Experienced high power consumption with both CONFIG_PM_DEVICE and CONFIG_NRF_SW_LPUART enabled

RE: Experienced high power consumption with both CONFIG_PM_DEVICE and CONFIG_NRF_SW_LPUART enabled

luca-aa — Fri, 27 Mar 2026 09:47:54 GMT

Hi Stian,
It’s working for me as well.

However, since I was sure I had already tried adding this parameter, I investigated further.
I reverted to the initial version of the code (see attached lpuart.zip), compiling with SDK 2.9.0.

In that case, CONFIG_PM_DEVICE_RUNTIME=y has no effect.

So I assume this is an issue with the older SDK.

Anyway, thank you very much for your help.

Luca

RE: Experienced high power consumption with both CONFIG_PM_DEVICE and CONFIG_NRF_SW_LPUART enabled

Stian Røed Hafskjold — Thu, 26 Mar 2026 19:23:54 GMT

Hi, can you try to add this kconfig?

CONFIG_PM_DEVICE_RUNTIME=y

I was able to reproduce what you are seeing with the zip-file you provided. Adding this kconfig seems to fix the issue

RE: Experienced high power consumption with both CONFIG_PM_DEVICE and CONFIG_NRF_SW_LPUART enabled

luca-aa — Thu, 26 Mar 2026 14:53:02 GMT

Hi Kazi,
are you asking if I used Pin12 or Pin13 for GPIOTE in a previous project test?
I don't think, but I can not be sure of it. It's a DK board. I used it for various test.
Pin 12 and Pin 13 are shorted for this test, as sujested in the lpuart sample documentation.

Why you're asking? Is there something that remain latched in GPIOTE Pin usage?

RE: Experienced high power consumption with both CONFIG_PM_DEVICE and CONFIG_NRF_SW_LPUART enabled

Kazi Afroza Sultana — Thu, 26 Mar 2026 14:19:41 GMT

Hello,

Have you used these pin12 and pin13 for GPIOTE before?

RE: Experienced high power consumption with both CONFIG_PM_DEVICE and CONFIG_NRF_SW_LPUART enabled

Kazi Afroza Sultana — Fri, 13 Mar 2026 14:28:50 GMT

Hello Luca,

I have measured again.

When CONFIG_PM_DEVICE is set, current approx 57uA and when it's not set approx 25uA. I think it's in line with your observation. To observe how PM_DEVICE is affecting the driver configuration I have tried to find the difference between two generated file of .config from these 2 different set up.

CONFIG_UART_0_NRF_ASYNC_LOW_POWER is only set when PM device is not set. I have checked the output dts file. UART0 is disabled. I have been investigating more. I will get back to you lately.

RE: Experienced high power consumption with both CONFIG_PM_DEVICE and CONFIG_NRF_SW_LPUART enabled

luca-aa — Thu, 12 Mar 2026 07:59:45 GMT

Hi Achim,

yes, I had already considered that it could be a sense-edge-mask issue. I also tried adding the directive to the device tree, but it didn’t change the result.
I also found a post in an old thread saying that the sense-edge-mask is automatically applied to the pins used by the lpuart.

RE: Power consumption about LPUART

Luca

RE: Experienced high power consumption with both CONFIG_PM_DEVICE and CONFIG_NRF_SW_LPUART enabled

Achim Kraus — Thu, 12 Mar 2026 06:13:36 GMT

Just a guess:

The lpuart uses a GPIO in interrupt edge mode.

That causes some more current, if not masked to emulate the edge mode with

&gpio0 {
sense-edge-mask = <0xffff>;
};

maybe that helps.

(But also maybe, the lpuart doesn't work with that ;-) ).

RE: Experienced high power consumption with both CONFIG_PM_DEVICE and CONFIG_NRF_SW_LPUART enabled

luca-aa — Wed, 11 Mar 2026 11:05:33 GMT

Hi Kazi,

It's so strange. I'm repeating the same test again and again, but my result is the same. With CONFIG_PM_DEVICE=y, I see a current consumption of about 23 uA. Are you sure you did a pristine buld after changing CONFIG_PM_DEVICE to y?

