Diff: vl53l0x_api_calibration.c

Revision:

0:e6fcdb78a136

diff -r 000000000000 -r e6fcdb78a136 vl53l0x_api_calibration.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/vl53l0x_api_calibration.c	Tue Aug 23 05:14:05 2016 +0000
@@ -0,0 +1,1273 @@
+/*******************************************************************************
+ Copyright © 2016, STMicroelectronics International N.V.
+ All rights reserved.
+
+ Redistribution and use in source and binary forms, with or without
+ modification, are permitted provided that the following conditions are met:
+ * Redistributions of source code must retain the above copyright
+ notice, this list of conditions and the following disclaimer.
+ * Redistributions in binary form must reproduce the above copyright
+ notice, this list of conditions and the following disclaimer in the
+ documentation and/or other materials provided with the distribution.
+ * Neither the name of STMicroelectronics nor the
+ names of its contributors may be used to endorse or promote products
+ derived from this software without specific prior written permission.
+
+ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND
+ NON-INFRINGEMENT OF INTELLECTUAL PROPERTY RIGHTS ARE DISCLAIMED.
+ IN NO EVENT SHALL STMICROELECTRONICS INTERNATIONAL N.V. BE LIABLE FOR ANY
+ DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ ******************************************************************************/
+
+#include "vl53l0x_api.h"
+#include "vl53l0x_api_core.h"
+#include "vl53l0x_api_calibration.h"
+
+#ifndef __KERNEL__
+#include <stdlib.h>
+#endif
+
+#define LOG_FUNCTION_START(fmt, ...) \
+	_LOG_FUNCTION_START(TRACE_MODULE_API, fmt, ##__VA_ARGS__)
+#define LOG_FUNCTION_END(status, ...) \
+	_LOG_FUNCTION_END(TRACE_MODULE_API, status, ##__VA_ARGS__)
+#define LOG_FUNCTION_END_FMT(status, fmt, ...) \
+	_LOG_FUNCTION_END_FMT(TRACE_MODULE_API, status, fmt, ##__VA_ARGS__)
+
+#define REF_ARRAY_SPAD_0  0
+#define REF_ARRAY_SPAD_5  5
+#define REF_ARRAY_SPAD_10 10
+
+uint32_t refArrayQuadrants[4] = {REF_ARRAY_SPAD_10, REF_ARRAY_SPAD_5,
+		REF_ARRAY_SPAD_0, REF_ARRAY_SPAD_5 };
+
+VL53L0X_Error VL53L0X_perform_xtalk_calibration(VL53L0X_DEV Dev,
+			FixPoint1616_t XTalkCalDistance,
+			FixPoint1616_t *pXTalkCompensationRateMegaCps)
+{
+	VL53L0X_Error Status = VL53L0X_ERROR_NONE;
+	uint16_t sum_ranging = 0;
+	uint16_t sum_spads = 0;
+	FixPoint1616_t sum_signalRate = 0;
+	FixPoint1616_t total_count = 0;
+	uint8_t xtalk_meas = 0;
+	VL53L0X_RangingMeasurementData_t RangingMeasurementData;
+	FixPoint1616_t xTalkStoredMeanSignalRate;
+	FixPoint1616_t xTalkStoredMeanRange;
+	FixPoint1616_t xTalkStoredMeanRtnSpads;
+	uint32_t signalXTalkTotalPerSpad;
+	uint32_t xTalkStoredMeanRtnSpadsAsInt;
+	uint32_t xTalkCalDistanceAsInt;
+	FixPoint1616_t XTalkCompensationRateMegaCps;
+
+	if (XTalkCalDistance <= 0)
+		Status = VL53L0X_ERROR_INVALID_PARAMS;
+
+	/* Disable the XTalk compensation */
+	if (Status == VL53L0X_ERROR_NONE)
+		Status = VL53L0X_SetXTalkCompensationEnable(Dev, 0);
+
+	/* Disable the RIT */
+	if (Status == VL53L0X_ERROR_NONE) {
+		Status = VL53L0X_SetLimitCheckEnable(Dev,
+				VL53L0X_CHECKENABLE_RANGE_IGNORE_THRESHOLD, 0);
+	}
+
+	/* Perform 50 measurements and compute the averages */
+	if (Status == VL53L0X_ERROR_NONE) {
+		sum_ranging = 0;
+		sum_spads = 0;
+		sum_signalRate = 0;
+		total_count = 0;
+		for (xtalk_meas = 0; xtalk_meas < 50; xtalk_meas++) {
+			Status = VL53L0X_PerformSingleRangingMeasurement(Dev,
+				&RangingMeasurementData);
+
+			if (Status != VL53L0X_ERROR_NONE)
+				break;
+
+			/* The range is valid when RangeStatus = 0 */
+			if (RangingMeasurementData.RangeStatus == 0) {
+				sum_ranging = sum_ranging +
+					RangingMeasurementData.RangeMilliMeter;
+				sum_signalRate = sum_signalRate +
+				RangingMeasurementData.SignalRateRtnMegaCps;
+				sum_spads = sum_spads +
+				RangingMeasurementData.EffectiveSpadRtnCount
+					/ 256;
+				total_count = total_count + 1;
+			}
+		}
+
+		/* no valid values found */
+		if (total_count == 0)
+			Status = VL53L0X_ERROR_RANGE_ERROR;
+
+	}
+
+
+	if (Status == VL53L0X_ERROR_NONE) {
+		/* FixPoint1616_t / uint16_t = FixPoint1616_t */
+		xTalkStoredMeanSignalRate = sum_signalRate / total_count;
+		xTalkStoredMeanRange = (FixPoint1616_t)((uint32_t)(
+			sum_ranging << 16) / total_count);
+		xTalkStoredMeanRtnSpads = (FixPoint1616_t)((uint32_t)(
+			sum_spads << 16) / total_count);
+
+		/* Round Mean Spads to Whole Number.
+		 * Typically the calculated mean SPAD count is a whole number
+		 * or very close to a whole
+		 * number, therefore any truncation will not result in a
+		 * significant loss in accuracy.
+		 * Also, for a grey target at a typical distance of around
+		 * 400mm, around 220 SPADs will
+		 * be enabled, therefore, any truncation will result in a loss
+		 * of accuracy of less than
+		 * 0.5%.
+		 */
+		xTalkStoredMeanRtnSpadsAsInt = (xTalkStoredMeanRtnSpads +
+			0x8000) >> 16;
+
+		/* Round Cal Distance to Whole Number.
