Control RPi.GPIO PWM, using Python on Raspberry Pi 2

Example show how to control PWM of RPi.GPIO using Python (work on both Python 2 and 3), run on Raspberry Pi 2.


Connection:

testGPIO.py

import sys
import RPi.GPIO as GPIO
import time

print("sys.version:")
print(sys.version + "\n")

print("GPIO.VERSION: " + GPIO.VERSION)
print("GPIO.RPI_INFO['P1_REVISION'] = " + str(GPIO.RPI_INFO['P1_REVISION']));

io20 = 20
io21 = 21

GPIO.setmode(GPIO.BCM)
GPIO.setup(io20, GPIO.IN, pull_up_down=GPIO.PUD_UP)
GPIO.setup(io21, GPIO.OUT)
#config GPIO 21 as PWM, frequency = 50 cycle/sec
pwm21 = GPIO.PWM(io21, 50)
pwm21.start(10)

print("Press button to change PWM");
try:
    while(True):
        if (GPIO.input(io20)):
            #duty cycle = 10%
            pwm21.ChangeDutyCycle(10)
        else:
            #duty cycle = 90%
            pwm21.ChangeDutyCycle(90)
    
except KeyboardInterrupt:
    print ("\n")
    print ("Exit by KeyboardInterrupt\n")
  
except:
    print ("\n")
    print ("Exit by Other case!\n")
  
finally:
    pwm21.stop()
    GPIO.cleanup()
    print ("Clean up GPIO\n")