Maybe there is something is different at compile time. I attach my log with west command line:

 *  Executing task: nRF Connect: Generate config nrf9151dk/nrf9151/ns for c:\work\nordic\nRF9151\lpuart.3.2.2 

Building lpuart.3.2.2
west build --build-dir c:/work/nordic/nRF9151/lpuart.3.2.2/build c:/work/nordic/nRF9151/lpuart.3.2.2 --pristine --board nrf9151dk/nrf9151/ns --sysbuild -- -DCONFIG_SIZE_OPTIMIZATIONS=y -DEXTRA_CONF_FILE=boards/nrf9151dk_nrf9151_ns.conf -DEXTRA_DTC_OVERLAY_FILE=boards/nrf9151dk_nrf9151_ns.overlay

-- west build: generating a build system
Loading Zephyr module(s) (Zephyr base): sysbuild_default
-- Found Python3: C:/ncs/toolchains/c717907b94/opt/bin/python.exe (found suitable version "3.12.4", minimum required is "3.10") found components: Interpreter 
-- Cache files will be written to: C:/ncs/v3.2.2/zephyr/.cache
-- Found west (found suitable version "1.4.0", minimum required is "0.14.0")
-- Board: nrf9151dk, qualifiers: nrf9151/ns
Parsing C:/ncs/v3.2.2/zephyr/share/sysbuild/Kconfig
Loaded configuration 'C:/work/nordic/nRF9151/lpuart.3.2.2/build/_sysbuild/empty.conf'
Merged configuration 'C:/work/nordic/nRF9151/lpuart.3.2.2/build/_sysbuild/empty.conf'
Configuration saved to 'C:/work/nordic/nRF9151/lpuart.3.2.2/build/zephyr/.config'
Kconfig header saved to 'C:/work/nordic/nRF9151/lpuart.3.2.2/build/_sysbuild/autoconf.h'
-- 
   **********************************
   * Running CMake for lpuart.3.2.2 *
   **********************************
Loading Zephyr default modules (Zephyr base).
-- Application: C:/work/nordic/nRF9151/lpuart.3.2.2
-- CMake version: 3.21.0
-- Found Python3: C:/ncs/toolchains/c717907b94/opt/bin/python.exe (found suitable version "3.12.4", minimum required is "3.10") found components: Interpreter 
-- Cache files will be written to: C:/ncs/v3.2.2/zephyr/.cache
-- Zephyr version: 4.2.99 (C:/ncs/v3.2.2/zephyr)
-- Found west (found suitable version "1.4.0", minimum required is "0.14.0")
-- Board: nrf9151dk, qualifiers: nrf9151/ns
-- Found host-tools: zephyr 0.17.0 (C:/ncs/toolchains/c717907b94/opt/zephyr-sdk)
-- Found toolchain: zephyr 0.17.0 (C:/ncs/toolchains/c717907b94/opt/zephyr-sdk)
-- Found Dtc: C:/ncs/toolchains/c717907b94/opt/bin/dtc.exe (found suitable version "1.4.7", minimum required is "1.4.6") 
-- Found BOARD.dts: C:/ncs/v3.2.2/zephyr/boards/nordic/nrf9151dk/nrf9151dk_nrf9151_ns.dts
-- Found devicetree overlay: C:/work/nordic/nRF9151/lpuart.3.2.2/boards/nrf9151dk_nrf9151_ns.overlay
-- Found devicetree overlay: boards/nrf9151dk_nrf9151_ns.overlay
-- Generated zephyr.dts: C:/work/nordic/nRF9151/lpuart.3.2.2/build/lpuart.3.2.2/zephyr/zephyr.dts
-- Generated pickled edt: C:/work/nordic/nRF9151/lpuart.3.2.2/build/lpuart.3.2.2/zephyr/edt.pickle
-- Generated devicetree_generated.h: C:/work/nordic/nRF9151/lpuart.3.2.2/build/lpuart.3.2.2/zephyr/include/generated/zephyr/devicetree_generated.h
Parsing C:/ncs/v3.2.2/zephyr/Kconfig
Loaded configuration 'C:/ncs/v3.2.2/zephyr/boards/nordic/nrf9151dk/nrf9151dk_nrf9151_ns_defconfig'
Merged configuration 'C:/work/nordic/nRF9151/lpuart.3.2.2/prj.conf'
Merged configuration 'C:/work/nordic/nRF9151/lpuart.3.2.2/boards/nrf9151dk_nrf9151_ns.conf'
Merged configuration 'C:/work/nordic/nRF9151/lpuart.3.2.2/boards/nrf9151dk_nrf9151_ns.conf'
Merged configuration 'C:/work/nordic/nRF9151/lpuart.3.2.2/build/lpuart.3.2.2/zephyr/misc/generated/extra_kconfig_options.conf'
Merged configuration 'C:/work/nordic/nRF9151/lpuart.3.2.2/build/lpuart.3.2.2/zephyr/.config.sysbuild'
Configuration saved to 'C:/work/nordic/nRF9151/lpuart.3.2.2/build/lpuart.3.2.2/zephyr/.config'
Kconfig header saved to 'C:/work/nordic/nRF9151/lpuart.3.2.2/build/lpuart.3.2.2/zephyr/include/generated/zephyr/autoconf.h'
-- Found GnuLd: c:/ncs/toolchains/c717907b94/opt/zephyr-sdk/arm-zephyr-eabi/arm-zephyr-eabi/bin/ld.bfd.exe (found version "2.38") 
-- The C compiler identification is GNU 12.2.0
-- The CXX compiler identification is GNU 12.2.0
-- The ASM compiler identification is GNU
-- Found assembler: C:/ncs/toolchains/c717907b94/opt/zephyr-sdk/arm-zephyr-eabi/bin/arm-zephyr-eabi-gcc.exe
-- Found gen_kobject_list: C:/ncs/v3.2.2/zephyr/scripts/build/gen_kobject_list.py
-- Configuring done
-- Generating done
-- Build files have been written to: C:/work/nordic/nRF9151/lpuart.3.2.2/build/lpuart.3.2.2
Dropping partition 'nrf_modem_lib_trace' since its size is 0.
Dropping partition 'nonsecure_storage' since it is empty.
-- Configuring done
-- Generating done
-- Build files have been written to: C:/work/nordic/nRF9151/lpuart.3.2.2/build
-- west build: building application
[4/269] Generating include/generated/zephyr/version.h
-- Zephyr version: 4.2.99 (C:/ncs/v3.2.2/zephyr), build: ncs-v3.2.2
[10/269] Generating ../../tfm/CMakeCache.txt
-- Found Git: C:/ncs/toolchains/c717907b94/mingw64/bin/git.exe (found version "2.52.0.windows.1") 
CMake Warning at CMakeLists.txt:43 (project):
  VERSION keyword not followed by a value or was followed by a value that
  expanded to nothing.

