PrusaFirmware/Firmware/mesh_bed_calibration.cpp

#include "Configuration.h"
#include "ConfigurationStore.h"
#include "util.h"
#include "language.h"
#include "mesh_bed_calibration.h"
#include "mesh_bed_leveling.h"
#include "stepper.h"
#include "ultralcd.h"
#include "temperature.h"

#ifdef TMC2130
#include "tmc2130.h"
#endif //TMC2130

#define DBG(args...) printf_P(args)

uint8_t world2machine_correction_mode;
float   world2machine_rotation_and_skew[2][2];
float   world2machine_rotation_and_skew_inv[2][2];
float   world2machine_shift[2];

// Weight of the Y coordinate for the least squares fitting of the bed induction sensor targets.
// Only used for the first row of the points, which may not befully in reach of the sensor.
#define WEIGHT_FIRST_ROW_X_HIGH (1.f)
#define WEIGHT_FIRST_ROW_X_LOW  (0.35f)
#define WEIGHT_FIRST_ROW_Y_HIGH (0.3f)
#define WEIGHT_FIRST_ROW_Y_LOW  (0.0f)



// Scaling of the real machine axes against the programmed dimensions in the firmware.
// The correction is tiny, here around 0.5mm on 250mm length.
//#define MACHINE_AXIS_SCALE_X ((250.f - 0.5f) / 250.f)
//#define MACHINE_AXIS_SCALE_Y ((250.f - 0.5f) / 250.f)
#define MACHINE_AXIS_SCALE_X 1.f
#define MACHINE_AXIS_SCALE_Y 1.f

#define BED_CALIBRATION_POINT_OFFSET_MAX_EUCLIDIAN  (1.5f)
#define BED_CALIBRATION_POINT_OFFSET_MAX_1ST_ROW_X  (1.5f)
#define BED_CALIBRATION_POINT_OFFSET_MAX_1ST_ROW_Y  (1.5f)

#define MIN_BED_SENSOR_POINT_RESPONSE_DMR           (2.0f)

//#define Y_MIN_POS_FOR_BED_CALIBRATION (MANUAL_Y_HOME_POS-0.2f)
#define Y_MIN_POS_FOR_BED_CALIBRATION (Y_MIN_POS)
// Distances toward the print bed edge may not be accurate.
#define Y_MIN_POS_CALIBRATION_POINT_ACCURATE (Y_MIN_POS + 3.f)
// When the measured point center is out of reach of the sensor, Y coordinate will be ignored
// by the Least Squares fitting and the X coordinate will be weighted low.
#define Y_MIN_POS_CALIBRATION_POINT_OUT_OF_REACH (Y_MIN_POS - 0.5f)

// 0.12 degrees equals to an offset of 0.5mm on 250mm length.
const float bed_skew_angle_mild = (0.12f * M_PI / 180.f);
// 0.25 degrees equals to an offset of 1.1mm on 250mm length.
const float bed_skew_angle_extreme = (0.25f * M_PI / 180.f);

// Positions of the bed reference points in the machine coordinates, referenced to the P.I.N.D.A sensor.
// The points are ordered in a zig-zag fashion to speed up the calibration.

#ifdef HEATBED_V2

/**
 * [0,0] bed print area point X coordinate in bed coordinates ver. 05d/24V
 */
#define BED_PRINT_ZERO_REF_X 2.f
/**
 * [0,0] bed print area point Y coordinate in bed coordinates ver. 05d/24V
 */
#define BED_PRINT_ZERO_REF_Y 9.4f

/**
 * @brief Positions of the bed reference points in print area coordinates. ver. 05d/24V
 *
 * Numeral constants are in bed coordinates, subtracting macro defined values converts it to print area coordinates.
 *
 * The points are the following:
 * MK2: center front, center right, center rear, center left.
 * MK25 and MK3: front left, front right, rear right, rear left
 */
const float bed_ref_points_4[] PROGMEM = {
	37.f - BED_PRINT_ZERO_REF_X - X_PROBE_OFFSET_FROM_EXTRUDER - SHEET_PRINT_ZERO_REF_X,
	18.4f - BED_PRINT_ZERO_REF_Y - Y_PROBE_OFFSET_FROM_EXTRUDER - SHEET_PRINT_ZERO_REF_Y,

	245.f - BED_PRINT_ZERO_REF_X - X_PROBE_OFFSET_FROM_EXTRUDER  - SHEET_PRINT_ZERO_REF_X,
	18.4f - BED_PRINT_ZERO_REF_Y - Y_PROBE_OFFSET_FROM_EXTRUDER - SHEET_PRINT_ZERO_REF_Y,

	245.f - BED_PRINT_ZERO_REF_X - X_PROBE_OFFSET_FROM_EXTRUDER  - SHEET_PRINT_ZERO_REF_X,
	210.4f - BED_PRINT_ZERO_REF_Y - Y_PROBE_OFFSET_FROM_EXTRUDER - SHEET_PRINT_ZERO_REF_Y,

	37.f - BED_PRINT_ZERO_REF_X - X_PROBE_OFFSET_FROM_EXTRUDER  - SHEET_PRINT_ZERO_REF_X,
	210.4f - BED_PRINT_ZERO_REF_Y - Y_PROBE_OFFSET_FROM_EXTRUDER - SHEET_PRINT_ZERO_REF_Y
};

#else

// Positions of the bed reference points in the machine coordinates, referenced to the P.I.N.D.A sensor.
// The points are the following: center front, center right, center rear, center left.
const float bed_ref_points_4[] PROGMEM = {
	115.f - BED_ZERO_REF_X,   8.4f - BED_ZERO_REF_Y,
	216.f - BED_ZERO_REF_X, 104.4f - BED_ZERO_REF_Y,
	115.f - BED_ZERO_REF_X, 202.4f - BED_ZERO_REF_Y,
	13.f - BED_ZERO_REF_X, 104.4f - BED_ZERO_REF_Y
};

#endif //not HEATBED_V2


static inline float sqr(float x) { return x * x; }

#ifdef HEATBED_V2
static inline bool point_on_1st_row(const uint8_t /*i*/)
{
	return false;
}
#else //HEATBED_V2
static inline bool point_on_1st_row(const uint8_t i)
{
	return (i < 3);
}
#endif //HEATBED_V2

// Weight of a point coordinate in a least squares optimization.
// The first row of points may not be fully reachable
// and the y values may be shortened a bit by the bed carriage
// pulling the belt up.
static inline float point_weight_x(const uint8_t i, const float &y)
{
    float w = 1.f;
    if (point_on_1st_row(i)) {
		if (y >= Y_MIN_POS_CALIBRATION_POINT_ACCURATE) {
            w = WEIGHT_FIRST_ROW_X_HIGH;
        } else if (y < Y_MIN_POS_CALIBRATION_POINT_OUT_OF_REACH) {
            // If the point is fully outside, give it some weight.
            w = WEIGHT_FIRST_ROW_X_LOW;
        } else {
            // Linearly interpolate the weight from 1 to WEIGHT_FIRST_ROW_X.
            float t = (y - Y_MIN_POS_CALIBRATION_POINT_OUT_OF_REACH) / (Y_MIN_POS_CALIBRATION_POINT_ACCURATE - Y_MIN_POS_CALIBRATION_POINT_OUT_OF_REACH);
            w = (1.f - t) * WEIGHT_FIRST_ROW_X_LOW + t * WEIGHT_FIRST_ROW_X_HIGH;
        }
    }
    return w;
}

// Weight of a point coordinate in a least squares optimization.
// The first row of points may not be fully reachable
// and the y values may be shortened a bit by the bed carriage
// pulling the belt up.
static inline float point_weight_y(const uint8_t i, const float &y)
{
    float w = 1.f;
    if (point_on_1st_row(i)) {
        if (y >= Y_MIN_POS_CALIBRATION_POINT_ACCURATE) {
            w = WEIGHT_FIRST_ROW_Y_HIGH;
        } else if (y < Y_MIN_POS_CALIBRATION_POINT_OUT_OF_REACH) {
            // If the point is fully outside, give it some weight.
            w = WEIGHT_FIRST_ROW_Y_LOW;
        } else {
            // Linearly interpolate the weight from 1 to WEIGHT_FIRST_ROW_X.
            float t = (y - Y_MIN_POS_CALIBRATION_POINT_OUT_OF_REACH) / (Y_MIN_POS_CALIBRATION_POINT_ACCURATE - Y_MIN_POS_CALIBRATION_POINT_OUT_OF_REACH);
            w = (1.f - t) * WEIGHT_FIRST_ROW_Y_LOW + t * WEIGHT_FIRST_ROW_Y_HIGH;
        }
    }
    return w;
}
/**
 * @brief Calculate machine skew and offset
 *
 * Non-Linear Least Squares fitting of the bed to the measured induction points
 * using the Gauss-Newton method.
 * This method will maintain a unity length of the machine axes,
 * which is the correct approach if the sensor points are not measured precisely.
 * @param measured_pts Matrix of 2D points (maximum 18 floats)
 * @param npts Number of points (maximum 9)
 * @param true_pts
 * @param [out] vec_x Resulting correction matrix. X axis vector
 * @param [out] vec_y Resulting correction matrix. Y axis vector
 * @param [out] cntr  Resulting correction matrix. [0;0] pont offset
 * @param verbosity_level
 * @return BedSkewOffsetDetectionResultType
 */
BedSkewOffsetDetectionResultType calculate_machine_skew_and_offset_LS(
    const float  *measured_pts,
    uint8_t       npts,
    const float  *true_pts,
    float        *vec_x,
    float        *vec_y,
    float        *cntr,
    int8_t
#ifdef SUPPORT_VERBOSITY
    verbosity_level
#endif //SUPPORT_VERBOSITY
    )
{
	float angleDiff;
	#ifdef SUPPORT_VERBOSITY
    if (verbosity_level >= 10) {
		SERIAL_ECHOLNPGM("calculate machine skew and offset LS");

        // Show the initial state, before the fitting.
        SERIAL_ECHOPGM("X vector, initial: ");
        MYSERIAL.print(vec_x[0], 5);
        SERIAL_ECHOPGM(", ");
        MYSERIAL.print(vec_x[1], 5);
        SERIAL_ECHOLNPGM("");

        SERIAL_ECHOPGM("Y vector, initial: ");
        MYSERIAL.print(vec_y[0], 5);
        SERIAL_ECHOPGM(", ");
        MYSERIAL.print(vec_y[1], 5);
        SERIAL_ECHOLNPGM("");

        SERIAL_ECHOPGM("center, initial: ");
        MYSERIAL.print(cntr[0], 5);
        SERIAL_ECHOPGM(", ");
        MYSERIAL.print(cntr[1], 5);
        SERIAL_ECHOLNPGM("");

        for (uint8_t i = 0; i < npts; ++i) {
            SERIAL_ECHOPGM("point #");
            MYSERIAL.print(int(i));
            SERIAL_ECHOPGM(" measured: (");
            MYSERIAL.print(measured_pts[i * 2], 5);
            SERIAL_ECHOPGM(", ");
            MYSERIAL.print(measured_pts[i * 2 + 1], 5);
            SERIAL_ECHOPGM("); target: (");
            MYSERIAL.print(pgm_read_float(true_pts + i * 2), 5);
            SERIAL_ECHOPGM(", ");
            MYSERIAL.print(pgm_read_float(true_pts + i * 2 + 1), 5);
            SERIAL_ECHOPGM("), error: ");
            MYSERIAL.print(sqrt(
                sqr(pgm_read_float(true_pts + i * 2) - measured_pts[i * 2]) +
                sqr(pgm_read_float(true_pts + i * 2 + 1) - measured_pts[i * 2 + 1])), 5);
            SERIAL_ECHOLNPGM("");
        }
        delay_keep_alive(100);
    }
	#endif // SUPPORT_VERBOSITY

    // Run some iterations of the Gauss-Newton method of non-linear least squares.
    // Initial set of parameters:
    // X,Y offset
    cntr[0] = 0.f;
    cntr[1] = 0.f;
    // Rotation of the machine X axis from the bed X axis.
    float a1 = 0;
    // Rotation of the machine Y axis from the bed Y axis.
    float a2 = 0;
    for (int8_t iter = 0; iter < 100; ++iter) {
        float c1 = cos(a1) * MACHINE_AXIS_SCALE_X;
        float s1 = sin(a1) * MACHINE_AXIS_SCALE_X;
        float c2 = cos(a2) * MACHINE_AXIS_SCALE_Y;
        float s2 = sin(a2) * MACHINE_AXIS_SCALE_Y;
        // Prepare the Normal equation for the Gauss-Newton method.
        float A[4][4] = { 0.f };
        float b[4] = { 0.f };
        float acc;
		delay_keep_alive(0); //manage heater, reset watchdog, manage inactivity
        for (uint8_t r = 0; r < 4; ++r) {
            for (uint8_t c = 0; c < 4; ++c) {
                acc = 0;
                // J^T times J
                for (uint8_t i = 0; i < npts; ++i) {
                    // First for the residuum in the x axis:
                    if (r != 1 && c != 1) {
                        float a = 
                             (r == 0) ? 1.f :
                            ((r == 2) ? (-s1 * measured_pts[2 * i]) :
                                        (-c2 * measured_pts[2 * i + 1]));
                        float b = 
                             (c == 0) ? 1.f :
                            ((c == 2) ? (-s1 * measured_pts[2 * i]) :
                                        (-c2 * measured_pts[2 * i + 1]));
                        float w = point_weight_x(i, measured_pts[2 * i + 1]);
                        acc += a * b * w;
                    }
                    // Second for the residuum in the y axis. 
                    // The first row of the points have a low weight, because their position may not be known
                    // with a sufficient accuracy.
                    if (r != 0 && c != 0) {
                        float a = 
                             (r == 1) ? 1.f :
                            ((r == 2) ? ( c1 * measured_pts[2 * i]) :
                                        (-s2 * measured_pts[2 * i + 1]));
                        float b = 
                             (c == 1) ? 1.f :
                            ((c == 2) ? ( c1 * measured_pts[2 * i]) :
                                        (-s2 * measured_pts[2 * i + 1]));
                        float w = point_weight_y(i, measured_pts[2 * i + 1]);
                        acc += a * b * w;
                    }
                }
                A[r][c] = acc;
            }
            // J^T times f(x)
            acc = 0.f;
            for (uint8_t i = 0; i < npts; ++i) {
                {
                    float j = 
                         (r == 0) ? 1.f :
                        ((r == 1) ? 0.f :
                        ((r == 2) ? (-s1 * measured_pts[2 * i]) :
                                    (-c2 * measured_pts[2 * i + 1])));
                    float fx = c1 * measured_pts[2 * i] - s2 * measured_pts[2 * i + 1] + cntr[0] - pgm_read_float(true_pts + i * 2);
                    float w = point_weight_x(i, measured_pts[2 * i + 1]);
                    acc += j * fx * w;
                }
                {
                    float j = 
                         (r == 0) ? 0.f :
                        ((r == 1) ? 1.f :
                        ((r == 2) ? ( c1 * measured_pts[2 * i]) :
                                    (-s2 * measured_pts[2 * i + 1])));
                    float fy = s1 * measured_pts[2 * i] + c2 * measured_pts[2 * i + 1] + cntr[1] - pgm_read_float(true_pts + i * 2 + 1);
                    float w = point_weight_y(i, measured_pts[2 * i + 1]);
                    acc += j * fy * w;
                }
            }
            b[r] = -acc;
        }

        // Solve for h by a Gauss iteration method.
        float h[4] = { 0.f };
        for (uint8_t gauss_iter = 0; gauss_iter < 100; ++gauss_iter) {
            h[0] = (b[0] - A[0][1] * h[1] - A[0][2] * h[2] - A[0][3] * h[3]) / A[0][0];
            h[1] = (b[1] - A[1][0] * h[0] - A[1][2] * h[2] - A[1][3] * h[3]) / A[1][1];
            h[2] = (b[2] - A[2][0] * h[0] - A[2][1] * h[1] - A[2][3] * h[3]) / A[2][2];
            h[3] = (b[3] - A[3][0] * h[0] - A[3][1] * h[1] - A[3][2] * h[2]) / A[3][3];
        }

        // and update the current position with h.
        // It may be better to use the Levenberg-Marquart method here,
        // but because we are very close to the solution alread,
        // the simple Gauss-Newton non-linear Least Squares method works well enough.
        cntr[0] += h[0];
        cntr[1] += h[1];
        a1 += h[2];
        a2 += h[3];

		#ifdef SUPPORT_VERBOSITY
        if (verbosity_level >= 20) {
            SERIAL_ECHOPGM("iteration: ");
            MYSERIAL.print(int(iter));
			SERIAL_ECHOPGM("; correction vector: ");
            MYSERIAL.print(h[0], 5);
            SERIAL_ECHOPGM(", ");
            MYSERIAL.print(h[1], 5);
            SERIAL_ECHOPGM(", ");
            MYSERIAL.print(h[2], 5);
            SERIAL_ECHOPGM(", ");
            MYSERIAL.print(h[3], 5);
            SERIAL_ECHOLNPGM("");
            SERIAL_ECHOPGM("corrected x/y: ");
            MYSERIAL.print(cntr[0], 5);
            SERIAL_ECHOPGM(", ");
            MYSERIAL.print(cntr[0], 5);
            SERIAL_ECHOLNPGM("");
            SERIAL_ECHOPGM("corrected angles: ");
            MYSERIAL.print(180.f * a1 / M_PI, 5);
            SERIAL_ECHOPGM(", ");
            MYSERIAL.print(180.f * a2 / M_PI, 5);
            SERIAL_ECHOLNPGM("");
        }
		#endif // SUPPORT_VERBOSITY
    }

    vec_x[0] =  cos(a1) * MACHINE_AXIS_SCALE_X;
    vec_x[1] =  sin(a1) * MACHINE_AXIS_SCALE_X;
    vec_y[0] = -sin(a2) * MACHINE_AXIS_SCALE_Y;
    vec_y[1] =  cos(a2) * MACHINE_AXIS_SCALE_Y;

    BedSkewOffsetDetectionResultType result = BED_SKEW_OFFSET_DETECTION_PERFECT;
    {
        angleDiff = fabs(a2 - a1);
        /// XY skew and Y-bed skew
        DBG(_n("Measured skews: %f %f\n"), degrees(a2 - a1), degrees(a2));
        eeprom_update_float((float *)(EEPROM_XYZ_CAL_SKEW), angleDiff); //storing xyz cal. skew to be able to show in support menu later
        if (angleDiff > bed_skew_angle_mild)
            result = (angleDiff > bed_skew_angle_extreme) ?
                BED_SKEW_OFFSET_DETECTION_SKEW_EXTREME :
                BED_SKEW_OFFSET_DETECTION_SKEW_MILD;
        if (fabs(a1) > bed_skew_angle_extreme ||
            fabs(a2) > bed_skew_angle_extreme)
            result = BED_SKEW_OFFSET_DETECTION_SKEW_EXTREME;
    }
	#ifdef SUPPORT_VERBOSITY
    if (verbosity_level >= 1) {
        SERIAL_ECHOPGM("correction angles: ");
        MYSERIAL.print(180.f * a1 / M_PI, 5);
        SERIAL_ECHOPGM(", ");
        MYSERIAL.print(180.f * a2 / M_PI, 5);
        SERIAL_ECHOLNPGM("");
    }

    if (verbosity_level >= 10) {
        // Show the adjusted state, before the fitting.
        SERIAL_ECHOPGM("X vector new, inverted: ");
        MYSERIAL.print(vec_x[0], 5);
        SERIAL_ECHOPGM(", ");
        MYSERIAL.print(vec_x[1], 5);
        SERIAL_ECHOLNPGM("");

