measurements points moved 10mm to the left; measure only chosen points (e.g. not points affected by magnets proximity)

Firmware/Marlin_main.cpp

@@ -4467,6 +4467,12 @@ if((eSoundMode==e_SOUND_MODE_LOUD)||(eSoundMode==e_SOUND_MODE_ONCE))
 			// Get coords of a measuring point.
 			uint8_t ix = mesh_point % nMeasPoints; // from 0 to MESH_NUM_X_POINTS - 1
 			uint8_t iy = mesh_point / nMeasPoints;
+			if (!mbl_point_measurement_valid(ix, iy, nMeasPoints)) {
+				printf_P(PSTR("Skipping point [%d;%d] \n"), ix, iy);
+				custom_message_state--;
+				mesh_point++;
+				continue; //skip
+			}
 			if (iy & 1) ix = (nMeasPoints - 1) - ix; // Zig zag
 			float z0 = 0.f;
 			if (has_z && (mesh_point > 0)) {
@@ -4686,7 +4692,7 @@ if((eSoundMode==e_SOUND_MODE_LOUD)||(eSoundMode==e_SOUND_MODE_ONCE))
 		}
 //		SERIAL_ECHOLNPGM("Bed leveling correction finished");
 		if (nMeasPoints == 3) {
-			mbl.upsample_3x3(); //bilinear interpolation from 3x3 to 7x7 points while using the same array z_values[iy][ix] for storing (just coppying measured data to new destination and interpolating between them)
+			mbl.upsample_3x3(); //interpolation from 3x3 to 7x7 points using largrangian polynomials while using the same array z_values[iy][ix] for storing (just coppying measured data to new destination and interpolating between them)
 		}
 //		SERIAL_ECHOLNPGM("Upsample finished");
 		mbl.active = 1; //activate mesh bed leveling

Firmware/mesh_bed_calibration.cpp

@@ -3065,4 +3065,28 @@ 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;
+}
+
+bool mbl_point_measurement_valid(uint8_t ix, uint8_t iy, uint8_t meas_points) {
+	    //"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
+		uint8_t valid_points_mask[7] = {
+					//[X_MAX,Y_MAX]
+			0b1111101,
+			0b1110111,
+			0b1111111,
+			0b0111011,
+			0b1110111,
+			0b1111111,
+			0b1110111,
+		//[0,0]
+		};
+		if (meas_points == 3) {
+			ix *= 3;
+			iy *= 3;
+		}
+		if((iy%2) == 0)	return (valid_points_mask[6 - iy] & (1 << (6 - ix)));
+		else return (valid_points_mask[6 - iy] & (1 << ix));
 }

Firmware/mesh_bed_calibration.h

@@ -6,9 +6,9 @@
 
 #ifdef HEATBED_V2
 
-#define BED_X0 (13.f - BED_ZERO_REF_X)
+#define BED_X0 (3.f - BED_ZERO_REF_X)
 #define BED_Y0 (10.4f - BED_ZERO_REF_Y)
-#define BED_Xn (216.f - BED_ZERO_REF_X)
+#define BED_Xn (206.f - BED_ZERO_REF_X)
 #define BED_Yn (202.4f - BED_ZERO_REF_Y)
 
 #else
@@ -210,4 +210,6 @@ extern e_MBL_TYPE e_mbl_type;
 extern void mbl_mode_set();
 extern void mbl_mode_init();
 
+extern bool mbl_point_measurement_valid(uint8_t ix, uint8_t iy, uint8_t meas_points);
+
 #endif /* MESH_BED_CALIBRATION_H */