Current consumption difference between SDK16 and SDK15.3

[Daichi]

Hello devzone!
I am using translation.

I am using a DK board (PCA10056) to examine the current consumption of nRF52840.
I commented out the advertising_start() of the SDK example ble_app_blinky and checked the current in the standby state (nrf_pwr_mgmt_run()).

SDK15.3's ble_app_blinky was 620uA, but SDK16's ble_app_blinky was 20uA.

Since SDK16 seems to use app_timer2.c, I changed it to call app_timer.c, but it was 20uA.
When I copied the contents of sdk_config.h of SDK16 to SDK15.3, 620uA didn't change.

What does the difference in current derive from?

Thank you so much as always.

[Jørgen Holmefjord]

Hi,

The current is caused by the NRF_LOG module, which is enable with UART backend. If you set NRF_LOG_ENABLED to 0 in the sdk_config.h file, you should see similar current in both SDK releases (I measure between 4-5 uA).

In nrfx driver library v1.7.0, a change was added to reduce the UARTE current when there is no activity. nRF5 SDK v15.3.0 included nrfx v1.6.2, while nRF5 SDK v16.0.0 includes nrfx v1.8.0, which should explain the difference in current when logging is enabled.

Best regards,
Jørgen

[Daichi]

Hi, Jørgen!

I set NRF_LOG ENABLED to 0, the result was the same as you.
I can understand. 

Thank you for your reply!

[Daichi]

Please tell me additionally.
Is there a function other than UARTE that consumes current even if there is no activity?