Enabling PM for blinky example on NRF9160 DK

RE: Enabling PM for blinky example on NRF9160 DK

Edvin — Wed, 15 Jan 2025 11:34:12 GMT

Hello,

Unfortunately, it is not possible to have a timer running in System Off mode, and hence, it can not be used to wake up the device. The possible wake-up sources are listed here:

https://docs.nordicsemi.com/bundle/ps_nrf9160/page/chapters/pmu/doc/operationmodes/system_off_mode.html

So if you want to wake up on a timer, you need to use System On mode, which is a lighter form of sleep. This is the default state when the CPU is not actually running. So if you e.g. calls: k_sleep(K_MSEC(1000)); then it will set up a timer interrupt 1 second ahead, and enter system on mode.

In reality, it is a bit more complex, since you can have several threads in Zephyr, but when all threads are done with their tasks for now, it will automatically enter sleep/system on mode automatically.

From system on mode, any interrupt will wake the device, and the application is not reset on wakeup.

Best regards,

Edvin

RE: Enabling PM for blinky example on NRF9160 DK

devMV — Fri, 10 Jan 2025 14:54:52 GMT

Hi Edwin, you are correct , it was renamed, however from SDK version 2.5.0 the PM subsystem was removed altogether. See: NCS 2.5.0 NRF9160 PM discussion . I got an older version , added the PM call to go into system off mode and was successful, I can wake with button press but I can see that it is impossible to wake with a timer , which is a requirement, do you have any suggestions to minimize power consumption?

RE: Enabling PM for blinky example on NRF9160 DK

Edvin — Fri, 10 Jan 2025 14:20:00 GMT

Hello,

[quote user=""]The issue is that when i try to set CONFIG_PM=y, in the project config file, i see the warning[/quote]

Try using CONFIG_PM_DEVICE=y instead of CONFIG_PM=y.

I see from zephyr's release notes that:

  * The following functions were renamed:

    * :c:func:`pm_power_state_next_get()` is now :c:func:`pm_state_next_get()`
    * :c:func:`pm_power_state_force()` is now :c:func:`pm_state_force()`

Sp perhaps you need to use pm_state_force() instead of pm_power_state_force().

However, you can also use sys_poweroff(), as demonstrated in the sample you can find in:

NCS\zephyr\samples\boards\nordic\system_off. It is a small sample that just writes a few lines to the UART console, before disabling the uart, setting a gpio/button for wakeup, and enters system off.

Best regards,

Edvin