gcode_button: Add support for analog buttons

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

config/example-extras.cfg

@@ -1330,6 +1330,14 @@
 #pin:
 #   The pin on which the button is connected. This parameter must be
 #   provided.
+#analog_range:
+#   Two comma separated resistances (in Ohms) specifying the minimum
+#   and maximum resistance range for the button. If analog_range is
+#   provided then the pin must be an analog capable pin. The default
+#   is to use digital gpio for the button.
+#analog_pullup_resistor:
+#   The pullup resistance (in Ohms) when analog_range is specified.
+#   The default is 4700 ohms.
 #press_gcode:
 #   A list of G-Code commands to execute when the button is pressed.
 #   G-Code templates are supported. This parameter must be provided.

klippy/extras/gcode_button.py

@@ -12,7 +12,17 @@ class GCodeButton:
         self.pin = config.get('pin')
         self.last_state = 0
         buttons = self.printer.load_object(config, "buttons")
+        analog_range = config.get('analog_range', None)
+        if analog_range is None:
             buttons.register_buttons([self.pin], self.button_callback)
+        else:
+            try:
+                amin, amax = map(float, analog_range.split(','))
+            except:
+                raise config.error("Unable to parse analog_range")
+            pullup = config.getfloat('analog_pullup_resistor', 4700., above=0.)
+            buttons.register_adc_button(self.pin, amin, amax, pullup,
+                                        self.button_callback)
         gcode_macro = self.printer.load_object(config, 'gcode_macro')
         self.press_template = gcode_macro.load_template(config, 'press_gcode')
         self.release_template = gcode_macro.load_template(config,