Add the ability to disable servo motor by setting angle or fraction to None, also renamed examples to pca9685 to separate them from plain-GPIO examples

Author: ladyada

adafruit_motor/servo.py

@@ -54,12 +54,17 @@ def set_pulse_width_range(self, min_pulse=750, max_pulse=2250):
     def fraction(self):
         """Pulse width expressed as fraction between 0.0 (`min_pulse`) and 1.0 (`max_pulse`).
         For conventional servos, corresponds to the servo position as a fraction
-        of the actuation range.
+        of the actuation range. Is None when servo is diabled (pulsewidth of 0ms).
         """
+        if self._pwm_out.duty_cycle == 0:      # Special case for disabled servos
+            return None
         return (self._pwm_out.duty_cycle - self._min_duty) / self._duty_range
 
     @fraction.setter
     def fraction(self, value):
+        if value is None:
+            self._pwm_out.duty_cycle = 0       # disable the motor
+            return
         if not 0.0 <= value <= 1.0:
             raise ValueError("Must be 0.0 to 1.0")
         duty_cycle = self._min_duty + int(value * self._duty_range)
@@ -102,11 +107,17 @@ def __init__(self, pwm_out, *, actuation_range=180, min_pulse=750, max_pulse=225
 
     @property
     def angle(self):
-        """The servo angle in degrees. Must be in the range ``0`` to ``actuation_range``."""
+        """The servo angle in degrees. Must be in the range ``0`` to ``actuation_range``.
+        Is None when servo is disabled."""
+        if self.fraction is None:  # special case for disabled servos
+            return None
         return self.actuation_range * self.fraction
 
     @angle.setter
     def angle(self, new_angle):
+        if new_angle is None:      # disable the servo by sending 0 signal
+            self.fraction = None
+            return
         if new_angle < 0 or new_angle > self.actuation_range:
             raise ValueError("Angle out of range")
         self.fraction = new_angle / self.actuation_range

examples/motor_continuous_servo.py renamed to examples/motor_pca9685_continuous_servo.py

@@ -0,0 +1,56 @@
+import time
+
+from board import SCL, SDA
+import busio
+
+# Import the PCA9685 module. Available in the bundle and here:
+#   https://github.com/adafruit/Adafruit_CircuitPython_PCA9685
+from adafruit_pca9685 import PCA9685
+from adafruit_motor import servo
+
+i2c = busio.I2C(SCL, SDA)
+
+# Create a simple PCA9685 class instance.
+pca = PCA9685(i2c)
+# You can optionally provide a finer tuned reference clock speed to improve the accuracy of the
+# timing pulses. This calibration will be specific to each board and its environment. See the
+# calibration.py example in the PCA9685 driver.
+# pca = PCA9685(i2c, reference_clock_speed=25630710)
+pca.frequency = 50
+
+# To get the full range of the servo you will likely need to adjust the min_pulse and max_pulse to
+# match the stall points of the servo.
+# This is an example for the Sub-micro servo: https://www.adafruit.com/product/2201
+# servo7 = servo.Servo(pca.channels[7], min_pulse=580, max_pulse=2350)
+# This is an example for the Micro Servo - High Powered, High Torque Metal Gear:
+#   https://www.adafruit.com/product/2307
+# servo7 = servo.Servo(pca.channels[7], min_pulse=500, max_pulse=2600)
+# This is an example for the Standard servo - TowerPro SG-5010 - 5010:
+#   https://www.adafruit.com/product/155
+# servo7 = servo.Servo(pca.channels[7], min_pulse=400, max_pulse=2400)
+# This is an example for the Analog Feedback Servo: https://www.adafruit.com/product/1404
+# servo7 = servo.Servo(pca.channels[7], min_pulse=600, max_pulse=2500)
+# This is an example for the Micro servo - TowerPro SG-92R: https://www.adafruit.com/product/169
+# servo7 = servo.Servo(pca.channels[7], min_pulse=500, max_pulse=2400)
+
+# The pulse range is 750 - 2250 by default. This range typically gives 135 degrees of
+# range, but the default is to use 180 degrees. You can specify the expected range if you wish:
+# servo7 = servo.Servo(pca.channels[7], actuation_range=135)
+servo7 = servo.Servo(pca.channels[7])
+
+# We sleep in the loops to give the servo time to move into position.
+for i in range(180):
+    servo7.angle = i
+    time.sleep(0.03)
+for i in range(180):
+    servo7.angle = 180 - i
+    time.sleep(0.03)
+
+# You can also specify the movement fractionally.
+fraction = 0.0
+while fraction < 1.0:
+    servo7.fraction = fraction
+    fraction += 0.01
+    time.sleep(0.03)
+
+pca.deinit()