        SERIAL_ECHOPGM("Y vector new, inverted: ");
        MYSERIAL.print(vec_y[0], 5);
        SERIAL_ECHOPGM(", ");
        MYSERIAL.print(vec_y[1], 5);
        SERIAL_ECHOLNPGM("");

        SERIAL_ECHOPGM("center new, inverted: ");
        MYSERIAL.print(cntr[0], 5);
        SERIAL_ECHOPGM(", ");
        MYSERIAL.print(cntr[1], 5);
        SERIAL_ECHOLNPGM("");
        delay_keep_alive(100);

        SERIAL_ECHOLNPGM("Error after correction: ");
    }
	#endif // SUPPORT_VERBOSITY
    // Measure the error after correction.
    for (uint8_t i = 0; i < npts; ++i) {
        float x = vec_x[0] * measured_pts[i * 2] + vec_y[0] * measured_pts[i * 2 + 1] + cntr[0];
        float y = vec_x[1] * measured_pts[i * 2] + vec_y[1] * measured_pts[i * 2 + 1] + cntr[1];
        float errX = pgm_read_float(true_pts + i * 2) - x;
        float errY = pgm_read_float(true_pts + i * 2 + 1) - y;
        float err = hypot(errX, errY);
		#ifdef SUPPORT_VERBOSITY
		if (verbosity_level >= 10) {
			SERIAL_ECHOPGM("point #");
			MYSERIAL.print(int(i));
			SERIAL_ECHOLNPGM(":");
		}
		#endif // SUPPORT_VERBOSITY

		if (point_on_1st_row(i)) {
				#ifdef SUPPORT_VERBOSITY
				if(verbosity_level >= 20) SERIAL_ECHOPGM("Point on first row");
				#endif // SUPPORT_VERBOSITY
				float w = point_weight_y(i, measured_pts[2 * i + 1]);
				if (errX > BED_CALIBRATION_POINT_OFFSET_MAX_1ST_ROW_X ||
					(w != 0.f && errY > BED_CALIBRATION_POINT_OFFSET_MAX_1ST_ROW_Y)) {
					result = BED_SKEW_OFFSET_DETECTION_FITTING_FAILED;
					#ifdef SUPPORT_VERBOSITY
					if (verbosity_level >= 20) {
						SERIAL_ECHOPGM(", weigth Y: ");
						MYSERIAL.print(w);
						if (errX > BED_CALIBRATION_POINT_OFFSET_MAX_1ST_ROW_X) SERIAL_ECHOPGM(", error X > max. error X");
						if (w != 0.f && errY > BED_CALIBRATION_POINT_OFFSET_MAX_1ST_ROW_Y) SERIAL_ECHOPGM(", error Y > max. error Y");
					}
					#endif // SUPPORT_VERBOSITY
				}
		}
		else {
			#ifdef SUPPORT_VERBOSITY
			if(verbosity_level >=20 ) SERIAL_ECHOPGM("Point not on first row");
			#endif // SUPPORT_VERBOSITY
			if (err > BED_CALIBRATION_POINT_OFFSET_MAX_EUCLIDIAN) {
				result = BED_SKEW_OFFSET_DETECTION_FITTING_FAILED;
				#ifdef SUPPORT_VERBOSITY
				if(verbosity_level >= 20) SERIAL_ECHOPGM(", error > max. error euclidian"); 
				#endif // SUPPORT_VERBOSITY
			}
        }
		#ifdef SUPPORT_VERBOSITY
        if (verbosity_level >= 10) {
			SERIAL_ECHOLNPGM("");
            SERIAL_ECHOPGM("measured: (");
            MYSERIAL.print(measured_pts[i * 2], 5);
            SERIAL_ECHOPGM(", ");
            MYSERIAL.print(measured_pts[i * 2 + 1], 5);
            SERIAL_ECHOPGM("); corrected: (");
            MYSERIAL.print(x, 5);
            SERIAL_ECHOPGM(", ");
            MYSERIAL.print(y, 5);
            SERIAL_ECHOPGM("); target: (");
            MYSERIAL.print(pgm_read_float(true_pts + i * 2), 5);
            SERIAL_ECHOPGM(", ");
            MYSERIAL.print(pgm_read_float(true_pts + i * 2 + 1), 5);
			SERIAL_ECHOLNPGM(")");
			SERIAL_ECHOPGM("error: ");
            MYSERIAL.print(err);
			SERIAL_ECHOPGM(", error X: ");
			MYSERIAL.print(errX);
			SERIAL_ECHOPGM(", error Y: ");
			MYSERIAL.print(errY);
			SERIAL_ECHOLNPGM("");
			SERIAL_ECHOLNPGM("");
        }
		#endif // SUPPORT_VERBOSITY
    }
	#ifdef SUPPORT_VERBOSITY
	if (verbosity_level >= 20) {
		SERIAL_ECHOLNPGM("Max. errors:");
		SERIAL_ECHOPGM("Max. error X:");
		MYSERIAL.println(BED_CALIBRATION_POINT_OFFSET_MAX_1ST_ROW_X);
		SERIAL_ECHOPGM("Max. error Y:");
		MYSERIAL.println(BED_CALIBRATION_POINT_OFFSET_MAX_1ST_ROW_Y);
		SERIAL_ECHOPGM("Max. error euclidian:");
		MYSERIAL.println(BED_CALIBRATION_POINT_OFFSET_MAX_EUCLIDIAN);
		SERIAL_ECHOLNPGM("");
	}
	#endif // SUPPORT_VERBOSITY

    #if 0
    if (result == BED_SKEW_OFFSET_DETECTION_PERFECT && fabs(a1) < bed_skew_angle_mild && fabs(a2) < bed_skew_angle_mild) {
		#ifdef SUPPORT_VERBOSITY
		if (verbosity_level > 0)
            SERIAL_ECHOLNPGM("Very little skew detected. Disabling skew correction.");
		#endif // SUPPORT_VERBOSITY
        // Just disable the skew correction.
        vec_x[0] = MACHINE_AXIS_SCALE_X;
        vec_x[1] = 0.f;
        vec_y[0] = 0.f;
        vec_y[1] = MACHINE_AXIS_SCALE_Y;
    }
    #else
    if (result == BED_SKEW_OFFSET_DETECTION_PERFECT) {
		#ifdef SUPPORT_VERBOSITY
		if (verbosity_level > 0)
            SERIAL_ECHOLNPGM("Very little skew detected. Orthogonalizing the axes.");
		#endif // SUPPORT_VERBOSITY
		// Orthogonalize the axes.
        a1 = 0.5f * (a1 + a2);
        vec_x[0] =  cos(a1) * MACHINE_AXIS_SCALE_X;
        vec_x[1] =  sin(a1) * MACHINE_AXIS_SCALE_X;
        vec_y[0] = -sin(a1) * MACHINE_AXIS_SCALE_Y;
        vec_y[1] =  cos(a1) * MACHINE_AXIS_SCALE_Y;
        // Refresh the offset.
        cntr[0] = 0.f;
        cntr[1] = 0.f;
        float wx = 0.f;
        float wy = 0.f;
        for (int8_t i = 0; i < npts; ++ i) {
            float x = vec_x[0] * measured_pts[i * 2] + vec_y[0] * measured_pts[i * 2 + 1];
            float y = vec_x[1] * measured_pts[i * 2] + vec_y[1] * measured_pts[i * 2 + 1];
            float w = point_weight_x(i, y);
			cntr[0] += w * (pgm_read_float(true_pts + i * 2) - x);
			wx += w;
			#ifdef SUPPORT_VERBOSITY
			if (verbosity_level >= 20) {
				MYSERIAL.print(i);
				SERIAL_ECHOLNPGM("");
				SERIAL_ECHOLNPGM("Weight_x:");
				MYSERIAL.print(w);
				SERIAL_ECHOLNPGM("");
				SERIAL_ECHOLNPGM("cntr[0]:");
				MYSERIAL.print(cntr[0]);
				SERIAL_ECHOLNPGM("");
				SERIAL_ECHOLNPGM("wx:");
				MYSERIAL.print(wx);
			}
			#endif // SUPPORT_VERBOSITY
            w = point_weight_y(i, y);
			cntr[1] += w * (pgm_read_float(true_pts + i * 2 + 1) - y);
			wy += w;
			#ifdef SUPPORT_VERBOSITY
			if (verbosity_level >= 20) {
				SERIAL_ECHOLNPGM("");
				SERIAL_ECHOLNPGM("Weight_y:");
				MYSERIAL.print(w);
				SERIAL_ECHOLNPGM("");
				SERIAL_ECHOLNPGM("cntr[1]:");
				MYSERIAL.print(cntr[1]);
				SERIAL_ECHOLNPGM("");
				SERIAL_ECHOLNPGM("wy:");
				MYSERIAL.print(wy);
				SERIAL_ECHOLNPGM("");
				SERIAL_ECHOLNPGM("");
			}
			#endif // SUPPORT_VERBOSITY

		}
        cntr[0] /= wx;
        cntr[1] /= wy;
		#ifdef SUPPORT_VERBOSITY
		if (verbosity_level >= 20) {
			SERIAL_ECHOLNPGM("");
			SERIAL_ECHOLNPGM("Final cntr values:");
			SERIAL_ECHOLNPGM("cntr[0]:");
			MYSERIAL.print(cntr[0]);
			SERIAL_ECHOLNPGM("");
			SERIAL_ECHOLNPGM("cntr[1]:");
			MYSERIAL.print(cntr[1]);
			SERIAL_ECHOLNPGM("");
		}
		#endif // SUPPORT_VERBOSITY
    }
    #endif

    // Invert the transformation matrix made of vec_x, vec_y and cntr.
    {
        float d = vec_x[0] * vec_y[1] - vec_x[1] * vec_y[0];
        float Ainv[2][2] = {
            { vec_y[1] / d, -vec_y[0] / d },
            { -vec_x[1] / d, vec_x[0] / d }
        };
        float cntrInv[2] = {
            -Ainv[0][0] * cntr[0] - Ainv[0][1] * cntr[1],
            -Ainv[1][0] * cntr[0] - Ainv[1][1] * cntr[1]
        };
        vec_x[0] = Ainv[0][0];
        vec_x[1] = Ainv[1][0];
        vec_y[0] = Ainv[0][1];
        vec_y[1] = Ainv[1][1];
        cntr[0] = cntrInv[0];
        cntr[1] = cntrInv[1];
    }
	#ifdef SUPPORT_VERBOSITY
    if (verbosity_level >= 1) {
        // Show the adjusted state, before the fitting.
        SERIAL_ECHOPGM("X vector, adjusted: ");
        MYSERIAL.print(vec_x[0], 5);
        SERIAL_ECHOPGM(", ");
        MYSERIAL.print(vec_x[1], 5);
        SERIAL_ECHOLNPGM("");

        SERIAL_ECHOPGM("Y vector, adjusted: ");
        MYSERIAL.print(vec_y[0], 5);
        SERIAL_ECHOPGM(", ");
        MYSERIAL.print(vec_y[1], 5);
        SERIAL_ECHOLNPGM("");

        SERIAL_ECHOPGM("center, adjusted: ");
        MYSERIAL.print(cntr[0], 5);
        SERIAL_ECHOPGM(", ");
        MYSERIAL.print(cntr[1], 5);
        SERIAL_ECHOLNPGM("");
        delay_keep_alive(100);
    }

    if (verbosity_level >= 2) {
        SERIAL_ECHOLNPGM("Difference after correction: ");
        for (uint8_t i = 0; i < npts; ++i) {
            float x = vec_x[0] * pgm_read_float(true_pts + i * 2) + vec_y[0] * pgm_read_float(true_pts + i * 2 + 1) + cntr[0];
            float y = vec_x[1] * pgm_read_float(true_pts + i * 2) + vec_y[1] * pgm_read_float(true_pts + i * 2 + 1) + cntr[1];
            SERIAL_ECHOPGM("point #");
            MYSERIAL.print(int(i));
            SERIAL_ECHOPGM("measured: (");
            MYSERIAL.print(measured_pts[i * 2], 5);
            SERIAL_ECHOPGM(", ");
            MYSERIAL.print(measured_pts[i * 2 + 1], 5);
            SERIAL_ECHOPGM("); measured-corrected: (");
            MYSERIAL.print(x, 5);
            SERIAL_ECHOPGM(", ");
            MYSERIAL.print(y, 5);
            SERIAL_ECHOPGM("); target: (");
            MYSERIAL.print(pgm_read_float(true_pts + i * 2), 5);
            SERIAL_ECHOPGM(", ");
            MYSERIAL.print(pgm_read_float(true_pts + i * 2 + 1), 5);
            SERIAL_ECHOPGM("), error: ");
            MYSERIAL.print( hypot(measured_pts[i * 2] - x, measured_pts[i * 2 + 1] - y) );
            SERIAL_ECHOLNPGM("");
        }
		if (verbosity_level >= 20) {
			SERIAL_ECHOLNPGM("");
			SERIAL_ECHOLNPGM("Calculate offset and skew returning result:");
			MYSERIAL.print(int(result));
			SERIAL_ECHOLNPGM("");
			SERIAL_ECHOLNPGM("");
		}
        delay_keep_alive(100);
    }
	#endif // SUPPORT_VERBOSITY


    return result;
}

/**
 * @brief Erase calibration data stored in EEPROM
 */
void reset_bed_offset_and_skew()
{
    eeprom_update_dword((uint32_t*)(EEPROM_BED_CALIBRATION_CENTER+0), 0x0FFFFFFFF);
    eeprom_update_dword((uint32_t*)(EEPROM_BED_CALIBRATION_CENTER+4), 0x0FFFFFFFF);
    eeprom_update_dword((uint32_t*)(EEPROM_BED_CALIBRATION_VEC_X +0), 0x0FFFFFFFF);
    eeprom_update_dword((uint32_t*)(EEPROM_BED_CALIBRATION_VEC_X +4), 0x0FFFFFFFF);
    eeprom_update_dword((uint32_t*)(EEPROM_BED_CALIBRATION_VEC_Y +0), 0x0FFFFFFFF);
    eeprom_update_dword((uint32_t*)(EEPROM_BED_CALIBRATION_VEC_Y +4), 0x0FFFFFFFF);

    // Reset the 8 16bit offsets.
    for (int8_t i = 0; i < 4; ++ i)
        eeprom_update_dword((uint32_t*)(EEPROM_BED_CALIBRATION_Z_JITTER+i*4), 0x0FFFFFFFF);
}

bool is_bed_z_jitter_data_valid()
// offsets of the Z heiths of the calibration points from the first point are saved as 16bit signed int, scaled to tenths of microns
// if at least one 16bit integer has different value then -1 (0x0FFFF), data are considered valid and function returns true, otherwise it returns false
{	
	bool data_valid = false;
	for (int8_t i = 0; i < 8; ++i) {
		if (eeprom_read_word((uint16_t*)(EEPROM_BED_CALIBRATION_Z_JITTER + i * 2)) != 0x0FFFF) data_valid = true;
	}
    return data_valid;
}

static void world2machine_update(const float vec_x[2], const float vec_y[2], const float cntr[2])
{
    world2machine_rotation_and_skew[0][0] = vec_x[0];
    world2machine_rotation_and_skew[1][0] = vec_x[1];
    world2machine_rotation_and_skew[0][1] = vec_y[0];
    world2machine_rotation_and_skew[1][1] = vec_y[1];
    world2machine_shift[0] = cntr[0];
    world2machine_shift[1] = cntr[1];
    // No correction.
    world2machine_correction_mode = WORLD2MACHINE_CORRECTION_NONE;
    if (world2machine_shift[0] != 0.f || world2machine_shift[1] != 0.f)
        // Shift correction.
        world2machine_correction_mode |= WORLD2MACHINE_CORRECTION_SHIFT;
    if (world2machine_rotation_and_skew[0][0] != 1.f || world2machine_rotation_and_skew[0][1] != 0.f ||
        world2machine_rotation_and_skew[1][0] != 0.f || world2machine_rotation_and_skew[1][1] != 1.f) {
        // Rotation & skew correction.
        world2machine_correction_mode |= WORLD2MACHINE_CORRECTION_SKEW;
        // Invert the world2machine matrix.
        float d = world2machine_rotation_and_skew[0][0] * world2machine_rotation_and_skew[1][1] - world2machine_rotation_and_skew[1][0] * world2machine_rotation_and_skew[0][1];
        world2machine_rotation_and_skew_inv[0][0] =  world2machine_rotation_and_skew[1][1] / d;
        world2machine_rotation_and_skew_inv[0][1] = -world2machine_rotation_and_skew[0][1] / d;
        world2machine_rotation_and_skew_inv[1][0] = -world2machine_rotation_and_skew[1][0] / d;
        world2machine_rotation_and_skew_inv[1][1] =  world2machine_rotation_and_skew[0][0] / d;
    } else {
        world2machine_rotation_and_skew_inv[0][0] = 1.f;
        world2machine_rotation_and_skew_inv[0][1] = 0.f;
        world2machine_rotation_and_skew_inv[1][0] = 0.f;
        world2machine_rotation_and_skew_inv[1][1] = 1.f;
    }
}

/**
 * @brief Set calibration matrix to identity
 *
 * In contrast with world2machine_revert_to_uncorrected(), it doesn't wait for finishing moves
 * nor updates the current position with the absolute values.
 */
void world2machine_reset()
{
    const float vx[] = { 1.f, 0.f };
    const float vy[] = { 0.f, 1.f };
    const float cntr[] = { 0.f, 0.f };
    world2machine_update(vx, vy, cntr);
}

/**
 * @brief Get calibration matrix default value
 *
 * This is used if no valid calibration data can be read from EEPROM.
 * @param [out] vec_x axis x vector
 * @param [out] vec_y axis y vector
 * @param [out] cntr offset vector
 */
static void world2machine_default(float vec_x[2], float vec_y[2], float cntr[2])
{
    vec_x[0] = 1.f;
    vec_x[1] = 0.f;
    vec_y[0] = 0.f;
    vec_y[1] = 1.f;
    cntr[0] =  0.f;
#ifdef DEFAULT_Y_OFFSET
    cntr[1] = DEFAULT_Y_OFFSET;
#else
    cntr[1] = 0.f;
#endif
}
/**
 * @brief Set calibration matrix to identity and update current position with absolute position
 *
 * Wait for the motors to stop and then update the current position with the absolute values.
 */
void world2machine_revert_to_uncorrected()
{
    if (world2machine_correction_mode != WORLD2MACHINE_CORRECTION_NONE) {
        world2machine_reset();
        st_synchronize();
        current_position[X_AXIS] = st_get_position_mm(X_AXIS);
        current_position[Y_AXIS] = st_get_position_mm(Y_AXIS);
    }
}

static inline bool vec_undef(const float v[2])
{
    const uint32_t *vx = (const uint32_t*)v;
    return vx[0] == 0x0FFFFFFFF || vx[1] == 0x0FFFFFFFF;
}


