User Manual

Note: Increasing the number of samples increases the accuracy, but also increases the time for calibration. The time
relative to number of samples is linear, and values follow the approximate timeout:
• 5 samples ≈ 750 milliseconds
• 10 samples ≈ 1000 milliseconds
• 20 samples ≈ 1500 milliseconds
Users can also call functions VL53L4CD_GetOffset() and VL53L4CD_SetOffset() to get the programmed value, or
set a new one.
2.2.3 Xtalk calibration procedure
For aesthetic and protective purposes, a protective window can be added on top of the module. Due to this cover
glass, a part of the light is reflected and returned to the receiver, causing a Xtalk phenomenon. Depending on the
cover glass quality, the amount of return signal may be significant and may affect sensor performances, as shown
in the following figure.
Figure 5. Impact on ranging with several Xtalk
The VL53L4CD has a built-in correction that allows the Xtalk compensation. The calibration needs to be
performed on a 17 % reflective target. Offset calibration needs to be performed before Xtalk calibration.
The calibration distance depends on the cover glass quality. The distance should correspond to the maximum
ranging distance without under-ranging. This point can be found doing a full sweep, with a target from near to far,
getting the ranging distance vs target distance.
UM2931
Calibrations
UM2931 - Rev 1
page 5/15