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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
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