Azure_iot_hub baseline power consumption

[Bard]

Hi

The baseline current consumption running the azure_iot_hub is very high.

I'm using nRF Connect SDKv1.6.1. The sample connects and sends data to azure as expected. But when looking at the current consumption it's way too high. I first observed this on a custom board, and then exactly the same on nRF9160DK. Current is measured using PPK2.

   

What causes these peaks? How can I remove them?

The azure_iot_hub sample is unmodified except for configuring the azure address and TLS sec 

[Hakon]

Hello,

the increased current draw is likely caused by UART logging. The peaks you are seeing could be caused by switching noise from the DCDC converter on the DK.

[Bard]

What do I have to do to turn off UART? I tried just config_serial=n, but then the application resets.

[Hakon]

You will probably need to disable the at host library, with CONFIG_AT_HOST_LIBRARY=n, since that is using the serial driver.