System Bus Architecture; Table 27. Bus_Sm_0; Table 28. Bus_Sm_1 - ST STM32F2 Series User Manual

3.6.4

System bus architecture

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
Multiple faults protection
Recommendations and known limitations
UM1845 - Rev 4
Table 27. BUS_SM_0
BUS_SM_0
Periodical software test for interconnections
End user
The intra-chip connection resources (Bus Matrix, AHB or APB bridges) needs to be periodically
tested for permanent faults detection. Note that STM32F2 Series MCUs 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
Depends on implementation
Depends on implementation
Permanent
None
Depends on implementation
Periodic
Not needed
CPU_SM_0: periodical core self-test software
Implementation can be considered in large part overlapping with the widely used "Periodical read-
back of configuration registers" required for several peripherals
Table 28. BUS_SM_1
BUS_SM_1
Information redundancy in intra-chip data exchanges
End user
This method requires to add some kind of redundancy (e.g. a CRC checksum at packet level) to
each data message exchanged inside the MCU.
Message integrity is verified using the checksum by the application software, before consuming
data.
Depends on implementation
Depends on implementation
Permanent and Transient
None
Depends on implementation
On demand
Not needed
CPU_SM_0: periodical core self-test software
Implementation can be in large part overlapping with other safety mechanisms requiring information
redundancy on data messages for communication peripherals. Optimizations are therefore possible
Description of hardware and software diagnostics
UM1845
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