stepper: Use a sane default for homing_positive_dir

Use the endstop position to determine a sane default for
homing_positive_dir.

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

config/example-corexy.cfg

@@ -15,9 +15,9 @@ dir_pin: ar55
 enable_pin: !ar38
 step_distance: .01
 endstop_pin: ^ar3
-homing_speed: 50.0
 position_endstop: 0
 position_max: 200
+homing_speed: 50
 
 # The stepper_y section is used to describe the Y axis as well as the
 # stepper controlling the X-Y movement.
@@ -27,9 +27,9 @@ dir_pin: ar61
 enable_pin: !ar56
 step_distance: .01
 endstop_pin: ^ar14
-homing_speed: 50.0
 position_endstop: 0
 position_max: 200
+homing_speed: 50
 
 [stepper_z]
 step_pin: ar46

config/example-delta.cfg

@@ -16,12 +16,12 @@ dir_pin: ar55
 enable_pin: !ar38
 step_distance: .01
 endstop_pin: ^ar2
-homing_speed: 50.0
 position_endstop: 297.05
 #angle:
 #   This option specifies the angle (in degrees) that the tower is
 #   at. The default is 210 for stepper_a, 330 for stepper_b, and 90
 #   for stepper_c.
+homing_speed: 50
 
 # The stepper_b section describes the stepper controlling the front
 # right tower (at 330 degrees).

config/example.cfg

@@ -35,15 +35,27 @@ step_distance: .0225
 endstop_pin: ^ar3
 #   Endstop switch detection pin. This parameter must be provided for
 #   the X, Y, and Z steppers on cartesian style printers.
+#position_min: 0
+#   Minimum valid distance (in mm) the user may command the stepper to
+#   move to.  The default is 0mm.
+position_endstop: 0
+#   Location of the endstop (in mm). This parameter must be provided
+#   for the X, Y, and Z steppers on cartesian style printers.
+position_max: 200
+#   Maximum valid distance (in mm) the user may command the stepper to
+#   move to. This parameter must be provided for the X, Y, and Z
+#   steppers on cartesian style printers.
 #homing_speed: 5.0
 #   Maximum velocity (in mm/s) of the stepper when homing. The default
 #   is 5mm/s.
 #homing_retract_dist: 5.0
 #   Distance to backoff (in mm) before homing a second time during
 #   homing. The default is 5mm.
-#homing_positive_dir: False
+#homing_positive_dir:
-#   If true, homes in a positive direction (away from zero). The
+#   If true, homing will cause the stepper to move in a positive
-#   default is False.
+#   direction (away from zero); if false, home towards zero. The
+#   default is true if position_endstop is near position_max and false
+#   if near position_min.
 #homing_stepper_phases: 0
 #   One may optionally set this to the number of phases of the stepper
 #   motor driver (which is the number of micro-steps multiplied by
@@ -64,16 +76,6 @@ endstop_pin: ^ar3
 #   reset. If this is not set, but homing_stepper_phases is set, then
 #   the stepper phase will be detected on the first home and that
 #   phase will be used on all subsequent homes.
-#position_min: 0
-#   Minimum valid distance (in mm) the user may command the stepper to
-#   move to.  The default is 0mm.
-position_endstop: 0
-#   Location of the endstop (in mm). This parameter must be provided
-#   for the X, Y, and Z steppers on cartesian style printers.
-position_max: 200
-#   Maximum valid distance (in mm) the user may command the stepper to
-#   move to. This parameter must be provided for the X, Y, and Z
-#   steppers on cartesian style printers.
 
 # The stepper_y section is used to describe the stepper controlling
 # the Y axis in a cartesian robot. It has the same settings as the

config/generic-cramps.cfg

@@ -11,9 +11,9 @@ dir_pin: P8_12
 enable_pin: !P9_14
 step_distance: .0125
 endstop_pin: ^P8_8
-homing_speed: 50
 position_endstop: 0
 position_max: 200
+homing_speed: 50
 
 [stepper_y]
 step_pin: P8_15
@@ -21,9 +21,9 @@ dir_pin: P8_14
 enable_pin: !P9_14
 step_distance: .0125
 endstop_pin: ^P8_10
-homing_speed: 50
 position_endstop: 0
 position_max: 200
+homing_speed: 50
 
 [stepper_z]
 step_pin: P8_19
@@ -31,7 +31,6 @@ dir_pin: P8_18
 enable_pin: !P9_14
 step_distance: 0.00025
 endstop_pin: ^P9_13
-homing_speed: 5
 position_endstop: 0
 position_max: 200
 

config/generic-rambo.cfg

@@ -10,9 +10,9 @@ enable_pin: !PA7
 step_distance: .0125
 endstop_pin: ^PB6
 #endstop_pin: ^PA2
-homing_speed: 50
 position_endstop: 0
 position_max: 200
+homing_speed: 50
 
