ultrasoon.py

import RPi.GPIO as GPIO
import time

try:
     GPIO.setmode(GPIO.BCM)
     PIN_TRIGGER = 27
     PIN_ECHO = 17

     GPIO.setup(PIN_TRIGGER, GPIO.OUT)
     GPIO.setup(PIN_ECHO, GPIO.IN)
     GPIO.output(PIN_TRIGGER, GPIO.LOW)

     print("Setting up Sensor")

     while(True):
         GPIO.output(PIN_TRIGGER, GPIO.HIGH)
         time.sleep(0.00001)
         GPIO.output(PIN_TRIGGER, GPIO.LOW)

         pulse_start_time = 0
         pulse_end_time = 0

         while GPIO.input(PIN_ECHO)==0:
               pulse_start_time = time.time()

         while GPIO.input(PIN_ECHO)==1:
               pulse_end_time = time.time()

         pulse_duration = pulse_end_time - pulse_start_time
         distance = round(pulse_duration * 17150, 2)
         print("Distance: ",distance,"cm")
         time.sleep(0.1)

finally:
     GPIO.cleanup()