servo: Remove servo ENABLE parameter

Allow one to disable servos via `SET_SERVO WIDTH=0` instead of using
an explicit ENABLE parameter.

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

config/example-extras.cfg

@@ -1254,9 +1254,6 @@
 #   the mcu resets.  Must be between minimum_pulse_width and maximum_pulse_width.
 #   This parameter is optional.  If both initial_angle and initial_pulse_width
 #   are set initial_angle will be used
-#enable: True
-#   Enable or disable servo. It can be enabled or disabled later using
-#   SET_SERVO SERVO=my_servo ENABLE=<0|1> g-command. The default is True (=enabled)
 
 # Neopixel (aka WS2812) LED support (one may define any number of
 # sections with a "neopixel" prefix). One may set the LED color via

docs/Config_Changes.md

@@ -6,6 +6,10 @@ All dates in this document are approximate.
 
 # Changes
 
+20200725: The servo `enable` config parameter and the SET_SERVO
+`ENABLE` parameter have been removed.  Update any macros to use
+`SET_SERVO SERVO=my_servo WIDTH=0` to disable a servo.
+
 20200608: The LCD display support has changed the name of some
 internal "glyphs".  If a custom display layout was implemented it may
 be necessary to update to the latest glyph names (see

docs/G-Codes.md

@@ -258,8 +258,9 @@ sections are enabled:
 
 The following commands are available when a "servo" config section is
 enabled:
-- `SET_SERVO SERVO=config_name [WIDTH=<seconds>] [ENABLE=<0|1>]`
+- `SET_SERVO SERVO=config_name [ANGLE=<degrees> | WIDTH=<seconds>]`:
-- `SET_SERVO SERVO=config_name [ANGLE=<degrees>] [ENABLE=<0|1>]`
+  Set the servo position to the given angle (in degrees) or pulse
+  width (in seconds). Use `WIDTH=0` to disable the servo output.
 
 ## Manual stepper Commands
 

klippy/extras/servo.py

@@ -23,8 +23,6 @@ class PrinterServo:
         self.angle_to_width = (self.max_width - self.min_width) / self.max_angle
         self.width_to_value = 1. / SERVO_SIGNAL_PERIOD
         self.last_value = self.last_value_time = 0.
-        self.enable = config.getboolean('enable', True)
-        self.last_enable = not self.enable
         servo_name = config.get_name().split()[1]
         gcode = self.printer.lookup_object('gcode')
         gcode.register_mux_command("SET_SERVO", "SERVO", servo_name,
@@ -53,37 +51,29 @@ class PrinterServo:
     def get_status(self, eventtime):
         return {'value': self.last_value}
     def _set_pwm(self, print_time, value):
-        if value == self.last_value and self.enable == self.last_enable:
+        if value == self.last_value:
             return
         print_time = max(print_time, self.last_value_time + PIN_MIN_TIME)
-        if self.enable:
         self.mcu_servo.set_pwm(print_time, value)
-        else:
-          self.mcu_servo.set_pwm(print_time, 0)
         self.last_value = value
-        self.last_enable = self.enable
         self.last_value_time = print_time
     def _get_pwm_from_angle(self, angle):
         angle = max(0., min(self.max_angle, angle))
         width = self.min_width + angle * self.angle_to_width
         return width * self.width_to_value
     def _get_pwm_from_pulse_width(self, width):
+        if width:
             width = max(self.min_width, min(self.max_width, width))
         return width * self.width_to_value
     cmd_SET_SERVO_help = "Set servo angle"
     def cmd_SET_SERVO(self, gcmd):
         print_time = self.printer.lookup_object('toolhead').get_last_move_time()
-        enable = gcmd.get_int('ENABLE', None)
         width = gcmd.get_float('WIDTH', None)
-        angle = gcmd.get_float('ANGLE', None)
-        if enable is not None:
-            self.enable = enable != 0
         if width is not None:
             self._set_pwm(print_time, self._get_pwm_from_pulse_width(width))
-        elif angle is not None:
-            self._set_pwm(print_time, self._get_pwm_from_angle(angle))
         else:
-            self._set_pwm(print_time, self.last_value)
+            angle = gcmd.get_float('ANGLE')
+            self._set_pwm(print_time, self._get_pwm_from_angle(angle))
 
 def load_config_prefix(config):
     return PrinterServo(config)