04_pwmLed.py

#!/usr/bin/env python3
import RPi.GPIO as GPIO
import time

LedPin = 18

def setup():
	global p
	GPIO.setmode(GPIO.BCM)       # Numbers GPIOs by BCM
	GPIO.setup(LedPin, GPIO.OUT)   # Set LedPin's mode is output
	GPIO.output(LedPin, GPIO.LOW)  # Set LedPin to low(0V)

	p = GPIO.PWM(LedPin, 1000)     # set Frequece to 1KHz
	p.start(0)                     # Duty Cycle = 0

def loop():
	while True:
		for dc in range(0, 101, 4):   # Increase duty cycle: 0~100
			p.ChangeDutyCycle(dc)     # Change duty cycle
			time.sleep(0.05)
		time.sleep(1)
		for dc in range(100, -1, -4): # Decrease duty cycle: 100~0
			p.ChangeDutyCycle(dc)
			time.sleep(0.05)
		time.sleep(1)

def destroy():
	p.stop()
	GPIO.cleanup()

if __name__ == '__main__':     # Program start from here
	setup()
	try:
		loop()
	except KeyboardInterrupt:  # When 'Ctrl+C' is pressed, the child program destroy() will be  executed.
		destroy()