SM CODE
CAN_SM_1
Test for the diagnostic
Not applicable
Multiple-fault protection
CAN_SM_2: Information redundancy techniques on messages, including end-to-end
protection.
Recommendations and known limitations
Enabling related interrupt generation on the detection of errors is highly recommended.
Table 144.
CAN_SM_2
SM CODE
CAN_SM_2
Description
Information redundancy techniques on messages, including end-to-end protection.
Ownership
End user
Detailed implementation
This method aims to protect the communication between a peripheral and his external
counterpart establishing a kind of “protected” channel. The aim is to specifically address
communication failure modes as reported in IEC61508:2, 7.4.11.1.
Implementation guidelines are as follows:
•
Data packet must be protected (encapsulated) by an information redundancy check,
like for instance a CRC checksum computed over the packet and added to payload.
Checksum encoding capability must be robust enough to guarantee at least 90%
probability of detection for a single-bit flip in the data packet.
•
Additional field added in payload reporting an unique identification of sender or receiver
and an unique increasing sequence packet number.
•
Timing monitoring of the message exchange (for example check the message
arrival within the expected time window), detecting therefore missed message arrival
conditions.
•
Application software
must verify before consuming data packet its consistency (CRC
check), its legitimacy (sender or receiver) and the sequence correctness (sequence
number check, no packets lost).
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
A major overlap between the requirements of this method and the implementation of complex
communication software protocols can exists. Due to large adoption of these protocols in
industrial applications, optimizations can be possible.
It is assumed that the remote counterpart has an equivalent capability of performing the
checks described.
3.6.41
Universal serial bus full-speed device interface (OTG_FS)
Table 145.
USB_SM_0
SM CODE
USB_SM_0
Description
Periodic read-back of configuration registers
Ownership
End user
Detailed implementation
This method must be applied to USB configuration registers.
Detailed information on the implementation of this method can be found in
Section 3.6.14 Extended interrupt and events controller (EXTI)
.
UM2305
Hardware and software diagnostics
UM2305
-
Rev 10
page 80/110
