python
import RPi.GPIO as GPIO
import time
GPIO.setmode(GPIO.BCM)
led_pin = 4
GPIO.setup(led_pin, GPIO.OUT)
pwm = GPIO.PWM(led_pin, 100)
pwm.start(0)
try:
while True:
for dc in range(0, 101, 5):
pwm.ChangeDutyCycle(dc)
time.sleep(0.1)
for dc in range(100, -1, -5):
pwm.ChangeDutyCycle(dc)
time.sleep(0.1)
except KeyboardInterrupt:
pass
pwm.stop()
GPIO.cleanup()
