VL53L1X: temperature and repeatability

[Jesus Reina]

Hi friends,

I want to measure the distance to an obstacle (120 mm) with the VL53L1X, but I am having problems with the repeatability.

NOTE: I measure 10 times to get a sample and I repeat every 10 seconds.

These are the results...

 

The distance measured is not stable, there is a ripple of 15 mm. This effect is worse when the environment temperature is under 24ºC.

Does the sensor range depend on the temperature?

I have made a function to compensate the temperature effect (see the code above), it is based on the function VL53L1X_ERROR VL53L1X_StartTemperatureUpdate (API Lite), I´m working with the standard API. I am calling this function before starting the measure ranging (but it doesn´t work).

VL53L1_WrByte(Dev,0x0008,0x81); /* full VHV */
 VL53L1_WrByte(Dev,0x0B,0x92);
 Intentos = 0;
 do
 { 
 status = VL53L1_StartMeasurement(Dev);
 Intentos++;
 }while ((status != VL53L1_ERROR_NONE)&&(Intentos < 3)); 
 
 byteData=0;
 Intentos = 0;
 do
 {
 status = VL53L1_GetMeasurementDataReady(Dev, &byteData);
 Intentos++;
 }
 while((!byteData)&&(status == VL53L1_ERROR_NONE)&&(Intentos < 3));
 
 VL53L1_ClearInterruptAndStartMeasurement(Dev);
 VL53L1_StopMeasurement(Dev); 
 
 VL53L1_WrByte(Dev, 0x0008, 0x09); /* two bounds VHV */
 VL53L1_WrByte(Dev, 0x0B, 0); /* start VHV from the previous temperature */

[Jesus Reina]

[Jesus Reina]

[Jesus Reina]

[Julien NGUYEN]

​Hi JR,

To get better repeatability, increase the timing budget. Try 200 ms of timing budget.

Julien

[Jesus Reina]

Hi Julien,

I changed that parameter, but this problem didn´t disappear. I am going to attach one example:

This ripple appears in short distances, from 100 to 200 mm. I also have changed the ROI but to no avail.

The sensors that I´m using, are working in a closed metalic box , in the next graph I turned on a hairdryer: (sample nº 880)

It seems that the measure degenerates as time goes by, for this reason I think the problem ca be in the temperature.

The sensor is working continously, I never stop the ranging measure. Should I stop the sensor to avoid this noise?

Thanks for your response.