-- The C compiler identification is GNU 12.2.0
-- The CXX compiler identification is GNU 12.2.0
-- The ASM compiler identification is GNU
-- Found assembler: C:/ncs/toolchains/c717907b94/opt/zephyr-sdk/arm-zephyr-eabi/bin/arm-zephyr-eabi-gcc.exe
-- Found Python3: C:/ncs/toolchains/c717907b94/opt/bin/python.exe (found version "3.12.4") found components: Interpreter 
-- Found Python3: C:/ncs/toolchains/c717907b94/opt/bin/python.exe (found suitable version "3.12.4", minimum required is "3.10") found components: Interpreter 
-- Cache files will be written to: C:/ncs/v3.2.2/zephyr/.cache
-- Configuring done
-- Generating done
-- Build files have been written to: C:/work/nordic/nRF9151/lpuart.3.2.2/build/lpuart.3.2.2/tfm
[147/151] Linking C executable bin\tfm_s.axf
Memory region         Used Size  Region Size  %age Used
           FLASH:       32216 B        32 KB     98.32%
             RAM:       10432 B        32 KB     31.84%
[17/269] Performing install step for 'tfm'
-- Install configuration: "MinSizeRel"
----- Installing platform NS -----
[269/269] Linking C executable zephyr\zephyr.elf
Memory region         Used Size  Region Size  %age Used
           FLASH:       48404 B       992 KB      4.77%
             RAM:       14288 B     211608 B      6.75%
        IDT_LIST:          0 GB        32 KB      0.00%
Generating files from C:/work/nordic/nRF9151/lpuart.3.2.2/build/lpuart.3.2.2/zephyr/zephyr.elf for board: nrf9151dk
[10/10] Generating ../merged.hex

I also atach the prj.conf file I use. The only difference from the previous attached file lpuart.3.2.2.zip is the CONFIG_PM_DEVICE=y

# Copyright (c) 2020 Nordic Semiconductor
#
# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
#
CONFIG_NRF_SW_LPUART=y
CONFIG_SERIAL=y
CONFIG_LOG=n

# Sample is showing low power capabilities of low power uart module thus
# console/logging uart is disabled.

CONFIG_CONSOLE=n
CONFIG_UART_CONSOLE=n

CONFIG_LOG=n
CONFIG_GPIO=y
CONFIG_NRF_MODEM_LIB=y
CONFIG_LTE_LINK_CONTROL=y
CONFIG_POWEROFF=y

CONFIG_PM_DEVICE=y

Thank you Kazi,

I hope it will help replicate the problem.

