Power optimizatio of battery operated device

[Ankit_chauhan]

Hello,

I have custom hardware running on nRF53 and there are multiple sensors connected with it for the measurement of their different entities. The hardware is battery-operated so I need to have a tight power profile that can run the battery as long as possible.

I have measured the idle current of my system around 1.2mA where BLE is advertising and all the sensor power is suspended using the Zephyr Power Management module. I have disabled the Serial Interface and UART for both the Application Core and Network Core. I have followed this thread and a couple of others to achieve this idle current from 3mA to 1.2mA.

I have two concerns,

1. The 1.2mA for an idle system is still higher. I want to reduce it to in terms of hundreds of microamps so that the device can be run with the battery longer time.
2. I am using the BLE DFU for OTA, as I mentioned I have disabled the Serial/UART interface and hence the BLE SHELL as well. But the BLE DFU requires the CONFIG_BT_SHELL because when I set CONFIG_BT_SHELL=n, I do not see the DFU button on the nRF Connect Mobile app. And if the CONFIG_BT_SHELL=y, the current reaches 3mA from 1.2mA.

Is there any configuration that can help to reduce the overall power consumption of the system? I know the Nordic nRF53 can be operated in less than 100uA.

[PjGlasso]

Hi there,

Yes I would agree that is too High, Over on the Seeed Studio forum , they have it down to 5uA for sleep. The code turns off the Flash , chip and a DCto DC regulator, disconnect the Serial connection and use the battery pads only for measure with PPKII .

The lowest power was achieved by using minimal Bootloader also. 

Look forward to a response here on this.

GL :-) PJ

[Ankit_chauhan]

Hi PJ,

Thanks for the response.

I agree on the minimal current advantage of nRF. I also achieved around 60uA with BLE working so my application could also reach around that current reading.

But here the issue is, as I mentioned in the second point I am not able to perform the BLE DFU without enabling the BT_SHELL, and if I enable the BT_SHELL my current jumps to 3mA.

Is it true that the BLE DFU requires the SHELL? I guess the DFU uses the service and characteristics only. If the DFU uses the SHELL, is there any configuration that can be done to reduce this 3mA?

Note: My SHELL is running on UART0.

Regards,

Ankit.

[Sigurd]

Hi!

No, you don't need BT_SHELL or UART for BLE OTA DFU.

Check out this guide on how to add BLE OTA DFU to your application:

https://academy.nordicsemi.com/courses/nrf-connect-sdk-intermediate/lessons/lesson-8-bootloaders-and-dfu-fota/topic/exercise-3-fota-over-bluetooth-low-energy/

[Ankit_chauhan]

Thanks for sharing the guide.