用PWM实现多个呼吸灯间歇发光

#!/usr/bin/env python2.7 import RPi.GPIO as GPIO # always needed with RPi.GPIOfrom time import sleep  # pull in the sleep function from time module GPIO.setmode(GPIO.BOARD)  # choose BCM or BOARD numbering schemes. I use BCM GPIO.setup(26, GPIO.OUT)# set GPIO 25 as output for white ledGPIO.setup(24, GPIO.OUT)# set GPIO 24 as output for red led white = GPIO.PWM(26, 100)    # create object white for PWM on port 25 at 100 Hertzred = GPIO.PWM(24, 100)      # create object red for PWM on port 24 at 100 Hertz white.start(0)              # start white led on 0 percent duty cycle (off)red.start(100)              # red fully on (100%) # now the fun starts, we'll vary the duty cycle to# dim/brighten the leds, so one is bright while the other is dim pause_time = 0.01           # you can change this to slow down/speed up try:    while True:        for i in range(0,101):      # 101 because it stops when it finishes 100            white.ChangeDutyCycle(i)            red.ChangeDutyCycle(100 - i)            sleep(pause_time)        for i in range(100,-1,-1):      # from 100 to zero in steps of -1            white.ChangeDutyCycle(i)            red.ChangeDutyCycle(100 - i)            sleep(pause_time) except KeyboardInterrupt:    white.stop()            # stop the white PWM output    red.stop()              # stop the red PWM output    GPIO.cleanup()          # clean up GPIO on CTRL+C exit