/**
 * @brief Read calibration data from EEPROM
 *
 * If no calibration data has been stored in EEPROM or invalid,
 * world2machine_default() is used.
 *
 * If stored calibration data is invalid, EEPROM storage is cleared.
 * @param [out] vec_x axis x vector
 * @param [out] vec_y axis y vector
 * @param [out] cntr offset vector
 */
void world2machine_read_valid(float vec_x[2], float vec_y[2], float cntr[2])
{
    vec_x[0] = eeprom_read_float((float*)(EEPROM_BED_CALIBRATION_VEC_X +0));
    vec_x[1] = eeprom_read_float((float*)(EEPROM_BED_CALIBRATION_VEC_X +4));
    vec_y[0] = eeprom_read_float((float*)(EEPROM_BED_CALIBRATION_VEC_Y +0));
    vec_y[1] = eeprom_read_float((float*)(EEPROM_BED_CALIBRATION_VEC_Y +4));
    cntr[0] = eeprom_read_float((float*)(EEPROM_BED_CALIBRATION_CENTER+0));
    cntr[1] = eeprom_read_float((float*)(EEPROM_BED_CALIBRATION_CENTER+4));

    bool reset = false;
    if (vec_undef(cntr) || vec_undef(vec_x) || vec_undef(vec_y))
    {
#if 0
        SERIAL_ECHOLNPGM("Undefined bed correction matrix.");
#endif
        reset = true;
    }
    else
    {
        // Length of the vec_x shall be close to unity.
        float l = hypot(vec_x[0], vec_x[1]);
        if (l < 0.9 || l > 1.1)
        {
#if 0
            SERIAL_ECHOLNPGM("X vector length:");
            MYSERIAL.println(l);
            SERIAL_ECHOLNPGM("Invalid bed correction matrix. Length of the X vector out of range.");
#endif
            reset = true;
        }
        // Length of the vec_y shall be close to unity.
        l = hypot(vec_y[0], vec_y[1]);
        if (l < 0.9 || l > 1.1)
        {
#if 0
            SERIAL_ECHOLNPGM("Y vector length:");
            MYSERIAL.println(l);
            SERIAL_ECHOLNPGM("Invalid bed correction matrix. Length of the Y vector out of range.");
#endif
            reset = true;
        }
        // Correction of the zero point shall be reasonably small.
        l = hypot(cntr[0], cntr[1]);
        if (l > 15.f)
        {
#if 0
            SERIAL_ECHOLNPGM("Zero point correction:");
            MYSERIAL.println(l);
            SERIAL_ECHOLNPGM("Invalid bed correction matrix. Shift out of range.");
#endif
            reset = true;
        }
        // vec_x and vec_y shall be nearly perpendicular.
        l = vec_x[0] * vec_y[0] + vec_x[1] * vec_y[1];
        if (fabs(l) > 0.1f)
        {
#if 0
            SERIAL_ECHOLNPGM("Invalid bed correction matrix. X/Y axes are far from being perpendicular.");
#endif
            reset = true;
        }
    }

    if (reset)
    {
#if 0
        SERIAL_ECHOLNPGM("Invalid bed correction matrix. Resetting to identity.");
#endif
        reset_bed_offset_and_skew();
        world2machine_default(vec_x, vec_y, cntr);
    }
}

/**
 * @brief Read and apply validated calibration data from EEPROM
 */
void world2machine_initialize()
{
#if 0
    SERIAL_ECHOLNPGM("world2machine_initialize");
#endif
    float vec_x[2];
    float vec_y[2];
    float cntr[2];
    world2machine_read_valid(vec_x, vec_y, cntr);
    world2machine_update(vec_x, vec_y, cntr);
#if 0
    SERIAL_ECHOPGM("world2machine_initialize() loaded: ");
    MYSERIAL.print(world2machine_rotation_and_skew[0][0], 5);
    SERIAL_ECHOPGM(", ");
    MYSERIAL.print(world2machine_rotation_and_skew[0][1], 5);
    SERIAL_ECHOPGM(", ");
    MYSERIAL.print(world2machine_rotation_and_skew[1][0], 5);
    SERIAL_ECHOPGM(", ");
    MYSERIAL.print(world2machine_rotation_and_skew[1][1], 5);
    SERIAL_ECHOPGM(", offset ");
    MYSERIAL.print(world2machine_shift[0], 5);
    SERIAL_ECHOPGM(", ");
    MYSERIAL.print(world2machine_shift[1], 5);
    SERIAL_ECHOLNPGM("");
#endif
}

/**
 * @brief Update current position after switching to corrected coordinates
 *
 * When switching from absolute to corrected coordinates,
 * this will get the absolute coordinates from the servos,
 * applies the inverse world2machine transformation
 * and stores the result into current_position[x,y].
 */
void world2machine_update_current()
{
    float x = current_position[X_AXIS] - world2machine_shift[0];
    float y = current_position[Y_AXIS] - world2machine_shift[1];
    current_position[X_AXIS] = world2machine_rotation_and_skew_inv[0][0] * x + world2machine_rotation_and_skew_inv[0][1] * y;
    current_position[Y_AXIS] = world2machine_rotation_and_skew_inv[1][0] * x + world2machine_rotation_and_skew_inv[1][1] * y;
}

static inline void go_xyz(float x, float y, float z, float fr)
{
    plan_buffer_line(x, y, z, current_position[E_AXIS], fr);
    st_synchronize();
}

static inline void go_xy(float x, float y, float fr)
{
    plan_buffer_line(x, y, current_position[Z_AXIS], current_position[E_AXIS], fr);
    st_synchronize();
}

static inline void go_to_current(float fr)
{
    plan_buffer_line_curposXYZE(fr);
    st_synchronize();
}

static inline void update_current_position_xyz()
{
      current_position[X_AXIS] = st_get_position_mm(X_AXIS);
      current_position[Y_AXIS] = st_get_position_mm(Y_AXIS);
      current_position[Z_AXIS] = st_get_position_mm(Z_AXIS);
      plan_set_position_curposXYZE();
}

static inline void update_current_position_z()
{
      current_position[Z_AXIS] = st_get_position_mm(Z_AXIS);
      plan_set_z_position(current_position[Z_AXIS]);
}

// At the current position, find the Z stop.

bool find_bed_induction_sensor_point_z(float minimum_z, uint8_t n_iter, int
#ifdef SUPPORT_VERBOSITY
    verbosity_level
#endif //SUPPORT_VERBOSITY
        )
{
	bool high_deviation_occured = false; 
    bedPWMDisabled = 1;
#ifdef TMC2130
	FORCE_HIGH_POWER_START;
#endif
	//printf_P(PSTR("Min. Z: %f\n"), minimum_z);
	#ifdef SUPPORT_VERBOSITY
    if(verbosity_level >= 10) SERIAL_ECHOLNPGM("find bed induction sensor point z");
	#endif // SUPPORT_VERBOSITY
	bool endstops_enabled  = enable_endstops(true);
    bool endstop_z_enabled = enable_z_endstop(false);
    float z = 0.f;
    endstop_z_hit_on_purpose();

    // move down until you find the bed
    current_position[Z_AXIS] = minimum_z;
    go_to_current(homing_feedrate[Z_AXIS]/60);
    // we have to let the planner know where we are right now as it is not where we said to go.
    update_current_position_z();
    if (! endstop_z_hit_on_purpose())
	{
		//printf_P(PSTR("endstop not hit 1, current_pos[Z]: %f \n"), current_position[Z_AXIS]);
		goto error;
	}
#ifdef TMC2130
	if (!READ(Z_TMC2130_DIAG))
	{
		//printf_P(PSTR("crash detected 1, current_pos[Z]: %f \n"), current_position[Z_AXIS]);
		goto error; //crash Z detected
	}
#endif //TMC2130
    for (uint8_t i = 0; i < n_iter; ++ i)
	{
		
		current_position[Z_AXIS] += high_deviation_occured ? 0.5 : 0.2;
		float z_bckp = current_position[Z_AXIS];
		go_to_current(homing_feedrate[Z_AXIS]/60);
		// Move back down slowly to find bed.
        current_position[Z_AXIS] = minimum_z;
		//printf_P(PSTR("init Z = %f, min_z = %f, i = %d\n"), z_bckp, minimum_z, i);
        go_to_current(homing_feedrate[Z_AXIS]/(4*60));
        // we have to let the planner know where we are right now as it is not where we said to go.
        update_current_position_z();
		//printf_P(PSTR("Zs: %f, Z: %f, delta Z: %f"), z_bckp, current_position[Z_AXIS], (z_bckp - current_position[Z_AXIS]));
		if (fabs(current_position[Z_AXIS] - z_bckp) < 0.025) {
			//printf_P(PSTR("PINDA triggered immediately, move Z higher and repeat measurement\n")); 
			raise_z(0.5);
			current_position[Z_AXIS] = minimum_z;
            go_to_current(homing_feedrate[Z_AXIS]/(4*60));
            // we have to let the planner know where we are right now as it is not where we said to go.
			update_current_position_z();
		}



		if (!endstop_z_hit_on_purpose())
		{
			//printf_P(PSTR("i = %d, endstop not hit 2, current_pos[Z]: %f \n"), i, current_position[Z_AXIS]);
			goto error;
		}
#ifdef TMC2130
		if (!READ(Z_TMC2130_DIAG)) {
			//printf_P(PSTR("crash detected 2, current_pos[Z]: %f \n"), current_position[Z_AXIS]);
			goto error; //crash Z detected
		}
#endif //TMC2130
//        SERIAL_ECHOPGM("Bed find_bed_induction_sensor_point_z low, height: ");
//        MYSERIAL.print(current_position[Z_AXIS], 5);
//        SERIAL_ECHOLNPGM("");
		float dz = i?fabs(current_position[Z_AXIS] - (z / i)):0;
        z += current_position[Z_AXIS];
		//printf_P(PSTR("Z[%d] = %d, dz=%d\n"), i, (int)(current_position[Z_AXIS] * 1000), (int)(dz * 1000));
		//printf_P(PSTR("Z- measurement deviation from avg value %f um\n"), dz);
		if (dz > 0.05) { //deviation > 50um
			if (high_deviation_occured == false) { //first occurence may be caused in some cases by mechanic resonance probably especially if printer is placed on unstable surface 
				//printf_P(PSTR("high dev. first occurence\n"));
				delay_keep_alive(500); //damping
				//start measurement from the begining, but this time with higher movements in Z axis which should help to reduce mechanical resonance
				high_deviation_occured = true;
				i = -1; 
				z = 0;
			}
			else {
				goto error;
			}
		}
		//printf_P(PSTR("PINDA triggered at %f\n"), current_position[Z_AXIS]);
    }
    current_position[Z_AXIS] = z;
    if (n_iter > 1)
        current_position[Z_AXIS] /= float(n_iter);


    enable_endstops(endstops_enabled);
    enable_z_endstop(endstop_z_enabled);
//    SERIAL_ECHOLNPGM("find_bed_induction_sensor_point_z 3");
#ifdef TMC2130
	FORCE_HIGH_POWER_END;
#endif
    bedPWMDisabled = 0;
	return true;

error:
//    SERIAL_ECHOLNPGM("find_bed_induction_sensor_point_z 4");
    enable_endstops(endstops_enabled);
    enable_z_endstop(endstop_z_enabled);
#ifdef TMC2130
	FORCE_HIGH_POWER_END;
#endif
    bedPWMDisabled = 0;
	return false;
}

#ifdef NEW_XYZCAL
BedSkewOffsetDetectionResultType xyzcal_find_bed_induction_sensor_point_xy();
#endif //NEW_XYZCAL
// Search around the current_position[X,Y],
// look for the induction sensor response.
// Adjust the  current_position[X,Y,Z] to the center of the target dot and its response Z coordinate.
#define FIND_BED_INDUCTION_SENSOR_POINT_X_RADIUS (8.f)
#define FIND_BED_INDUCTION_SENSOR_POINT_Y_RADIUS (4.f)
#define FIND_BED_INDUCTION_SENSOR_POINT_XY_STEP  (1.f)
#ifdef HEATBED_V2
#define FIND_BED_INDUCTION_SENSOR_POINT_Z_STEP   (2.f)
#define FIND_BED_INDUCTION_SENSOR_POINT_MAX_Z_ERROR  (0.03f)
#else //HEATBED_V2
#define FIND_BED_INDUCTION_SENSOR_POINT_Z_STEP   (0.2f)
#endif //HEATBED_V2

#ifdef HEATBED_V2
BedSkewOffsetDetectionResultType find_bed_induction_sensor_point_xy(int
#if !defined (NEW_XYZCAL) && defined (SUPPORT_VERBOSITY)
        verbosity_level
#endif
        )
{
#ifdef NEW_XYZCAL
	return xyzcal_find_bed_induction_sensor_point_xy();
#else //NEW_XYZCAL
	#ifdef SUPPORT_VERBOSITY
	if (verbosity_level >= 10) MYSERIAL.println("find bed induction sensor point xy");
	#endif // SUPPORT_VERBOSITY
	float feedrate = homing_feedrate[X_AXIS] / 60.f;
	bool found = false;

	{
		float x0 = current_position[X_AXIS] - FIND_BED_INDUCTION_SENSOR_POINT_X_RADIUS;
		float x1 = current_position[X_AXIS] + FIND_BED_INDUCTION_SENSOR_POINT_X_RADIUS;
		float y0 = current_position[Y_AXIS] - FIND_BED_INDUCTION_SENSOR_POINT_Y_RADIUS;
		float y1 = current_position[Y_AXIS] + FIND_BED_INDUCTION_SENSOR_POINT_Y_RADIUS;
		uint8_t nsteps_y;
		uint8_t i;
		if (x0 < X_MIN_POS) {
			x0 = X_MIN_POS;
			#ifdef SUPPORT_VERBOSITY
			if (verbosity_level >= 20) SERIAL_ECHOLNPGM("X searching radius lower than X_MIN. Clamping was done.");
			#endif // SUPPORT_VERBOSITY
		}
		if (x1 > X_MAX_POS) {
			x1 = X_MAX_POS;
			#ifdef SUPPORT_VERBOSITY
			if (verbosity_level >= 20) SERIAL_ECHOLNPGM("X searching radius higher than X_MAX. Clamping was done.");
			#endif // SUPPORT_VERBOSITY
		}
		if (y0 < Y_MIN_POS_FOR_BED_CALIBRATION) {
			y0 = Y_MIN_POS_FOR_BED_CALIBRATION;
			#ifdef SUPPORT_VERBOSITY
			if (verbosity_level >= 20) SERIAL_ECHOLNPGM("Y searching radius lower than Y_MIN. Clamping was done.");
			#endif // SUPPORT_VERBOSITY
		}
		if (y1 > Y_MAX_POS) {
			y1 = Y_MAX_POS;
			#ifdef SUPPORT_VERBOSITY
			if (verbosity_level >= 20) SERIAL_ECHOLNPGM("Y searching radius higher than X_MAX. Clamping was done.");
			#endif // SUPPORT_VERBOSITY
		}
		nsteps_y = int(ceil((y1 - y0) / FIND_BED_INDUCTION_SENSOR_POINT_XY_STEP));

		enable_endstops(false);
		bool  dir_positive = true;
		float z_error = 2 * FIND_BED_INDUCTION_SENSOR_POINT_Z_STEP;
		float find_bed_induction_sensor_point_z_step = FIND_BED_INDUCTION_SENSOR_POINT_Z_STEP;
		float initial_z_position = current_position[Z_AXIS];

		//        go_xyz(current_position[X_AXIS], current_position[Y_AXIS], MESH_HOME_Z_SEARCH, homing_feedrate[Z_AXIS]/60);
		go_xyz(x0, y0, current_position[Z_AXIS], feedrate);
		// Continuously lower the Z axis.
		endstops_hit_on_purpose();
		enable_z_endstop(true);
		bool direction = false;
		while (current_position[Z_AXIS] > -10.f && z_error > FIND_BED_INDUCTION_SENSOR_POINT_MAX_Z_ERROR) {
			// Do nsteps_y zig-zag movements.

