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I am reading sensor data off of a Dell gateway, and noticing that the sensor data at iio:device2 seems to have a delay of ~1 second when reading using cat /sys/bus/iio/devices/iio:device2/in_temp_raw or similar. This sensor is identified as an ST Micro LPS22HB pressure sensor in the manual. When I read the same off device0 (an ST Micro HTS221 temperature/humidity sensor) any delay is imperceptible.

I don't know the IIO subsystem well at all but I'm wondering what the reason for this delay is? My best guess is that the pressure sensor needs to use multiple readings spaced over some period of time to report its status but I would love to understand better.

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  • Do you have access to the code running on it? It could be doing exactly as described, taking a reading ten times in a second and giving the average value as an output. May 26 '20 at 3:59
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    Also, you know lessthandot.com is hitting the default nginx page right? May 26 '20 at 4:15
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    I will see if I can gain access to it @Tim_Stewart, this is all pretty new to me. Thanks for letting me know about lessthandot, its been archived for a couple years but I guess the static copy has been taken down as well.
    – AlexCuse
    May 27 '20 at 9:01
  • You are welcome. May 27 '20 at 17:00
  • Have you read IIO wiki? wiki.analog.com/resources/tools-software/linux-software/libiio Does iio_info give you similar delays? Does hardware have a hysteresis when measuring a single value? Datasheet mentions FIFO mode, etc st.com/resource/en/application_note/… Have you setup the measurement frequency? As far as the ODR setting is concerned, ranging in active mode among 1,10,25,50, 75 Hz,
    – 0andriy
    Feb 12 at 15:05

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