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OTP3 safety feature

Francisco Torres
Intellectual 585 points

Hello,

I need to implement safety feature OTP3.

In spnu521A_safetyanalysisreportsummary.pdf I can see: 

"OTP3 : Periodic software readback of static Flash Static configuration registers"

 and in spnu511b.pdf :

 "5.14.4 Periodic Read Back of Configuration Registers

Periodic read back of configuration registers can provide a diagnostic for inadvertent writes or disturb of

these registers. Error response, diagnostic testability, and any necessary software requirements are

defined by the software implemented by the system integrator. The use of read back of configuration

registers mechanism is recommended."

 

I have been checking spnu499b.pdf and the only OTP registers that I have found are:

 

TI OTP Bank 0 Sector Information (F008 0158h)

TI OTP Bank 0 Package and Memory Size Information (F008 015Ch)

TI OTP Bank 0 LPO Trim and Max HCLK Information Field Descriptions

TI OTP Bank 0 Symbolization Information (F008 01E0h-F008 01FFh)

TI OTP Bank 0 Sector Information Field Descriptions

all of them are read-only

 

So, question is, what registers should be readback to implement OTP3 safety feature?

 

Regards,

Francis.

  • 0
    TI__Mastermind 49120 points

    Hi Francis,

    The OTP3 involves periodic reading of the actual flash OTP region to ensure that none of the bits have changed state.

    Regards,

    Sunil

  • 0 in reply to Sunil Oak
    Intellectual 585 points

    Hello Sunil,

    Thanks for your reply but I am afraid that this is not helping as you said is basically what is written in the requirement.

    What I would like to know if what OTP registers or flash memory I need to read to implement this safety feature. Apart from the registers that I specified, which are read only, I can not see any other register o memory to read.

    Regards,

    Francis.

  • 0 in reply to Francisco Torres
    Intellectual 830 points

    Hello Sunil.

    Since this topic is for me in the same way unclear as for Francis, I allow myself to ask you the following question: Any updates regarding this topic?

    Thank you and regards

    Oliver.

  • 0 in reply to oliver.gruendonner
    TI__Mastermind 23000 points

    Hi All,

    As a general rule, the safety manual does not call out which registers should be considered "safety critical" as this will depend on how the hardware is used in the customer's safety design.  The user needs to take a look at their system and make the determination of which registers are critical for their specific usage.

    Best Regards,

    Karl Greb

  • 0 in reply to KGreb
    Intellectual 830 points

    Hi Karl.

    Thank you for the fast feedback. I understand what you mean with your answer. But it still does not satisfies me with 100%. I try to reformulate my understanding problem:

    To fulfill safety feature OTP3, there is a set of registers which have to be read back by the software. Which registers have to be read back depends on the application. Until now everything is clear. But what is not clear: What is the OVERALL set of registers which COULD be relevant to fulfill OTP3?

    Once I know this overall set of registers, I can start to decide which registers are relevant in my application and which are not.

    In case my problem is still not clear, just let me know.

    Thank you and regards

    Oliver.

  • 0 in reply to oliver.gruendonner
    TI__Mastermind 23000 points

    Oliver,

    The OTP is part of the flash module; as such all flash module registers could be considered the superset of user accessible registers.

    Best Regards,

    Karl