import RPi.GPIO as GPIO
import time

GPIO.setmode(GPIO.BCM)
TRIG = 23
ECHO = 24

print "Distance Measurement In Progress"

GPIO.setup(TRIG,GPIO.OUT)
GPIO.setup(ECHO,GPIO.IN)

GPIO.output(TRIG,False)
print "Waiting for Sensor"
time.sleep(2)

GPIO.output(TRIG,True)
time.sleep(0.00001)
GPIO.output(TRIG,False)

while GPIO.input(ECHO)==0:
    pulse_start = time.time()

while GPIO.input(ECHO)==1:
    pulse_end = time.time()

pulse_duration = pulse_end - pulse_start
distance = pulse_duration * 17150
distance = round(distance,2)
print "Distance:",distance,"cm"
GPIO.cleanup()