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Sitara PRU - question to timers

Roman Dohnal
Prodigy 10 points

Hi,

I have a kind of newbie question to the Sitara PRU and using its timers.

My problem is that I need to use several timers in parallel - what i found in manuals for the Sitara CPU is that the PRU can access directly timers for UART and IEP. That's fine, but it seems that only IEP timer can be configured to generate pulses as I need (1 us). Or am I missing something?

The worst part is that I actually need three timers - so there are 6 peripheral. I'm not quite sure how to connect them into the PRU. So my question is if it is possible to use these timers for the invoking ISR inside the PRU software?

I also have follow-on question - as the main CPU is running application that is kind of demanding on the L3/L4 bus, could I cause some lags or delays to the main routine by using the peripheral timers?

Thanks,

Roman

  • 0
    TI__Intellectual 1340 points

    Hi Roman,

    I am not PRU specialist but as I checked there no other timer for 1 us GP use in PRU than IEP one.

    There are of course the DM timers in the AM335x but they do not have direct IRQ maped to PRU. You can redirect it from MPU system by software but have to consider the latency of course.

    Here some documents about PRU (if you do not have them already):

    https://github.com/beagleboard/am335x_pru_package

    There is a zip with documentation there.

    Also as a suggestion cant you use three SW counters based on IEP timer ticks? 

    Hope this helps.

    Best regards,

    Vidin