examples/motor_dc_motor.py renamed to examples/motor_pca9685_dc_motor.py

@@ -1,56 +1,52 @@
 import time
-
-from board import SCL, SDA
-import busio
-
-# Import the PCA9685 module. Available in the bundle and here:
-#   https://github.com/adafruit/Adafruit_CircuitPython_PCA9685
-from adafruit_pca9685 import PCA9685
+import board
+import pulseio
 from adafruit_motor import servo
 
-i2c = busio.I2C(SCL, SDA)
-
-# Create a simple PCA9685 class instance.
-pca = PCA9685(i2c)
-# You can optionally provide a finer tuned reference clock speed to improve the accuracy of the
-# timing pulses. This calibration will be specific to each board and its environment. See the
-# calibration.py example in the PCA9685 driver.
-# pca = PCA9685(i2c, reference_clock_speed=25630710)
-pca.frequency = 50
+# create a PWMOut object on the control pin.
+pwm = pulseio.PWMOut(board.D5, duty_cycle=0, frequency=50)
 
 # To get the full range of the servo you will likely need to adjust the min_pulse and max_pulse to
 # match the stall points of the servo.
 # This is an example for the Sub-micro servo: https://www.adafruit.com/product/2201
-# servo7 = servo.Servo(pca.channels[7], min_pulse=580, max_pulse=2350)
+# servo = servo.Servo(pwm, min_pulse=580, max_pulse=2350)
 # This is an example for the Micro Servo - High Powered, High Torque Metal Gear:
 #   https://www.adafruit.com/product/2307
-# servo7 = servo.Servo(pca.channels[7], min_pulse=500, max_pulse=2600)
+# servo = servo.Servo(pwm, min_pulse=500, max_pulse=2600)
 # This is an example for the Standard servo - TowerPro SG-5010 - 5010:
 #   https://www.adafruit.com/product/155
-# servo7 = servo.Servo(pca.channels[7], min_pulse=400, max_pulse=2400)
+# servo = servo.Servo(pwm, min_pulse=400, max_pulse=2400)
 # This is an example for the Analog Feedback Servo: https://www.adafruit.com/product/1404
-# servo7 = servo.Servo(pca.channels[7], min_pulse=600, max_pulse=2500)
+# servo = servo.Servo(pwm, min_pulse=600, max_pulse=2500)
 # This is an example for the Micro servo - TowerPro SG-92R: https://www.adafruit.com/product/169
-# servo7 = servo.Servo(pca.channels[7], min_pulse=500, max_pulse=2400)
+# servo = servo.Servo(pwm, min_pulse=500, max_pulse=2400)
 
 # The pulse range is 750 - 2250 by default. This range typically gives 135 degrees of
 # range, but the default is to use 180 degrees. You can specify the expected range if you wish:
-# servo7 = servo.Servo(pca.channels[7], actuation_range=135)
-servo7 = servo.Servo(pca.channels[7])
+# servo = servo.Servo(board.D5, actuation_range=135)
+servo = servo.Servo(pwm)
 
 # We sleep in the loops to give the servo time to move into position.
+print("Sweep from 0 to 180")
 for i in range(180):
-    servo7.angle = i
-    time.sleep(0.03)
+    servo.angle = i
+    time.sleep(0.01)
+print("Sweep from 180 to 0")
 for i in range(180):
-    servo7.angle = 180 - i
-    time.sleep(0.03)
+    servo.angle = 180 - i
+    time.sleep(0.01)
+
+print("Move to 90 degrees")
+servo.angle = 90
+time.sleep(1)
+print("Release servo motor for 10 seconds")
+servo.fraction = None
+time.sleep(10)
 
 # You can also specify the movement fractionally.
+print("Sweep from 0 to 1.0 fractionally")
 fraction = 0.0
 while fraction < 1.0:
-    servo7.fraction = fraction
+    servo.fraction = fraction
     fraction += 0.01
-    time.sleep(0.03)
-
-pca.deinit()
+    time.sleep(0.01)