+		 * Note that the cal distance is in mm, therefore no resolution
+		 * is lost.*/
+		 xTalkCalDistanceAsInt = (XTalkCalDistance + 0x8000) >> 16;
+
+		if (xTalkStoredMeanRtnSpadsAsInt == 0 ||
+		   xTalkCalDistanceAsInt == 0 ||
+		   xTalkStoredMeanRange >= XTalkCalDistance) {
+			XTalkCompensationRateMegaCps = 0;
+		} else {
+			/* Round Cal Distance to Whole Number.
+			   Note that the cal distance is in mm, therefore no
+			   resolution is lost.*/
+			xTalkCalDistanceAsInt = (XTalkCalDistance +
+				0x8000) >> 16;
+
+			/* Apply division by mean spad count early in the
+			 * calculation to keep the numbers small.
+			 * This ensures we can maintain a 32bit calculation.
+			 * Fixed1616 / int := Fixed1616 */
+			signalXTalkTotalPerSpad = (xTalkStoredMeanSignalRate) /
+				xTalkStoredMeanRtnSpadsAsInt;
+
+			/* Complete the calculation for total Signal XTalk per
+			 * SPAD
+			 * Fixed1616 * (Fixed1616 - Fixed1616/int) :=
+			 * (2^16 * Fixed1616)
+			 */
+			signalXTalkTotalPerSpad *= ((1 << 16) -
+				(xTalkStoredMeanRange / xTalkCalDistanceAsInt));
+
+			/* Round from 2^16 * Fixed1616, to Fixed1616. */
+			XTalkCompensationRateMegaCps = (signalXTalkTotalPerSpad
+				+ 0x8000) >> 16;
+		}
+
+		*pXTalkCompensationRateMegaCps = XTalkCompensationRateMegaCps;
+
+		/* Enable the XTalk compensation */
+		if (Status == VL53L0X_ERROR_NONE)
+			Status = VL53L0X_SetXTalkCompensationEnable(Dev, 1);
+
+		/* Enable the XTalk compensation */
+		if (Status == VL53L0X_ERROR_NONE)
+			Status = VL53L0X_SetXTalkCompensationRateMegaCps(Dev,
+					XTalkCompensationRateMegaCps);
+
+	}
+
+	return Status;
+}
+
+VL53L0X_Error VL53L0X_perform_offset_calibration(VL53L0X_DEV Dev,
+			FixPoint1616_t CalDistanceMilliMeter,
+			int32_t *pOffsetMicroMeter)
+{
+	VL53L0X_Error Status = VL53L0X_ERROR_NONE;
+	uint16_t sum_ranging = 0;
+	FixPoint1616_t total_count = 0;
+	VL53L0X_RangingMeasurementData_t RangingMeasurementData;
+	FixPoint1616_t StoredMeanRange;
+	uint32_t StoredMeanRangeAsInt;
+	uint32_t CalDistanceAsInt_mm;
+	uint8_t SequenceStepEnabled;
+	int meas = 0;
+
+	if (CalDistanceMilliMeter <= 0)
+		Status = VL53L0X_ERROR_INVALID_PARAMS;
+
+	if (Status == VL53L0X_ERROR_NONE)
+		Status = VL53L0X_SetOffsetCalibrationDataMicroMeter(Dev, 0);
+
+
+	/* Get the value of the TCC */
+	if (Status == VL53L0X_ERROR_NONE)
+		Status = VL53L0X_GetSequenceStepEnable(Dev,
+				VL53L0X_SEQUENCESTEP_TCC, &SequenceStepEnabled);
+
+
+	/* Disable the TCC */
+	if (Status == VL53L0X_ERROR_NONE)
+		Status = VL53L0X_SetSequenceStepEnable(Dev,
+				VL53L0X_SEQUENCESTEP_TCC, 0);
+
+
+	/* Disable the RIT */
+	if (Status == VL53L0X_ERROR_NONE)
+		Status = VL53L0X_SetLimitCheckEnable(Dev,
+				VL53L0X_CHECKENABLE_RANGE_IGNORE_THRESHOLD, 0);
+
+	/* Perform 50 measurements and compute the averages */
+	if (Status == VL53L0X_ERROR_NONE) {
+		sum_ranging = 0;
+		total_count = 0;
+		for (meas = 0; meas < 50; meas++) {
+			Status = VL53L0X_PerformSingleRangingMeasurement(Dev,
+					&RangingMeasurementData);
+
+			if (Status != VL53L0X_ERROR_NONE)
+				break;
+
+			/* The range is valid when RangeStatus = 0 */
+			if (RangingMeasurementData.RangeStatus == 0) {
+				sum_ranging = sum_ranging +
+					RangingMeasurementData.RangeMilliMeter;
+				total_count = total_count + 1;
+			}
+		}
+
+		/* no valid values found */
+		if (total_count == 0)
+			Status = VL53L0X_ERROR_RANGE_ERROR;
+	}
+
+
+	if (Status == VL53L0X_ERROR_NONE) {
+		/* FixPoint1616_t / uint16_t = FixPoint1616_t */
+		StoredMeanRange = (FixPoint1616_t)((uint32_t)(sum_ranging << 16)
+			/ total_count);
+
+		StoredMeanRangeAsInt = (StoredMeanRange + 0x8000) >> 16;
+
+		/* Round Cal Distance to Whole Number.
+		 * Note that the cal distance is in mm, therefore no resolution
+		 * is lost.*/
+		 CalDistanceAsInt_mm = (CalDistanceMilliMeter + 0x8000) >> 16;
+
+		 *pOffsetMicroMeter = (CalDistanceAsInt_mm -
+				 StoredMeanRangeAsInt) * 1000;
+
+		/* Apply the calculated offset */
+		if (Status == VL53L0X_ERROR_NONE) {
+			VL53L0X_SETPARAMETERFIELD(Dev, RangeOffsetMicroMeters,
+					*pOffsetMicroMeter);
+			Status = VL53L0X_SetOffsetCalibrationDataMicroMeter(Dev,
+					*pOffsetMicroMeter);
+		}
+
+	}
+
+	/* Restore the TCC */
+	if (Status == VL53L0X_ERROR_NONE) {
+		if (SequenceStepEnabled != 0)
+			Status = VL53L0X_SetSequenceStepEnable(Dev,
+					VL53L0X_SEQUENCESTEP_TCC, 1);
+	}
+
+	return Status;
+}
+
+
+VL53L0X_Error VL53L0X_set_offset_calibration_data_micro_meter(VL53L0X_DEV Dev,
+		int32_t OffsetCalibrationDataMicroMeter)
+{
+	VL53L0X_Error Status = VL53L0X_ERROR_NONE;
+	int32_t cMaxOffsetMicroMeter = 511000;
+	int32_t cMinOffsetMicroMeter = -512000;
+	int16_t cOffsetRange = 4096;
+	uint32_t encodedOffsetVal;
+
+	LOG_FUNCTION_START("");
+
+	if (OffsetCalibrationDataMicroMeter > cMaxOffsetMicroMeter)
+		OffsetCalibrationDataMicroMeter = cMaxOffsetMicroMeter;
+	else if (OffsetCalibrationDataMicroMeter < cMinOffsetMicroMeter)
+		OffsetCalibrationDataMicroMeter = cMinOffsetMicroMeter;
+
+	/* The offset register is 10.2 format and units are mm
+	 * therefore conversion is applied by a division of
+	 * 250.
