VL6180 datasheet(29/73 Pages) STMICROELECTRONICS

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VL6180

Functional description

2.15.3

Offset calibration procedure

Complete steps 1-4 to see if part-to-part offset calibration is required.

Read scaling factor VL6180x_UpscaleGetScaling(), turn off WAF

VL6180x_FilterSetState() = 0, turn off range ignore features

VL6180x_RangeIgnoreSetEnable() = 0 and clear all interrupts

VL6180x_ClearAllInterrupt().

Position a white target (88% reflectance(g)) at a distance of 50mm (scaling factor 1) or

100 mm (scaling factor 2/3) from the top of the cover glass.

Perform a minimum of 10 range measurements and compute the average range using

VL6180x_RangePollMeasurement().

If the average range is within target distance

 3 mm, offset calibration is not required.

Otherwise, complete the calibration procedure.

Set VL6180x_SetOffsetCalibrationData() = 0.

Perform a minimum of 10 range measurements and compute the average range from

VL6180x_RangePollMeasurement().

Calculate the part-to-part offset as follows:

The new offset value should be stored on system and written to the VL6180 by using

VL6180x_SetOffsetCalibrationData() each time the device is reset.

2.15.4

Cross-talk calibration procedure

This section describes a procedure for calibrating system cross-talk.

Perform offset calibration if required (see Section 2.15.3) and write the value to the

device by using VL6180x_SetOffsetCalibrationData().

Note:

If the offset is incorrectly calibrated, cross-talk calibration will be inaccurate.

Read scaling factor VL6180x_UpscaleGetScaling(), turn off WAF

VL6180x_FilterSetState() = 0 turn off range ignore features

VL6180x_RangeIgnoreSetEnable() = 0 and clear all interrupts

VL6180x_ClearAllInterrupt().

Position a grey target (17% reflectance(h)) at a distance of 100mm (scaling factor 1) or

300mm (scaling factor 2) or 400mm (scaling factor 3) from the top of the cover glass.

Write 0 to VL6180x_SetXTalkCompensationRate().

Perform a minimum of 10 range measurements and compute the average return rate

and range value from VL6180x_RangePollMeasurement().

Calculate the cross-talk factor as follows:

The cross-talk value should be stored on system and written to the VL6180 by using

VL6180x_SetXTalkCompensationRate() each time the device is reset.

g. Target reflectance should be high but absolute value is not critical.

part-to-part offset

target distance(mm) average range(mm)

–

h. Target reflectance should be low but absolute value is not critical.

cross-talk (in Mcps)

average return rate

average range(mm)

target distance(mm)

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VL6180 数据表(PDF) 29 Page - STMicroelectronics

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