Disabling VL53L5CX Autocalibration?

[TVos.1]

Hi there!

I was wondering, for a school project, if it is possible to disable te autocalibration on the VL53L5CX and if it would be possible to manually calibrate it?

Thanks! :fox_face:

[John E KVAM]

There are several calibrations for the VL53L5CX.

Two are not mentioned in the user manual.

1 is the reference spad calibation - happens automatically at the start.

2 is a temperture adjustment - Any increase in silicon temperature either from selfheating or a change in ambient temperature results in a range offset drift which may be minimised by performing periodic autocalibration, resulting in typical drift of 0.05 mm/°C

This happens with a stop/start. Should do it every now and again.

But I'm guessing you are asking about the cross-talk calibration. This measures the number of photons that are returned by the coverglass. And we need to know how many there are in order to improve the distance measurements up to 80cm. (After that there is no influence.)

If you have no coverglass - then there is no need to calibrate for the crosstalk. There is none.

I suppose you can do it by hand - but it's a lot of work for something we have already done.

For a school project I have two solutions.

1) don't use the coverglass, and don't worry about the crosstalk.

2) purchase a crosstalk-free coverglass from www.Hornix.com.tw It's part number IR109C0-IC-A066. You can also buy it from https://www.gilisymo.com/ in Europe.

I hard a rumor that Sparkfun.com was going to carry it as well, but I not sure if that's true.

[WJLO]

HI,

 I have a question that"which may be minimised by performing periodic autocalibration, resulting in typical drift of 0.05 mm/°C"

Why even do the periodic autocalibration, still has this drift(0.05 mm/°C)?? it's may cause from clock or digital delay?

[John E KVAM · Accepted solution]

As the device heats up, the range answer will start to drift. The part will self-correct as it checks the temperature of the device, and adjusts in 2 degree steps. So if you look really closely at the distances and warm the sensor you will see little changes in distance, then a step as the device corrects, then a slow drift of a few mm, and a correction. Basically a saw-tooth pattern.  You can even read back the temperature of the sensor.

But you don't need to do anything. Although a stop/start will do the autocalibration at the start.