			SERIAL_ECHOPGM("z_error: ");
			MYSERIAL.println(z_error);
			current_position[Y_AXIS] = direction ? y1 : y0;
			initial_z_position = current_position[Z_AXIS];
			for (i = 0; i < (nsteps_y - 1); (direction == false) ? (current_position[Y_AXIS] += (y1 - y0) / float(nsteps_y - 1)) : (current_position[Y_AXIS] -= (y1 - y0) / float(nsteps_y - 1)), ++i) {
				// Run with a slightly decreasing Z axis, zig-zag movement. Stop at the Z end-stop.
				current_position[Z_AXIS] -= find_bed_induction_sensor_point_z_step / float(nsteps_y - 1);
				go_xyz(dir_positive ? x1 : x0, current_position[Y_AXIS], current_position[Z_AXIS], feedrate);
				dir_positive = !dir_positive;
				if (endstop_z_hit_on_purpose()) {
					update_current_position_xyz();
					z_error = initial_z_position - current_position[Z_AXIS] + find_bed_induction_sensor_point_z_step;
					if (z_error > FIND_BED_INDUCTION_SENSOR_POINT_MAX_Z_ERROR) {
						find_bed_induction_sensor_point_z_step = z_error / 2;
						current_position[Z_AXIS] += z_error;
						enable_z_endstop(false);
						(direction == false) ? go_xyz(x0, y0, current_position[Z_AXIS], feedrate) : go_xyz(x0, y1, current_position[Z_AXIS], feedrate);
						enable_z_endstop(true);
					}
					goto endloop;
				}
			}
			for (i = 0; i < (nsteps_y - 1); (direction == false) ? (current_position[Y_AXIS] -= (y1 - y0) / float(nsteps_y - 1)) : (current_position[Y_AXIS] += (y1 - y0) / float(nsteps_y - 1)), ++i) {
				// Run with a slightly decreasing Z axis, zig-zag movement. Stop at the Z end-stop.
				current_position[Z_AXIS] -= find_bed_induction_sensor_point_z_step / float(nsteps_y - 1);
				go_xyz(dir_positive ? x1 : x0, current_position[Y_AXIS], current_position[Z_AXIS], feedrate);
				dir_positive = !dir_positive;
				if (endstop_z_hit_on_purpose()) {
					update_current_position_xyz();
					z_error = initial_z_position - current_position[Z_AXIS];
					if (z_error > FIND_BED_INDUCTION_SENSOR_POINT_MAX_Z_ERROR) {
						find_bed_induction_sensor_point_z_step = z_error / 2;
						current_position[Z_AXIS] += z_error;
						enable_z_endstop(false);
						direction = !direction;
						(direction == false) ? go_xyz(x0, y0, current_position[Z_AXIS], feedrate) : go_xyz(x0, y1, current_position[Z_AXIS], feedrate);
						enable_z_endstop(true);
					}
					goto endloop;
				}
			}
		endloop:;
		}
		#ifdef SUPPORT_VERBOSITY
		if (verbosity_level >= 20) {
			SERIAL_ECHO("First hit");
			SERIAL_ECHO("- X: ");
			MYSERIAL.print(current_position[X_AXIS]);
			SERIAL_ECHO("; Y: ");
			MYSERIAL.print(current_position[Y_AXIS]);
			SERIAL_ECHO("; Z: ");
			MYSERIAL.println(current_position[Z_AXIS]);
		}
		#endif //SUPPORT_VERBOSITY
		//lcd_show_fullscreen_message_and_wait_P(PSTR("First hit"));
		//lcd_update_enable(true);

		float init_x_position = current_position[X_AXIS];
		float init_y_position = current_position[Y_AXIS];

		// we have to let the planner know where we are right now as it is not where we said to go.
		update_current_position_xyz();
		enable_z_endstop(false);
		
		for (int8_t iter = 0; iter < 2; ++iter) {
			/*SERIAL_ECHOPGM("iter: ");
			MYSERIAL.println(iter);
			SERIAL_ECHOPGM("1 - current_position[Z_AXIS]: ");
			MYSERIAL.println(current_position[Z_AXIS]);*/

			// Slightly lower the Z axis to get a reliable trigger.
			current_position[Z_AXIS] -= 0.1f;
			go_xyz(current_position[X_AXIS], current_position[Y_AXIS], current_position[Z_AXIS], homing_feedrate[Z_AXIS] / (60 * 10));

			SERIAL_ECHOPGM("2 - current_position[Z_AXIS]: ");
			MYSERIAL.println(current_position[Z_AXIS]);
			// Do nsteps_y zig-zag movements.
			float a, b;
			float avg[2] = { 0,0 };
			invert_z_endstop(true);
			for (int iteration = 0; iteration < 8; iteration++) {

				found = false;				
				enable_z_endstop(true);
				go_xy(init_x_position + 16.0f, current_position[Y_AXIS], feedrate / 5);
				update_current_position_xyz();
				if (!endstop_z_hit_on_purpose()) {
					//                SERIAL_ECHOLN("Search X span 0 - not found");
					continue;
				}
				//            SERIAL_ECHOLN("Search X span 0 - found");
				a = current_position[X_AXIS];
				enable_z_endstop(false);
				go_xy(init_x_position, current_position[Y_AXIS], feedrate / 5);
				enable_z_endstop(true);
				go_xy(init_x_position - 16.0f, current_position[Y_AXIS], feedrate / 5);
				update_current_position_xyz();
				if (!endstop_z_hit_on_purpose()) {
					//                SERIAL_ECHOLN("Search X span 1 - not found");
					continue;
				}
				//            SERIAL_ECHOLN("Search X span 1 - found");
				b = current_position[X_AXIS];
				// Go to the center.
				enable_z_endstop(false);
				current_position[X_AXIS] = 0.5f * (a + b);
				go_xy(current_position[X_AXIS], init_y_position, feedrate / 5);
				found = true;
				
				// Search in the Y direction along a cross.
				found = false;
				enable_z_endstop(true);
				go_xy(current_position[X_AXIS], init_y_position + 16.0f, feedrate / 5);
				update_current_position_xyz();
				if (!endstop_z_hit_on_purpose()) {
					//                SERIAL_ECHOLN("Search Y2 span 0 - not found");
					continue;
				}
				//            SERIAL_ECHOLN("Search Y2 span 0 - found");
				a = current_position[Y_AXIS];
				enable_z_endstop(false);
				go_xy(current_position[X_AXIS], init_y_position, feedrate / 5);
				enable_z_endstop(true);
				go_xy(current_position[X_AXIS], init_y_position - 16.0f, feedrate / 5);
				update_current_position_xyz();
				if (!endstop_z_hit_on_purpose()) {
					//                SERIAL_ECHOLN("Search Y2 span 1 - not found");
					continue;
				}
				//            SERIAL_ECHOLN("Search Y2 span 1 - found");
				b = current_position[Y_AXIS];
				// Go to the center.
				enable_z_endstop(false);
				current_position[Y_AXIS] = 0.5f * (a + b);
				go_xy(current_position[X_AXIS], current_position[Y_AXIS], feedrate / 5);

				#ifdef SUPPORT_VERBOSITY
				if (verbosity_level >= 20) {
					SERIAL_ECHOPGM("ITERATION: ");
					MYSERIAL.println(iteration);
					SERIAL_ECHOPGM("CURRENT POSITION X: ");
					MYSERIAL.println(current_position[X_AXIS]);
					SERIAL_ECHOPGM("CURRENT POSITION Y: ");
					MYSERIAL.println(current_position[Y_AXIS]);
				}
				#endif //SUPPORT_VERBOSITY

				if (iteration > 0) {
					// Average the last 7 measurements.
					avg[X_AXIS] += current_position[X_AXIS];
					avg[Y_AXIS] += current_position[Y_AXIS];
				}

				init_x_position = current_position[X_AXIS];
				init_y_position = current_position[Y_AXIS];

				found = true;

			}
			invert_z_endstop(false);
			avg[X_AXIS] *= (1.f / 7.f);
			avg[Y_AXIS] *= (1.f / 7.f);

			current_position[X_AXIS] = avg[X_AXIS];
			current_position[Y_AXIS] = avg[Y_AXIS];
			#ifdef SUPPORT_VERBOSITY
			if (verbosity_level >= 20) {
				SERIAL_ECHOPGM("AVG CURRENT POSITION X: ");
				MYSERIAL.println(current_position[X_AXIS]);
				SERIAL_ECHOPGM("AVG CURRENT POSITION Y: ");
				MYSERIAL.println(current_position[Y_AXIS]);
			}
			#endif // SUPPORT_VERBOSITY
			go_xy(current_position[X_AXIS], current_position[Y_AXIS], feedrate);
			#ifdef SUPPORT_VERBOSITY
			if (verbosity_level >= 20) {
				lcd_show_fullscreen_message_and_wait_P(PSTR("Final position"));
				lcd_update_enable(true);
			}
			#endif //SUPPORT_VERBOSITY

			break;
		}
	}
	
	enable_z_endstop(false);
	invert_z_endstop(false);
	return found;
#endif //NEW_XYZCAL
}
#else //HEATBED_V2
BedSkewOffsetDetectionResultType find_bed_induction_sensor_point_xy(int verbosity_level)
{
#ifdef NEW_XYZCAL
	return xyzcal_find_bed_induction_sensor_point_xy();
#else //NEW_XYZCAL
	#ifdef SUPPORT_VERBOSITY
	if (verbosity_level >= 10) MYSERIAL.println("find bed induction sensor point xy");
	#endif // SUPPORT_VERBOSITY
	float feedrate = homing_feedrate[X_AXIS] / 60.f;
	bool found = false;

	{
		float x0 = current_position[X_AXIS] - FIND_BED_INDUCTION_SENSOR_POINT_X_RADIUS;
		float x1 = current_position[X_AXIS] + FIND_BED_INDUCTION_SENSOR_POINT_X_RADIUS;
		float y0 = current_position[Y_AXIS] - FIND_BED_INDUCTION_SENSOR_POINT_Y_RADIUS;
		float y1 = current_position[Y_AXIS] + FIND_BED_INDUCTION_SENSOR_POINT_Y_RADIUS;
		uint8_t nsteps_y;
		uint8_t i;
		if (x0 < X_MIN_POS) {
			x0 = X_MIN_POS;
			#ifdef SUPPORT_VERBOSITY
			if (verbosity_level >= 20) SERIAL_ECHOLNPGM("X searching radius lower than X_MIN. Clamping was done.");
			#endif // SUPPORT_VERBOSITY
		}
		if (x1 > X_MAX_POS) {
			x1 = X_MAX_POS;
			#ifdef SUPPORT_VERBOSITY
			if (verbosity_level >= 20) SERIAL_ECHOLNPGM("X searching radius higher than X_MAX. Clamping was done.");
			#endif // SUPPORT_VERBOSITY
		}
		if (y0 < Y_MIN_POS_FOR_BED_CALIBRATION) {
			y0 = Y_MIN_POS_FOR_BED_CALIBRATION;
			#ifdef SUPPORT_VERBOSITY
			if (verbosity_level >= 20) SERIAL_ECHOLNPGM("Y searching radius lower than Y_MIN. Clamping was done.");
			#endif // SUPPORT_VERBOSITY
		}
		if (y1 > Y_MAX_POS) {
			y1 = Y_MAX_POS;
			#ifdef SUPPORT_VERBOSITY
			if (verbosity_level >= 20) SERIAL_ECHOLNPGM("Y searching radius higher than X_MAX. Clamping was done.");
			#endif // SUPPORT_VERBOSITY
		}
		nsteps_y = int(ceil((y1 - y0) / FIND_BED_INDUCTION_SENSOR_POINT_XY_STEP));

		enable_endstops(false);
		bool  dir_positive = true;

		//        go_xyz(current_position[X_AXIS], current_position[Y_AXIS], MESH_HOME_Z_SEARCH, homing_feedrate[Z_AXIS]/60);
		go_xyz(x0, y0, current_position[Z_AXIS], feedrate);
		// Continuously lower the Z axis.
		endstops_hit_on_purpose();
		enable_z_endstop(true);
		while (current_position[Z_AXIS] > -10.f) {
			// Do nsteps_y zig-zag movements.
			current_position[Y_AXIS] = y0;
			for (i = 0; i < nsteps_y; current_position[Y_AXIS] += (y1 - y0) / float(nsteps_y - 1), ++i) {
				// Run with a slightly decreasing Z axis, zig-zag movement. Stop at the Z end-stop.
				current_position[Z_AXIS] -= FIND_BED_INDUCTION_SENSOR_POINT_Z_STEP / float(nsteps_y);
				go_xyz(dir_positive ? x1 : x0, current_position[Y_AXIS], current_position[Z_AXIS], feedrate);
				dir_positive = !dir_positive;
				if (endstop_z_hit_on_purpose())
					goto endloop;
			}
			for (i = 0; i < nsteps_y; current_position[Y_AXIS] -= (y1 - y0) / float(nsteps_y - 1), ++i) {
				// Run with a slightly decreasing Z axis, zig-zag movement. Stop at the Z end-stop.
				current_position[Z_AXIS] -= FIND_BED_INDUCTION_SENSOR_POINT_Z_STEP / float(nsteps_y);
				go_xyz(dir_positive ? x1 : x0, current_position[Y_AXIS], current_position[Z_AXIS], feedrate);
				dir_positive = !dir_positive;
				if (endstop_z_hit_on_purpose())
					goto endloop;
			}
		}
	endloop:
		//        SERIAL_ECHOLN("First hit");

		// we have to let the planner know where we are right now as it is not where we said to go.
		update_current_position_xyz();

		// Search in this plane for the first hit. Zig-zag first in X, then in Y axis.
		for (int8_t iter = 0; iter < 3; ++iter) {
			if (iter > 0) {
				// Slightly lower the Z axis to get a reliable trigger.
				current_position[Z_AXIS] -= 0.02f;
				go_xyz(current_position[X_AXIS], current_position[Y_AXIS], MESH_HOME_Z_SEARCH, homing_feedrate[Z_AXIS] / 60);
			}

			// Do nsteps_y zig-zag movements.
			float a, b;
			enable_endstops(false);
			enable_z_endstop(false);
			current_position[Y_AXIS] = y0;
			go_xy(x0, current_position[Y_AXIS], feedrate);
			enable_z_endstop(true);
			found = false;
			for (i = 0, dir_positive = true; i < nsteps_y; current_position[Y_AXIS] += (y1 - y0) / float(nsteps_y - 1), ++i, dir_positive = !dir_positive) {
				go_xy(dir_positive ? x1 : x0, current_position[Y_AXIS], feedrate);
				if (endstop_z_hit_on_purpose()) {
					found = true;
					break;
				}
			}
			update_current_position_xyz();
			if (!found) {
				//                SERIAL_ECHOLN("Search in Y - not found");
				continue;
			}
			//            SERIAL_ECHOLN("Search in Y - found");
			a = current_position[Y_AXIS];

			enable_z_endstop(false);
			current_position[Y_AXIS] = y1;
			go_xy(x0, current_position[Y_AXIS], feedrate);
			enable_z_endstop(true);
			found = false;
			for (i = 0, dir_positive = true; i < nsteps_y; current_position[Y_AXIS] -= (y1 - y0) / float(nsteps_y - 1), ++i, dir_positive = !dir_positive) {
				go_xy(dir_positive ? x1 : x0, current_position[Y_AXIS], feedrate);
				if (endstop_z_hit_on_purpose()) {
					found = true;
					break;
				}
			}
			update_current_position_xyz();
			if (!found) {
				//                SERIAL_ECHOLN("Search in Y2 - not found");
				continue;
			}
			//            SERIAL_ECHOLN("Search in Y2 - found");
			b = current_position[Y_AXIS];
			current_position[Y_AXIS] = 0.5f * (a + b);

			// Search in the X direction along a cross.
			found = false;
			enable_z_endstop(false);
			go_xy(x0, current_position[Y_AXIS], feedrate);
			enable_z_endstop(true);
			go_xy(x1, current_position[Y_AXIS], feedrate);
			update_current_position_xyz();
			if (!endstop_z_hit_on_purpose()) {
				//                SERIAL_ECHOLN("Search X span 0 - not found");
				continue;
			}
			//            SERIAL_ECHOLN("Search X span 0 - found");
			a = current_position[X_AXIS];
			enable_z_endstop(false);
			go_xy(x1, current_position[Y_AXIS], feedrate);
			enable_z_endstop(true);
			go_xy(x0, current_position[Y_AXIS], feedrate);
			update_current_position_xyz();
			if (!endstop_z_hit_on_purpose()) {
				//                SERIAL_ECHOLN("Search X span 1 - not found");
				continue;
			}
			//            SERIAL_ECHOLN("Search X span 1 - found");
			b = current_position[X_AXIS];
			// Go to the center.
			enable_z_endstop(false);
			current_position[X_AXIS] = 0.5f * (a + b);
			go_xy(current_position[X_AXIS], current_position[Y_AXIS], feedrate);
			found = true;

#if 1
			// Search in the Y direction along a cross.
			found = false;
			enable_z_endstop(false);
			go_xy(current_position[X_AXIS], y0, feedrate);
			enable_z_endstop(true);
			go_xy(current_position[X_AXIS], y1, feedrate);
			update_current_position_xyz();
			if (!endstop_z_hit_on_purpose()) {
				//                SERIAL_ECHOLN("Search Y2 span 0 - not found");
				continue;
			}
			//            SERIAL_ECHOLN("Search Y2 span 0 - found");
			a = current_position[Y_AXIS];
			enable_z_endstop(false);
			go_xy(current_position[X_AXIS], y1, feedrate);
			enable_z_endstop(true);
			go_xy(current_position[X_AXIS], y0, feedrate);
			update_current_position_xyz();
			if (!endstop_z_hit_on_purpose()) {
				//                SERIAL_ECHOLN("Search Y2 span 1 - not found");
				continue;
			}
			//            SERIAL_ECHOLN("Search Y2 span 1 - found");
			b = current_position[Y_AXIS];
			// Go to the center.
			enable_z_endstop(false);
			current_position[Y_AXIS] = 0.5f * (a + b);
			go_xy(current_position[X_AXIS], current_position[Y_AXIS], feedrate);
			found = true;
#endif
			break;
		}
	}

	enable_z_endstop(false);
    if (found)
        return BED_SKEW_OFFSET_DETECTION_POINT_FOUND;
    return BED_SKEW_OFFSET_DETECTION_POINT_NOT_FOUND;
#endif //NEW_XYZCAL
}

#endif //HEATBED_V2

#ifndef NEW_XYZCAL
// Search around the current_position[X,Y,Z].
// It is expected, that the induction sensor is switched on at the current position.
// Look around this center point by painting a star around the point.
inline bool improve_bed_induction_sensor_point()
{
    static const float search_radius = 8.f;

    bool  endstops_enabled  = enable_endstops(false);
    bool  endstop_z_enabled = enable_z_endstop(false);
    bool  found = false;
    float feedrate = homing_feedrate[X_AXIS] / 60.f;
    float center_old_x = current_position[X_AXIS];
    float center_old_y = current_position[Y_AXIS];
    float center_x = 0.f;
    float center_y = 0.f;

    for (uint8_t iter = 0; iter < 4; ++ iter) {
        switch (iter) {
        case 0:
            destination[X_AXIS] = center_old_x - search_radius * 0.707;
            destination[Y_AXIS] = center_old_y - search_radius * 0.707;
            break;
        case 1:
            destination[X_AXIS] = center_old_x + search_radius * 0.707;
            destination[Y_AXIS] = center_old_y + search_radius * 0.707;
            break;
        case 2:
            destination[X_AXIS] = center_old_x + search_radius * 0.707;
            destination[Y_AXIS] = center_old_y - search_radius * 0.707;
            break;
        case 3:
        default:
            destination[X_AXIS] = center_old_x - search_radius * 0.707;
            destination[Y_AXIS] = center_old_y + search_radius * 0.707;
            break;
        }

        // Trim the vector from center_old_[x,y] to destination[x,y] by the bed dimensions.
        float vx = destination[X_AXIS] - center_old_x;
        float vy = destination[Y_AXIS] - center_old_y;
        float l  = hypot(vx, vy);
        float t;
        if (destination[X_AXIS] < X_MIN_POS) {
            // Exiting the bed at xmin.
            t = (center_x - X_MIN_POS) / l;
            destination[X_AXIS] = X_MIN_POS;
            destination[Y_AXIS] = center_old_y + t * vy;
        } else if (destination[X_AXIS] > X_MAX_POS) {
            // Exiting the bed at xmax.
            t = (X_MAX_POS - center_x) / l;
            destination[X_AXIS] = X_MAX_POS;
            destination[Y_AXIS] = center_old_y + t * vy;
        }
        if (destination[Y_AXIS] < Y_MIN_POS_FOR_BED_CALIBRATION) {
            // Exiting the bed at ymin.
            t = (center_y - Y_MIN_POS_FOR_BED_CALIBRATION) / l;
            destination[X_AXIS] = center_old_x + t * vx;
            destination[Y_AXIS] = Y_MIN_POS_FOR_BED_CALIBRATION;
        } else if (destination[Y_AXIS] > Y_MAX_POS) {
            // Exiting the bed at xmax.
            t = (Y_MAX_POS - center_y) / l;
            destination[X_AXIS] = center_old_x + t * vx;
            destination[Y_AXIS] = Y_MAX_POS;
        }

