MPSL ASSERT: 112, 1617 on single board, suspect hardware

[Anthony Ambuehl]

NCS 2.7.0, NRF52840, SYSBUILD with MCUBOOT

We have 1 specific board which is failing with a hardfault and assert MPSL ASSERT: 112, 1617   it occurs whenever we activate bluetooth.  Other boards of the same PCB do not have this problem.  This board previously did not have a problem but recently started.

!) Any idea what might be the root cause for the assertion?

2) If this would be caused by a hardware issue, is it possible for us to create a specific manufacturing test software to catch the issue?

[Priyanka]

Hi Anthony,

This must be a hardware related issue since you do not see this on other boards. Could be an issue with the 32MHz HFCLK, maybe the supply to this, or soldering round the crystal or the crystal itself. I would suggest you to examine the crystal and it's related components and it's surrounding/connected area on the PCB. 

Regards,

Priyanka

[Anthony Ambuehl]

could give any info on the MPSL assertion.. what do the number mean?

[Anthony Ambuehl]

I also notice that if my mfg test code starts the HFCLK but does not turn it off, I no longer get the MPSL assertion.  It seems possibly the failure is related to increased start up time exceeding some limit within MPSL.  

I could measure the time for clock_control_on to complete and set a maximum threshold to match the MPSL library.  

Can you tell me what startup time would be too high for MPSL ?

[Anthony Ambuehl]

By measuring the time taken by clock_control_on I was able to differentiate between acceptable HFCLK modules and unacceptable modules.. eg modules that took longer than 1.5mS to start.

[Priyanka]

Thank you for the updates. Looking into tis and will keep you updated.

-Priyanka

[Anthony Ambuehl]

On this page: https://docs.nordicsemi.com/bundle/ncs-latest/page/nrfxlib/mpsl/doc/clock.html

it says the startup time must be less than 1.5mS.

[Priyanka]

Hi,

Anthony Ambuehl said:

it says the startup time must be less than 1.5mS.

Yes, ~1.5ms, but we've made it configurable. https://github.com/nrfconnect/sdk-nrf/blob/e9fd9ca8783ee2a32e67813e591a7fe13986ef65/subsys/mpsl/init/Kconfig#L78 

-Priyanka