Add more servo examples, close gpiozero#758

Author: bennuttall

docs/examples/angular_servo.py

@@ -0,0 +1,16 @@
+from gpiozero import AngularServo
+from time import sleep
+
+servo = AngularServo(17, min_angle=-90, max_angle=90)
+
+while True:
+    servo.angle = -90
+    sleep(2)
+    servo.angle = -45
+    sleep(2)
+    servo.angle = 0
+    sleep(2)
+    servo.angle = 45
+    sleep(2)
+    servo.angle = 90
+    sleep(2)

docs/examples/servo_1.py

@@ -0,0 +1,12 @@
+from gpiozero import Servo
+from time import sleep
+
+servo = Servo(17)
+
+while True:
+    servo.min()
+    sleep(2)
+    servo.mid()
+    sleep(2)
+    servo.max()
+    sleep(2)

docs/examples/servo_2.py

@@ -0,0 +1,10 @@
+from gpiozero import Servo, Button
+
+servo = Servo(17)
+btn = Button(14)
+
+while True:
+    servo.min()
+    btn.wait_for_press()
+    servo.max()
+    btn.wait_for_press()

docs/examples/servo_sweep.py

@@ -0,0 +1,7 @@
+from gpiozero import Servo
+from gpiozero.tools import sin_values
+
+servo = Servo(17)
+
+servo.source = sin_values()
+servo.source_delay = 0.1

docs/recipes.rst

@@ -377,6 +377,26 @@ Run a function when something gets near the sensor:
 
 .. literalinclude:: examples/distance_sensor_2.py
 
+Servo
+=====
+
+Control a servo between its minimum, mid-point and maximum positions in
+sequence:
+
+.. literalinclude:: examples/servo_1.py
+
+Use a button to control the servo between its minimum and maximum positions:
+
+.. literalinclude:: examples/servo_2.py
+
+Automate the servo to continuously slowly sweep:
+
+.. literalinclude:: examples/servo_sweep.py
+
+Use :class:`AngularServo` so you can specify an angle:
+
+.. literalinclude:: examples/angular_servo.py
+
 Motors
 ======
 

gpiozero/output_devices.py

@@ -1461,6 +1461,7 @@ class Servo(SourceMixin, CompositeDevice):
         from time import sleep
 
         servo = Servo(17)
+
         while True:
             servo.min()
             sleep(1)
@@ -1469,6 +1470,16 @@ class Servo(SourceMixin, CompositeDevice):
             servo.max()
             sleep(1)
 
+    You can also use the :attr:`value` property to move the servo to a
+    particular position, on a scale from -1 (mid) to 1 (max) where 0 is the
+    mid-point::
+
+        from gpiozero import Servo
+
+        servo = Servo(17)
+
+        servo.value = 0.5
+
     :type pin: int or str
     :param pin:
         The GPIO pin that the servo is connected to. See :ref:`pin-numbering`