LSM6DSOX: How to configure MLC / UNICO to wake MCU using INT1 on only ONE specific gesture (ignore all others)?

[mminhaj23]

Hello ST community,

I am working with LSM6DSOX and using the Machine Learning Core (MLC) configured through UNICO GUI. My goal is to use the sensor as a low-power wake-up source for my system.

System overview:

• MCU: nRF52840 (goes to deep sleep / system OFF)

• Sensor: LSM6DSOX

• Interface: I²C

• Interrupt: INT1 used as hardware wake-up source

• MCU is sleeping, so no software filtering is possible before wake-up

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What I want to achieve

I want the MCU to wake up ONLY when one specific gesture occurs (for example a “wave” gesture).

• INT1 should assert only for this one gesture

• INT1 should NOT trigger for:

  • static state

  • random shake

  • other trained gestures

  • noise or motion not matching the target gesture

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What I have already done

• I successfully trained multiple gestures in UNICO GUI using MLC.

• I can export and load the UCF correctly.

• INT1 triggers when any gesture is detected.

• I can read MLC status (Get_MLC_Status) after MCU wakes, but this does not help because:

  • The MCU must already be awake to do software filtering.

  • I need hardware-level filtering, since INT1 is the wake source.

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Problems / limitations

1. Training only one gesture

   • Training with a single gesture often produces false positives.

   • In practice, accuracy improves when training with two or more gestures, but then:

     • INT1 triggers for all detected classes.

2. Interrupt behavior

   • INT1 appears to trigger on any MLC state change, not on a specific class.

   • I want INT1 to be asserted only for one Meta Classifier output (e.g., class 0).

3. UNICO configuration uncertainty

   • It is unclear how to:

     • Properly define “everything else” as negative class

     • Tune features / windows to avoid false wakeups

     • Map only one MLC class to INT1 at hardware level

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My questions

1. Training question (UNICO / MLC)

   • What is the recommended way to train one wake-up gesture while ignoring all other motions?

   • Is it better to:

     • Train one gesture + “no motion”?

     • Train multiple gestures but only use one as wake-up?

   • Which UNICO features are recommended to minimize false positives for wake-up use cases?

2. Interrupt routing question

   • Is it possible to configure LSM6DSOX so that:

     • INT1 is asserted only for one specific MLC class (Meta Classifier index)?

     • Other classes do not toggle INT1 at all?

   • If yes:

     • Which register(s) should be used?

     • Should MLC_INT1 be programmed manually?

     • Is this configurable directly from UNICO with offline mode?

3. Best-practice question

   • What is the recommended ST approach for using LSM6DSOX MLC as a gesture-based wake-up source when the MCU is fully asleep?