Luca

RE: Experienced high power consumption with both CONFIG_PM_DEVICE and CONFIG_NRF_SW_LPUART enabled

Kazi Afroza Sultana — Wed, 11 Mar 2026 10:07:01 GMT

Hello Luca,

I have run your sample on NCS v3.2.2 and I got almost same current by setting and unsetting the CONFIG_PM_DEVICE

config_pm_device=y

config_pm_device=n

RE: Experienced high power consumption with both CONFIG_PM_DEVICE and CONFIG_NRF_SW_LPUART enabled

luca-aa — Fri, 27 Feb 2026 14:26:30 GMT

Hi Kazi,
I tried updating to SDK 3.2.2 and compiling the related lpuart example, but I don't see any changes from before. The example compiled with SDK 2.9.0 and SDK 3.2.2 give the same results and the same power consumption. I'll provide you with the diagrams again for the cases with CONFIG_PM_DEVICE set to y and n.

I'm also attaching the new code for the lpuart example for SDK 3.2.2.
Perhaps, are there other CONFIG to enable the configuration to avoid this behaviour?

Thank you

Luca

devzone.nordicsemi.com/.../lpuart.3.2.2.zip

CONFIG_PM_DEVICE=y

CONFIG_PM_DEVICE=n

RE: Experienced high power consumption with both CONFIG_PM_DEVICE and CONFIG_NRF_SW_LPUART enabled

Kazi Afroza Sultana — Fri, 27 Feb 2026 13:00:42 GMT

Hello Luca,

I got reply from team:

When it system on idle, LPUART consumes 31uA current. So, it seems that CONFIG_PM_DEVICE=y prevents the CONFIG_PM_DEVICE_RUNTIME=y from working properly. It was an issue in the time of NCS v2.9.0 (https://github.com/zephyrproject-rtos/zephyr/issues/75963). This is solved in the current NCS version.

RE: Experienced high power consumption with both CONFIG_PM_DEVICE and CONFIG_NRF_SW_LPUART enabled

luca-aa — Fri, 27 Feb 2026 07:56:21 GMT

Hi Kazi,

In your test, something was probably left enabled in the case with CONFIG_PM_DEVICE=y, which is why you're seeing currents in the milliamp range. However, even if you manage to disable whatever is consuming too much power, the current still remains inexplicably around 22µA.

I’m looking forward to the team’s feedback.

Thanks you for your help.

Luca

RE: Experienced high power consumption with both CONFIG_PM_DEVICE and CONFIG_NRF_SW_LPUART enabled

Kazi Afroza Sultana — Wed, 25 Feb 2026 08:40:24 GMT

Hello Luca,

I have tried to reproduce your issue. The result is not same in terms of current value but in terms of CONFIG_PM_DEVICE issue we have the same observation.

This is when CONFIG_PM_DEVICE=y

This is when CONFIG_PM_DEVICE=n

I am not sure why setting CONFIG_PM_DEVICE causes higher current. I have asked team if it is a bug in the application. I will get back to you when there is a reply.

Thanks.

BR
Kazi

RE: Experienced high power consumption with both CONFIG_PM_DEVICE and CONFIG_NRF_SW_LPUART enabled

luca-aa — Fri, 13 Feb 2026 16:17:00 GMT

Hi Kazi,

[quote userid="108933" url="~/f/nordic-q-a/126988/experienced-high-power-consumption-with-both-config_pm_device-and-config_nrf_sw_lpuart-enabled/561144"]Did you measure sleep current?[/quote]

Yes I was measuring sleep current on my project board.

But, please also look at the second part of my post (after "My Test" underlined label)

I got the same current increment with the lpuart example and the nRF9151-DK (not SMA) board.

So, my test condition are:

- nRF9151-DK (not SMA)

- RX(pin 10) and TX (pin11) shorted

- REQ (pin 12) and RDY (pins 13) shorted

- lpuart example code (slightly modified to be compatible with 9151, see attached code)

- CONFIG_PM_DEVICE=n, low current case (first picture)

- CONFIG_PM_DEVICE=y, high current case (second picture)

thank you for your answer

Luca

RE: Experienced high power consumption with both CONFIG_PM_DEVICE and CONFIG_NRF_SW_LPUART enabled

Kazi Afroza Sultana — Fri, 13 Feb 2026 15:49:01 GMT

Hello,

''With both configurations enabled, I measure a current consumption of approximately 30 µA, while I would expect something closer to 8 µA''

Did you measure sleep current?

Did you use SMA DK?