VL53L0X crosstalk calibration

[Hardwariano]

Hello.

I'm using a VL53L0X sensor with cover glass from www.gilisymo.com, so I need to do crosstalk calibration to get an accurate measurement. The problem is that the correction is too big.

The process is as follows:

1) SPAD calibration (ok)

2) Ref calibration (ok)

3) Offset calibration. I use a white card located at 100mm from the sensor. Distance measured is accurate.

4) Crosstalk calibration. As UM2039 says: "The starting point of the valid distance to perform cross-talk calibration is when the actual signal starts to deviate from the ideal curve".

In my case that distance is 150 mm, so I place a grey card at that distance from the sensor and call "VL53L0X_PerformXTalkCalibration()". The sensor returns a value of approximately 26000 MegaCps.

5) Ranging. When an object is located at a distance of:

• 50 mm --> Sensor measures 55 mm
• 80 mm --> Sensor measures 100 mm
• 110 mm --> Sensor measures 210 mm
• 150 mm --> Sensor measures 8191mm (0x1FFF, no object detected)

I think the correction applied is very excessive considering the cover glass is specifically designed for VL53L0X. What I did do wrong in the process? Should the calibration be done in complete darkness?

Regards

[John E KVAM]

You are right of course. (We fixed that in the L1 and L3 chips. They VHV cal on every range.) So the right answer would be to load the cal data, and then run the ref cal.

Stop the sensor and re-run the ref cal whenever you think the temperature might have changed by 8 degrees C.

[NCao]

We have a cover window that is a few cms away from the sensor. What kind of calibration would make the sensor ignore it?

[John E KVAM]

this is such a good question, I'm going to move it to it's own thread. Please look for the answer in a few mintes.

[John E KVAM]

No, those are 2 separate issues. Just redo the temp and you will be fine.

Although you might notice that as the temp increases, you are a little less accurate, and then you re-calibrate and your accuracy improves.

This is expected.

• john