Proper VL53L1X calibration procedure

[will3]

Hi ST,

I wanted to validate/confirm our Calibration procedure.  When we calibrate prior to calibration we set timing budget and intermeasurement to what they are normally when our code boots up.  So,  during calibration we do the same.  Can someone please confirm this is the correct procedure? Meaning,  should we set TimingBudget, InterMeasure, ROI and ROI Center to "anything" prior to running calibration or are we correct in how we are doing this.

.....

VL53L1X_SetTimingBudgetInMs(33);
VL53L1X_SetInterMeasurementInMs(40);
VL53L1X_SetROI(4, 4);
VL53L1X_SetROICenter(191);
status = VL53L1X_CalibrateOffset(TargetDist, &Offset);

.....

Thanks,

Will

[John E KVAM]

In our documentation we don't demand you do this, but it's a good idea.

The timing budget might make a tiny bit of difference, but only a tiny bit. (30ms is the default.)  The sensor is supposed to be able to change timing budgets, so the calibration has to work. 

A long inter-measurement period does NOT make a difference, and makes your calibration take longer. Might want to skip that setting. 

But if this is your only ROI setting, then by all means, use that!!

Changing the ROI does have an effect on the crosstalk. (One side is worse than the other due to the physics of how the light bounces off the coverglass. But we keep a measure of the gradient, so we have an idea of what to change based on your ROI. But if you only have one ROI, calibrating with that would be better.

But I'm going to guess that if you picked the center region as an ROI that you won't see much difference. That's the 'average' area. 

- john