Serial LTE Modem - too long initialization after RESET by pin

[Michal Mühlpachr]

NCS main, Serial LTE Modem app

prj.conf
CONFIG_SLM_START_SLEEP=y
CONFIG_SLM_WAKEUP_PIN=6
CONFIG_SLM_INDICATE_PIN=2
CONFIG_NRF_MODEM_LIB_TRACE_ENABLED=y

SLM initialization takes an unexpectedly long time ~1,5s.

Expected is ~25ms.

Host must wait ~1,5s after nRF9160 RESET by pin before WAKEUP activation, otherwise WAKEUP is not picked by SLM.

It is also visible from nRF9160 PPK2 power profile after RESET, see below.

Because CONFIG_SLM_START_SLEEP=y is used in SLM config, SLM should trasit into sleep within reasonable time (Lorenzo Amicucci expects ~25ms).

You can reproduce it easily by automated test scenario with WAKEUP activation with a shorter time interval from RESET than 1,5s.

Regards,
Michal

[Håkon Alseth]

Hi,

 

The time from reset to "Ready" is printed is around 800 ms from reset:

And it is similar when waking up from system off (last line is the button press):

 

This is because there's essentially three applications starting:

* mcuboot

* spm

* SLM

 

In addition, the startup of the 32 kHz source is in the range of several hundred milliseconds:

infocenter.nordicsemi.com/.../pmu_oscillators.html

 

Kind regards,

Håkon