        // Move away from the measurement point.
        enable_endstops(false);
        go_xy(destination[X_AXIS], destination[Y_AXIS], feedrate);
        // Move towards the measurement point, until the induction sensor triggers.
        enable_endstops(true);
        go_xy(center_old_x, center_old_y, feedrate);
        update_current_position_xyz();
//        if (! endstop_z_hit_on_purpose()) return false;
        center_x += current_position[X_AXIS];
        center_y += current_position[Y_AXIS];
    }

    // Calculate the new center, move to the new center.
    center_x /= 4.f;
    center_y /= 4.f;
    current_position[X_AXIS] = center_x;
    current_position[Y_AXIS] = center_y;
    enable_endstops(false);
    go_xy(current_position[X_AXIS], current_position[Y_AXIS], feedrate);

    enable_endstops(endstops_enabled);
    enable_z_endstop(endstop_z_enabled);
    return found;
}
#endif //NEW_XYZCAL

#ifndef NEW_XYZCAL
static inline void debug_output_point(const char *type, const float &x, const float &y, const float &z)
{
    SERIAL_ECHOPGM("Measured ");
    SERIAL_ECHORPGM(type);
    SERIAL_ECHOPGM(" ");
    MYSERIAL.print(x, 5);
    SERIAL_ECHOPGM(", ");
    MYSERIAL.print(y, 5);
    SERIAL_ECHOPGM(", ");
    MYSERIAL.print(z, 5);
    SERIAL_ECHOLNPGM("");
}
#endif //NEW_XYZCAL

#ifndef NEW_XYZCAL
// Search around the current_position[X,Y,Z].
// It is expected, that the induction sensor is switched on at the current position.
// Look around this center point by painting a star around the point.
#define IMPROVE_BED_INDUCTION_SENSOR_SEARCH_RADIUS (8.f)
inline bool improve_bed_induction_sensor_point2(bool lift_z_on_min_y, int8_t verbosity_level)
{
    float center_old_x = current_position[X_AXIS];
    float center_old_y = current_position[Y_AXIS];
    float a, b;
    bool  point_small = false;

    enable_endstops(false);

    {
        float x0 = center_old_x - IMPROVE_BED_INDUCTION_SENSOR_SEARCH_RADIUS;
        float x1 = center_old_x + IMPROVE_BED_INDUCTION_SENSOR_SEARCH_RADIUS;
        if (x0 < X_MIN_POS)
            x0 = X_MIN_POS;
        if (x1 > X_MAX_POS)
            x1 = X_MAX_POS;

        // Search in the X direction along a cross.
        enable_z_endstop(false);
        go_xy(x0, current_position[Y_AXIS], homing_feedrate[X_AXIS] / 60.f);
        enable_z_endstop(true);
        go_xy(x1, current_position[Y_AXIS], homing_feedrate[X_AXIS] / 60.f);
        update_current_position_xyz();
        if (! endstop_z_hit_on_purpose()) {
            current_position[X_AXIS] = center_old_x;
            goto canceled;
        }
        a = current_position[X_AXIS];
        enable_z_endstop(false);
        go_xy(x1, current_position[Y_AXIS], homing_feedrate[X_AXIS] / 60.f);
        enable_z_endstop(true);
        go_xy(x0, current_position[Y_AXIS], homing_feedrate[X_AXIS] / 60.f);
        update_current_position_xyz();
        if (! endstop_z_hit_on_purpose()) {
            current_position[X_AXIS] = center_old_x;
            goto canceled;
        }
        b = current_position[X_AXIS];
        if (b - a < MIN_BED_SENSOR_POINT_RESPONSE_DMR) {
			#ifdef SUPPORT_VERBOSITY
            if (verbosity_level >= 5) {
                SERIAL_ECHOPGM("Point width too small: ");
                SERIAL_ECHO(b - a);
                SERIAL_ECHOLNPGM("");
            }
			#endif // SUPPORT_VERBOSITY
            // We force the calibration routine to move the Z axis slightly down to make the response more pronounced.
            if (b - a < 0.5f * MIN_BED_SENSOR_POINT_RESPONSE_DMR) {
                // Don't use the new X value.
                current_position[X_AXIS] = center_old_x;
                goto canceled;
            } else {
                // Use the new value, but force the Z axis to go a bit lower.
                point_small = true;
            }
        }
		#ifdef SUPPORT_VERBOSITY
        if (verbosity_level >= 5) {
            debug_output_point(PSTR("left" ), a, current_position[Y_AXIS], current_position[Z_AXIS]);
            debug_output_point(PSTR("right"), b, current_position[Y_AXIS], current_position[Z_AXIS]);
        }
		#endif // SUPPORT_VERBOSITY

        // Go to the center.
        enable_z_endstop(false);
        current_position[X_AXIS] = 0.5f * (a + b);
        go_xy(current_position[X_AXIS], current_position[Y_AXIS], homing_feedrate[X_AXIS] / 60.f);
    }

    {
        float y0 = center_old_y - IMPROVE_BED_INDUCTION_SENSOR_SEARCH_RADIUS;
        float y1 = center_old_y + IMPROVE_BED_INDUCTION_SENSOR_SEARCH_RADIUS;
        if (y0 < Y_MIN_POS_FOR_BED_CALIBRATION)
            y0 = Y_MIN_POS_FOR_BED_CALIBRATION;
        if (y1 > Y_MAX_POS)
            y1 = Y_MAX_POS;

        // Search in the Y direction along a cross.
        enable_z_endstop(false);
        go_xy(current_position[X_AXIS], y0, homing_feedrate[X_AXIS] / 60.f);
        if (lift_z_on_min_y) {
            // The first row of points are very close to the end stop.
            // Lift the sensor to disengage the trigger. This is necessary because of the sensor hysteresis.
            go_xyz(current_position[X_AXIS], y0, current_position[Z_AXIS]+1.5f, homing_feedrate[Z_AXIS] / 60.f);
            // and go back.
            go_xyz(current_position[X_AXIS], y0, current_position[Z_AXIS], homing_feedrate[Z_AXIS] / 60.f);
        }
        if (lift_z_on_min_y && (READ(Z_MIN_PIN) ^ Z_MIN_ENDSTOP_INVERTING) == 1) {
            // Already triggering before we started the move.
            // Shift the trigger point slightly outwards.
            // a = current_position[Y_AXIS] - 1.5f;
            a = current_position[Y_AXIS];
        } else {
            enable_z_endstop(true);
            go_xy(current_position[X_AXIS], y1, homing_feedrate[X_AXIS] / 60.f);
            update_current_position_xyz();
            if (! endstop_z_hit_on_purpose()) {
                current_position[Y_AXIS] = center_old_y;
                goto canceled;
            }
            a = current_position[Y_AXIS];
        }
        enable_z_endstop(false);
        go_xy(current_position[X_AXIS], y1, homing_feedrate[X_AXIS] / 60.f);
        enable_z_endstop(true);
        go_xy(current_position[X_AXIS], y0, homing_feedrate[X_AXIS] / 60.f);
        update_current_position_xyz();
        if (! endstop_z_hit_on_purpose()) {
            current_position[Y_AXIS] = center_old_y;
            goto canceled;
        }
        b = current_position[Y_AXIS];
        if (b - a < MIN_BED_SENSOR_POINT_RESPONSE_DMR) {
            // We force the calibration routine to move the Z axis slightly down to make the response more pronounced.
			#ifdef SUPPORT_VERBOSITY
			if (verbosity_level >= 5) {
                SERIAL_ECHOPGM("Point height too small: ");
                SERIAL_ECHO(b - a);
                SERIAL_ECHOLNPGM("");
            }
			#endif // SUPPORT_VERBOSITY
            if (b - a < 0.5f * MIN_BED_SENSOR_POINT_RESPONSE_DMR) {
                // Don't use the new Y value.
                current_position[Y_AXIS] = center_old_y;
                goto canceled;
            } else {
                // Use the new value, but force the Z axis to go a bit lower.
                point_small = true;
            }
        }
		#ifdef SUPPORT_VERBOSITY
        if (verbosity_level >= 5) {
            debug_output_point(PSTR("top" ), current_position[X_AXIS], a, current_position[Z_AXIS]);
            debug_output_point(PSTR("bottom"), current_position[X_AXIS], b, current_position[Z_AXIS]);
        }
		#endif // SUPPORT_VERBOSITY

        // Go to the center.
        enable_z_endstop(false);
        current_position[Y_AXIS] = 0.5f * (a + b);
        go_xy(current_position[X_AXIS], current_position[Y_AXIS], homing_feedrate[X_AXIS] / 60.f);
    }

    // If point is small but not too small, then force the Z axis to be lowered a bit,
    // but use the new value. This is important when the initial position was off in one axis,
    // for example if the initial calibration was shifted in the Y axis systematically.
    // Then this first step will center.
    return ! point_small;

canceled:
    // Go back to the center.
    enable_z_endstop(false);
    go_xy(current_position[X_AXIS], current_position[Y_AXIS], homing_feedrate[X_AXIS] / 60.f);
    return false;
}
#endif //NEW_XYZCAL

#ifndef NEW_XYZCAL
// Searching the front points, where one cannot move the sensor head in front of the sensor point.
// Searching in a zig-zag movement in a plane for the maximum width of the response.
// This function may set the current_position[Y_AXIS] below Y_MIN_POS, if the function succeeded.
// If this function failed, the Y coordinate will never be outside the working space.
#define IMPROVE_BED_INDUCTION_SENSOR_POINT3_SEARCH_RADIUS (8.f)
#define IMPROVE_BED_INDUCTION_SENSOR_POINT3_SEARCH_STEP_FINE_Y (0.1f)
inline bool improve_bed_induction_sensor_point3(int verbosity_level)
{	
    float center_old_x = current_position[X_AXIS];
    float center_old_y = current_position[Y_AXIS];
    float a, b;
    bool  result = true;
	#ifdef SUPPORT_VERBOSITY
	if (verbosity_level >= 20) MYSERIAL.println("Improve bed induction sensor point3");
	#endif // SUPPORT_VERBOSITY
    // Was the sensor point detected too far in the minus Y axis?
    // If yes, the center of the induction point cannot be reached by the machine.
    {
        float x0 = center_old_x - IMPROVE_BED_INDUCTION_SENSOR_POINT3_SEARCH_RADIUS;
        float x1 = center_old_x + IMPROVE_BED_INDUCTION_SENSOR_POINT3_SEARCH_RADIUS;
        float y0 = center_old_y - IMPROVE_BED_INDUCTION_SENSOR_POINT3_SEARCH_RADIUS;
        float y1 = center_old_y + IMPROVE_BED_INDUCTION_SENSOR_POINT3_SEARCH_RADIUS;
        float y = y0;

        if (x0 < X_MIN_POS)
            x0 = X_MIN_POS;
        if (x1 > X_MAX_POS)
            x1 = X_MAX_POS;
        if (y0 < Y_MIN_POS_FOR_BED_CALIBRATION)
            y0 = Y_MIN_POS_FOR_BED_CALIBRATION;
        if (y1 > Y_MAX_POS)
            y1 = Y_MAX_POS;
		#ifdef SUPPORT_VERBOSITY
        if (verbosity_level >= 20) {
            SERIAL_ECHOPGM("Initial position: ");
            SERIAL_ECHO(center_old_x);
            SERIAL_ECHOPGM(", ");
            SERIAL_ECHO(center_old_y);
            SERIAL_ECHOLNPGM("");
        }
		#endif // SUPPORT_VERBOSITY

        // Search in the positive Y direction, until a maximum diameter is found.
        // (the next diameter is smaller than the current one.)
        float dmax = 0.f;
        float xmax1 = 0.f;
        float xmax2 = 0.f;
        for (y = y0; y < y1; y += IMPROVE_BED_INDUCTION_SENSOR_POINT3_SEARCH_STEP_FINE_Y) {
            enable_z_endstop(false);
            go_xy(x0, y, homing_feedrate[X_AXIS] / 60.f);
            enable_z_endstop(true);
            go_xy(x1, y, homing_feedrate[X_AXIS] / 60.f);
            update_current_position_xyz();
            if (! endstop_z_hit_on_purpose()) {
                continue;
                // SERIAL_PROTOCOLPGM("Failed 1\n");
                // current_position[X_AXIS] = center_old_x;
                // goto canceled;
            }
            a = current_position[X_AXIS];
            enable_z_endstop(false);
            go_xy(x1, y, homing_feedrate[X_AXIS] / 60.f);
            enable_z_endstop(true);
            go_xy(x0, y, homing_feedrate[X_AXIS] / 60.f);
            update_current_position_xyz();
            if (! endstop_z_hit_on_purpose()) {
                continue;
                // SERIAL_PROTOCOLPGM("Failed 2\n");
                // current_position[X_AXIS] = center_old_x;
                // goto canceled;
            }
            b = current_position[X_AXIS];
			#ifdef SUPPORT_VERBOSITY
            if (verbosity_level >= 5) {
                debug_output_point(PSTR("left" ), a, current_position[Y_AXIS], current_position[Z_AXIS]);
                debug_output_point(PSTR("right"), b, current_position[Y_AXIS], current_position[Z_AXIS]);
            }
			#endif // SUPPORT_VERBOSITY
            float d = b - a;
            if (d > dmax) {
                xmax1 = 0.5f * (a + b);
                dmax = d;
            } else if (dmax > 0.) {
                y0 = y - IMPROVE_BED_INDUCTION_SENSOR_POINT3_SEARCH_STEP_FINE_Y;
                break;
            }
        }
        if (dmax == 0.) {
			#ifdef SUPPORT_VERBOSITY
            if (verbosity_level > 0)
                SERIAL_PROTOCOLPGM("failed - not found\n");
			#endif // SUPPORT_VERBOSITY
			current_position[X_AXIS] = center_old_x;
            current_position[Y_AXIS] = center_old_y;
            goto canceled;
        }

        {
            // Find the positive Y hit. This gives the extreme Y value for the search of the maximum diameter in the -Y direction.
            enable_z_endstop(false);
            go_xy(xmax1, y0 + IMPROVE_BED_INDUCTION_SENSOR_SEARCH_RADIUS, homing_feedrate[X_AXIS] / 60.f);
            enable_z_endstop(true);
            go_xy(xmax1, max(y0 - IMPROVE_BED_INDUCTION_SENSOR_SEARCH_RADIUS, Y_MIN_POS_FOR_BED_CALIBRATION), homing_feedrate[X_AXIS] / 60.f);
            update_current_position_xyz();
            if (! endstop_z_hit_on_purpose()) {
                current_position[Y_AXIS] = center_old_y;
                goto canceled;
            }
			#ifdef SUPPORT_VERBOSITY
            if (verbosity_level >= 5)
                debug_output_point(PSTR("top" ), current_position[X_AXIS], current_position[Y_AXIS], current_position[Z_AXIS]);
			#endif // SUPPORT_VERBOSITY
			y1 = current_position[Y_AXIS];
        }

        if (y1 <= y0) {
            // Either the induction sensor is too high, or the induction sensor target is out of reach.
            current_position[Y_AXIS] = center_old_y;
            goto canceled;
        }

        // Search in the negative Y direction, until a maximum diameter is found.
        dmax = 0.f;
        // if (y0 + 1.f < y1)
        //    y1 = y0 + 1.f;
        for (y = y1; y >= y0; y -= IMPROVE_BED_INDUCTION_SENSOR_POINT3_SEARCH_STEP_FINE_Y) {
            enable_z_endstop(false);
            go_xy(x0, y, homing_feedrate[X_AXIS] / 60.f);
            enable_z_endstop(true);
            go_xy(x1, y, homing_feedrate[X_AXIS] / 60.f);
            update_current_position_xyz();
            if (! endstop_z_hit_on_purpose()) {
                continue;
                /*
                current_position[X_AXIS] = center_old_x;
                SERIAL_PROTOCOLPGM("Failed 3\n");
                goto canceled;
                */
            }
            a = current_position[X_AXIS];
            enable_z_endstop(false);
            go_xy(x1, y, homing_feedrate[X_AXIS] / 60.f);
            enable_z_endstop(true);
            go_xy(x0, y, homing_feedrate[X_AXIS] / 60.f);
            update_current_position_xyz();
            if (! endstop_z_hit_on_purpose()) {
                continue;
                /*
                current_position[X_AXIS] = center_old_x;
                SERIAL_PROTOCOLPGM("Failed 4\n");
                goto canceled;
                */
            }
            b = current_position[X_AXIS];
			#ifdef SUPPORT_VERBOSITY
            if (verbosity_level >= 5) {
                debug_output_point(PSTR("left" ), a, current_position[Y_AXIS], current_position[Z_AXIS]);
                debug_output_point(PSTR("right"), b, current_position[Y_AXIS], current_position[Z_AXIS]);
            }
			#endif // SUPPORT_VERBOSITY
            float d = b - a;
            if (d > dmax) {
                xmax2 = 0.5f * (a + b);
                dmax = d;
            } else if (dmax > 0.) {
                y1 = y + IMPROVE_BED_INDUCTION_SENSOR_POINT3_SEARCH_STEP_FINE_Y;
                break;
            }
        }
        float xmax, ymax;
        if (dmax == 0.f) {
            // Only the hit in the positive direction found.
            xmax = xmax1;
            ymax = y0;
        } else {
            // Both positive and negative directions found.
            xmax = xmax2;
            ymax = 0.5f * (y0 + y1);
            for (; y >= y0; y -= IMPROVE_BED_INDUCTION_SENSOR_POINT3_SEARCH_STEP_FINE_Y) {
                enable_z_endstop(false);
                go_xy(x0, y, homing_feedrate[X_AXIS] / 60.f);
                enable_z_endstop(true);
                go_xy(x1, y, homing_feedrate[X_AXIS] / 60.f);
                update_current_position_xyz();
                if (! endstop_z_hit_on_purpose()) {
                    continue;
                    /*
                    current_position[X_AXIS] = center_old_x;
                    SERIAL_PROTOCOLPGM("Failed 3\n");
                    goto canceled;
                    */
                }
                a = current_position[X_AXIS];
                enable_z_endstop(false);
                go_xy(x1, y, homing_feedrate[X_AXIS] / 60.f);
                enable_z_endstop(true);
                go_xy(x0, y, homing_feedrate[X_AXIS] / 60.f);
                update_current_position_xyz();
                if (! endstop_z_hit_on_purpose()) {
                    continue;
                    /*
                    current_position[X_AXIS] = center_old_x;
                    SERIAL_PROTOCOLPGM("Failed 4\n");
                    goto canceled;
                    */
                }
                b = current_position[X_AXIS];
				#ifdef SUPPORT_VERBOSITY
                if (verbosity_level >= 5) {
                    debug_output_point(PSTR("left" ), a, current_position[Y_AXIS], current_position[Z_AXIS]);
                    debug_output_point(PSTR("right"), b, current_position[Y_AXIS], current_position[Z_AXIS]);
                }
				#endif // SUPPORT_VERBOSITY
                float d = b - a;
                if (d > dmax) {
                    xmax = 0.5f * (a + b);
                    ymax = y;
                    dmax = d;
                }
            }
        }

