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TMS570LS3137: About the description of the safety manual "SPNU511D"

Falcon
Prodigy 230 points
Part Number: TMS570LS3137

"Table 4. Summary of Safety Features and Diagnostics" of the target file.
Unique Identifer = 2 items of CPU2A, CPU2B.

I would like to confirm the part that seems to be a mistake in the manual.

As for these two items, in the "Safety Feature or Diagnostic" column
· CPU2A [Boot Time Execution of LBIST STC]
· CPU2B [Periodic Execution of LBIST STC]
There is.

I recognize that both refer to LBIST execution.
Depending on the execution timing,
I think that it is divided into these two terms, is not there a mistake?
If there is no error in the above recognition,
I think that Diagnostic Operation (execution timing) of CPU2A should be "At Boot Time".
In the target file, it is described as "Periodic/On-Demand".

Would you please teach me whether it is a simple mistake or a mistake in my perception.
※ I also inquired at TI Forum,
　but I could not get the answer we wanted and we will contact you again.

  • 0
    TI__Guru 59540 points

    Hello Falcon,

    The two diagnostics are the same diagnostic but executed at different intervals. They are separated into 'A' and 'B' because some use cases only require the execution at startup and some periodically.

    Falcon said:
    I recognize that both refer to LBIST execution.
    Depending on the execution timing,
    I think that it is divided into these two terms, is not there a mistake?

    No, there is no mistake. the LBIST execution has to be initiated by software. It is not a continuous or automatic diagnostic.

    Falcon said:
    If there is no error in the above recognition,
    I think that Diagnostic Operation (execution timing) of CPU2A should be "At Boot Time".
    In the target file, it is described as "Periodic/On-Demand".

    The column (Diagnostic Operation) is not intended as a directive to the application/integrator as to how the diagnostic is to be implemented. It is simply a description of the diagnostic. In other words, the CPU2A and CPU2B diagnostics are not continuously diagnosing an issue (as the CCMR4 would be). but are only effectively diagnosing when they are executed. This makes the diagnostic function periodic or on demand as noted in the table.

    As an example, CPU2A is only executed at startup/boot time. That means it is only a valid diagnostic at boot time/during boot time and effective only for latent fault detection. It will not catch any active faults during the application execution. This is on-demand diagnosis.

    For CPU2B, it is, again, only diagnosing during execution even though it may be executed during the application. It, again, is only going to catch latent faults and not faults that occur on demand. Again, this diagnostic is diagnosing only when it is executed or on demand of the application software on a periodic basis.

    Note also that even a boot time execution of the STC LBIST can be considered periodic if the system level requirements require a restart/reboot at a defined interval such as every 24 hours, once a week, monthly, etc. It depends on the system requirements and context in which you look at it.

    For ongoing detection of single point faults during the application execution, CCMR4 is the most prevalent/effective diagnostic.