import time
import RPi.GPIO as GPIO  
GPIO.setmode(GPIO.BCM)  

# GPIO 23 set up as input. It is pulled up to stop false signals  
GPIO.setup(23, GPIO.IN, pull_up_down=GPIO.PUD_UP)  

print ("Make sure you have a button connected so that when pressed"  )
print ("it will connect GPIO port 23 (pin 16) to GND (pin 6)\n" ) 
#raw_input("Press Enter when ready\n>")  

print ("Waiting for falling edge on port 23" ) 
# now the program will do nothing until the signal on port 23   
# starts to fall towards zero. This is why we used the pullup  
# to keep the signal high and prevent a false interrupt  

print ("During this waiting time, your computer is not" )  
print ("wasting resources by polling for a button press.\n" ) 
print ("Press your button when ready to initiate a falling edge interrupt." )
GPIO.wait_for_edge(23, GPIO.FALLING)

print ("\nFalling edge detected. Now your program can continue with")  
print ("whatever was waiting for a button press."  )

while(1):
    print("SAI SRI VATSAVA")
    time.sleep(1)    
GPIO.cleanup()           # clean up GPIO on normal exit 