VL53L5CX mutual influence of multiple sensors

[mf101]

In some of our products we are using VL53L1 sensors. During evaluation, we figured out that there is an effect of mutual influence between multiple sensors measuring simultaneously (especially when using the histogram based measuring approach of the VL53L1CB full API).

According to the user manual, the VL53L5CX also uses histogram processing. What kind of mutual influence is to be expected, when multiple of these sensors are operated simultaneously and receive light portions of each other ? Is there a strong effect on the distance measurement value / status (maybe even corrupted results, wrong distance but status OK) ? Did ST perform some tests regarding this potential issue ?

[John E KVAM]

They do interfere a bit. One effect is that the sensor will return an extra target. But this false target will have a invalid status. This becomes an issue if you ask for more than one target per zone - otherwise the valid target will be promoted and returned. In this case, please check the target status before accepting it.

We tested multiple sensors at different angles - assuming you wanted to cover a larger field of view with more than one sensor. And the effect was minimal. But we did not spend a lot of time with other configurations.

[mf101]

Thanks for the response. As all sensors use the same wavelength, how is it possible to detect false targets and mark them with an invalid status in such cases ?

[John E KVAM]

When processing the data we compare the histogram we receive with what we know is valid. The signal from an interferer has a 'footprint' that we know to be invalid.

So we return the signal with a 'invalid' status allowing you to either filter it out, or accept it. If you know something we don't, you can choose to accept the range data, and treat the status as a warning. But generally, just ignore it.