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AM6422: AM6422 PRU Interrupt Vector Table Location

Seth Appleman
Prodigy 30 points

Part Number: AM6422

I am setting up a timer on the AM6422 PRU_ICSSG to act as a frame interrupt timer, using the PRU IEP module. I am setting up the timer compare function per AM64x TRM section 6.4.13.2.4.

 

When the timer expires, as indicated by register IEP_CMP_STATUS_REG, I want to configure the PRU_INTC event 7 (pr0_iep_tim_cap_cmp_pend) to fire an interrupt. I want the fired interrupt to invoke an interrupt handler I can use to trigger my periodic frame processing within the PRU firmware. Is there some sort of Interrupt Vector Table within the PRU firmware that I can setup to map the interrupt firing to an interrupt handler routine? I have seen this concept for mapping interrupts to handlers in one of the other processing cores (A53, R5F, M4F), but not in the PRU itself.

  • +1
    TI__Guru** 108080 points

    Hello Seth,

    PRU deals with interrupts a bit differently from other cores.

    The interrupt controller INTC does not actually have the capability to preempt currently running code - this makes your code 100% deterministic by default. For more information about the INTC, please start by taking a look at 
    https://dev.ti.com/tirex/explore/node?isTheia=false&node=A__ARwLDTX.JuwQ7FVKGFsVJg__AM64-ACADEMY__WI1KRXP__LATEST

    PRU_ICSSG subsystems have an additional tool, called the task manager, which IS capable of preempting PRU execution - we added the task manager specifically because it helped us to get to gigabit Ethernet speeds.

    I have not had time yet to write documentation on the task manager, so you are stuck with the Technical Reference Manual (TRM) for our public documentation for now. However, we just published a new example to the OpenPRU repo which uses task manager. You can find that project here, hopefully we included enough comments and documentation to give you an idea of how it is programmed:
    https://github.com/TexasInstruments/open-pru/tree/main/examples/multicore_scheduler 

    Don't be surprised if you see some includes shift around in that project in the next week or so, I am getting rid of external dependencies within the PRU firmware to make future porting efforts between processors easier.

    Regards,

    Nick

  • 0 in reply to Nick Saulnier
    TI__Guru** 108080 points

    Also, I sent you an e2e friend request so we can have an offline discussion about connecting you with your company's TI representative. Please accept that so we can have a sideband chat.