+	 */
+	if (OffsetCalibrationDataMicroMeter >= 0) {
+		encodedOffsetVal =
+			OffsetCalibrationDataMicroMeter/250;
+	} else {
+		encodedOffsetVal =
+			cOffsetRange +
+			OffsetCalibrationDataMicroMeter/250;
+	}
+
+	Status = VL53L0X_WrWord(Dev,
+		VL53L0X_REG_ALGO_PART_TO_PART_RANGE_OFFSET_MM,
+		encodedOffsetVal);
+
+	LOG_FUNCTION_END(Status);
+	return Status;
+}
+
+VL53L0X_Error VL53L0X_get_offset_calibration_data_micro_meter(VL53L0X_DEV Dev,
+		int32_t *pOffsetCalibrationDataMicroMeter)
+{
+	VL53L0X_Error Status = VL53L0X_ERROR_NONE;
+	uint16_t RangeOffsetRegister;
+	int16_t cMaxOffset = 2047;
+	int16_t cOffsetRange = 4096;
+
+	/* Note that offset has 10.2 format */
+
+	Status = VL53L0X_RdWord(Dev,
+				VL53L0X_REG_ALGO_PART_TO_PART_RANGE_OFFSET_MM,
+				&RangeOffsetRegister);
+
+	if (Status == VL53L0X_ERROR_NONE) {
+		RangeOffsetRegister = (RangeOffsetRegister & 0x0fff);
+
+		/* Apply 12 bit 2's compliment conversion */
+		if (RangeOffsetRegister > cMaxOffset)
+			*pOffsetCalibrationDataMicroMeter =
+				(int16_t)(RangeOffsetRegister - cOffsetRange)
+					* 250;
+		else
+			*pOffsetCalibrationDataMicroMeter =
+				(int16_t)RangeOffsetRegister * 250;
+
+	}
+
+	return Status;
+}
+
+
+VL53L0X_Error VL53L0X_apply_offset_adjustment(VL53L0X_DEV Dev)
+{
+	VL53L0X_Error Status = VL53L0X_ERROR_NONE;
+	int32_t CorrectedOffsetMicroMeters;
+	int32_t CurrentOffsetMicroMeters;
+
+	/* if we run on this function we can read all the NVM info
+	 * used by the API */
+	Status = VL53L0X_get_info_from_device(Dev, 7);
+
+	/* Read back current device offset */
+	if (Status == VL53L0X_ERROR_NONE) {
+		Status = VL53L0X_GetOffsetCalibrationDataMicroMeter(Dev,
+					&CurrentOffsetMicroMeters);
+	}
+
+	/* Apply Offset Adjustment derived from 400mm measurements */
+	if (Status == VL53L0X_ERROR_NONE) {
+
+		/* Store initial device offset */
+		PALDevDataSet(Dev, Part2PartOffsetNVMMicroMeter,
+			CurrentOffsetMicroMeters);
+
+		CorrectedOffsetMicroMeters = CurrentOffsetMicroMeters +
+			(int32_t)PALDevDataGet(Dev,
+				Part2PartOffsetAdjustmentNVMMicroMeter);
+
+		Status = VL53L0X_SetOffsetCalibrationDataMicroMeter(Dev,
+					CorrectedOffsetMicroMeters);
+
+		/* store current, adjusted offset */
+		if (Status == VL53L0X_ERROR_NONE) {
+			VL53L0X_SETPARAMETERFIELD(Dev, RangeOffsetMicroMeters,
+					CorrectedOffsetMicroMeters);
+		}
+	}
+
+	return Status;
+}
+
+void get_next_good_spad(uint8_t goodSpadArray[], uint32_t size,
+			uint32_t curr, int32_t *next)
+{
+	uint32_t startIndex;
+	uint32_t fineOffset;
+	uint32_t cSpadsPerByte = 8;
+	uint32_t coarseIndex;
+	uint32_t fineIndex;
+	uint8_t dataByte;
+	uint8_t success = 0;
+
+	/*
+	 * Starting with the current good spad, loop through the array to find
+	 * the next. i.e. the next bit set in the sequence.
+	 *
+	 * The coarse index is the byte index of the array and the fine index is
+	 * the index of the bit within each byte.
+	 */
+
+	*next = -1;
+
+	startIndex = curr / cSpadsPerByte;
+	fineOffset = curr % cSpadsPerByte;
+
+	for (coarseIndex = startIndex; ((coarseIndex < size) && !success);
+				coarseIndex++) {
+		fineIndex = 0;
+		dataByte = goodSpadArray[coarseIndex];
+
+		if (coarseIndex == startIndex) {
+			/* locate the bit position of the provided current
+			 * spad bit before iterating */
+			dataByte >>= fineOffset;
+			fineIndex = fineOffset;
+		}
+
+		while (fineIndex < cSpadsPerByte) {
+			if ((dataByte & 0x1) == 1) {
+				success = 1;
+				*next = coarseIndex * cSpadsPerByte + fineIndex;
+				break;
+			}
+			dataByte >>= 1;
+			fineIndex++;
+		}
+	}
+}
+
+
+uint8_t is_aperture(uint32_t spadIndex)
+{
+	/*
+	 * This function reports if a given spad index is an aperture SPAD by
+	 * deriving the quadrant.
