On Sun, 20 Jul 2025 20:49:48 +0200 Lothar Rubusch <l.rubusch@xxxxxxxxx> wrote: > Hi > > On Sun, Jul 6, 2025 at 6:16 PM Jonathan Cameron <jic23@xxxxxxxxxx> wrote: > > > > On Wed, 2 Jul 2025 23:03:15 +0000 > > Lothar Rubusch <l.rubusch@xxxxxxxxx> wrote: > > > > > Describe the inactivity detection additionally using the free-fall > > > register. Due to the controversial discussions on the mailing list, this > > > section of the documentation will be committed separately to allow for a > > > more focused and detailed elaboration of the topic. > > > > > > Signed-off-by: Lothar Rubusch <l.rubusch@xxxxxxxxx> > > > --- > > > Documentation/iio/adxl345.rst | 25 +++++++++++++++++++++++++ > > > 1 file changed, 25 insertions(+) > > > > > > diff --git a/Documentation/iio/adxl345.rst b/Documentation/iio/adxl345.rst > > > index 8ee01b8b87f4..c5525267ea12 100644 > > > --- a/Documentation/iio/adxl345.rst > > > +++ b/Documentation/iio/adxl345.rst > > > @@ -150,6 +150,31 @@ functions, so that one follows the other. The auto-sleep function puts the > > > sensor into sleep mode when inactivity is detected, reducing power consumption > > > to the sub-12.5 Hz rate. > > > > > > +The inactivity time is configurable between 1 and 255 seconds. In addition to > > > +inactivity detection, the sensor also supports free-fall detection, which, from > > > +the IIO perspective, is treated as a fall in magnitude across all axes. In > > > +sensor terms, free-fall is defined using an inactivity period ranging from 0.000 > > > +to 1.000 seconds. > > > + > > > +The driver behaves as follows: > > > +* If the configured inactivity period is 1 second or more, the driver uses the > > > + sensor's inactivity register. This allows the event to be linked with > > > + activity detection, use auto-sleep, and be either AC- or DC-coupled. > > > + > > > +* If the inactivity period is less than 1 second, the event is treated as plain > > > + inactivity or free-fall detection. In this case, auto-sleep and coupling > > > + (AC/DC) are not applied. > > > + > > > +* If an inactivity time of 0 seconds is configured, the driver selects a > > > + heuristically determined default period (greater than 1 second) to optimize > > > + power consumption. This also uses the inactivity register. > > > + > > > +Note: It is recommended to use the activity, inactivity, or free-fall registers > > > +when operating with an ODR between 12.5 Hz and 400 Hz. > > > > This seems a tiny bit backwards. It is recommend that the activity, inactivity or > > free-fall registers are only used when operating with an ODR... > > > > Ehm, Doesn't the sensor always have an ODR? I was lazy. The ODR... was meant to be ODR between 12.5 Hz and 400 Hz (so original text for that bit). > The real question is which > ODR should be configured. There are recommendations for specific > features. I may have either misunderstood or misdocumented this part. > > > As currently written it seems to be recommending that if you want those sampling > > frequencies you should also enable one of these detectors. > > > > Ah, no. The other way around, when someone wants one of events > detected, the recommended frequencies should be used. I'll have a look > at it. Sounds like you got my rubbish explanation. > > > Reminds me of the classic London underground sign that said "Dogs must be > > carried." which raised the question of how people with out dogs were meant to travel. > > > > Otherwise this new section looks good to me. Thanks, > > > > Jonathan > >... > > Best, > Lothar
