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TMDSEVM437X: PRUs running in power state standby

Katu Txakur
Prodigy 70 points
Part Number: TMDSEVM437X

Hi,

Is it possible to have the PRUs running when the processor is in standby?

If possible, could someone point me to the section in the AM437x TRM where this is explained?

Regards

  • 0
    Prodigy 70 points
    Also, what would be the estimated power of the processor in standby with one PRU running?
  • 0 in reply to Katu Txakur
    TI__Guru**** 161600 points
    Hi,

    I've notified the factory team.

    Best Regards,
    Yordan
  • 0
    TI__Genius 13505 points

    Hi Katu,


    Unfortunately, the power management strategy used today does not allow the PRU to remain active during standby.  Standby mode is defined to have all clock domains in bypass mode, so PRU cannot be active in this mode.

    Can you share what you're roughly trying to accomplish in your application, and your system power goals during this mode?  Also, what are you expecting for a resume time, in the event the PRU needs to wake the ARM?

    Regards,
    Mike

  • 0 in reply to Michael Erdahl
    Prodigy 70 points

    Hi Mike,

    Thanks for your answer. My hope was to have a PRU running a signal detection whilst the processor sleeps. My power goal is < 20 mA in this state and a wake up time < 300ms.

    I have read people saying that standby with PRUs is possible in the am335x and I though it might be possible with the am437x too.

  • 0 in reply to Katu Txakur
    TI__Genius 13505 points

    Katu,

    Are you looking for a simple logic transition on a pin associated with a PRU, or are you requiring a certain amount of processing, i.e., analyzing communication packets for a specific address or pattern?

    To be clear, it is possible to have the PRUs remain active during standby with modification to the suspend/ resume path to maintain clocks to the PRU.

    Does your power goal represent processor power consumption only, or for the entire system?  Your resume time target is fine.  

    Regards,
    Mike

  • 0 in reply to Michael Erdahl
    Prodigy 70 points

    Hi Mike,

    I do require a certain amount of signal processing in the PRU. I am very interested in knowing more details about how to modify the suspend/resume path to keep the clocks to the PRU.

    Is this also possible in suspend to RAM state?

    Is this a device tree change?

    Alternatively, is it possible to run the PRUs with an external clock?

    The power goal is for the entire board. It's a battery powered system that will sit doing nothing for a long time until a signal is detected by the PRU. We need to reduce the power as much as possible because in our environment it's not possible to recharge/replace the battery. I have read that this processor will consume ~5mW in suspend to RAM state, but I don't know about standby.

    Thanks for your help,

    Katu