update motor.py and pca9685 example

Author: CedarGroveStudios

adafruit_motor/motor.py

@@ -1,4 +1,4 @@
-# SPDX-FileCopyrightText: 2017 Scott Shawcroft  for Adafruit Industries
+# SPDX-FileCopyrightText: 2021 Scott Shawcroft for Adafruit Industries
 #
 # SPDX-License-Identifier: MIT
 
@@ -38,9 +38,9 @@ class DCMotor:
     threshold, speed-to-throttle linearity, and PWM frequency sensitivity.
 
     Decay mode settings only effect the operational performance of controller chips such
-    as the DRV8833, DRV8871, and TB6612. Although either decay mode setting is compatible
-    with discrete h-bridge controller circuitry such as the L9110H and L293D, operational
-    performance will not be altered.
+    as the DRV8833, DRV8871, and TB6612. Either decay mode setting is compatible
+    with discrete h-bridge controller circuitry such as the L9110H and L293D; operational
+    performance is not altered.
 
     :param ~pwmio.PWMOut positive_pwm: The motor input that causes the motor to spin forwards
       when high and the other is low.

examples/motor_pca9685_dc_motor.py

@@ -32,6 +32,7 @@
 # See here for more info: https://learn.adafruit.com/adafruit-motor-shield-v2-for-arduino/faq#faq-13
 pca.channels[7].duty_cycle = 0xFFFF
 motor4 = motor.DCMotor(pca.channels[5], pca.channels[6])
+motor4.decay_mode = motor.SLOW_DECAY  # Set motor to active braking mode to improve performance
 
 print("Forwards slow")
 motor4.throttle = 0.5