VL53L4CX Error turning on the "extended range" function results in a distance error.

[sctz]

Hi:

I'm testing the VL53L4CX and I'm experiencing some problems:
1. When an object is within 3.5m and there's a wall 5 metres away, sometimes the returned distance alternates between two distances.
2. When there is a mirror within 3.5m, VL53L4CX sometimes will return a distance more than 3.5m incorrectly.

After researching the returned data, I found that "Extended Range" is turned on incorrectly.
Can I know how the "Extended Range" function works and how to control it?

 

Thankyou.

Cyt

[Anne BIGOT]

Hello,

If you have a look to the STSW-IMG029 package you will find some documentation.

It is noticed that :

◆ ExtendedRange

uint8_t VL53LX_TargetRangeData_t::ExtendedRange

Extended range flag for the current measurement. Value = 1 means timings A&B are combined to increase the maximum distance range.

Definition at line 166 of file vl53lx_def.h.

Hope this helps,

 

[sctz]

Hi,

I read the docs and have a guess:

The ExtendedRange function works when a target is 3.3m away, because without it the chip only gets data within 3.3m.

Here's what happens in my case:

There are two objects within my fov. A is  inside 3.3m and B is outside 3.3m.

Normally the ExtenedRange will not run, so  B  will be recognised as an error.

But under some conditions, ExtenedRange opens without reason, which causes the data it returns to vary between A and B.

So my question is:

How does the L4CX determine that the ExtendedRange function needs to be activated? Is it possible to control it , or adjust its sensitivity?

Thank you.

[Zhiyuan.Han]

Hi Sctz,

ST sensor will report the strongest reflective target by default, if you have two targets inside FOV, and the return signal rates from two target are similar to each other, you will see alternate distance reported. 

Extend range is used to let sensor range further, if you want to disable it, sensor range ability will be limited inside 3.2 meter.

 

 

Br

Zhiyuan.Han