extruder: Add support for reversing the direction of extruder stepper movement

Extend SET_EXTRUDER_ROTATION_DISTANCE to support reversing the
direction of extruder movement.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

docs/G-Codes.md

@@ -303,11 +303,13 @@ extruder.
 #### SET_EXTRUDER_ROTATION_DISTANCE
 `SET_EXTRUDER_ROTATION_DISTANCE EXTRUDER=<config_name>
 [DISTANCE=<distance>]`: Set a new value for the provided extruder's
-"rotation distance". Value is not retained on Klipper reset. Use with
+"rotation distance". If the rotation distance is a negative number
-caution as small changes can result in excessive pressure between
+then the stepper motion will be inverted (relative to the stepper
-extruder and hot end. Do proper calibration with filament before use.
+direction specified in the config file). Changed settings are not
-If 'DISTANCE' value is not included command will return current
+retained on Klipper reset. Use with caution as small changes can
-rotation distance.
+result in excessive pressure between extruder and hot end. Do proper
+calibration with filament before use. If 'DISTANCE' value is not
+included command will return current rotation distance.
 
 #### SET_EXTRUDER_STEP_DISTANCE
 `SET_EXTRUDER_STEP_DISTANCE EXTRUDER=<config_name>

klippy/chelper/__init__.py

@@ -38,8 +38,9 @@ defs_stepcompress = """
 
     struct stepcompress *stepcompress_alloc(uint32_t oid);
     void stepcompress_fill(struct stepcompress *sc, uint32_t max_error
-        , uint32_t invert_sdir, int32_t queue_step_msgtag
+        , int32_t queue_step_msgtag, int32_t set_next_step_dir_msgtag);
-        , int32_t set_next_step_dir_msgtag);
+    void stepcompress_set_invert_sdir(struct stepcompress *sc
+        , uint32_t invert_sdir);
     void stepcompress_free(struct stepcompress *sc);
     int stepcompress_reset(struct stepcompress *sc, uint64_t last_step_clock);
     int stepcompress_set_last_position(struct stepcompress *sc

klippy/chelper/stepcompress.c

@@ -259,15 +259,25 @@ stepcompress_alloc(uint32_t oid)
 // Fill message id information
 void __visible
 stepcompress_fill(struct stepcompress *sc, uint32_t max_error
-                  , uint32_t invert_sdir, int32_t queue_step_msgtag
+                  , int32_t queue_step_msgtag, int32_t set_next_step_dir_msgtag)
-                  , int32_t set_next_step_dir_msgtag)
 {
     sc->max_error = max_error;
-    sc->invert_sdir = !!invert_sdir;
     sc->queue_step_msgtag = queue_step_msgtag;
     sc->set_next_step_dir_msgtag = set_next_step_dir_msgtag;
 }
 
+// Set the inverted stepper direction flag
+void __visible
+stepcompress_set_invert_sdir(struct stepcompress *sc, uint32_t invert_sdir)
+{
+    invert_sdir = !!invert_sdir;
+    if (invert_sdir != sc->invert_sdir) {
+        sc->invert_sdir = invert_sdir;
+        if (sc->sdir >= 0)
+            sc->sdir ^= 1;
+    }
+}
+
 // Helper to free items from the history_list
 static void
 free_history(struct stepcompress *sc, uint64_t end_clock)

klippy/chelper/stepcompress.h

@@ -13,8 +13,10 @@ struct pull_history_steps {
 
 struct stepcompress *stepcompress_alloc(uint32_t oid);
 void stepcompress_fill(struct stepcompress *sc, uint32_t max_error
-                       , uint32_t invert_sdir, int32_t queue_step_msgtag
+                       , int32_t queue_step_msgtag
                        , int32_t set_next_step_dir_msgtag);
+void stepcompress_set_invert_sdir(struct stepcompress *sc
+                                  , uint32_t invert_sdir);
 void stepcompress_free(struct stepcompress *sc);
 uint32_t stepcompress_get_oid(struct stepcompress *sc);
 int stepcompress_get_step_dir(struct stepcompress *sc);

klippy/extras/motion_report.py

@@ -139,7 +139,7 @@ class DumpStepper:
         mcu_pos = first.start_position
         start_position = self.mcu_stepper.mcu_to_commanded_position(mcu_pos)
         step_dist = self.mcu_stepper.get_step_dist()
-        if self.mcu_stepper.is_dir_inverted():
+        if self.mcu_stepper.get_dir_inverted()[0]:
             step_dist = -step_dist
         d = [(s.interval, s.step_count, s.add) for s in data]
         return {"data": d, "start_position": start_position,

klippy/extras/tmc.py

@@ -224,6 +224,8 @@ class TMCCommandHelper:
         self.stepper_enable = self.printer.load_object(config, "stepper_enable")
         self.printer.register_event_handler("stepper:sync_mcu_position",
                                             self._handle_sync_mcu_pos)
+        self.printer.register_event_handler("stepper:set_sdir_inverted",
+                                            self._handle_sync_mcu_pos)
         self.printer.register_event_handler("klippy:mcu_identify",
                                             self._handle_mcu_identify)
         self.printer.register_event_handler("klippy:connect",
@@ -306,7 +308,7 @@ class TMCCommandHelper:
             if enable_line.is_motor_enabled():
                 raise
             return
-        if not stepper.is_dir_inverted():
+        if not stepper.get_dir_inverted()[0]:
             driver_phase = 1023 - driver_phase
         phases = self._get_phases()
         phase = int(float(driver_phase) / 1024 * phases + .5) % phases