+	 */
+	uint32_t quadrant;
+	uint8_t isAperture = 1;
+	quadrant = spadIndex >> 6;
+	if (refArrayQuadrants[quadrant] == REF_ARRAY_SPAD_0)
+		isAperture = 0;
+
+	return isAperture;
+}
+
+
+VL53L0X_Error enable_spad_bit(uint8_t spadArray[], uint32_t size,
+	uint32_t spadIndex)
+{
+	VL53L0X_Error status = VL53L0X_ERROR_NONE;
+	uint32_t cSpadsPerByte = 8;
+	uint32_t coarseIndex;
+	uint32_t fineIndex;
+
+	coarseIndex = spadIndex / cSpadsPerByte;
+	fineIndex = spadIndex % cSpadsPerByte;
+	if (coarseIndex >= size)
+		status = VL53L0X_ERROR_REF_SPAD_INIT;
+	else
+		spadArray[coarseIndex] |= (1 << fineIndex);
+
+	return status;
+}
+
+VL53L0X_Error count_enabled_spads(uint8_t spadArray[],
+		uint32_t byteCount, uint32_t maxSpads,
+		uint32_t *pTotalSpadsEnabled, uint8_t *pIsAperture)
+{
+	VL53L0X_Error status = VL53L0X_ERROR_NONE;
+	uint32_t cSpadsPerByte = 8;
+	uint32_t lastByte;
+	uint32_t lastBit;
+	uint32_t byteIndex = 0;
+	uint32_t bitIndex = 0;
+	uint8_t tempByte;
+	uint8_t spadTypeIdentified = 0;
+
+	/* The entire array will not be used for spads, therefore the last
+	 * byte and last bit is determined from the max spads value.
+	 */
+
+	lastByte = maxSpads / cSpadsPerByte;
+	lastBit = maxSpads % cSpadsPerByte;
+
+	/* Check that the max spads value does not exceed the array bounds. */
+	if (lastByte >= byteCount)
+		status = VL53L0X_ERROR_REF_SPAD_INIT;
+
+	*pTotalSpadsEnabled = 0;
+
+	/* Count the bits enabled in the whole bytes */
+	for (byteIndex = 0; byteIndex <= (lastByte - 1); byteIndex++) {
+		tempByte = spadArray[byteIndex];
+
+		for (bitIndex = 0; bitIndex <= cSpadsPerByte; bitIndex++) {
+			if ((tempByte & 0x01) == 1) {
+				(*pTotalSpadsEnabled)++;
+
+				if (!spadTypeIdentified) {
+					*pIsAperture = 1;
+					if ((byteIndex < 2) && (bitIndex < 4))
+							*pIsAperture = 0;
+					spadTypeIdentified = 1;
+				}
+			}
+			tempByte >>= 1;
+		}
+	}
+
+	/* Count the number of bits enabled in the last byte accounting
+	 * for the fact that not all bits in the byte may be used.
+	 */
+	tempByte = spadArray[lastByte];
+
+	for (bitIndex = 0; bitIndex <= lastBit; bitIndex++) {
+		if ((tempByte & 0x01) == 1)
+			(*pTotalSpadsEnabled)++;
+	}
+
+	return status;
+}
+
+VL53L0X_Error set_ref_spad_map(VL53L0X_DEV Dev, uint8_t *refSpadArray)
+{
+	VL53L0X_Error status = VL53L0X_WriteMulti(Dev,
+				VL53L0X_REG_GLOBAL_CONFIG_SPAD_ENABLES_REF_0,
+				refSpadArray, 6);
+	return status;
+}
+
+VL53L0X_Error get_ref_spad_map(VL53L0X_DEV Dev, uint8_t *refSpadArray)
+{
+	VL53L0X_Error status = VL53L0X_ReadMulti(Dev,
+				VL53L0X_REG_GLOBAL_CONFIG_SPAD_ENABLES_REF_0,
+				refSpadArray,
+				6);
+	return status;
+}
+
+VL53L0X_Error enable_ref_spads(VL53L0X_DEV Dev,
+				uint8_t apertureSpads,
+				uint8_t goodSpadArray[],
+				uint8_t spadArray[],
+				uint32_t size,
+				uint32_t start,
+				uint32_t offset,
+				uint32_t spadCount,
+				uint32_t *lastSpad)
+{
+	VL53L0X_Error status = VL53L0X_ERROR_NONE;
+	uint32_t index;
+	uint32_t i;
+	int32_t nextGoodSpad = offset;
+	uint32_t currentSpad;
+	uint8_t checkSpadArray[6];
+
+	/*
+	 * This function takes in a spad array which may or may not have SPADS
+	 * already enabled and appends from a given offset a requested number
+	 * of new SPAD enables. The 'good spad map' is applied to
+	 * determine the next SPADs to enable.
+	 *
+	 * This function applies to only aperture or only non-aperture spads.
+	 * Checks are performed to ensure this.
+	 */
+
+	currentSpad = offset;
+	for (index = 0; index < spadCount; index++) {
+		get_next_good_spad(goodSpadArray, size, currentSpad,
+			&nextGoodSpad);
+
+		if (nextGoodSpad == -1) {
+			status = VL53L0X_ERROR_REF_SPAD_INIT;
+			break;
+		}
+
+		/* Confirm that the next good SPAD is non-aperture */
+		if (is_aperture(start + nextGoodSpad) != apertureSpads) {
+			/* if we can't get the required number of good aperture
+			 * spads from the current quadrant then this is an error
+			 */
+			status = VL53L0X_ERROR_REF_SPAD_INIT;
+			break;
+		}
+		currentSpad = (uint32_t)nextGoodSpad;
+		enable_spad_bit(spadArray, size, currentSpad);
+		currentSpad++;
+	}
+	*lastSpad = currentSpad;
+
+	if (status == VL53L0X_ERROR_NONE)
+		status = set_ref_spad_map(Dev, spadArray);
+
+
+	if (status == VL53L0X_ERROR_NONE) {
+		status = get_ref_spad_map(Dev, checkSpadArray);
+
+		i = 0;
+
+		/* Compare spad maps. If not equal report error. */
+		while (i < size) {
+			if (spadArray[i] != checkSpadArray[i]) {
+				status = VL53L0X_ERROR_REF_SPAD_INIT;
+				break;
+			}
+			i++;
+		}
+	}
+	return status;
+}
+
+
+VL53L0X_Error perform_ref_signal_measurement(VL53L0X_DEV Dev,
+		uint16_t *refSignalRate)
+{
+	VL53L0X_Error status = VL53L0X_ERROR_NONE;
+	VL53L0X_RangingMeasurementData_t rangingMeasurementData;
+
+	uint8_t SequenceConfig = 0;
+
+	/* store the value of the sequence config,
+	 * this will be reset before the end of the function
+	 */
+
+	SequenceConfig = PALDevDataGet(Dev, SequenceConfig);
+
+	/*
+	 * This function performs a reference signal rate measurement.