 [stepper_y]
 step_pin: PC1
@@ -21,9 +21,9 @@ enable_pin: !PA6
 step_distance: .0125
 endstop_pin: ^PB5
 #endstop_pin: ^PA1
-homing_speed: 50
 position_endstop: 0
 position_max: 200
+homing_speed: 50
 
 [stepper_z]
 step_pin: PC2
@@ -32,7 +32,6 @@ enable_pin: !PA5
 step_distance: 0.00025
 endstop_pin: ^PB4
 #endstop_pin: ^PC7
-homing_speed: 5
 position_endstop: 0.5
 position_max: 200
 

config/generic-ramps.cfg

@@ -11,9 +11,9 @@ enable_pin: !ar38
 step_distance: .0125
 endstop_pin: ^ar3
 #endstop_pin: ^ar2
-homing_speed: 50
 position_endstop: 0
 position_max: 200
+homing_speed: 50
 
 [stepper_y]
 step_pin: ar60
@@ -22,9 +22,9 @@ enable_pin: !ar56
 step_distance: .0125
 endstop_pin: ^ar14
 #endstop_pin: ^ar15
-homing_speed: 50
 position_endstop: 0
 position_max: 200
+homing_speed: 50
 
 [stepper_z]
 step_pin: ar46
@@ -33,7 +33,6 @@ enable_pin: !ar62
 step_distance: 0.00025
 endstop_pin: ^ar18
 #endstop_pin: ^ar19
-homing_speed: 5
 position_endstop: 0.5
 position_max: 200
 

config/generic-replicape.cfg

@@ -11,9 +11,9 @@ dir_pin: P8_26
 enable_pin: !P9_41
 step_distance: .0125
 endstop_pin: ^P9_25
-homing_speed: 50
 position_endstop: 0
 position_max: 200
+homing_speed: 50
 
 [stepper_y]
 step_pin: P8_12
@@ -21,9 +21,9 @@ dir_pin: P8_19
 enable_pin: !P9_41
 step_distance: .0125
 endstop_pin: ^P9_23
-homing_speed: 50
 position_endstop: 0
 position_max: 200
+homing_speed: 50
 
 [stepper_z]
 step_pin: P8_13
@@ -31,7 +31,6 @@ dir_pin: P8_14
 enable_pin: !P9_41
 step_distance: 0.00025
 endstop_pin: ^P9_13
-homing_speed: 5
 position_endstop: 0
 position_max: 200
 

config/makergear-m2-2012.cfg

@@ -9,12 +9,11 @@ dir_pin: !PL1
 enable_pin: !PA7
 step_distance: .0225
 endstop_pin: ^!PB6
-homing_speed: 50.0
-homing_stepper_phases: 32
-homing_endstop_accuracy: .200
-position_min: -0.25
 position_endstop: 0.0
 position_max: 200
+homing_speed: 50
+homing_stepper_phases: 32
+homing_endstop_accuracy: .200
 
 [stepper_y]
 step_pin: PC1
@@ -22,12 +21,11 @@ dir_pin: PL0
 enable_pin: !PA6
 step_distance: .0225
 endstop_pin: ^!PB5
-homing_speed: 50.0
-homing_stepper_phases: 32
-homing_endstop_accuracy: .200
-position_min: -0.25
 position_endstop: 0.0
 position_max: 250
+homing_speed: 50
+homing_stepper_phases: 32
+homing_endstop_accuracy: .200
 
 [stepper_z]
 step_pin: PC2
@@ -35,13 +33,12 @@ dir_pin: !PL2
 enable_pin: !PA5
 step_distance: .005
 endstop_pin: ^!PB4
-homing_speed: 4.0
-homing_retract_dist: 2.0
-homing_stepper_phases: 32
-homing_endstop_accuracy: .050
 position_min: 0.1
 position_endstop: 0.7
 position_max: 200
+homing_retract_dist: 2.0
+homing_stepper_phases: 32
+homing_endstop_accuracy: .070
 
 [extruder]
 step_pin: PC3

klippy/stepper.py

@@ -57,8 +57,17 @@ class PrinterHomingStepper(PrinterStepper):
         self.position_endstop = config.getfloat('position_endstop')
 
         self.homing_speed = config.getfloat('homing_speed', 5.0, above=0.)
-        self.homing_positive_dir = config.getboolean(
+        self.homing_positive_dir = config.getboolean('homing_positive_dir', None)
-            'homing_positive_dir', False)
+        if self.homing_positive_dir is None:
+            axis_len = self.position_max - self.position_min
+            if self.position_endstop <= self.position_min + axis_len / 4.:
+                self.homing_positive_dir = False
+            elif self.position_endstop >= self.position_max - axis_len / 4.:
+                self.homing_positive_dir = True
+            else:
+                raise config.error(
+                    "Unable to infer homing_positive_dir in section '%s'" % (
+                        config.section,))
         self.homing_retract_dist = config.getfloat(
             'homing_retract_dist', 5., above=0.)
         self.homing_stepper_phases = config.getint(