        {
            // Compare the distance in the Y+ direction with the diameter in the X direction.
            // Find the positive Y hit once again, this time along the Y axis going through the X point with the highest diameter.
            enable_z_endstop(false);
            go_xy(xmax, ymax + IMPROVE_BED_INDUCTION_SENSOR_SEARCH_RADIUS, homing_feedrate[X_AXIS] / 60.f);
            enable_z_endstop(true);
            go_xy(xmax, max(ymax - IMPROVE_BED_INDUCTION_SENSOR_SEARCH_RADIUS, Y_MIN_POS_FOR_BED_CALIBRATION), homing_feedrate[X_AXIS] / 60.f);
            update_current_position_xyz();
            if (! endstop_z_hit_on_purpose()) {
                current_position[Y_AXIS] = center_old_y;
                goto canceled;
            }
			#ifdef SUPPORT_VERBOSITY
            if (verbosity_level >= 5)
                debug_output_point(PSTR("top" ), current_position[X_AXIS], current_position[Y_AXIS], current_position[Z_AXIS]);
			#endif // SUPPORT_VERBOSITY
			if (current_position[Y_AXIS] - Y_MIN_POS_FOR_BED_CALIBRATION < 0.5f * dmax) {
                // Probably not even a half circle was detected. The induction point is likely too far in the minus Y direction.
                // First verify, if the measurement has been done at a sufficient height. If no, lower the Z axis a bit.
                if (current_position[Y_AXIS] < ymax || dmax < 0.5f * MIN_BED_SENSOR_POINT_RESPONSE_DMR) {
					#ifdef SUPPORT_VERBOSITY
					if (verbosity_level >= 5) {
                        SERIAL_ECHOPGM("Partial point diameter too small: ");
                        SERIAL_ECHO(dmax);
                        SERIAL_ECHOLNPGM("");
                    }
					#endif // SUPPORT_VERBOSITY
                    result = false;
                } else {
                    // Estimate the circle radius from the maximum diameter and height:
                    float h = current_position[Y_AXIS] - ymax;
                    float r = dmax * dmax / (8.f * h) + 0.5f * h;
                    if (r < 0.8f * MIN_BED_SENSOR_POINT_RESPONSE_DMR) {
						#ifdef SUPPORT_VERBOSITY
						if (verbosity_level >= 5) {
                            SERIAL_ECHOPGM("Partial point estimated radius too small: ");
                            SERIAL_ECHO(r);
                            SERIAL_ECHOPGM(", dmax:");
                            SERIAL_ECHO(dmax);
                            SERIAL_ECHOPGM(", h:");
                            SERIAL_ECHO(h);
                            SERIAL_ECHOLNPGM("");
                        }
						#endif // SUPPORT_VERBOSITY
                        result = false;
                    } else {
                        // The point may end up outside of the machine working space.
                        // That is all right as it helps to improve the accuracy of the measurement point
                        // due to averaging.
                        // For the y correction, use an average of dmax/2 and the estimated radius.
                        r = 0.5f * (0.5f * dmax + r);
                        ymax = current_position[Y_AXIS] - r;
                    }
                }
            } else {
                // If the diameter of the detected spot was smaller than a minimum allowed,
                // the induction sensor is probably too high. Returning false will force
                // the sensor to be lowered a tiny bit.
                result = xmax >= MIN_BED_SENSOR_POINT_RESPONSE_DMR;
                if (y0 > Y_MIN_POS_FOR_BED_CALIBRATION + 0.2f)
                    // Only in case both left and right y tangents are known, use them.
                    // If y0 is close to the bed edge, it may not be symmetric to the right tangent.
                    ymax = 0.5f * ymax + 0.25f * (y0 + y1);
            }
        }

        // Go to the center.
        enable_z_endstop(false);
        current_position[X_AXIS] = xmax;
        current_position[Y_AXIS] = ymax;
		#ifdef SUPPORT_VERBOSITY
        if (verbosity_level >= 20) {
            SERIAL_ECHOPGM("Adjusted position: ");
            SERIAL_ECHO(current_position[X_AXIS]);
            SERIAL_ECHOPGM(", ");
            SERIAL_ECHO(current_position[Y_AXIS]);
            SERIAL_ECHOLNPGM("");
        }
		#endif // SUPPORT_VERBOSITY

        // Don't clamp current_position[Y_AXIS], because the out-of-reach Y coordinate may actually be true.
        // Only clamp the coordinate to go.
        go_xy(current_position[X_AXIS], max(Y_MIN_POS, current_position[Y_AXIS]), homing_feedrate[X_AXIS] / 60.f);
        // delay_keep_alive(3000);
    }

    if (result)
        return true;
    // otherwise clamp the Y coordinate

canceled:
    // Go back to the center.
    enable_z_endstop(false);
    if (current_position[Y_AXIS] < Y_MIN_POS)
        current_position[Y_AXIS] = Y_MIN_POS;
    go_xy(current_position[X_AXIS], current_position[Y_AXIS], homing_feedrate[X_AXIS] / 60.f);
    return false;
}
#endif //NEW_XYZCAL

#ifndef NEW_XYZCAL
// Scan the mesh bed induction points one by one by a left-right zig-zag movement,
// write the trigger coordinates to the serial line.
// Useful for visualizing the behavior of the bed induction detector.
inline void scan_bed_induction_sensor_point()
{
    float center_old_x = current_position[X_AXIS];
    float center_old_y = current_position[Y_AXIS];
    float x0 = center_old_x - IMPROVE_BED_INDUCTION_SENSOR_POINT3_SEARCH_RADIUS;
    float x1 = center_old_x + IMPROVE_BED_INDUCTION_SENSOR_POINT3_SEARCH_RADIUS;
    float y0 = center_old_y - IMPROVE_BED_INDUCTION_SENSOR_POINT3_SEARCH_RADIUS;
    float y1 = center_old_y + IMPROVE_BED_INDUCTION_SENSOR_POINT3_SEARCH_RADIUS;
    float y = y0;

    if (x0 < X_MIN_POS)
        x0 = X_MIN_POS;
    if (x1 > X_MAX_POS)
        x1 = X_MAX_POS;
    if (y0 < Y_MIN_POS_FOR_BED_CALIBRATION)
        y0 = Y_MIN_POS_FOR_BED_CALIBRATION;
    if (y1 > Y_MAX_POS)
        y1 = Y_MAX_POS;

    for (float y = y0; y < y1; y += IMPROVE_BED_INDUCTION_SENSOR_POINT3_SEARCH_STEP_FINE_Y) {
        enable_z_endstop(false);
        go_xy(x0, y, homing_feedrate[X_AXIS] / 60.f);
        enable_z_endstop(true);
        go_xy(x1, y, homing_feedrate[X_AXIS] / 60.f);
        update_current_position_xyz();
        if (endstop_z_hit_on_purpose())
            debug_output_point(PSTR("left" ), current_position[X_AXIS], current_position[Y_AXIS], current_position[Z_AXIS]);
        enable_z_endstop(false);
        go_xy(x1, y, homing_feedrate[X_AXIS] / 60.f);
        enable_z_endstop(true);
        go_xy(x0, y, homing_feedrate[X_AXIS] / 60.f);
        update_current_position_xyz();
        if (endstop_z_hit_on_purpose())
            debug_output_point(PSTR("right"), current_position[X_AXIS], current_position[Y_AXIS], current_position[Z_AXIS]);
    }

    enable_z_endstop(false);
    current_position[X_AXIS] = center_old_x;
    current_position[Y_AXIS] = center_old_y;
    go_xy(current_position[X_AXIS], current_position[Y_AXIS], homing_feedrate[X_AXIS] / 60.f);
}
#endif //NEW_XYZCAL

#define MESH_BED_CALIBRATION_SHOW_LCD

BedSkewOffsetDetectionResultType find_bed_offset_and_skew(int8_t verbosity_level, uint8_t &too_far_mask)
{	
    // Don't let the manage_inactivity() function remove power from the motors.
    refresh_cmd_timeout();

    // Reusing the z_values memory for the measurement cache.
    // 7x7=49 floats, good for 16 (x,y,z) vectors.
    float *pts = &mbl.z_values[0][0];
    float *vec_x = pts + 2 * 4;
    float *vec_y = vec_x + 2;
    float *cntr  = vec_y + 2;
    memset(pts, 0, sizeof(float) * 7 * 7);
	uint8_t iteration = 0; 
	BedSkewOffsetDetectionResultType result;

//    SERIAL_ECHOLNPGM("find_bed_offset_and_skew verbosity level: ");
//    SERIAL_ECHO(int(verbosity_level));
//    SERIAL_ECHOPGM("");
	
#ifdef NEW_XYZCAL
	{
#else //NEW_XYZCAL
	while (iteration < 3) {
#endif //NEW_XYZCAL

		SERIAL_ECHOPGM("Iteration: ");
		MYSERIAL.println(int(iteration + 1));
		#ifdef SUPPORT_VERBOSITY
		if (verbosity_level >= 20) {
		SERIAL_ECHOLNPGM("Vectors: ");
		
			SERIAL_ECHOPGM("vec_x[0]:");
			MYSERIAL.print(vec_x[0], 5);
			SERIAL_ECHOLNPGM("");
			SERIAL_ECHOPGM("vec_x[1]:");
			MYSERIAL.print(vec_x[1], 5);
			SERIAL_ECHOLNPGM("");
			SERIAL_ECHOPGM("vec_y[0]:");
			MYSERIAL.print(vec_y[0], 5);
			SERIAL_ECHOLNPGM("");
			SERIAL_ECHOPGM("vec_y[1]:");
			MYSERIAL.print(vec_y[1], 5);
			SERIAL_ECHOLNPGM("");
			SERIAL_ECHOPGM("cntr[0]:");
			MYSERIAL.print(cntr[0], 5);
			SERIAL_ECHOLNPGM("");
			SERIAL_ECHOPGM("cntr[1]:");
			MYSERIAL.print(cntr[1], 5);
			SERIAL_ECHOLNPGM("");
		}
		#endif // SUPPORT_VERBOSITY
#ifdef MESH_BED_CALIBRATION_SHOW_LCD
    lcd_display_message_fullscreen_P(_T(MSG_FIND_BED_OFFSET_AND_SKEW_LINE1));
#endif /* MESH_BED_CALIBRATION_SHOW_LCD */

    // Collect the rear 2x3 points.
	current_position[Z_AXIS] = MESH_HOME_Z_SEARCH + FIND_BED_INDUCTION_SENSOR_POINT_Z_STEP * iteration * 0.3;

    /// Retry point scanning if a point with bad data appears.
    /// Bad data could be cause by "cold" sensor.
    /// This behavior vanishes after few point scans so retry will help.
    for (uint8_t retries = 0; retries <= 1; ++retries) {
        bool retry = false;
        for (int k = 0; k < 4; ++k) {
            // Don't let the manage_inactivity() function remove power from the motors.
            refresh_cmd_timeout();
#ifdef MESH_BED_CALIBRATION_SHOW_LCD
		lcd_set_cursor(0, 3);
		lcd_printf_P(PSTR("%d/4"),(k+1));

		if (iteration > 0) {
			lcd_printf_P(PSTR(" %S %d/1"),_T(MSG_ITERATION),int(iteration + 1));
		}
#endif /* MESH_BED_CALIBRATION_SHOW_LCD */
		float *pt = pts + k * 2;
		// Go up to z_initial.

		go_to_current(homing_feedrate[Z_AXIS] / 60.f);
		#ifdef SUPPORT_VERBOSITY
		if (verbosity_level >= 20) {
			// Go to Y0, wait, then go to Y-4.
			current_position[Y_AXIS] = 0.f;
			go_to_current(homing_feedrate[X_AXIS] / 60.f);
			SERIAL_ECHOLNPGM("At Y0");
			delay_keep_alive(5000);
			current_position[Y_AXIS] = Y_MIN_POS;
			go_to_current(homing_feedrate[X_AXIS] / 60.f);
			SERIAL_ECHOLNPGM("At Y_MIN_POS");
			delay_keep_alive(5000);
		}
		#endif // SUPPORT_VERBOSITY
		// Go to the measurement point position.
		//if (iteration == 0) {
			current_position[X_AXIS] = pgm_read_float(bed_ref_points_4 + k * 2);
			current_position[Y_AXIS] = pgm_read_float(bed_ref_points_4 + k * 2 + 1);
		/*}
		else {
			// if first iteration failed, count corrected point coordinates as initial
			// Use the corrected coordinate, which is a result of find_bed_offset_and_skew().
			
			current_position[X_AXIS] = vec_x[0] * pgm_read_float(bed_ref_points_4 + k * 2) + vec_y[0] * pgm_read_float(bed_ref_points_4 + k * 2 + 1) + cntr[0];
			current_position[Y_AXIS] = vec_x[1] * pgm_read_float(bed_ref_points_4 + k * 2) + vec_y[1] * pgm_read_float(bed_ref_points_4 + k * 2 + 1) + cntr[1];

			// The calibration points are very close to the min Y.
			if (current_position[Y_AXIS] < Y_MIN_POS_FOR_BED_CALIBRATION)
				current_position[Y_AXIS] = Y_MIN_POS_FOR_BED_CALIBRATION;

		}*/
		#ifdef SUPPORT_VERBOSITY
		if (verbosity_level >= 20) {
			SERIAL_ECHOPGM("current_position[X_AXIS]:");
			MYSERIAL.print(current_position[X_AXIS], 5);
			SERIAL_ECHOLNPGM("");
			SERIAL_ECHOPGM("current_position[Y_AXIS]:");
			MYSERIAL.print(current_position[Y_AXIS], 5);
			SERIAL_ECHOLNPGM("");
			SERIAL_ECHOPGM("current_position[Z_AXIS]:");
			MYSERIAL.print(current_position[Z_AXIS], 5);
			SERIAL_ECHOLNPGM("");
		}
		#endif // SUPPORT_VERBOSITY

		go_to_current(homing_feedrate[X_AXIS] / 60.f);
		#ifdef SUPPORT_VERBOSITY
		if (verbosity_level >= 10)
			delay_keep_alive(3000);
		#endif // SUPPORT_VERBOSITY

        BedSkewOffsetDetectionResultType result;
        result = find_bed_induction_sensor_point_xy(verbosity_level);
        switch(result){
            case BED_SKEW_OFFSET_DETECTION_POINT_NOT_FOUND:
                return BED_SKEW_OFFSET_DETECTION_POINT_NOT_FOUND;
            case BED_SKEW_OFFSET_DETECTION_POINT_SCAN_FAILED:
                retry = true;
                break;
            default:
                break;
        }

#ifndef NEW_XYZCAL
#ifndef HEATBED_V2
		
			if (k == 0 || k == 1) {
				// Improve the position of the 1st row sensor points by a zig-zag movement.
				find_bed_induction_sensor_point_z();
				int8_t i = 4;
				for (;;) {
					if (improve_bed_induction_sensor_point3(verbosity_level))
						break;
					if (--i == 0)
						return BED_SKEW_OFFSET_DETECTION_POINT_NOT_FOUND;
					// Try to move the Z axis down a bit to increase a chance of the sensor to trigger.
					current_position[Z_AXIS] -= 0.025f;
					enable_endstops(false);
					enable_z_endstop(false);
					go_to_current(homing_feedrate[Z_AXIS]);
				}
				if (i == 0)
					// not found
					return BED_SKEW_OFFSET_DETECTION_POINT_NOT_FOUND;
			}
#endif //HEATBED_V2
#endif
			#ifdef SUPPORT_VERBOSITY
			if (verbosity_level >= 10)
				delay_keep_alive(3000);
			#endif // SUPPORT_VERBOSITY
			// Save the detected point position and then clamp the Y coordinate, which may have been estimated
			// to lie outside the machine working space.
			#ifdef SUPPORT_VERBOSITY
			if (verbosity_level >= 20) {
				SERIAL_ECHOLNPGM("Measured:");
				MYSERIAL.println(current_position[X_AXIS]);
				MYSERIAL.println(current_position[Y_AXIS]);
			}
			#endif // SUPPORT_VERBOSITY
			pt[0] = (pt[0] * iteration) / (iteration + 1);
			pt[0] += (current_position[X_AXIS]/(iteration + 1)); //count average
			pt[1] = (pt[1] * iteration) / (iteration + 1);
			pt[1] += (current_position[Y_AXIS] / (iteration + 1));
			
			
			//pt[0] += current_position[X_AXIS];
			//if(iteration > 0) pt[0] = pt[0] / 2;
						
			//pt[1] += current_position[Y_AXIS];
			//if (iteration > 0) pt[1] = pt[1] / 2;

			#ifdef SUPPORT_VERBOSITY
			if (verbosity_level >= 20) {
				SERIAL_ECHOLNPGM("");
				SERIAL_ECHOPGM("pt[0]:");
				MYSERIAL.println(pt[0]);
				SERIAL_ECHOPGM("pt[1]:");
				MYSERIAL.println(pt[1]);
			}
			#endif // SUPPORT_VERBOSITY

			if (current_position[Y_AXIS] < Y_MIN_POS)
				current_position[Y_AXIS] = Y_MIN_POS;
			// Start searching for the other points at 3mm above the last point.
			current_position[Z_AXIS] += 3.f + FIND_BED_INDUCTION_SENSOR_POINT_Z_STEP * iteration * 0.3;
			//cntr[0] += pt[0];
			//cntr[1] += pt[1];
			#ifdef SUPPORT_VERBOSITY
			if (verbosity_level >= 10 && k == 0) {
				// Show the zero. Test, whether the Y motor skipped steps.
				current_position[Y_AXIS] = MANUAL_Y_HOME_POS;
				go_to_current(homing_feedrate[X_AXIS] / 60.f);
				delay_keep_alive(3000);
			}
			#endif // SUPPORT_VERBOSITY
        }
        if (!retry)
            break;
    }
        DBG(_n("All 4 calibration points found.\n"));
        delay_keep_alive(0); //manage_heater, reset watchdog, manage inactivity
		
