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VL53L1X offset calibration and xtalk calibration

MOB1
Associate II

Hello I want to add a glass to my VL53L1X ToF sensor . How should I calibrate for using with glass?

I tried to calibrate with the help of the um2510 pdf (I used VL53L1X_CalibrateOffset and VL53L1X_CalibrateXtalk respectively).  After the calibration when I try to move the object away, the result distance is decreasing.  I dont get what the problem is but when I remove the glass ıt gives the correct result.

Thanks for your helps.

1 ACCEPTED SOLUTION

Accepted Solutions
John E KVAM
ST Employee

if the distance measure DECREASES when actual distance INCREASES, then it's a classic case of crosstalk.

With a large number of zero-distance "bad' photons averaged with the ones that did what you want 'good photons' you will under-range. But as your target gets farther away there will be fewer 'good' photons and a fixed number of  'bad' ones, causing the number to go distance measure to decrease.

If you've done a good calibration, you will get a value for the number of 'bad' photons. You can simply increase that number and try again. Be sure you are using a current driver, there was a bug in this area a couple of years ago. 

please note you have to calibrate, extract the value, store it in your memory and re-write it back into the sensor at every boot. 

I'm guessing it's this last requirement that is messing you up.

"Please click on Accept as Solution on the reply which solved your issue or answered your question. It gives better visibility on the answered topics."

View solution in original post

1 REPLY 1
John E KVAM
ST Employee

if the distance measure DECREASES when actual distance INCREASES, then it's a classic case of crosstalk.

With a large number of zero-distance "bad' photons averaged with the ones that did what you want 'good photons' you will under-range. But as your target gets farther away there will be fewer 'good' photons and a fixed number of  'bad' ones, causing the number to go distance measure to decrease.

If you've done a good calibration, you will get a value for the number of 'bad' photons. You can simply increase that number and try again. Be sure you are using a current driver, there was a bug in this area a couple of years ago. 

please note you have to calibrate, extract the value, store it in your memory and re-write it back into the sensor at every boot. 

I'm guessing it's this last requirement that is messing you up.

"Please click on Accept as Solution on the reply which solved your issue or answered your question. It gives better visibility on the answered topics."