stepper: Support stepper phase adjustments when homing

Add support for enhancing the precision of endstop switches by also
inspecting the phase of the stepper motor when the endstop triggers.

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

1 files changed, 21 insertions, 1 deletions

diff --git a/config/example.cfg b/config/example.cfg
index b458e8b4..5614b5fc 100644
--- a/config/example.cfg
+++ b/config/example.cfg
@@ -11,7 +11,7 @@
 # available pin and board names.)
 # Pin names may be preceded by an '!' to indicate that a reverse
 # polarity should be used (eg, trigger on low instead of high). Input
-# pins may be prceded by an '^' to indicate that a hardware pull-up
+# pins may be preceded by a '^' to indicate that a hardware pull-up
 # resistor should be enabled for the pin.
 
 
@@ -38,6 +38,26 @@ homing_retract_dist: 5.0
 #   Distance to backoff (in mm) before homing a second time during homing
 homing_positive_dir: False
 #   If true, homes in a positive direction (away from zero)
+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
+#   four). When set, the phase of the stepper driver will be used
+#   during homing to improve the accuracy of the endstop switch.
+homing_endstop_accuracy: 0.200
+#   Sets the expected accuracy (in mm) of the endstop. This represents
+#   the maximum error distance the endstop may trigger (eg, if an
+#   endstop may occasionally trigger 100um early or up to 100um late
+#   then set this to 0.200 for 200um). This setting is used with
+#   homing_stepper_phases and is only useful if that parameter is also
+#   configured.
+#homing_endstop_phase: 0
+#   This specifies the phase of the stepper motor driver to expect
+#   when hitting the endstop. This setting is only meaningful if
+#   homing_stepper_phases is also set. Only set this value if one is
+#   sure the stepper motor driver is reset every time the mcu is
+#   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: -0.25
 #   Minimum valid distance (in mm) the user may command the stepper to
 #   move to (not currently enforced)