+	 */
+	if (status == VL53L0X_ERROR_NONE)
+		status = VL53L0X_WrByte(Dev,
+			VL53L0X_REG_SYSTEM_SEQUENCE_CONFIG, 0xC0);
+
+	if (status == VL53L0X_ERROR_NONE)
+		status = VL53L0X_PerformSingleRangingMeasurement(Dev,
+				&rangingMeasurementData);
+
+	if (status == VL53L0X_ERROR_NONE)
+		status = VL53L0X_WrByte(Dev, 0xFF, 0x01);
+
+	if (status == VL53L0X_ERROR_NONE)
+		status = VL53L0X_RdWord(Dev,
+			VL53L0X_REG_RESULT_PEAK_SIGNAL_RATE_REF,
+			refSignalRate);
+
+	if (status == VL53L0X_ERROR_NONE)
+		status = VL53L0X_WrByte(Dev, 0xFF, 0x00);
+
+	if (status == VL53L0X_ERROR_NONE) {
+		/* restore the previous Sequence Config */
+		status = VL53L0X_WrByte(Dev, VL53L0X_REG_SYSTEM_SEQUENCE_CONFIG,
+				SequenceConfig);
+		if (status == VL53L0X_ERROR_NONE)
+			PALDevDataSet(Dev, SequenceConfig, SequenceConfig);
+	}
+
+	return status;
+}
+
+VL53L0X_Error VL53L0X_perform_ref_spad_management(VL53L0X_DEV Dev,
+				uint32_t *refSpadCount,
+				uint8_t *isApertureSpads)
+{
+	VL53L0X_Error Status = VL53L0X_ERROR_NONE;
+	uint8_t lastSpadArray[6];
+	uint8_t startSelect = 0xB4;
+	uint32_t minimumSpadCount = 3;
+	uint32_t maxSpadCount = 44;
+	uint32_t currentSpadIndex = 0;
+	uint32_t lastSpadIndex = 0;
+	int32_t nextGoodSpad = 0;
+	uint16_t targetRefRate = 0x0A00; /* 20 MCPS in 9:7 format */
+	uint16_t peakSignalRateRef;
+	uint32_t needAptSpads = 0;
+	uint32_t index = 0;
+	uint32_t spadArraySize = 6;
+	uint32_t signalRateDiff = 0;
+	uint32_t lastSignalRateDiff = 0;
+	uint8_t complete = 0;
+	uint8_t VhvSettings = 0;
+	uint8_t PhaseCal = 0;
+	uint32_t refSpadCount_int = 0;
+	uint8_t	 isApertureSpads_int = 0;
+
+	/*
+	 * The reference SPAD initialization procedure determines the minimum
+	 * amount of reference spads to be enables to achieve a target reference
+	 * signal rate and should be performed once during initialization.
+	 *
+	 * Either aperture or non-aperture spads are applied but never both.
+	 * Firstly non-aperture spads are set, begining with 5 spads, and
+	 * increased one spad at a time until the closest measurement to the
+	 * target rate is achieved.
+	 *
+	 * If the target rate is exceeded when 5 non-aperture spads are enabled,
+	 * initialization is performed instead with aperture spads.
+	 *
+	 * When setting spads, a 'Good Spad Map' is applied.
+	 *
+	 * This procedure operates within a SPAD window of interest of a maximum
+	 * 44 spads.
+	 * The start point is currently fixed to 180, which lies towards the end
+	 * of the non-aperture quadrant and runs in to the adjacent aperture
+	 * quadrant.
+	 */
+
+
+	targetRefRate = PALDevDataGet(Dev, targetRefRate);
+
+	/*
+	 * Initialize Spad arrays.
+	 * Currently the good spad map is initialised to 'All good'.
+	 * This is a short term implementation. The good spad map will be
+	 * provided as an input.
+	 * Note that there are 6 bytes. Only the first 44 bits will be used to
+	 * represent spads.
+	 */
+	for (index = 0; index < spadArraySize; index++)
+		Dev->Data.SpadData.RefSpadEnables[index] = 0;
+
+
+	Status = VL53L0X_WrByte(Dev, 0xFF, 0x01);
+
+	if (Status == VL53L0X_ERROR_NONE)
+		Status = VL53L0X_WrByte(Dev,
+			VL53L0X_REG_DYNAMIC_SPAD_REF_EN_START_OFFSET, 0x00);
+
+	if (Status == VL53L0X_ERROR_NONE)
+		Status = VL53L0X_WrByte(Dev,
+			VL53L0X_REG_DYNAMIC_SPAD_NUM_REQUESTED_REF_SPAD, 0x2C);
+
+	if (Status == VL53L0X_ERROR_NONE)
+		Status = VL53L0X_WrByte(Dev, 0xFF, 0x00);
+
+	if (Status == VL53L0X_ERROR_NONE)
+		Status = VL53L0X_WrByte(Dev,
+			VL53L0X_REG_GLOBAL_CONFIG_REF_EN_START_SELECT,
+			startSelect);
+
+
+	if (Status == VL53L0X_ERROR_NONE)
+		Status = VL53L0X_WrByte(Dev,
+				VL53L0X_REG_POWER_MANAGEMENT_GO1_POWER_FORCE, 0);
+
+	/* Perform ref calibration */
+	if (Status == VL53L0X_ERROR_NONE)
+		Status = VL53L0X_perform_ref_calibration(Dev, &VhvSettings,
+			&PhaseCal, 0);
+
+	if (Status == VL53L0X_ERROR_NONE) {
+		/* Enable Minimum NON-APERTURE Spads */
+		currentSpadIndex = 0;
+		lastSpadIndex = currentSpadIndex;
+		needAptSpads = 0;
+		Status = enable_ref_spads(Dev,
+					needAptSpads,
+					Dev->Data.SpadData.RefGoodSpadMap,
+					Dev->Data.SpadData.RefSpadEnables,
+					spadArraySize,
+					startSelect,
+					currentSpadIndex,
+					minimumSpadCount,
+					&lastSpadIndex);
+	}
+
+	if (Status == VL53L0X_ERROR_NONE) {
+		currentSpadIndex = lastSpadIndex;
+
+		Status = perform_ref_signal_measurement(Dev,
+			&peakSignalRateRef);
+		if ((Status == VL53L0X_ERROR_NONE) &&
+			(peakSignalRateRef > targetRefRate)) {
+			/* Signal rate measurement too high,
+			 * switch to APERTURE SPADs */
+
+			for (index = 0; index < spadArraySize; index++)
+				Dev->Data.SpadData.RefSpadEnables[index] = 0;
+
+
+			/* Increment to the first APERTURE spad */
+			while ((is_aperture(startSelect + currentSpadIndex)
+				== 0) && (currentSpadIndex < maxSpadCount)) {
+				currentSpadIndex++;
+			}
+
+			needAptSpads = 1;
+
+			Status = enable_ref_spads(Dev,
+					needAptSpads,
+					Dev->Data.SpadData.RefGoodSpadMap,
+					Dev->Data.SpadData.RefSpadEnables,
+					spadArraySize,
+					startSelect,
+					currentSpadIndex,
+					minimumSpadCount,
+					&lastSpadIndex);
+
+			if (Status == VL53L0X_ERROR_NONE) {
+				currentSpadIndex = lastSpadIndex;
+				Status = perform_ref_signal_measurement(Dev,
+						&peakSignalRateRef);
+
+				if ((Status == VL53L0X_ERROR_NONE) &&
+					(peakSignalRateRef > targetRefRate)) {
+					/* Signal rate still too high after
+					 * setting the minimum number of
+					 * APERTURE spads. Can do no more
+					 * therefore set the min number of
+					 * aperture spads as the result.
