One of the important reasons that it works so well is because it uses the Hexagon DSP in the Snapdragon processors to catch the events. That's why it's so hard to replicate. It's possible to do it entirely in software, but it chews through battery if you do it that way. I can't find it now, but there was an article a few years ago that explained how the feature worked.

And there's no way to program the DSP without being the creator of the device because Qualcomm requires DSP programs to be signed, as far as I'm aware, and the key has to be trusted by the device vendor.

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EvanAnderson 4 hours ago | parent | next [-]

Wild. Thanks for the keywords to search-engine this with. I found "Reverse engineering the Motorola Sensorhub: Part 1"[0]. To this point I hadn't thought about how they might have implemented the feature. That article sheds some light on it.

[0] https://ristovski.github.io/posts/moto-sensorhub/

	▲	nhubbard 4 hours ago \| parent [-]
		That's the one!

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microsoftedging 4 hours ago | parent | prev [-]

This one? https://www.xda-developers.com/qualcomm-snapdragon-845-hexag...

	▲	nhubbard 4 hours ago \| parent [-]
		That's the right chip. The other comment shows off the article. I forgot that it was called the "sensor hub", that's why I couldn't find the post showing how it works.