Re: [PATCH 2/2] iio: imu: st_lsm6dsx: Decouple sensor ODR from FIFO batch data rate

Lorenzo Bianconi
2025-10-10T08:13:33Z

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> On Fri, 2025-10-10 at 00:30 +0200, Lorenzo Bianconi wrote:
> > > The rate at which accelerometer or gyroscope sensor samples are fed
> > > to the hardware FIFO (batch data rate, or BDR) does not have to
> > > coincide with the sensor sampling frequency (output data rate, or
> > > ODR); the only requirement is for the BDR to not be greater than
> > > the ODR. Having a BDR lower than the ODR is useful in cases where
> > > an application requires a high sampling rate for accurate detection
> > > of motion events (e.g. wakeup events), but wants to read sensor
> > > sample values from the device buffer at a lower data rate.
> >
> > can you please provide more details here? Are you using the hw fifo to
> > read
> > data? If we configure the hw fifo according to the BDR (even assuming the
> > watermark is set 1) the hw will generate interrupts according to the BDR
> > (bdr < odr).
>
> Yes, I'm using the hw fifo to read data. The use case is to enable event
> detection (which works best at high sampling rates) and sensor data
> streaming at the same time, without requiring the data stream to be at the
> same rate as the sensor sampling rate. So the amount of I2C (or SPI)
> traffic (as well as the rate of periodic interrupts) required by the data
> stream is kept to a minimum without sacrificing the accuracy of event
> detection.

I guess you can get the same result (reduce sensor data interrupt rate
keeping high odr value) configuring the hw fifo watermark.
Does it work for you?

Regards,
Lorenzo

>
>

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