1 files changed, 144 insertions, 0 deletions
diff --git a/Marlin/src/feature/backlash.cpp b/Marlin/src/feature/backlash.cpp
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+/**
+ * Marlin 3D Printer Firmware
+ * Copyright (c) 2020 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
+ *
+ * Based on Sprinter and grbl.
+ * Copyright (c) 2011 Camiel Gubbels / Erik van der Zalm
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "../inc/MarlinConfigPre.h"
+
+#if ENABLED(BACKLASH_COMPENSATION)
+
+#include "backlash.h"
+
+#include "../module/motion.h"
+#include "../module/planner.h"
+
+#ifdef BACKLASH_DISTANCE_MM
+  #if ENABLED(BACKLASH_GCODE)
+    xyz_float_t Backlash::distance_mm = BACKLASH_DISTANCE_MM;
+  #else
+    const xyz_float_t Backlash::distance_mm = BACKLASH_DISTANCE_MM;
+  #endif
+#endif
+
+#if ENABLED(BACKLASH_GCODE)
+  uint8_t Backlash::correction = (BACKLASH_CORRECTION) * 0xFF;
+  #ifdef BACKLASH_SMOOTHING_MM
+    float Backlash::smoothing_mm = BACKLASH_SMOOTHING_MM;
+  #endif
+#endif
+
+#if ENABLED(MEASURE_BACKLASH_WHEN_PROBING)
+  xyz_float_t Backlash::measured_mm{0};
+  xyz_uint8_t Backlash::measured_count{0};
+#endif
+
+Backlash backlash;
+
+/**
+ * To minimize seams in the printed part, backlash correction only adds
+ * steps to the current segment (instead of creating a new segment, which
+ * causes discontinuities and print artifacts).
+ *
+ * With a non-zero BACKLASH_SMOOTHING_MM value the backlash correction is
+ * spread over multiple segments, smoothing out artifacts even more.
+ */
+
+void Backlash::add_correction_steps(const int32_t &da, const int32_t &db, const int32_t &dc, const uint8_t dm, block_t * const block) {
+  static uint8_t last_direction_bits;
+  uint8_t changed_dir = last_direction_bits ^ dm;
+  // Ignore direction change if no steps are taken in that direction
+  if (da == 0) CBI(changed_dir, X_AXIS);
+  if (db == 0) CBI(changed_dir, Y_AXIS);
+  if (dc == 0) CBI(changed_dir, Z_AXIS);
+  last_direction_bits ^= changed_dir;
+
+  if (correction == 0) return;
+
+  #ifdef BACKLASH_SMOOTHING_MM
+    // The segment proportion is a value greater than 0.0 indicating how much residual_error
+    // is corrected for in this segment. The contribution is based on segment length and the
+    // smoothing distance. Since the computation of this proportion involves a floating point
+    // division, defer computation until needed.
+    float segment_proportion = 0;
+
+    // Residual error carried forward across multiple segments, so correction can be applied
+    // to segments where there is no direction change.
+    static xyz_long_t residual_error{0};
+  #else
+    // No direction change, no correction.
+    if (!changed_dir) return;
+    // No leftover residual error from segment to segment
+    xyz_long_t residual_error{0};
+  #endif
+
+  const float f_corr = float(correction) / 255.0f;
+
+  LOOP_XYZ(axis) {
+    if (distance_mm[axis]) {
+      const bool reversing = TEST(dm,axis);
+
+      // When an axis changes direction, add axis backlash to the residual error
+      if (TEST(changed_dir, axis))
+        residual_error[axis] += (reversing ? -f_corr : f_corr) * distance_mm[axis] * planner.settings.axis_steps_per_mm[axis];
+
+      // Decide how much of the residual error to correct in this segment
+      int32_t error_correction = residual_error[axis];
+      #ifdef BACKLASH_SMOOTHING_MM
+        if (error_correction && smoothing_mm != 0) {
+          // Take up a portion of the residual_error in this segment, but only when
+          // the current segment travels in the same direction as the correction
+          if (reversing == (error_correction < 0)) {
+            if (segment_proportion == 0)
+              segment_proportion = _MIN(1.0f, block->millimeters / smoothing_mm);
+            error_correction = CEIL(segment_proportion * error_correction);
+          }
+          else
+            error_correction = 0; // Don't take up any backlash in this segment, as it would subtract steps
+        }
+      #endif
+      // Making a correction reduces the residual error and adds block steps
+      if (error_correction) {
+        block->steps[axis] += ABS(error_correction);
+        residual_error[axis] -= error_correction;
+      }
+    }
+  }
+}
+
+#if ENABLED(MEASURE_BACKLASH_WHEN_PROBING)
+
+  #include "../module/probe.h"
+
+  // Measure Z backlash by raising nozzle in increments until probe deactivates
+  void Backlash::measure_with_probe() {
+    if (measured_count.z == 255) return;
+
+    const float start_height = current_position.z;
+    while (current_position.z < (start_height + BACKLASH_MEASUREMENT_LIMIT) && PROBE_TRIGGERED())
+      do_blocking_move_to_z(current_position.z + BACKLASH_MEASUREMENT_RESOLUTION, MMM_TO_MMS(BACKLASH_MEASUREMENT_FEEDRATE));
+
+    // The backlash from all probe points is averaged, so count the number of measurements
+    measured_mm.z += current_position.z - start_height;
+    measured_count.z++;
+  }
+
+#endif
+
+#endif // BACKLASH_COMPENSATION