MCX Microcontrollers中的主题 Resets from unknown sources MCXN947

Resets from unknown sources MCXN947

robert_hines — Thu, 17 Sep 2026 16:55:15 GMT

I have a device with an MCXN947. It's running FreeRTOS. Using LPTMR, it periodically goes into power-down mode, wakes up on the timer interrupt, maybe does a few things, then goes back into power-down mode. Something like this:

vTaskSuspendAll(); // FreeRTOS

PM_EnterLowPower(); // LPTMR interrupt will wake us up

xTaskResumeAll(); // FreeRTOS

There's really only one other task running when it wakes up and it does some I2C comms.

The problem is that the processor occasionally resets (can't reliably reproduce). The CMC SRS register reads 0x00004010, a warm SW reset. Code isn't calling reset anywhere, maybe NXP's assert() or FreeRTOS's configASSERT().

Are there other internal sources could be causing a SW reset?

Re: Resets from unknown sources MCXN947

robert_hines — Thu, 17 Sep 2026 17:52:15 GMT

Would this errata (MCXN_1P02G) cause resets?

ERR051704 DCDC: Failure changing to Low drive-strength mode

Re: Resets from unknown sources MCXN947

robert_hines — Thu, 17 Sep 2026 22:05:15 GMT

The SSRS register reads 0x00004430, so the RSTACK bit is set; could ERR051704 cause that?

Re: Resets from unknown sources MCXN947

Alice_Yang — Fri, 18 Sep 2026 08:14:17 GMT

Hello @robert_hines

Yes, it is very likely related.

Please first refer to ERR051704 and ERR051993 for verification.

Also, SSRS contains cumulative status information, so it should be analyzed together with the current SRS value.

Thank you.

Alice

Re: Resets from unknown sources MCXN947

robert_hines — Fri, 18 Sep 2026 14:16:23 GMT

Changing the active voltage to midvoltage (and high drive strength) and the low-power voltage to overdrive (and low drive strength) while dropping in and out of power-down mode once a second, did increase the number of resets, all of the form:

SRS 0x00004010
SSRS 0x00004430

It would be nice if NXP could describe the downstream effects of the errata so I could be more confident this is the source of these spurious resets.

Re: Resets from unknown sources MCXN947

Alice_Yang — Wed, 23 Sep 2026 09:09:18 GMT

Hello @robert_hines

Thanks for your testing and feedback.

Based on your test results, the observed behavior is very similar to the issue described in ERR051704. While I'm sorry NXP does not currently provide a more detailed description of the downstream effects of this issue.

I recommend validating the workaround provided in ERR051704.

If you continue to experience any issues after applying the workaround, please feel free to contact me.

Thank you.

Alice