Skip to main content
MFabb.1
MFabb.1
Associate III
September 12, 2022
Solved

VL53L5CX Ultra Lite Driver (ULD) - Reflectance Value Format

  • September 12, 2022
  • 2 replies
  • 1432 views

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

This topic has been closed for replies.
Best answer by John E KVAM

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

2 replies

John E KVAM
John E KVAMAnswer
ST Employee
September 12, 2022

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
If this or any post solves your issue, please mark them as 'Accept as Solution' It really helps. And if you notice anything wrong do not hesitate to 'Report Inappropriate Content'. Someone will review it.
MFabb.1
MFabb.1Author
Associate III
September 12, 2022

Thank you John,

Your quick answer has been really appreciated.

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

Terms & ConditionsAccessibility statement