filament_motion_sensor: Add filament_motion_sensor (#3857)

Add functionality to support a Filament Motion Sensor for detecting extruder jams as well as runouts.  Works by an encoder toggling the switch_pin 0/1 as the filament is pulled through the sensor.

Signed-off-by: Joshua Wherrett <thejoshw.code@gmail.com>

klippy/extras/filament_motion_sensor.py

@@ -0,0 +1,76 @@
+# Filament Motion Sensor Module
+#
+# Copyright (C) 2021 Joshua Wherrett <thejoshw.code@gmail.com>
+#
+# This file may be distributed under the terms of the GNU GPLv3 license.
+import logging
+from . import filament_switch_sensor
+
+CHECK_RUNOUT_TIMEOUT = .250
+
+class EncoderSensor:
+    def __init__(self, config):
+        # Read config
+        self.printer = config.get_printer()
+        switch_pin = config.get('switch_pin')
+        self.extruder_name = config.get('extruder')
+        self.detection_length = config.getfloat(
+                'detection_length', 7., above=0.)
+        # Configure pins
+        buttons = self.printer.load_object(config, 'buttons')
+        buttons.register_buttons([switch_pin], self.encoder_event)
+        # Get printer objects
+        self.reactor = self.printer.get_reactor()
+        self.runout_helper = filament_switch_sensor.RunoutHelper(config)
+        self.extruder = None
+        self.estimated_print_time = None
+        # Initialise internal state
+        self.filament_runout_pos = None
+        # Register commands and event handlers
+        self.printer.register_event_handler('klippy:ready',
+                self._handle_ready)
+        self.printer.register_event_handler('idle_timeout:printing',
+                self._handle_printing)
+        self.printer.register_event_handler('idle_timeout:ready',
+                self._handle_not_printing)
+        self.printer.register_event_handler('idle_timeout:idle',
+                self._handle_not_printing)
+    def _update_filament_runout_pos(self, eventtime=None):
+        if eventtime is None:
+            eventtime = self.reactor.monotonic()
+        self.filament_runout_pos = (
+                self._get_extruder_pos(eventtime) +
+                self.detection_length)
+    def _handle_ready(self):
+        self.extruder = self.printer.lookup_object(self.extruder_name)
+        self.estimated_print_time = (
+                self.printer.lookup_object('mcu').estimated_print_time)
+        self._update_filament_runout_pos()
+        self._extruder_pos_update_timer = self.reactor.register_timer(
+                self._extruder_pos_update_event)
+    def _handle_printing(self, print_time):
+        self.reactor.update_timer(self._extruder_pos_update_timer,
+                self.reactor.NOW)
+    def _handle_not_printing(self, print_time):
+        self.reactor.update_timer(self._extruder_pos_update_timer,
+                self.reactor.NEVER)
+    def _get_extruder_pos(self, eventtime=None):
+        if eventtime is None:
+            eventtime = self.reactor.monotonic()
+        print_time = self.estimated_print_time(eventtime)
+        return self.extruder.find_past_position(print_time)
+    def _extruder_pos_update_event(self, eventtime):
+        extruder_pos = self._get_extruder_pos(eventtime)
+        # Check for filament runout
+        self.runout_helper.note_filament_present(
+                extruder_pos < self.filament_runout_pos)
+        return eventtime + CHECK_RUNOUT_TIMEOUT
+    def encoder_event(self, eventtime, state):
+        if self.extruder is not None:
+            self._update_filament_runout_pos(eventtime)
+            # Check for filament insertion
+            # Filament is always assumed to be present on an encoder event
+            self.runout_helper.note_filament_present(True)
+
+def load_config_prefix(config):
+    return EncoderSensor(config)