Ownership
End user
or ST
UM2305
Hardware and software diagnostics
UM2305
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Rev 10
page 17/110