klippy/kinematics/extruder.py

@@ -91,13 +91,24 @@ class ExtruderStepper:
         gcmd.respond_info(msg, log=False)
     cmd_SET_E_ROTATION_DISTANCE_help = "Set extruder rotation distance"
     def cmd_SET_E_ROTATION_DISTANCE(self, gcmd):
-        rotation_dist = gcmd.get_float('DISTANCE', None, above=0.)
+        rotation_dist = gcmd.get_float('DISTANCE', None)
         if rotation_dist is not None:
+            if not rotation_dist:
+                raise gcmd.error("Rotation distance can not be zero")
+            invert_dir, orig_invert_dir = self.stepper.get_dir_inverted()
+            next_invert_dir = orig_invert_dir
+            if rotation_dist < 0.:
+                next_invert_dir = not orig_invert_dir
+                rotation_dist = -rotation_dist
             toolhead = self.printer.lookup_object('toolhead')
             toolhead.flush_step_generation()
             self.stepper.set_rotation_distance(rotation_dist)
+            self.stepper.set_dir_inverted(next_invert_dir)
         else:
             rotation_dist, spr = self.stepper.get_rotation_distance()
+        invert_dir, orig_invert_dir = self.stepper.get_dir_inverted()
+        if invert_dir != orig_invert_dir:
+            rotation_dist = -rotation_dist
         gcmd.respond_info("Extruder '%s' rotation distance set to %0.6f"
                           % (self.name, rotation_dist))
     cmd_SET_E_STEP_DISTANCE_help = "Set extruder step distance"

klippy/stepper.py

@@ -36,7 +36,7 @@ class MCU_stepper:
             raise self._mcu.get_printer().config_error(
                 "Stepper dir pin must be on same mcu as step pin")
         self._dir_pin = dir_pin_params['pin']
-        self._invert_dir = dir_pin_params['invert']
+        self._invert_dir = self._orig_invert_dir = dir_pin_params['invert']
         self._step_both_edge = self._req_step_both_edge = False
         self._mcu_position_offset = 0.
         self._reset_cmd_tag = self._get_position_cmd = None
@@ -44,6 +44,7 @@ class MCU_stepper:
         ffi_main, ffi_lib = chelper.get_ffi()
         self._stepqueue = ffi_main.gc(ffi_lib.stepcompress_alloc(oid),
                                       ffi_lib.stepcompress_free)
+        ffi_lib.stepcompress_set_invert_sdir(self._stepqueue, self._invert_dir)
         self._mcu.register_stepqueue(self._stepqueue)
         self._stepper_kinematics = None
         self._itersolve_generate_steps = ffi_lib.itersolve_generate_steps
@@ -101,7 +102,7 @@ class MCU_stepper:
         max_error_ticks = self._mcu.seconds_to_clock(max_error)
         ffi_main, ffi_lib = chelper.get_ffi()
         ffi_lib.stepcompress_fill(self._stepqueue, max_error_ticks,
-                                  self._invert_dir, step_cmd_tag, dir_cmd_tag)
+                                  step_cmd_tag, dir_cmd_tag)
     def get_oid(self):
         return self._oid
     def get_step_dist(self):
@@ -114,8 +115,16 @@ class MCU_stepper:
         self._step_dist = rotation_dist / self._steps_per_rotation
         self.set_stepper_kinematics(self._stepper_kinematics)
         self._set_mcu_position(mcu_pos)
-    def is_dir_inverted(self):
+    def get_dir_inverted(self):
-        return self._invert_dir
+        return self._invert_dir, self._orig_invert_dir
+    def set_dir_inverted(self, invert_dir):
+        invert_dir = not not invert_dir
+        if invert_dir == self._invert_dir:
+            return
+        self._invert_dir = invert_dir
+        ffi_main, ffi_lib = chelper.get_ffi()
+        ffi_lib.stepcompress_set_invert_sdir(self._stepqueue, invert_dir)
+        self._mcu.get_printer().send_event("stepper:set_dir_inverted", self)
     def calc_position_from_coord(self, coord):
         ffi_main, ffi_lib = chelper.get_ffi()
         return ffi_lib.itersolve_calc_position_from_coord(

test/klippy/extruders.test

@@ -13,9 +13,13 @@ G1 X20 Y20 Z1
 G1 X25 Y25 E7.5
 
 # Update step_distance
-SET_EXTRUDER_STEP_DISTANCE EXTRUDER=extruder DISTANCE=.005
+SET_EXTRUDER_ROTATION_DISTANCE EXTRUDER=extruder DISTANCE=33.2
 G1 X30 Y30 E8.0
 
+# Reverse step_distance
+SET_EXTRUDER_ROTATION_DISTANCE EXTRUDER=extruder DISTANCE=-33.1
+G1 X30 Y30 E8.2
+
 # Disable extruder stepper motor
 SYNC_STEPPER_TO_EXTRUDER STEPPER=extruder EXTRUDER=
 G1 X35 Y35 E8.5