added h-bridge dc motor example

examples/motor_h-bridge_dc_motor.py

@@ -0,0 +1,69 @@
+# This example uses an L9110 H-bridge driver to run a DC Motor using two PWM pins.
+#  https://www.adafruit.com/product/4489
+
+# Hardware setup:
+#   DC motor via L9110 H-bridge driver on two PWM pins that are on their own channels
+#   e.g., RP2040 Pico pins GP28, GP27
+
+import time
+import board
+import pwmio
+from adafruit_motor import motor
+
+PWM_PIN_A = board.GP28  # pick any pwm pins on their own channels
+PWM_PIN_B = board.GP27
+
+# DC motor setup
+# DC Motors generate electrical noise when running that can reset the microcontroller in extreme
+# cases. A capacitor can be used to help prevent this.
+pwm_a = pwmio.PWMOut(PWM_PIN_A, frequency=50)
+pwm_b = pwmio.PWMOut(PWM_PIN_B, frequency=50)
+motor1 = motor.DCMotor(pwm_a, pwm_b)
+
+print("***DC motor test***")
+
+print("\nForwards slow")
+motor1.throttle = 0.5
+print("  throttle:", motor1.throttle)
+time.sleep(1)
+
+print("\nStop")
+motor1.throttle = 0
+print("  throttle:", motor1.throttle)
+time.sleep(1)
+
+print("\nForwards")
+motor1.throttle = 1.0
+print("  throttle:", motor1.throttle)
+time.sleep(1)
+
+print("\nStop")
+motor1.throttle = 0
+print("throttle:", motor1.throttle)
+time.sleep(1)
+
+print("\nBackwards")
+motor1.throttle = -1.0
+print("  throttle:", motor1.throttle)
+time.sleep(1)
+
+print("\nStop")
+motor1.throttle = 0
+print("throttle:", motor1.throttle)
+time.sleep(1)
+
+print("\nBackwards slow")
+motor1.throttle = -0.5
+print("  throttle:", motor1.throttle)
+time.sleep(1)
+
+print("\nStop")
+motor1.throttle = 0
+print("  throttle:", motor1.throttle)
+time.sleep(1)
+
+print("\nSpin freely")
+motor1.throttle = None
+print("  throttle:", motor1.throttle)
+
+print("\n***Motor test is complete***")