VL53L4CX temperature update

[Gabor23]

Hi,

I was wondering if someone can help me with temperature update on the VL53L4CX.

According to UM2931  that describes the temperature update in paragraph 3.5 there is a dedicated function named VL53L4CD_Start_Temperature_Update() and can be used when the ambient temperature have changed by more than 8 degrees Celsius. This guide unfortunately is for the VL53L4CD but I just wanted to know does the same apply to the VL53L4CX? Does the CX has the same functionality to improve ranging accuracy?

Thanks,

[Anne BIGOT · Accepted solution]

Hi,

With the VL53L4CX sensor, to improve the ranging accuracy because of a temperature change a stop and restart is enough. There is no specific function for as for the VL53L4CD.
Regards

[Gabor23]

Hi Anne, thank you for your feedback. We are doing environmental testing on the CX and we still see drifting on the distance measurement even though we have the stop/restart function implemented. 

Do you have any further advice?

Regards

[Anne BIGOT]

Hello,

Can you tell what is the drift value you are seeing ? 

Many customers are using this feature to solve the drift due to temperature without any issues.
The reason of the drift you are seeing could be different than the temperature.

Regards

[Gabor23]

Hi Anne, 

So we tested two sensors(both SATEL-VL53L4CX) in our environmental chamber that was set up for a temperature elevation from 10°C to 49°C. Started on the lower end(10°) we elevated the temperature with 10°C by every ~45min which then gave us a full length of about 3.5h. On the graph attached (I hope it did go through) you can see from the trendline that we have about 15% discrepancy in the distance measured between the two temperature extremes(please note that the horizontal axis represents the data points we gathered over the period of the time). 

We have used the stop/restart function to recalibrate at every 5min(the vertical lines on the graph - first 7 are highlighted red). 

I am wondering maybe the rate of the temperature elevation could be too fast for the sensors?

Thanks,

Gabriel

[Gabor23]

Hi Anne,

Is there a recommendation of the frequency of the stop/restart function to avoid temp drifting? We perform it now in every 5min.

Kind Regards,

Gabriel

[John E KVAM]

Every time the sensor runs it checks the temperature. But to save time, we don't do a full calibration. We only allow it to adjust +/- 2 degrees C. If you are not continuously ranging, or expect a large temperature shift, a start/stop will do the full range of temperature calibration. 

It was assumed that if you range at least every few seconds, the sensor could adapt to normal changes in temperature. But a stop/start doesn't hurt anything.