Zigbee + FreeRTOS End Device power consumption

[sjf]

Hi,

We have been working with an end device based on nRF52840 with nRF5_SDK_for_Thread_and_Zigbee_v4.0.0_dc7186b

By measuring with the power profiler kit, we got a system's power consumption of about 50uA. But after we call zboss_start_no_autostart() and zboss_main_loop_iteration() periodically (we tried from 50ms to 1s) we realized that the current consumption varies from 500uA to 1mA. This is how the Zed is configured:

  zb_set_ed_timeout(ED_AGING_TIMEOUT_64MIN);
  zb_set_keepalive_timeout(ZB_MILLISECONDS_TO_BEACON_INTERVAL(3000));
  zb_set_rx_on_when_idle(ZB_FALSE);

Since we're using FreeRTOS and SoftDeivce, we can't call zb_sleep_now(). Is there any way to turn off radio during inactivity times or any other
considerations?
Also, is there any improvements on this topic betweennRF5_SDK_for_Thread_and_Zigbee_v4.0.0 andnRF5_SDK_for_Thread_and_Zigbee_v4.1.0?

Thanks in advance.
Regards,

Santiago

[Edvin]

Can you please test either way?

Can you also see whether the current consumption is the same if you try one of the non-freertos examples? As far as I can tell, there are no changes on the FreeRTOS front between SDK 4.0.0 and 4.1.0.

Let me know if the current consumption differs a lot between the non-FreeRTOS and FreeRTOS examples. I will check with our Zigbee team if a higher current consumption is a known issue, and if there is a workaround for.

Is there a particular reason for why you need to use FreeRTOS? 

BR,

Edvin

[sjf]

Hi Edvin,

No, there is no chance to remove FreeRTOS since it is not a demo or a simple project. Radio power is automatically handled by SoftDevice?

What about Zboss stack? Was there any remarkable change from 4.0 to 4.1 about power? Is there any extra tunning in this stack to implement?

Regards,

[Edvin]

sjf said:

No, there is no chance to remove FreeRTOS since it is not a demo or a simple project.

 You may of course have your reasons, but I am just saying that you can do quite complex things without FreeRTOS, and possibly more effective. It is worth noticing that you can do quite a lot based on events.

However, Yes. It is the softdevice that has first priority on the radio. The Zigbee stack will ask the softdevice for timeslots in between the BLE events. The softdevice will grant timeslots to the zboss stack, so inside these the zboss stack controls the radio. 

When you are using the mesh technologies in combination with BLE, the mesh technologies will have control of the radio most of the time. BLE is only used in short bursts. 

I am still waiting for a reply from our Zigbee team. Stay tuned. 

BR,

Edvin

[Edvin]

Hello,

Unfortunately, it doesn't look like the FreeRTOS implementation of Zigbee is power optimized, and there are no plans to do so in the nRF5 SDK. 

Our zigbee team says:

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In order to suspend the task, while the timer is disabled, you have to implement ZB_COMMON_SIGNAL_CAN_SLEEP ZBOSS signal handler. Otherwise, you are simply leveraging only the ZBOSS IDLE state, not the ZBOSS SLEEP state (more information about those states can be found here: https://infocenter.nordicsemi.com/topic/sdk_tz_v4.1.0/zigbee_application_reference_component.html?cp=7_3_3_5_1#zarco_sleep).

For some guidance and ideas how to implement this, it might be good to look at the OSIF implementation in NCS:

 - CAN_SLEEP handler: https://github.com/nrfconnect/sdk-nrf/blob/7a8861f03674ca0cf2f859de8ebbfebbfa0581ad/subsys/zigbee/common/zigbee_helpers.c#L455
 - sleep routine (will be called by zb_sleep_now()): https://github.com/nrfconnect/sdk-nrf/blob/7a8861f03674ca0cf2f859de8ebbfebbfa0581ad/subsys/zigbee/osif/zb_nrf_pwr_mgmt.c#L30
 - Poll function: https://github.com/nrfconnect/sdk-nrf/blob/7a8861f03674ca0cf2f859de8ebbfebbfa0581ad/subsys/zigbee/osif/zb_nrf_platform.c#L501

The Signal mechanism is used to wake up the ZBOSS task by other tasks that wants to send something over Zigbee, as well as to wake up the ZBOSS task earlier than the sleep period, passed to the sleep function as an argument.

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I still mean you can do quite complex things without using FreeRTOS, but I don't know what sort of device you are planning to develop.