User Manual

DocID029105 Rev 1 7/26
UM2039 Initial customer manufacturing calibration
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2.4.1 Ref calibration procedure
User has two options:
1. Perform the calibration after VL53L0X_PerformRefSPADManagement,by calling
VL53L0X_PerformRefCalibration().
2. If user wants to improve the boot time, they can load only the calibration parameters
after VL53L0X_PerformRefSPADManagement by using
VL53L0X_SetRefCalibration(). This assumes that user has previously
performed a calibration and stored the two parameters in the Host memory. See
Section 4.3.2.
There is no specific setup needed to perform ref calibration. It has only to be done before
offset and cross-talk calibrations, after Reference SPADs management and before the first
ranging is performed.
2.5 Offset calibration
Range offset is performed during Final Module Test at STMicroelectronics, and the offset is
stored into the device NVM.
For some cases, it can appear that the value programmed in the NVM is not correct. This
can happen when the customer is using a cover window. In this case, ranging can be
affected by an offset, due to the cover window and so the customer should perform a new
offset calibration on its manufacturing line.
2.5.1 Offset calibration procedure
• Recommendation is to use a white (88%reflectance) target at 100mm, in a dark
environment. Target distance can be changed depending on customer’s constraints,
but it has to be chosen in the linear part of the ranging curve.
• Both Reference SPADs and Ref calibrations have to be performed before calling offset
calibration.
• A dedicated API function has to be called to compute the offset:
VL53L0X_PerformOffsetCalibration().
• The output of this function is the offset calibration value, in micrometers.
• Offset calibration value has to be stored into Host memory. See Section 4.3.3 for
loading calibration data from Host.
2.6 Cross-talk calibration
This section presents the effect of the cover window on ranging, and proposes a method for
cross-talk calibration.
2.6.1 Cover window impact on ranging
The ranging performance is dependent on the quality of the cover window. Figure 3 shows
the cover window impact on ranging with low, medium and high cross-talk.
The ideal curve (with no cover window) is the green dotted line.