Import RP1.GPIO as GPIO

import time

GPIO.setmode(GPIO.BCM)

GPIO.setwarnings (False)

GPIO.setup(20, GPIO.OUT)

GPIO.setup(21, GPIO.OUT)

p1-GPIO.PWM(20,100)

p2-GPIO.PWM(21,100)

p1.start(0)

p2.start(0)

try:

while True:

for dc in range(0,101,5):

p1.ChangeDutyCycle(dc)

p2.ChangeDutycle(dc)

time.sleep(0.025)

for dc in range(100,-1,-5):

p1.ChangeDutyCycle(dc)

p2.ChangeDutyCycle(dc)

time.sleep(0.025)

except KeyboardInterrupt:

pass

p1.stop()

p2.stop()

GPIO.output(20,GPIO.LOW)

GPIO.output(21,GPIO.LOW)

GPIO.Cleanup ()