Regarding the MPSL ASSERT: 1, 1519 issue

[sean]

Hi，

    During full-device testing, we observed that two devices encounter the MPSL ASSERT: 1, 1519 error after approximately one hour of operation, which causes the MCU to reboot. In addition, several other devices experience the same error about once per day, while the majority of devices operate normally.

    We have confirmed that this is related to an HF crystal oscillator startup timeout. We would like to confirm the timeout duration and the number of retry attempts for the crystal startup.

The main MCU is nRF54L15, using SDK v3.1.0.
CONFIG_MPSL_HFCLK_LATENCY = 1800

[Susheel Nuguru]

MPSL ASSERT: 1, 1519 in NCS 3.1 happens if HFXO takes too long to wake up.

CONFIG_MPSL_HFCLK_LATENCY should be selected based on PCB design (HFXO model, capacitance, voltage etc). It is possible that the customer need to measure HFXO startup time and change CONFIG_MPSL_HFCLK_LATENCY (or device-tree hfxo,startup-time-us entry) based on the measurement results.

There is a relevant documentation in Kconfig:

https://github.com/nrfconnect/sdk-nrf/blob/v3.1.0/subsys/mpsl/init/Kconfig#L79

[Ron Liu]

Through our experimental verification, the crystal oscillator startup time is fixed at 1000us, rather than CONFIG_MPSL_HFCLK_LATENCY. We need to confirm this.

[sean]

Hi，

    Ron Liu is our customer，the owner of the problem，please help check.

[Susheel Nuguru]

Hi Liu, 

I am not sure if I understood your statement correctly. You need to set CONFIG_MPSL_HFCLK_LATENCY atleast to 1000 in your project configuration to tell MPSL to wait that time for the crystal startup. What is the value set to it now? If it is less than 1000 for a crystal that takes 1000us in your board, then that might explain the assert.

[Ron Liu]

Currently, we have set CONFIG_MPSL_HFCLK_LATENCY to 1800, but the actual measured crystal oscillator time is around 1000 µs. In theory, an assertion should not occur, but in practice, it does. We infer that the time triggering the assertion is 1000 µs instead of CONFIG_MPSL_HFCLK_LATENCY. We need the Nordic team to review the MPSL source code to confirm this.