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Is dual Lockstep CPU same as dual Core processor?

Dino David
Intellectual 645 points
Other Parts Discussed in Thread: TMS570LS3137

I have a TMS570LS3137 Hercules Development Board which has dual cpu lockstep mechanism in it.

I wanted to know if I can disable this dual CPU lockstep and use it as a dual core cpu. 

To be more precise, Can I execute different tasks on these cores parallelly?

  • 0
    TI__Guru 68830 points

    Dino,

    No they stay locked.  2nd core always checks the 1st.

  • 0
    Guru 15175 points
    Anthony what he says is what differentiates the Hercules with other processors , Hercules family is a highly secure processor implemented.
    two processors working as one and comparing answers, so you have a high confidence that your application will not fail
  • 0 in reply to Martin Valencia
    Intellectual 645 points

    I understand that this lockstep mechanism gives a level of confidence for saftey critical applications.

    But I am confused now...Suppose if there is a change in the state of processors, what is next step ?

    Does it raise a flag to interrupt the user about the discrepancies or does the second cpu will be in action on behalf of faulty one?

  • 0 in reply to Dino David
    TI__Guru 68830 points
    Dino,

    The configuration is called 1oo1D -- it's one channel plus a diagnostic.
    So it can be used for fail-safe systems - where you can enter a safe state on an error.

    See the intro to chapter 9 of www.ti.com/.../spnu499b.pdf for a good intro.

    In general when the error occurs you don't know if it's a soft error caused by an event like radiation or if it's a hard error. So there is the possiblity to enter an ISR and run the BIST self test of the CPUs to check to see if it's a hard error. If it's just a soft error you may decide to restart or resume your application.

    Key point here is that the 2nd CPU is always a diagnostic - it's never a 2nd channel that can act independently of the 1st CPU.
  • 0 in reply to Anthony F. Seely
    Intellectual 645 points
    Thanks Anthony for the clarifications