extruder: Allow an extruder object to be created without a stepper

This may be useful for dual hotend printers that have only one
stepper.

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

1 files changed, 16 insertions, 7 deletions

diff --git a/klippy/kinematics/extruder.py b/klippy/kinematics/extruder.py
index 99d5daf8..e3303982 100644
--- a/klippy/kinematics/extruder.py
+++ b/klippy/kinematics/extruder.py
@@ -79,6 +79,8 @@ class ExtruderStepper:
     cmd_SET_PRESSURE_ADVANCE_help = "Set pressure advance parameters"
     def cmd_default_SET_PRESSURE_ADVANCE(self, gcmd):
         extruder = self.printer.lookup_object('toolhead').get_extruder()
+        if extruder.extruder_stepper is None:
+            raise gcmd.error("Active extruder does not have a stepper")
         extruder.extruder_stepper.cmd_SET_PRESSURE_ADVANCE(gcmd)
     def cmd_SET_PRESSURE_ADVANCE(self, gcmd):
         pressure_advance = gcmd.get_float('ADVANCE', self.pressure_advance,
@@ -181,12 +183,16 @@ class PrinterExtruder:
         self.trapq_append = ffi_lib.trapq_append
         self.trapq_finalize_moves = ffi_lib.trapq_finalize_moves
         # Setup extruder stepper
-        self.extruder_stepper = ExtruderStepper(config)
-        self.extruder_stepper.stepper.set_trapq(self.trapq)
-        pa = config.getfloat('pressure_advance', 0., minval=0.)
-        smooth_time = config.getfloat('pressure_advance_smooth_time',
-                                      0.040, above=0., maxval=.200)
-        self.extruder_stepper._set_pressure_advance(pa, smooth_time)
+        self.extruder_stepper = None
+        if (config.get('step_pin', None) is not None
+            or config.get('dir_pin', None) is not None
+            or config.get('rotation_distance', None) is not None):
+            self.extruder_stepper = ExtruderStepper(config)
+            self.extruder_stepper.stepper.set_trapq(self.trapq)
+            pa = config.getfloat('pressure_advance', 0., minval=0.)
+            smooth_time = config.getfloat('pressure_advance_smooth_time',
+                                          0.040, above=0., maxval=.200)
+            self.extruder_stepper._set_pressure_advance(pa, smooth_time)
         # Register commands
         gcode = self.printer.lookup_object('gcode')
         if self.name == 'extruder':
@@ -201,7 +207,8 @@ class PrinterExtruder:
     def get_status(self, eventtime):
         sts = self.heater.get_status(eventtime)
         sts['can_extrude'] = self.heater.can_extrude
-        sts.update(self.extruder_stepper.get_status(eventtime))
+        if self.extruder_stepper is not None:
+            sts.update(self.extruder_stepper.get_status(eventtime))
         return sts
     def get_name(self):
         return self.name
@@ -259,6 +266,8 @@ class PrinterExtruder:
                           start_v, cruise_v, accel)
         self.last_position = move.end_pos[3]
     def find_past_position(self, print_time):
+        if self.extruder_stepper is None:
+            return 0.
         return self.extruder_stepper.find_past_position(print_time)
     def cmd_M104(self, gcmd, wait=False):
         # Set Extruder Temperature