knock.py

import RPi.GPIO as GPIO
import time

class KNOCK(object): 

	#GPIO.setmode(GPIO.BCM)
#This is where the access pin to which the sensor is connected is declared. The pullup resistor at the input is also activated
#	GPIO_PIN = 24
#	GPIO.setup(GPIO_PIN, GPIO.IN)
  
	print "Sensor-Test [ctrl+c to stop]"
	def detection():
#This output function is performed during signal detection
		def printf(null):
			print("khocked")
			return 1
#When a signal (falling signal edge) is detected, the output function is triggered
		GPIO.add_event_detect(GPIO_PIN, GPIO.FALLING, callback=printf, bouncetime=100) 
	detection()
#main proj loop
	try:
		while True:
			time.sleep(1)
  
#Clean up after the program has finished
	except KeyboardInterrupt:
		GPIO.cleanup()