		#ifdef SUPPORT_VERBOSITY
		if (verbosity_level >= 20) {
			// Test the positions. Are the positions reproducible? Now the calibration is active in the planner.
			delay_keep_alive(3000);
			for (int8_t mesh_point = 0; mesh_point < 4; ++mesh_point) {
				// Don't let the manage_inactivity() function remove power from the motors.
				refresh_cmd_timeout();
				// Go to the measurement point.
				// Use the corrected coordinate, which is a result of find_bed_offset_and_skew().
				current_position[X_AXIS] = pts[mesh_point * 2];
				current_position[Y_AXIS] = pts[mesh_point * 2 + 1];
				go_to_current(homing_feedrate[X_AXIS] / 60);
				delay_keep_alive(3000);
			}
		}
		#endif // SUPPORT_VERBOSITY
		if (pts[1] < Y_MIN_POS_CALIBRATION_POINT_OUT_OF_REACH) {
			too_far_mask |= 1 << 1; //front center point is out of reach
				SERIAL_ECHOLNPGM("");
				SERIAL_ECHOPGM("WARNING: Front point not reachable. Y coordinate:");
				MYSERIAL.print(pts[1]);
				SERIAL_ECHOPGM(" < ");
				MYSERIAL.println(Y_MIN_POS_CALIBRATION_POINT_OUT_OF_REACH);
		}
		result = calculate_machine_skew_and_offset_LS(pts, 4, bed_ref_points_4, vec_x, vec_y, cntr, verbosity_level);
		delay_keep_alive(0); //manage_heater, reset watchdog, manage inactivity
		
		if (result >= 0) {
            DBG(_n("Calibration success.\n"));
			world2machine_update(vec_x, vec_y, cntr);
#if 1
			// Fearlessly store the calibration values into the eeprom.
			eeprom_update_float((float*)(EEPROM_BED_CALIBRATION_CENTER + 0), cntr[0]);
			eeprom_update_float((float*)(EEPROM_BED_CALIBRATION_CENTER + 4), cntr[1]);
			eeprom_update_float((float*)(EEPROM_BED_CALIBRATION_VEC_X + 0), vec_x[0]);
			eeprom_update_float((float*)(EEPROM_BED_CALIBRATION_VEC_X + 4), vec_x[1]);
			eeprom_update_float((float*)(EEPROM_BED_CALIBRATION_VEC_Y + 0), vec_y[0]);
			eeprom_update_float((float*)(EEPROM_BED_CALIBRATION_VEC_Y + 4), vec_y[1]);
#endif
			#ifdef SUPPORT_VERBOSITY
			if (verbosity_level >= 10) {
				// Length of the vec_x
				float l = hypot(vec_x[0], vec_x[1]);
				SERIAL_ECHOLNPGM("X vector length:");
				MYSERIAL.println(l);

				// Length of the vec_y
				l = hypot(vec_y[0], vec_y[1]);
				SERIAL_ECHOLNPGM("Y vector length:");
				MYSERIAL.println(l);
				// Zero point correction
				l = hypot(cntr[0], cntr[1]);
				SERIAL_ECHOLNPGM("Zero point correction:");
				MYSERIAL.println(l);

				// vec_x and vec_y shall be nearly perpendicular.
				l = vec_x[0] * vec_y[0] + vec_x[1] * vec_y[1];
				SERIAL_ECHOLNPGM("Perpendicularity");
				MYSERIAL.println(fabs(l));
				SERIAL_ECHOLNPGM("Saving bed calibration vectors to EEPROM");
			}
			#endif // SUPPORT_VERBOSITY
			// Correct the current_position to match the transformed coordinate system after world2machine_rotation_and_skew and world2machine_shift were set.
			world2machine_update_current();

			#ifdef SUPPORT_VERBOSITY
			if (verbosity_level >= 20) {
				// Test the positions. Are the positions reproducible? Now the calibration is active in the planner.
				delay_keep_alive(3000);
				for (int8_t mesh_point = 0; mesh_point < 9; ++mesh_point) {
					// Don't let the manage_inactivity() function remove power from the motors.
					refresh_cmd_timeout();
					// Go to the measurement point.
					// Use the corrected coordinate, which is a result of find_bed_offset_and_skew().
					uint8_t ix = mesh_point % MESH_MEAS_NUM_X_POINTS; // from 0 to MESH_NUM_X_POINTS - 1
					uint8_t iy = mesh_point / MESH_MEAS_NUM_X_POINTS;
					if (iy & 1) ix = (MESH_MEAS_NUM_X_POINTS - 1) - ix;
					current_position[X_AXIS] = BED_X(ix, MESH_MEAS_NUM_X_POINTS);
					current_position[Y_AXIS] = BED_Y(iy, MESH_MEAS_NUM_Y_POINTS);
					go_to_current(homing_feedrate[X_AXIS] / 60);
					delay_keep_alive(3000);
				}
			}
			#endif // SUPPORT_VERBOSITY
			return result;
		}
        if (result == BED_SKEW_OFFSET_DETECTION_FITTING_FAILED && too_far_mask == 2){
            DBG(_n("Fitting failed => calibration failed.\n"));
            return result; //if fitting failed and front center point is out of reach, terminate calibration and inform user
        }
        iteration++;
	}
	return result;    
}

#ifndef NEW_XYZCAL
BedSkewOffsetDetectionResultType improve_bed_offset_and_skew(int8_t method, int8_t verbosity_level, uint8_t &too_far_mask)
{
    // Don't let the manage_inactivity() function remove power from the motors.
    refresh_cmd_timeout();

    // Mask of the first three points. Are they too far?
    too_far_mask = 0;

    // Reusing the z_values memory for the measurement cache.
    // 7x7=49 floats, good for 16 (x,y,z) vectors.
    float *pts = &mbl.z_values[0][0];
    float *vec_x = pts + 2 * 9;
    float *vec_y = vec_x + 2;
    float *cntr  = vec_y + 2;
    memset(pts, 0, sizeof(float) * 7 * 7);
	#ifdef SUPPORT_VERBOSITY
	if (verbosity_level >= 10) SERIAL_ECHOLNPGM("Improving bed offset and skew");
	#endif // SUPPORT_VERBOSITY
    // Cache the current correction matrix.
    world2machine_initialize();
    vec_x[0] = world2machine_rotation_and_skew[0][0];
    vec_x[1] = world2machine_rotation_and_skew[1][0];
    vec_y[0] = world2machine_rotation_and_skew[0][1];
    vec_y[1] = world2machine_rotation_and_skew[1][1];
    cntr[0] = world2machine_shift[0];
    cntr[1] = world2machine_shift[1];
    // and reset the correction matrix, so the planner will not do anything.
    world2machine_reset();

    bool endstops_enabled  = enable_endstops(false);
    bool endstop_z_enabled = enable_z_endstop(false);

#ifdef MESH_BED_CALIBRATION_SHOW_LCD
    lcd_display_message_fullscreen_P(_i("Improving bed calibration point"));////MSG_IMPROVE_BED_OFFSET_AND_SKEW_LINE1 c=20 r=4
#endif /* MESH_BED_CALIBRATION_SHOW_LCD */

    // Collect a matrix of 9x9 points.
    BedSkewOffsetDetectionResultType result = BED_SKEW_OFFSET_DETECTION_PERFECT;
    for (int8_t mesh_point = 0; mesh_point < 4; ++ mesh_point) {
        // Don't let the manage_inactivity() function remove power from the motors.
        refresh_cmd_timeout();
        // Print the decrasing ID of the measurement point.
#ifdef MESH_BED_CALIBRATION_SHOW_LCD
        lcd_set_cursor(0, 3);
        lcd_printf_P(PSTR("%d/4"),mesh_point+1);
#endif /* MESH_BED_CALIBRATION_SHOW_LCD */

        // Move up.
        current_position[Z_AXIS] = MESH_HOME_Z_SEARCH;
        enable_endstops(false);
        enable_z_endstop(false);
        go_to_current(homing_feedrate[Z_AXIS]/60);
		#ifdef SUPPORT_VERBOSITY
        if (verbosity_level >= 20) {
            // Go to Y0, wait, then go to Y-4.
            current_position[Y_AXIS] = 0.f;
            go_to_current(homing_feedrate[X_AXIS] / 60.f);
            SERIAL_ECHOLNPGM("At Y0");
            delay_keep_alive(5000);
            current_position[Y_AXIS] = Y_MIN_POS;
            go_to_current(homing_feedrate[X_AXIS] / 60.f);
			SERIAL_ECHOLNPGM("At Y_MIN_POS");
            delay_keep_alive(5000);
        }
		#endif // SUPPORT_VERBOSITY
        // Go to the measurement point.
        // Use the coorrected coordinate, which is a result of find_bed_offset_and_skew().
        current_position[X_AXIS] = vec_x[0] * pgm_read_float(bed_ref_points_4+mesh_point*2) + vec_y[0] * pgm_read_float(bed_ref_points_4+mesh_point*2+1) + cntr[0];
        current_position[Y_AXIS] = vec_x[1] * pgm_read_float(bed_ref_points_4+mesh_point*2) + vec_y[1] * pgm_read_float(bed_ref_points_4+mesh_point*2+1) + cntr[1];
        // The calibration points are very close to the min Y.
        if (current_position[Y_AXIS] < Y_MIN_POS_FOR_BED_CALIBRATION){
            current_position[Y_AXIS] = Y_MIN_POS_FOR_BED_CALIBRATION;
			#ifdef SUPPORT_VERBOSITY
			if (verbosity_level >= 20) {
				SERIAL_ECHOPGM("Calibration point ");
				SERIAL_ECHO(mesh_point);
				SERIAL_ECHOPGM("lower than Ymin. Y coordinate clamping was used.");
				SERIAL_ECHOLNPGM("");
			}
			#endif // SUPPORT_VERBOSITY
		}
        go_to_current(homing_feedrate[X_AXIS]/60);
        // Find its Z position by running the normal vertical search.
		#ifdef SUPPORT_VERBOSITY
		if (verbosity_level >= 10)
            delay_keep_alive(3000);
		#endif // SUPPORT_VERBOSITY
		find_bed_induction_sensor_point_z();
		#ifdef SUPPORT_VERBOSITY
		if (verbosity_level >= 10)
            delay_keep_alive(3000);
		#endif // SUPPORT_VERBOSITY
		// Try to move the Z axis down a bit to increase a chance of the sensor to trigger.
        current_position[Z_AXIS] -= 0.025f;
        // Improve the point position by searching its center in a current plane.
        int8_t n_errors = 3;
        for (int8_t iter = 0; iter < 8; ) {
			#ifdef SUPPORT_VERBOSITY
            if (verbosity_level > 20) {
                SERIAL_ECHOPGM("Improving bed point ");
                SERIAL_ECHO(mesh_point);
                SERIAL_ECHOPGM(", iteration ");
                SERIAL_ECHO(iter);
                SERIAL_ECHOPGM(", z");
                MYSERIAL.print(current_position[Z_AXIS], 5);
                SERIAL_ECHOLNPGM("");
            }
			#endif // SUPPORT_VERBOSITY
            bool found = false;
            if (mesh_point < 2) {
                // Because the sensor cannot move in front of the first row
                // of the sensor points, the y position cannot be measured
                // by a cross center method.
                // Use a zig-zag search for the first row of the points.
                found = improve_bed_induction_sensor_point3(verbosity_level);
            } else {
                switch (method) {
                    case 0: found = improve_bed_induction_sensor_point(); break;
                    case 1: found = improve_bed_induction_sensor_point2(mesh_point < 2, verbosity_level); break;
                    default: break;
                }
            }
            if (found) {
                if (iter > 3) {
                    // Average the last 4 measurements.
                    pts[mesh_point*2  ] += current_position[X_AXIS];
                    pts[mesh_point*2+1] += current_position[Y_AXIS];
                }
                if (current_position[Y_AXIS] < Y_MIN_POS)
                    current_position[Y_AXIS] = Y_MIN_POS;
                ++ iter;
            } else if (n_errors -- == 0) {
                // Give up.
                result = BED_SKEW_OFFSET_DETECTION_POINT_NOT_FOUND;
                goto canceled;
            } else {
                // Try to move the Z axis down a bit to increase a chance of the sensor to trigger.
                current_position[Z_AXIS] -= 0.05f;
                enable_endstops(false);
                enable_z_endstop(false);
                go_to_current(homing_feedrate[Z_AXIS]);
				#ifdef SUPPORT_VERBOSITY
                if (verbosity_level >= 5) {
                    SERIAL_ECHOPGM("Improving bed point ");
                    SERIAL_ECHO(mesh_point);
                    SERIAL_ECHOPGM(", iteration ");
                    SERIAL_ECHO(iter);
                    SERIAL_ECHOPGM(" failed. Lowering z to ");
                    MYSERIAL.print(current_position[Z_AXIS], 5);
                    SERIAL_ECHOLNPGM("");
                }
				#endif // SUPPORT_VERBOSITY
            }
        }
		#ifdef SUPPORT_VERBOSITY
        if (verbosity_level >= 10)
            delay_keep_alive(3000);
		#endif // SUPPORT_VERBOSITY
    }
    // Don't let the manage_inactivity() function remove power from the motors.
    refresh_cmd_timeout();

    // Average the last 4 measurements.
    for (int8_t i = 0; i < 8; ++ i)
        pts[i] *= (1.f/4.f);

    enable_endstops(false);
    enable_z_endstop(false);

	#ifdef SUPPORT_VERBOSITY
    if (verbosity_level >= 5) {
        // Test the positions. Are the positions reproducible?
		current_position[Z_AXIS] = MESH_HOME_Z_SEARCH;
        for (int8_t mesh_point = 0; mesh_point < 4; ++ mesh_point) {
            // Don't let the manage_inactivity() function remove power from the motors.
            refresh_cmd_timeout();
            // Go to the measurement point.
            // Use the coorrected coordinate, which is a result of find_bed_offset_and_skew().
            current_position[X_AXIS] = pts[mesh_point*2];
            current_position[Y_AXIS] = pts[mesh_point*2+1];
            if (verbosity_level >= 10) {
                go_to_current(homing_feedrate[X_AXIS]/60);
                delay_keep_alive(3000);
            }
            SERIAL_ECHOPGM("Final measured bed point ");
            SERIAL_ECHO(mesh_point);
            SERIAL_ECHOPGM(": ");
            MYSERIAL.print(current_position[X_AXIS], 5);
            SERIAL_ECHOPGM(", ");
            MYSERIAL.print(current_position[Y_AXIS], 5);
            SERIAL_ECHOLNPGM("");
        }
    }
	#endif // SUPPORT_VERBOSITY

    {
        // First fill in the too_far_mask from the measured points.
        for (uint8_t mesh_point = 0; mesh_point < 2; ++ mesh_point)
            if (pts[mesh_point * 2 + 1] < Y_MIN_POS_CALIBRATION_POINT_OUT_OF_REACH)
                too_far_mask |= 1 << mesh_point;
        result = calculate_machine_skew_and_offset_LS(pts, 4, bed_ref_points_4, vec_x, vec_y, cntr, verbosity_level);
        if (result < 0) {
            SERIAL_ECHOLNPGM("Calculation of the machine skew and offset failed.");
            goto canceled;
        }
        // In case of success, update the too_far_mask from the calculated points.
        for (uint8_t mesh_point = 0; mesh_point < 2; ++ mesh_point) {
            float y = vec_x[1] * pgm_read_float(bed_ref_points_4+mesh_point*2) + vec_y[1] * pgm_read_float(bed_ref_points_4+mesh_point*2+1) + cntr[1];
			#ifdef SUPPORT_VERBOSITY
			if (verbosity_level >= 20) {
				SERIAL_ECHOLNPGM("");
				SERIAL_ECHOPGM("Distance from min:");
				MYSERIAL.print(y - Y_MIN_POS_CALIBRATION_POINT_OUT_OF_REACH);
				SERIAL_ECHOLNPGM("");
				SERIAL_ECHOPGM("y:");
				MYSERIAL.print(y);
				SERIAL_ECHOLNPGM("");
			}
			#endif // SUPPORT_VERBOSITY
			if (y < Y_MIN_POS_CALIBRATION_POINT_OUT_OF_REACH)
                too_far_mask |= 1 << mesh_point;
        }
    }

    world2machine_update(vec_x, vec_y, cntr);
#if 1
    // Fearlessly store the calibration values into the eeprom.
    eeprom_update_float((float*)(EEPROM_BED_CALIBRATION_CENTER+0), cntr [0]);
    eeprom_update_float((float*)(EEPROM_BED_CALIBRATION_CENTER+4), cntr [1]);
    eeprom_update_float((float*)(EEPROM_BED_CALIBRATION_VEC_X +0), vec_x[0]);
    eeprom_update_float((float*)(EEPROM_BED_CALIBRATION_VEC_X +4), vec_x[1]);
    eeprom_update_float((float*)(EEPROM_BED_CALIBRATION_VEC_Y +0), vec_y[0]);
    eeprom_update_float((float*)(EEPROM_BED_CALIBRATION_VEC_Y +4), vec_y[1]);
#endif

    // Correct the current_position to match the transformed coordinate system after world2machine_rotation_and_skew and world2machine_shift were set.
	world2machine_update_current();

    enable_endstops(false);
    enable_z_endstop(false);
	#ifdef SUPPORT_VERBOSITY
    if (verbosity_level >= 5) {
        // Test the positions. Are the positions reproducible? Now the calibration is active in the planner.
        delay_keep_alive(3000);
		current_position[Z_AXIS] = MESH_HOME_Z_SEARCH;
        for (int8_t mesh_point = 0; mesh_point < 4; ++ mesh_point) {
            // Don't let the manage_inactivity() function remove power from the motors.
            refresh_cmd_timeout();
            // Go to the measurement point.
            // Use the coorrected coordinate, which is a result of find_bed_offset_and_skew().
            current_position[X_AXIS] = pgm_read_float(bed_ref_points_4+mesh_point*2);
            current_position[Y_AXIS] = pgm_read_float(bed_ref_points_4+mesh_point*2+1);
            if (verbosity_level >= 10) {
                go_to_current(homing_feedrate[X_AXIS]/60);
                delay_keep_alive(3000);
            }
            {
                float x, y;
                world2machine(current_position[X_AXIS], current_position[Y_AXIS], x, y);
                SERIAL_ECHOPGM("Final calculated bed point ");
                SERIAL_ECHO(mesh_point);
                SERIAL_ECHOPGM(": ");
                MYSERIAL.print(x, 5);
                SERIAL_ECHOPGM(", ");
                MYSERIAL.print(y, 5);
                SERIAL_ECHOLNPGM("");
            }
        }
    }
	#endif // SUPPORT_VERBOSITY

	if(!sample_z())
        goto canceled;

    enable_endstops(endstops_enabled);
    enable_z_endstop(endstop_z_enabled);
    // Don't let the manage_inactivity() function remove power from the motors.
    refresh_cmd_timeout();
    return result;

canceled:
    // Don't let the manage_inactivity() function remove power from the motors.
    refresh_cmd_timeout();
    // Print head up.
    current_position[Z_AXIS] = MESH_HOME_Z_SEARCH;
    go_to_current(homing_feedrate[Z_AXIS]/60);
    // Store the identity matrix to EEPROM.
    reset_bed_offset_and_skew();
    enable_endstops(endstops_enabled);
    enable_z_endstop(endstop_z_enabled);
    return result;
}
#endif //NEW_XYZCAL

bool sample_z() {
	bool sampled = true;
	//make space
	raise_z(150);
	lcd_show_fullscreen_message_and_wait_P(_T(MSG_PLACE_STEEL_SHEET));

