STM32WLE5CC (RAK3172) LoRaWAN end node unable to reduce power below 150uA

[JMate.3]

I have created this easy project for the RAK3172 based on the LoRaWAN end node skeleton (myIoTopenTech/TiposDeDispositivos/TTNMAD_SOUND/STM32CUBEIDE/ttnmad_noise/) available on GITHUB.

The program works properly joining to The Things Network using OTAA and sending a dummy payload every 20 seconds... but in the interval between transmisions, the power consumption is about 150uA... I would expect something closer to 15 uA (that is what I get on the same hardware with a similar program developep using MbedOS).

I am using the RAK3272S breakout board, so there is nothing connected to the STM32WLE5, and the st-link is disconnected during power consumption measurements.

[Uwe Bonnes]

• Check for floating pins
• Remove debugger and revert settings that were done with debugger connect

[JMate.3]

Thank you very much for answering @Uwe Bonnes​ 

I have checked this option so there shouldn't be floating pins.

And also disabled debugger

[JMate.3]

Something very odd.

Tying the RX pin of USART2 to GND the power consumption is finally reduced to 1.5uA.

I have the USART2 configured for only transmissión, but this does not reduce the consumption unless the RX pin is physically connected to GND.

Anyone know how to avoid this without the physicall connection to GND?