Comments: APDS-9301 Sensor Hookup Guide


Comments 5 comments

  • The text in the Hookup Guide says:

    INT pin - The APDS-9301 can be programmed to generate an interrupt under certain conditions. This pin will be asserted high when those conditions are met.

    However, the bar over INT is conventionally used to indicate that the signal is ACTIVE LOW, meaning that it’s LOW when it is asserted and HIGH when it is not asserted.

    Checking the datasheet, I find

    The interrupt is active-low and remains asserted until cleared by writing the COMMAND register with the CLEAR bit set.

    I recall a time (decades ago) when I was confused by something similar, so I’m sure there are people just getting into electronics who will be confused if it doesn’t get corrected.

    • I’ll fix that. Thanks for letting us know!

      • The tutorial states: “this value is only accurate to within 35%-40% of the actual absolute lux value.” Do you know what the repeatability error is? That is, for the same light level, how much will the lux value change from reading to reading?

        • We’ve done no terribly rigorous testing, but my experience on the bench suggests that it’s fairly repeatable.

          This is a hard thing to test because it’s difficult to get repeatable light conditions. Leaving it sit, the repeatability from one reading to the next is high. You won’t see it vary much from one reading to the next.

    1. You write: “It is non-instantaneous”. Nevertheless it looks quite fast to me. You were able to diplay a reading every second. It seems you could have gotten a reading every tenth of a second, but probably not much more quickly.
    2. The interrupt and thresholds system are interesting, e.g. if you want to use this device to trigger a camera only when there is a significant change of luminosity.

If you've found a bug or have other constructive feedback for our tutorial authors, please send us your feedback!