+					 */
+					isApertureSpads_int = 1;
+					refSpadCount_int = minimumSpadCount;
+				}
+			}
+		} else {
+			needAptSpads = 0;
+		}
+	}
+
+	if ((Status == VL53L0X_ERROR_NONE) &&
+		(peakSignalRateRef < targetRefRate)) {
+		/* At this point, the minimum number of either aperture
+		 * or non-aperture spads have been set. Proceed to add
+		 * spads and perform measurements until the target
+		 * reference is reached.
+		 */
+		isApertureSpads_int = needAptSpads;
+		refSpadCount_int	= minimumSpadCount;
+
+		memcpy(lastSpadArray, Dev->Data.SpadData.RefSpadEnables,
+				spadArraySize);
+		lastSignalRateDiff = abs(peakSignalRateRef -
+			targetRefRate);
+		complete = 0;
+
+		while (!complete) {
+			get_next_good_spad(
+				Dev->Data.SpadData.RefGoodSpadMap,
+				spadArraySize, currentSpadIndex,
+				&nextGoodSpad);
+
+			if (nextGoodSpad == -1) {
+				Status = VL53L0X_ERROR_REF_SPAD_INIT;
+				break;
+			}
+
+			(refSpadCount_int)++;
+
+			/* Cannot combine Aperture and Non-Aperture spads, so
+			 * ensure the current spad is of the correct type.
+			 */
+			if (is_aperture((uint32_t)startSelect + nextGoodSpad) !=
+					needAptSpads) {
+				Status = VL53L0X_ERROR_REF_SPAD_INIT;
+				break;
+			}
+
+			currentSpadIndex = nextGoodSpad;
+			Status = enable_spad_bit(
+					Dev->Data.SpadData.RefSpadEnables,
+					spadArraySize, currentSpadIndex);
+
+			if (Status == VL53L0X_ERROR_NONE) {
+				currentSpadIndex++;
+				/* Proceed to apply the additional spad and
+				 * perform measurement. */
+				Status = set_ref_spad_map(Dev,
+					Dev->Data.SpadData.RefSpadEnables);
+			}
+
+			if (Status != VL53L0X_ERROR_NONE)
+				break;
+
+			Status = perform_ref_signal_measurement(Dev,
+					&peakSignalRateRef);
+
+			if (Status != VL53L0X_ERROR_NONE)
+				break;
+
+			signalRateDiff = abs(peakSignalRateRef - targetRefRate);
+
+			if (peakSignalRateRef > targetRefRate) {
+				/* Select the spad map that provides the
+				 * measurement closest to the target rate,
+				 * either above or below it.
+				 */
+				if (signalRateDiff > lastSignalRateDiff) {
+					/* Previous spad map produced a closer
+					 * measurement, so choose this. */
+					Status = set_ref_spad_map(Dev,
+							lastSpadArray);
+					memcpy(
+					Dev->Data.SpadData.RefSpadEnables,
+					lastSpadArray, spadArraySize);
+
+					(refSpadCount_int)--;
+				}
+				complete = 1;
+			} else {
+				/* Continue to add spads */
+				lastSignalRateDiff = signalRateDiff;
+				memcpy(lastSpadArray,
+					Dev->Data.SpadData.RefSpadEnables,
+					spadArraySize);
+			}
+
+		} /* while */
+	}
+
+	if (Status == VL53L0X_ERROR_NONE) {
+		*refSpadCount = refSpadCount_int;
+		*isApertureSpads = isApertureSpads_int;
+
+		VL53L0X_SETDEVICESPECIFICPARAMETER(Dev, RefSpadsInitialised, 1);
+		VL53L0X_SETDEVICESPECIFICPARAMETER(Dev,
+			ReferenceSpadCount, (uint8_t)(*refSpadCount));
+		VL53L0X_SETDEVICESPECIFICPARAMETER(Dev,
+			ReferenceSpadType, *isApertureSpads);
+	}
+
+	return Status;
+}
+
+VL53L0X_Error VL53L0X_set_reference_spads(VL53L0X_DEV Dev,
+				 uint32_t count, uint8_t isApertureSpads)
+{
+	VL53L0X_Error Status = VL53L0X_ERROR_NONE;
+	uint32_t currentSpadIndex = 0;
+	uint8_t startSelect = 0xB4;
+	uint32_t spadArraySize = 6;
+	uint32_t maxSpadCount = 44;
+	uint32_t lastSpadIndex;
+	uint32_t index;
+
+	/*
+	 * This function applies a requested number of reference spads, either
+	 * aperture or
+	 * non-aperture, as requested.
+	 * The good spad map will be applied.
