vl53l1x: unreliable measurement beyond ~1 m with a small target

Sensors Distance
1

Hi,

I have a vl53l1x hooked up to a Qwiic RedBoard via a Qwiic mux. The board is running the distance measurement sketch from the vl53l1x tutorial. I am testing the sensor by holding my hand above it, gradually increasing the distance.

I noticed that the distance looks correct on the range of about 10-110 cm. After that, moving the hand up even slightly increases the distance reading by a lot — it goes from 110 cm quickly to 200, and then peaks at the distance to my ceiling. If I use an A4 sheet of paper, the measurements go a little further, to ~130 cm, before doing the same. I suspect the ceiling “takes over” the actual target at some point, and it happens sooner if the target is smaller?

My end goal is to detect hand movement above the sensor, on the range of 80 to 180 cm. I do not need an accurate distance measurement, only to know that the hand crossed the sensor. Is there any configuration I could change on the sensor to make it work better in this particular case?

2

There are some functions in the library for setting the range, you might try experimenting with that.

3

Nope, and they don’t seem to be affecting the range, strangely. After setting it to short distance, I’m still getting readings at 230 cm, even though it’s supposed to cut off at 130.

Also tried different timing budgets, but they don’t make it much different either.

4

There any sunlight or other bright light shining on the sensor? Have you tried turning the sensor sideways to see if your results start working better?