VL53L7CX range fluctuation

Rick Hamilton · ‎2024-03-20

Hi I am developing a commercial footfall counter based on the VL53L7CX and ESP32.

The API is (Version : VL53L7CX_1.2.10)

I have produced a mockup using the VL53L7CX breakout board.

IOVCC is 3.3 volts
I am using the on board regulator for AVDD powered from 5 volts.

I2C is 1 MHz.

I am using the 4 x 4 resolution.

I am only using the Results.distance_mm the rest of the Structure and I2C communication is disabled in the platform.h

I have developed a PC app to capture the ranges and visualize the range data.

With the sensor facing a blank wall 3000 mm away I am getting a mixture of ranges in the 16 zones with almost 2000mm difference on adjacent zones.

I have also found some zones just do not update their range unless you wave your hand in front of the sensor. This is not a data issue I am receiving the data it just does not change.

The worse problem I have is the range on some zones is intermittently fluctuating by more than 400mm between samples.

I have tried VL53L7CX_RANGING_MODE_AUTONOMOUS and VL53L7CX_RANGING_MODE_CONTINUOUS.

I have tried ranging frequency from 2 to 60 Hz (Along with Integration time 2ms to 1000ms)

I have tried setting the sharpener percentage 0 to 99

I have tried the xtalk calibration.

I have tuned out all the lights in the room is is no ambient light.

I can not continue with this sensor unless I can make the ranges consistent what else can I try?

Thank you.

Zhiyuan.Han · ‎2024-05-14

Hi

From your description, 3-meter target return signal rate is too low to get a valid range result.

May I know a bit more about your test setup,

What's the target material is, is it a high reflectance target? is it a diffuse reflection target.
Have you tried short distance, is it same issue, or much better.
suggest you also output the range status, status 5 is a valid output. if the range result on certain zones is not update, that means no target was detected, and status will not be 5.
From your description, seems you are testing with a cover glass on top of VL53L7CX? as you have tried xtalk calibration, can you remove it and have a try.

Below is my test result more than 3 meter with 5hz range frequence.

R: range distance
P: return signal rate
A: Ambient level
S: Range status
Z: Zone number.

Br

Zhiyuan.Han

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