+	 */
+
+	Status = VL53L0X_WrByte(Dev, 0xFF, 0x01);
+
+	if (Status == VL53L0X_ERROR_NONE)
+		Status = VL53L0X_WrByte(Dev,
+			VL53L0X_REG_DYNAMIC_SPAD_REF_EN_START_OFFSET, 0x00);
+
+	if (Status == VL53L0X_ERROR_NONE)
+		Status = VL53L0X_WrByte(Dev,
+			VL53L0X_REG_DYNAMIC_SPAD_NUM_REQUESTED_REF_SPAD, 0x2C);
+
+	if (Status == VL53L0X_ERROR_NONE)
+		Status = VL53L0X_WrByte(Dev, 0xFF, 0x00);
+
+	if (Status == VL53L0X_ERROR_NONE)
+		Status = VL53L0X_WrByte(Dev,
+			VL53L0X_REG_GLOBAL_CONFIG_REF_EN_START_SELECT,
+			startSelect);
+
+	for (index = 0; index < spadArraySize; index++)
+		Dev->Data.SpadData.RefSpadEnables[index] = 0;
+
+	if (isApertureSpads) {
+		/* Increment to the first APERTURE spad */
+		while ((is_aperture(startSelect + currentSpadIndex) == 0) &&
+			  (currentSpadIndex < maxSpadCount)) {
+			currentSpadIndex++;
+		}
+	}
+	Status = enable_ref_spads(Dev,
+				isApertureSpads,
+				Dev->Data.SpadData.RefGoodSpadMap,
+				Dev->Data.SpadData.RefSpadEnables,
+				spadArraySize,
+				startSelect,
+				currentSpadIndex,
+				count,
+				&lastSpadIndex);
+
+	if (Status == VL53L0X_ERROR_NONE) {
+		VL53L0X_SETDEVICESPECIFICPARAMETER(Dev, RefSpadsInitialised, 1);
+		VL53L0X_SETDEVICESPECIFICPARAMETER(Dev,
+			ReferenceSpadCount, (uint8_t)(count));
+		VL53L0X_SETDEVICESPECIFICPARAMETER(Dev,
+			ReferenceSpadType, isApertureSpads);
+	}
+
+	return Status;
+}
+
+VL53L0X_Error VL53L0X_get_reference_spads(VL53L0X_DEV Dev,
+			uint32_t *pSpadCount, uint8_t *pIsApertureSpads)
+{
+	VL53L0X_Error Status = VL53L0X_ERROR_NONE;
+	uint8_t refSpadsInitialised;
+	uint8_t refSpadArray[6];
+	uint32_t cMaxSpadCount = 44;
+	uint32_t cSpadArraySize = 6;
+	uint32_t spadsEnabled;
+	uint8_t isApertureSpads = 0;
+
+	refSpadsInitialised = VL53L0X_GETDEVICESPECIFICPARAMETER(Dev,
+					RefSpadsInitialised);
+
+	if (refSpadsInitialised == 1) {
+
+		*pSpadCount = (uint32_t)VL53L0X_GETDEVICESPECIFICPARAMETER(Dev,
+			ReferenceSpadCount);
+		*pIsApertureSpads = VL53L0X_GETDEVICESPECIFICPARAMETER(Dev,
+			ReferenceSpadType);
+	} else {
+
+		/* obtain spad info from device.*/
+		Status = get_ref_spad_map(Dev, refSpadArray);
+
+		if (Status == VL53L0X_ERROR_NONE) {
+			/* count enabled spads within spad map array and
+			 * determine if Aperture or Non-Aperture.
+			 */
+			Status = count_enabled_spads(refSpadArray,
+							cSpadArraySize,
+							cMaxSpadCount,
+							&spadsEnabled,
+							&isApertureSpads);
+
+			if (Status == VL53L0X_ERROR_NONE) {
+
+				*pSpadCount = spadsEnabled;
+				*pIsApertureSpads = isApertureSpads;
+
+				VL53L0X_SETDEVICESPECIFICPARAMETER(Dev,
+					RefSpadsInitialised, 1);
+				VL53L0X_SETDEVICESPECIFICPARAMETER(Dev,
+					ReferenceSpadCount,
+					(uint8_t)spadsEnabled);
+				VL53L0X_SETDEVICESPECIFICPARAMETER(Dev,
+					ReferenceSpadType, isApertureSpads);
+			}
+		}
+	}
+
+	return Status;
+}
+
+
+VL53L0X_Error VL53L0X_perform_single_ref_calibration(VL53L0X_DEV Dev,
+		uint8_t vhv_init_byte)
+{
+	VL53L0X_Error Status = VL53L0X_ERROR_NONE;
+
+	if (Status == VL53L0X_ERROR_NONE)
+		Status = VL53L0X_WrByte(Dev, VL53L0X_REG_SYSRANGE_START,
+				VL53L0X_REG_SYSRANGE_MODE_START_STOP |
+				vhv_init_byte);
+
+	if (Status == VL53L0X_ERROR_NONE)
+		Status = VL53L0X_measurement_poll_for_completion(Dev);
+
+	if (Status == VL53L0X_ERROR_NONE)
+		Status = VL53L0X_ClearInterruptMask(Dev, 0);
+
+	if (Status == VL53L0X_ERROR_NONE)
+		Status = VL53L0X_WrByte(Dev, VL53L0X_REG_SYSRANGE_START, 0x00);
+
+	return Status;
+}
+
+
+VL53L0X_Error VL53L0X_ref_calibration_io(VL53L0X_DEV Dev, uint8_t read_not_write,
+	uint8_t VhvSettings, uint8_t PhaseCal,
+	uint8_t *pVhvSettings, uint8_t *pPhaseCal,
+	const uint8_t vhv_enable, const uint8_t phase_enable)
+{
+	VL53L0X_Error Status = VL53L0X_ERROR_NONE;
+	uint8_t PhaseCalint = 0;
+
+	/* Read VHV from device */
+	Status |= VL53L0X_WrByte(Dev, 0xFF, 0x01);
+	Status |= VL53L0X_WrByte(Dev, 0x00, 0x00);
+	Status |= VL53L0X_WrByte(Dev, 0xFF, 0x00);
+
+	if (read_not_write) {
+		if (vhv_enable)
+			Status |= VL53L0X_RdByte(Dev, 0xCB, pVhvSettings);
+		if (phase_enable)
+			Status |= VL53L0X_RdByte(Dev, 0xEE, &PhaseCalint);
+	} else {
+		if (vhv_enable)
+			Status |= VL53L0X_WrByte(Dev, 0xCB, VhvSettings);
+		if (phase_enable)
+			Status |= VL53L0X_UpdateByte(Dev, 0xEE, 0x80, PhaseCal);
+	}
+
+	Status |= VL53L0X_WrByte(Dev, 0xFF, 0x01);
+	Status |= VL53L0X_WrByte(Dev, 0x00, 0x01);
