ST VL53L3CX TOF Sensor - Wrong Measurement in Water Level Sensing.

[GSuke.1]

Dear ST and Team,

Am using ST's VL53L3CX STEL Board for water level sensing project prototyping. I Have Queries following below

1. is VL53L3CX is suitable for water level sensing ?
2. do we need any calibration for accuracy ?
3. i have generated code simple raging application using STCubeMx (Using STM32F103RCT6 Controller ). is simple ranging application can also measure water level ?
4. While detecting object am getting almost better accuracy distance, while distance is increasing of object from accuracy is becoming low. +- 20mm is for upto 1000 mm target is getting. how to increase the accuracy ?
5. While testing for Water detection, Some times distance is showing totally wrong and some times distance accuracy is +- 10mm for 150mm target.
6. i have tested in multiple containers like Glass, Jug and Bucket. but not able to read correct values.
7. am using some cables for interfacing the VL53L3Cx. attaching the pic. Does it anything wrong using some length cable ?

I am sharing some pics for your reference. Please Help me out.

[ACHOU.18]

1. is VL53L3CX is suitable for water level sensing ?

Ans: Yes, it can be used but if your maximum height of container is less than 1.3meter then VL53L4CD is recommended, it gives better accuracy.

2.Yes, you can do offset calibration with 100m distance in water itself.

3. I would say you need to make a simple rolling average of few iteration of ranging data to improve ranging result. For example: Set longer timing budget to 50 or 60 ms then average value of 20 iteration, So every sec you would get final ranging data. This is one way to improve accuracy if you don't have constraint of update result in 1sec.

4. Do offset calibration .

5. There may be a pattern occur, result may get over ranging in low water (major error contribution from base reflectance)and result may get under ranging in high water. You could create a simple lookup table between water level and expected distance, deviation. and for the subsequent experiment you could apply those offset deviation on those defined level to improve accuracy.

6. How much % error do you find ? if you are looking for high accuracy then need to do above method but out of the box it give ranging result with minor deviation if liquid is still.

7. Make sure water and setup is not shaken.

Hope it helps.