	// Sample Z heights for the mesh bed leveling.
	// In addition, store the results into an eeprom, to be used later for verification of the bed leveling process.
	if (!sample_mesh_and_store_reference()) sampled = false;

	return sampled;
}

void go_home_with_z_lift()
{
    // Don't let the manage_inactivity() function remove power from the motors.
    refresh_cmd_timeout();
    // Go home.
    // First move up to a safe height.
    current_position[Z_AXIS] = MESH_HOME_Z_SEARCH;
    go_to_current(homing_feedrate[Z_AXIS]/60);
    // Second move to XY [0, 0].
    current_position[X_AXIS] = X_MIN_POS+0.2;
    current_position[Y_AXIS] = Y_MIN_POS+0.2;
    // Clamp to the physical coordinates.
    world2machine_clamp(current_position[X_AXIS], current_position[Y_AXIS]);
	go_to_current(homing_feedrate[X_AXIS]/20);
    // Third move up to a safe height.
    current_position[Z_AXIS] = Z_MIN_POS;
    go_to_current(homing_feedrate[Z_AXIS]/60);    
}

// Sample the 9 points of the bed and store them into the EEPROM as a reference.
// When calling this function, the X, Y, Z axes should be already homed,
// and the world2machine correction matrix should be active.
// Returns false if the reference values are more than 3mm far away.
bool sample_mesh_and_store_reference()
{
    bool endstops_enabled  = enable_endstops(false);
    bool endstop_z_enabled = enable_z_endstop(false);

    // Don't let the manage_inactivity() function remove power from the motors.
    refresh_cmd_timeout();

#ifdef MESH_BED_CALIBRATION_SHOW_LCD
    lcd_display_message_fullscreen_P(_T(MSG_MEASURE_BED_REFERENCE_HEIGHT_LINE1));
    // display "point xx of yy"
    lcd_puts_at_P(0,3,_n("1/9"));
#endif /* MESH_BED_CALIBRATION_SHOW_LCD */

    // Sample Z heights for the mesh bed leveling.
    // In addition, store the results into an eeprom, to be used later for verification of the bed leveling process.
    {
        // The first point defines the reference.
        current_position[Z_AXIS] = MESH_HOME_Z_SEARCH;
        go_to_current(homing_feedrate[Z_AXIS]/60);
        current_position[X_AXIS] = BED_X0;
        current_position[Y_AXIS] = BED_Y0;
        world2machine_clamp(current_position[X_AXIS], current_position[Y_AXIS]);
        go_to_current(homing_feedrate[X_AXIS]/60);
        set_destination_to_current();
        enable_endstops(true);
        homeaxis(Z_AXIS);

#ifdef TMC2130
		if (!axis_known_position[Z_AXIS] && (!READ(Z_TMC2130_DIAG))) //Z crash
		{
			kill(_T(MSG_BED_LEVELING_FAILED_POINT_LOW));
			return false;
		}
#endif //TMC2130

        enable_endstops(false);
		if (!find_bed_induction_sensor_point_z()) //Z crash or deviation > 50um
		{
			kill(_T(MSG_BED_LEVELING_FAILED_POINT_LOW));
			return false;
		}
        mbl.set_z(0, 0, current_position[Z_AXIS]);
    }
    static_assert(MESH_MEAS_NUM_X_POINTS * MESH_MEAS_NUM_Y_POINTS <= 255, "overflow.....");
    for (uint8_t mesh_point = 1; mesh_point != MESH_MEAS_NUM_X_POINTS * MESH_MEAS_NUM_Y_POINTS; ++ mesh_point) {
        // Don't let the manage_inactivity() function remove power from the motors.
        refresh_cmd_timeout();
        // Print the decrasing ID of the measurement point.
        current_position[Z_AXIS] = MESH_HOME_Z_SEARCH;
        go_to_current(homing_feedrate[Z_AXIS]/60);
		uint8_t ix = mesh_point % MESH_MEAS_NUM_X_POINTS;
		uint8_t iy = mesh_point / MESH_MEAS_NUM_X_POINTS;
		if (iy & 1) ix = (MESH_MEAS_NUM_X_POINTS - 1) - ix; // Zig zag
		current_position[X_AXIS] = BED_X(ix, MESH_MEAS_NUM_X_POINTS);
		current_position[Y_AXIS] = BED_Y(iy, MESH_MEAS_NUM_Y_POINTS);
        world2machine_clamp(current_position[X_AXIS], current_position[Y_AXIS]);
        go_to_current(homing_feedrate[X_AXIS]/60);
#ifdef MESH_BED_CALIBRATION_SHOW_LCD
        // display "point xx of yy"
		lcd_set_cursor(0, 3);
        lcd_printf_P(PSTR("%d/9"),mesh_point+1);
#endif /* MESH_BED_CALIBRATION_SHOW_LCD */
		if (!find_bed_induction_sensor_point_z()) //Z crash or deviation > 50um
		{
			kill(_T(MSG_BED_LEVELING_FAILED_POINT_LOW));
			return false;
		}
        // Get cords of measuring point
       
        mbl.set_z(ix, iy, current_position[Z_AXIS]);
    }
    {
        // Verify the span of the Z values.
        float zmin = mbl.z_values[0][0];
        float zmax = zmin;
        for (int8_t j = 0; j < 3; ++ j)
           for (int8_t i = 0; i < 3; ++ i) {
                zmin = min(zmin, mbl.z_values[j][i]);
                zmax = max(zmax, mbl.z_values[j][i]);
           }
        if (zmax - zmin > 3.f) {
            // The span of the Z offsets is extreme. Give up.
            // Homing failed on some of the points.
            SERIAL_PROTOCOLLNPGM("Exreme span of the Z values!");
            return false;
        }
    }

    // Store the correction values to EEPROM.
    // Offsets of the Z heiths of the calibration points from the first point.
    // The offsets are saved as 16bit signed int, scaled to tenths of microns.
    {
        uint16_t addr = EEPROM_BED_CALIBRATION_Z_JITTER;
        for (int8_t j = 0; j < 3; ++ j)
            for (int8_t i = 0; i < 3; ++ i) {
                if (i == 0 && j == 0)
                    continue;
                float dif = mbl.z_values[j][i] - mbl.z_values[0][0];
                int16_t dif_quantized = int16_t(floor(dif * 100.f + 0.5f));
                eeprom_update_word((uint16_t*)addr, *reinterpret_cast<uint16_t*>(&dif_quantized));
                #if 0
                {
                    uint16_t z_offset_u = eeprom_read_word((uint16_t*)addr);
                    float dif2 = *reinterpret_cast<int16_t*>(&z_offset_u) * 0.01;

                    SERIAL_ECHOPGM("Bed point ");
                    SERIAL_ECHO(i);
                    SERIAL_ECHOPGM(",");
                    SERIAL_ECHO(j);
                    SERIAL_ECHOPGM(", differences: written ");
                    MYSERIAL.print(dif, 5);
                    SERIAL_ECHOPGM(", read: ");
                    MYSERIAL.print(dif2, 5);
                    SERIAL_ECHOLNPGM("");
                }
                #endif
                addr += 2;
            }
    }

    mbl.upsample_3x3();
    mbl.active = true;

    go_home_with_z_lift();

    enable_endstops(endstops_enabled);
    enable_z_endstop(endstop_z_enabled);
    return true;
}

#ifndef NEW_XYZCAL
bool scan_bed_induction_points(int8_t verbosity_level)
{
    // Don't let the manage_inactivity() function remove power from the motors.
    refresh_cmd_timeout();

    // Reusing the z_values memory for the measurement cache.
    // 7x7=49 floats, good for 16 (x,y,z) vectors.
    float *pts = &mbl.z_values[0][0];
    float *vec_x = pts + 2 * 9;
    float *vec_y = vec_x + 2;
    float *cntr  = vec_y + 2;
    memset(pts, 0, sizeof(float) * 7 * 7);

    // Cache the current correction matrix.
    world2machine_initialize();
    vec_x[0] = world2machine_rotation_and_skew[0][0];
    vec_x[1] = world2machine_rotation_and_skew[1][0];
    vec_y[0] = world2machine_rotation_and_skew[0][1];
    vec_y[1] = world2machine_rotation_and_skew[1][1];
    cntr[0] = world2machine_shift[0];
    cntr[1] = world2machine_shift[1];
    // and reset the correction matrix, so the planner will not do anything.
    world2machine_reset();

    bool endstops_enabled  = enable_endstops(false);
    bool endstop_z_enabled = enable_z_endstop(false);

    // Collect a matrix of 9x9 points.
    for (int8_t mesh_point = 0; mesh_point < 9; ++ mesh_point) {
        // Don't let the manage_inactivity() function remove power from the motors.
        refresh_cmd_timeout();

        // Move up.
        current_position[Z_AXIS] = MESH_HOME_Z_SEARCH;
        enable_endstops(false);
        enable_z_endstop(false);
        go_to_current(homing_feedrate[Z_AXIS]/60);
        // Go to the measurement point.
        // Use the coorrected coordinate, which is a result of find_bed_offset_and_skew().
		uint8_t ix = mesh_point % MESH_MEAS_NUM_X_POINTS; // from 0 to MESH_NUM_X_POINTS - 1
		uint8_t iy = mesh_point / MESH_MEAS_NUM_X_POINTS;
		if (iy & 1) ix = (MESH_MEAS_NUM_X_POINTS - 1) - ix;
		float bedX = BED_X(ix, MESH_MEAS_NUM_X_POINTS);
		float bedY = BED_Y(iy, MESH_MEAS_NUM_Y_POINTS);
        current_position[X_AXIS] = vec_x[0] * bedX + vec_y[0] * bedY + cntr[0];
        current_position[Y_AXIS] = vec_x[1] * bedX + vec_y[1] * bedY + cntr[1];
        // The calibration points are very close to the min Y.
        if (current_position[Y_AXIS] < Y_MIN_POS_FOR_BED_CALIBRATION)
            current_position[Y_AXIS] = Y_MIN_POS_FOR_BED_CALIBRATION;
        go_to_current(homing_feedrate[X_AXIS]/60);
        find_bed_induction_sensor_point_z();
		scan_bed_induction_sensor_point();
    }
    // Don't let the manage_inactivity() function remove power from the motors.
    refresh_cmd_timeout();

    enable_endstops(false);
    enable_z_endstop(false);

    // Don't let the manage_inactivity() function remove power from the motors.
    refresh_cmd_timeout();

    enable_endstops(endstops_enabled);
    enable_z_endstop(endstop_z_enabled);
    return true;
}
#endif //NEW_XYZCAL

// Shift a Z axis by a given delta.
// To replace loading of the babystep correction.
static void shift_z(float delta)
{
    plan_buffer_line(current_position[X_AXIS], current_position[Y_AXIS], current_position[Z_AXIS] - delta, current_position[E_AXIS], homing_feedrate[Z_AXIS]/40);
    st_synchronize();
    plan_set_z_position(current_position[Z_AXIS]);
}

// Number of baby steps applied
static int babystepLoadZ = 0;

void babystep_load()
{
	babystepLoadZ = 0;
    // Apply Z height correction aka baby stepping before mesh bed leveling gets activated.
    if (calibration_status_get(CALIBRATION_STATUS_LIVE_ADJUST))
    {
        check_babystep(); //checking if babystep is in allowed range, otherwise setting babystep to 0
        
        // End of G80: Apply the baby stepping value.
        babystepLoadZ = eeprom_read_word(reinterpret_cast<uint16_t *>(&(EEPROM_Sheets_base->
                    s[(eeprom_read_byte(&(EEPROM_Sheets_base->active_sheet)))].z_offset)));
                            
    #if 0
        SERIAL_ECHO("Z baby step: ");
        SERIAL_ECHO(babystepLoadZ);
        SERIAL_ECHO(", current Z: ");
        SERIAL_ECHO(current_position[Z_AXIS]);
        SERIAL_ECHO("correction: ");
        SERIAL_ECHO(float(babystepLoadZ) / float(axis_steps_per_unit[Z_AXIS]));
        SERIAL_ECHOLN("");
    #endif
    }
}

void babystep_apply()
{
    babystep_load();
    shift_z(- float(babystepLoadZ) / float(cs.axis_steps_per_unit[Z_AXIS]));
}

void babystep_undo()
{
      shift_z(float(babystepLoadZ) / float(cs.axis_steps_per_unit[Z_AXIS]));
      babystepLoadZ = 0;
}

void babystep_reset()
{
	babystepLoadZ = 0;    
}

void count_xyz_details(float (&distanceMin)[2]) {
	float cntr[2] = {
		eeprom_read_float((float*)(EEPROM_BED_CALIBRATION_CENTER + 0)),
		eeprom_read_float((float*)(EEPROM_BED_CALIBRATION_CENTER + 4))
	};
	float vec_x[2] = {
		eeprom_read_float((float*)(EEPROM_BED_CALIBRATION_VEC_X + 0)),
		eeprom_read_float((float*)(EEPROM_BED_CALIBRATION_VEC_X + 4))
	};
	float vec_y[2] = {
		eeprom_read_float((float*)(EEPROM_BED_CALIBRATION_VEC_Y + 0)),
		eeprom_read_float((float*)(EEPROM_BED_CALIBRATION_VEC_Y + 4))
	};
#if 0
	a2 = -1 * asin(vec_y[0] / MACHINE_AXIS_SCALE_Y);
	a1 = asin(vec_x[1] / MACHINE_AXIS_SCALE_X);
	angleDiff = fabs(a2 - a1);
#endif
	for (uint8_t mesh_point = 0; mesh_point < 2; ++mesh_point) {
		float y = vec_x[1] * pgm_read_float(bed_ref_points_4 + mesh_point * 2) + vec_y[1] * pgm_read_float(bed_ref_points_4 + mesh_point * 2 + 1) + cntr[1];
		distanceMin[mesh_point] = (y - Y_MIN_POS_CALIBRATION_POINT_OUT_OF_REACH);
	}
}
/*
e_MBL_TYPE e_mbl_type = e_MBL_OPTIMAL;

void mbl_mode_set() {
	switch (e_mbl_type) {
		case e_MBL_OPTIMAL: e_mbl_type = e_MBL_PREC; break;
		case e_MBL_PREC: e_mbl_type = e_MBL_FAST; break;
		case e_MBL_FAST: e_mbl_type = e_MBL_OPTIMAL; break;
		default: e_mbl_type = e_MBL_OPTIMAL; break;
	}
	eeprom_update_byte((uint8_t*)EEPROM_MBL_TYPE,(uint8_t)e_mbl_type);
}

void mbl_mode_init() {
	uint8_t mbl_type = eeprom_read_byte((uint8_t*)EEPROM_MBL_TYPE);
	if (mbl_type == 0xFF) e_mbl_type = e_MBL_OPTIMAL;
	else e_mbl_type = mbl_type;
}
*/

void mbl_settings_init() {
//3x3 mesh; 3 Z-probes on each point, magnet elimination on
//magnet elimination: use aaproximate Z-coordinate instead of measured values for points which are near magnets
	eeprom_init_default_byte((uint8_t*)EEPROM_MBL_MAGNET_ELIMINATION, 1);
	eeprom_init_default_byte((uint8_t*)EEPROM_MBL_POINTS_NR, 3);
	mbl_z_probe_nr = eeprom_init_default_byte((uint8_t*)EEPROM_MBL_PROBE_NR, 3);
}

//parameter ix: index of mesh bed leveling point in X-axis (for meas_points == 7 is valid range from 0 to 6; for meas_points == 3 is valid range from 0 to 2 )  
//parameter iy: index of mesh bed leveling point in Y-axis (for meas_points == 7 is valid range from 0 to 6; for meas_points == 3 is valid range from 0 to 2 ) 
//parameter meas_points: number of mesh bed leveling points in one axis; currently designed and tested for values 3 and 7
//parameter zigzag: false if ix is considered 0 on left side of bed and ix rises with rising X coordinate; true if ix is considered 0 on the right side of heatbed for odd iy values (zig zag mesh bed leveling movements)  
//function returns true if point is considered valid (typicaly in safe distance from magnet or another object which inflences PINDA measurements)
bool mbl_point_measurement_valid(uint8_t ix, uint8_t iy, uint8_t meas_points, bool zigzag) {
	    //"human readable" heatbed plan
		//magnet proximity influence Z coordinate measurements significantly (40 - 100 um)
		//0 - measurement point is above magnet and Z coordinate can be influenced negatively
		//1 - we should be in safe distance from magnets, measurement should be accurate
		if ((ix >= meas_points) || (iy >= meas_points)) return false;

		uint8_t valid_points_mask[7] = {
					//[X_MAX,Y_MAX]
			//0123456
			0b1111111,//6
			0b1111111,//5
			0b1110111,//4
			0b1111011,//3
			0b1110111,//2
			0b1111111,//1
			0b1111111,//0
		//[0,0]
		};
		if (meas_points == 3) {
			ix *= 3;
			iy *= 3;
		}
		if (zigzag) {
			if ((iy % 2) == 0)	return (valid_points_mask[6 - iy] & (1 << (6 - ix)));
			else return (valid_points_mask[6 - iy] & (1 << ix));
		}
		else {
			return (valid_points_mask[6 - iy] & (1 << (6 - ix)));
		}
}

void mbl_single_point_interpolation(uint8_t x, uint8_t y, uint8_t meas_points) {
	//printf_P(PSTR("x = %d; y = %d \n"), x, y);
		uint8_t count = 0;
		float z = 0;
		if (mbl_point_measurement_valid(x, y + 1, meas_points, false)) { z += mbl.z_values[y + 1][x]; /*printf_P(PSTR("x; y+1: Z = %f \n"), mbl.z_values[y + 1][x]);*/ count++; }
		if (mbl_point_measurement_valid(x, y - 1, meas_points, false)) { z += mbl.z_values[y - 1][x]; /*printf_P(PSTR("x; y-1: Z = %f \n"), mbl.z_values[y - 1][x]);*/ count++; }
		if (mbl_point_measurement_valid(x + 1, y, meas_points, false)) { z += mbl.z_values[y][x + 1]; /*printf_P(PSTR("x+1; y: Z = %f \n"), mbl.z_values[y][x + 1]);*/ count++; }
		if (mbl_point_measurement_valid(x - 1, y, meas_points, false)) { z += mbl.z_values[y][x - 1]; /*printf_P(PSTR("x-1; y: Z = %f \n"), mbl.z_values[y][x - 1]);*/ count++; }
		if(count != 0) mbl.z_values[y][x] = z / count; //if we have at least one valid point in surrounding area use average value, otherwise use inaccurately measured Z-coordinate
		//printf_P(PSTR("result: Z = %f \n\n"), mbl.z_values[y][x]);
}

void mbl_interpolation(uint8_t meas_points) {
	for (uint8_t x = 0; x < meas_points; x++) {
		for (uint8_t y = 0; y < meas_points; y++) {
			if (!mbl_point_measurement_valid(x, y, meas_points, false)) {
				mbl_single_point_interpolation(x, y, meas_points);
			}
		}
	}
}