+	Status |= VL53L0X_WrByte(Dev, 0xFF, 0x00);
+
+	*pPhaseCal = (uint8_t)(PhaseCalint&0xEF);
+
+	return Status;
+}
+
+
+VL53L0X_Error VL53L0X_perform_vhv_calibration(VL53L0X_DEV Dev,
+	uint8_t *pVhvSettings, const uint8_t get_data_enable,
+	const uint8_t restore_config)
+{
+	VL53L0X_Error Status = VL53L0X_ERROR_NONE;
+	uint8_t SequenceConfig = 0;
+	uint8_t VhvSettings = 0;
+	uint8_t PhaseCal = 0;
+	uint8_t PhaseCalInt = 0;
+
+	/* store the value of the sequence config,
+	 * this will be reset before the end of the function
+	 */
+
+	if (restore_config)
+		SequenceConfig = PALDevDataGet(Dev, SequenceConfig);
+
+	/* Run VHV */
+	Status = VL53L0X_WrByte(Dev, VL53L0X_REG_SYSTEM_SEQUENCE_CONFIG, 0x01);
+
+	if (Status == VL53L0X_ERROR_NONE)
+		Status = VL53L0X_perform_single_ref_calibration(Dev, 0x40);
+
+	/* Read VHV from device */
+	if ((Status == VL53L0X_ERROR_NONE) && (get_data_enable == 1)) {
+		Status = VL53L0X_ref_calibration_io(Dev, 1,
+			VhvSettings, PhaseCal, /* Not used here */
+			pVhvSettings, &PhaseCalInt,
+			1, 0);
+	} else
+		*pVhvSettings = 0;
+
+
+	if ((Status == VL53L0X_ERROR_NONE) && restore_config) {
+		/* restore the previous Sequence Config */
+		Status = VL53L0X_WrByte(Dev, VL53L0X_REG_SYSTEM_SEQUENCE_CONFIG,
+				SequenceConfig);
+		if (Status == VL53L0X_ERROR_NONE)
+			PALDevDataSet(Dev, SequenceConfig, SequenceConfig);
+
+	}
+
+	return Status;
+}
+
+VL53L0X_Error VL53L0X_perform_phase_calibration(VL53L0X_DEV Dev,
+	uint8_t *pPhaseCal, const uint8_t get_data_enable,
+	const uint8_t restore_config)
+{
+	VL53L0X_Error Status = VL53L0X_ERROR_NONE;
+	uint8_t SequenceConfig = 0;
+	uint8_t VhvSettings = 0;
+	uint8_t PhaseCal = 0;
+	uint8_t VhvSettingsint;
+
+	/* store the value of the sequence config,
+	 * this will be reset before the end of the function
+	 */
+
+	if (restore_config)
+		SequenceConfig = PALDevDataGet(Dev, SequenceConfig);
+
+	/* Run PhaseCal */
+	Status = VL53L0X_WrByte(Dev, VL53L0X_REG_SYSTEM_SEQUENCE_CONFIG, 0x02);
+
+	if (Status == VL53L0X_ERROR_NONE)
+		Status = VL53L0X_perform_single_ref_calibration(Dev, 0x0);
+
+	/* Read PhaseCal from device */
+	if ((Status == VL53L0X_ERROR_NONE) && (get_data_enable == 1)) {
+		Status = VL53L0X_ref_calibration_io(Dev, 1,
+			VhvSettings, PhaseCal, /* Not used here */
+			&VhvSettingsint, pPhaseCal,
+			0, 1);
+	} else
+		*pPhaseCal = 0;
+
+
+	if ((Status == VL53L0X_ERROR_NONE) && restore_config) {
+		/* restore the previous Sequence Config */
+		Status = VL53L0X_WrByte(Dev, VL53L0X_REG_SYSTEM_SEQUENCE_CONFIG,
+				SequenceConfig);
+		if (Status == VL53L0X_ERROR_NONE)
+			PALDevDataSet(Dev, SequenceConfig, SequenceConfig);
+
+	}
+
+	return Status;
+}
+
+VL53L0X_Error VL53L0X_perform_ref_calibration(VL53L0X_DEV Dev,
+	uint8_t *pVhvSettings, uint8_t *pPhaseCal, uint8_t get_data_enable)
+{
+	VL53L0X_Error Status = VL53L0X_ERROR_NONE;
+	uint8_t SequenceConfig = 0;
+
+	/* store the value of the sequence config,
+	 * this will be reset before the end of the function
+	 */
+
+	SequenceConfig = PALDevDataGet(Dev, SequenceConfig);
+
+	/* In the following function we don't save the config to optimize
+	 * writes on device. Config is saved and restored only once. */
+	Status = VL53L0X_perform_vhv_calibration(
+			Dev, pVhvSettings, get_data_enable, 0);
+
+
+	if (Status == VL53L0X_ERROR_NONE)
+		Status = VL53L0X_perform_phase_calibration(
+			Dev, pPhaseCal, get_data_enable, 0);
+
+
+	if (Status == VL53L0X_ERROR_NONE) {
+		/* restore the previous Sequence Config */
+		Status = VL53L0X_WrByte(Dev, VL53L0X_REG_SYSTEM_SEQUENCE_CONFIG,
+				SequenceConfig);
+		if (Status == VL53L0X_ERROR_NONE)
+			PALDevDataSet(Dev, SequenceConfig, SequenceConfig);
+
+	}
+
+	return Status;
+}
+
+VL53L0X_Error VL53L0X_set_ref_calibration(VL53L0X_DEV Dev,
+		uint8_t VhvSettings, uint8_t PhaseCal)
+{
+	VL53L0X_Error Status = VL53L0X_ERROR_NONE;
+	uint8_t pVhvSettings;
+	uint8_t pPhaseCal;
+
+	Status = VL53L0X_ref_calibration_io(Dev, 0,
+		VhvSettings, PhaseCal,
+		&pVhvSettings, &pPhaseCal,
+		1, 1);
+
+	return Status;
+}
+
+VL53L0X_Error VL53L0X_get_ref_calibration(VL53L0X_DEV Dev,
+		uint8_t *pVhvSettings, uint8_t *pPhaseCal)
+{
+	VL53L0X_Error Status = VL53L0X_ERROR_NONE;
+	uint8_t VhvSettings = 0;
+	uint8_t PhaseCal = 0;
+
+	Status = VL53L0X_ref_calibration_io(Dev, 1,
+		VhvSettings, PhaseCal,
+		pVhvSettings, pPhaseCal,
+		1, 1);
+
+	return Status;
+}