nRF52833 Errata 78 and Writing to Deprecated TASKS_SHUTDOWN Register

[Akash Patel]

Hello,

Looking at the errata entry [78] TIMER: High current consumption when using timer STOP task only, I see that it recommended to use TASKS_SHUTDOWN instead of TASKS_STOP to actually turn off the timer and reduce power consumption. However, the TASKS_SHUTDOWN register is deprecated. Is it still valid to write to this register and will it still turn off the timer and reduce current? Why is it deprecated?

Regards,

Akash Patel

[Einar Thorsrud]

Hi Akash,

I looked at the history and the SHUTDOWN task is marked as deprecated because there is no short between it and STOP. Using the term is a bit confusing, particularly as it is required for the workaround, but the "deprecated" state has no practical consequences. 

[Arjun]

Hello Einar,

So how do we reduce the power consumption caused due to the timer not shutdown?

In our project, we are using the nRF52833 chipset for 802.15.4 transmission. We would like to turn off the radio and all its supporting peripherals such that we are in the lowest possible current draw state. We noticed that the 802.15.4 driver (version.1.6.0/1) uses timers, while turning off the radio we found that the driver is making an inline call  for “nrf_timer_task_trigger(TIMER, NRF_TIMER_TASK_SHUTDOWN)”. After knowing that the the SHUTDOWN Register is deprecated. what is the best way to turn-off the timer?  

I also notice when I don't use the Radio(802.15.4) functionality I receive about 300-350uA saving compared to the time I use my radio(This measurement is when the processor is running pwr_mgmt_run()).

Is there a specific Register other than the SHUTDOWN Register what we can write to to shutdown the timer?
Is there a specific process to turn off the timer so that we obtain best power savings? 

Best Regard,

Arjun Warty

[Einar Thorsrud]

HI Arjun,

You should not put much emphasis on the "deprecated" statement. The feature is there and will not go way. The best way to turn off the timer is still to use SHUTDOWN.

Arjun said:

Is there a specific Register other than the SHUTDOWN Register what we can write to to shutdown the timer?

No.

Arjun said:

Is there a specific process to turn off the timer so that we obtain best power savings? 

Use SHUTDOWN.