Pin Connect

1. 
   import time
   import RPi.GPIO as GPIO
   
   
   GPIO.setmode(GPIO.BCM)
   
   # Define GPIO to use on Pi
   GPIO_TRIGGER = 23
   GPIO_ECHO = 24
   
   print "Ultrasonic Measurement"
   
   # Set pins as output and input
   GPIO.setup(GPIO_TRIGGER,GPIO.OUT)  # Trigger
   GPIO.setup(GPIO_ECHO,GPIO.IN)      # Echo
       
   def reading():
       # Set trigger to False (Low)
       GPIO.output(GPIO_TRIGGER, False)
   
       # Allow module to settle
       time.sleep(0.5)
   
       # Send 10us pulse to trigger
       GPIO.output(GPIO_TRIGGER, True)
       time.sleep(0.00001)
       GPIO.output(GPIO_TRIGGER, False)
       start = time.time()
       while GPIO.input(GPIO_ECHO)==0:
         start = time.time()
   
       while GPIO.input(GPIO_ECHO)==1:
         stop = time.time()
   
       # Calculate pulse length
       elapsed = stop-start
   
       # Distance pulse travelled in that time is time
       # multiplied by the speed of sound (cm/s)
       distance = elapsed * 50000
   
       # That was the distance there and back so halve the value
       distance = distance / 3
     
       return distance
       
   while True: 
       print "Distance : %.1f cm" % reading()
       time.sleep(1);
   
   # Reset GPIO settings
   GPIO.cleanup()