VL53L5CX Ultra Lite Driver (ULD) - Reflectance Value Format

[MFabb.1]

Hi,

I would need a technical information about VL53L5CX Ultra Lite Driver (ULD).

Specifically, what is the format of the reflectance value returned by the vl53l5cx_get_ranging_data() function?

I am supposing that the format is a percent value expressed as a decimal number limited to the range [0, 100].

However, in particular conditions, with high reflectivity targets, it happens that values above 100 (i.e. 127) are returned by the above function. How could be explained and handled correctly?

Furthermore, in vl53l5cx_api.c, the reflectance value is halved before being returned:

#ifndef VL53L5CX_DISABLE_REFLECTANCE_PERCENT
		p_results->reflectance[i] /= (uint8_t)2;
#endif

This change appears to have been introduced from the release v.1.3.0.

Version : 1.3.0
Date : 02/11/2022
Comments : 
- Corrected reflectance format (output divided by /2 vs previous driver version)
...

Could you elaborate on the subject?

Thank you

[John E KVAM · Accepted solution]

In the ULD, he reflectance is measured in percent where bright white paper is considered to be 100%

(Actually standard printer paper comes in at around 88%). So numbers above 100% are possible.

And it has a lot to do with if your target is specular (mirror-like) or Lamperatain (matte finish).

But it's best to use that number as a relitive value - it's how we order the strongest singal for instance.

• john

[MFabb.1]

Thank you John,

Your quick answer has been really appreciated.

I further investigated and now I have a better understood the definition of reflectance.