Table 130. Spi_Sm_3; Table 131. Spi_Sm_4 - ST STM32L4 Series User Manual

SM CODE
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
SM CODE
Description
Ownership
UM2305 - Rev 10
This method is implemented adding to data packets transferred by SPI a redundancy check
(such as a CRC check, or similar one) with encoding capability. The checksum encoding
capability must be robust enough to guarantee at least 90% probability of detection for a
single bit flip in the data packet.
Consistency of data packet must be checked by Application software before consuming data.
Depends on implementation
Depends on implementation
Permanent/transient
None
Depends on implementation
On demand
Not applicable
CPU_SM_0: Periodic core self-test software
It is assumed that the remote SPI counterpart has an equivalent capability of performing the
check described.
To give an example on checksum encoding capability, using just a bit-by-bit addition is
unappropriated.
Table 130. SPI_SM_3
CRC packet-level
ST
SPI communication module allows to activate automatic insertion (and check) of CRC-8 or
CRC-18 checksums to packet data.
Error flag raise and optional Interrupt Event generation
Depends on peripheral configuration (for example baud rate). Refer to functional
documentation.
Permanent/transient
None
Depends on implementation
Continuous
Direct test procedure for CRC efficiency is not available. CRC run-time hardware failures
leading to disabling such protection fall into multiple-fault scenario, from IEC61508
perspective. Related failures are adequately mitigated by the combination of safety
mechanisms reported in this table, field Multiple-fault protection.
SPI_SM_2: Information redundancy techniques on messages
This method can be part of the implementation for SPI_SM_2 or SPI_SM_4. In that case,
because of the warning issued in the Test for the diagnostic field, this mechanism can not be
the only one to guarantee message integrity.
Table 131. SPI_SM_4
Information redundancy techniques on messages, including end-to-end protection
End user
Hardware and software diagnostics
SPI_SM_2
SPI_SM_3
SPI_SM_4
UM2305
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