ST VL53L3CX - Offset Calibration Procedure; Getting Offset Calibration Results; Selecting the Offset Correction Mode

6.3.2 Offset calibration procedure
Customers can select any chart reflectance placed at any distance (using the same setup as the crosstalk
calibration). The only point to check is to ensure the signal rate is measured between 2 and 80MCps with the
chosen setup.
Table 3. Offset calibration setup
Chart Distance Ambient conditions Signal Rate
Any Any Dark (no IR contribution) 2MCps < Signal Rate <80Mcps
Two warning messages are returned by these functions:
• VL53LX_WARNING_OFFSET_CAL_INSUFFICIENT_MM1_SPADS
The signal is too low, Accuracy of offset calibration may be degraded.
• VL53LX_WARNING_OFFSET_CAL_PRE_RANGE_RATE_TOO_HIGH
Signal is too high. Accuracy of offset calibration may be degraded.
6.3.3 Getting offset calibration results
The function VL53LX_GetCalibrationData() returns all calibration data. The returned structure
VL53LX_CalibrationData_t contains another structure called VL53LX_customer_nvm_managed_t which contains
the three offset calibration results:
• algo__part_to_part_range_offset_mm
• mm_config__inner_offset_mm
• mm_config__outer_offset_mm
The overall offset applied to the device is the average of the two last values
If a perVCSELCalibration is selected, the output of the function is includes the following data:
• short_a_offset_mm
• short_b_offset_mm
• medium_a_offset_mm
• medium_b_offset_mm
• long_a_offset_mm
• long_bb_offset_mm
Depending of the distance mode (VCSEL period) chosen, one of these offset will be applied automatically.
6.3.4 Selecting the offset correction mode
The offset correction mode can be set with two options, using the VL53LX_SetOffsetCorrectionMode function.
Note: VL53LX_OFFSETCORRECTIONMODE_PERVCSEL should be used by default. It allows to increase the offset
accuracy per VCSEL period.
Table 4. Offset correction options
Offset Calibration function called Correction mode option to be used
PerformSimpleOffsetCalibration VL53LX_OFFSETCORRECTIONMODE_STANDARD
PerfromPerVCSELOffsetCalibration VL53LX_OFFSETCORRECTIONMODE_PERVCSEL
Note: If only one offset calibration type results are available, it is mandatory to set the offset correction mode to the
corresponding option. This is not done automatically.
UM2778
Offset calibration
UM2778 - Rev 1
page 17/25