ultrasonic_distance_sensor.py

#!/usr/bin/python

# Written by pcmanbob
# https://www.raspberrypi.org/forums/memberlist.php?mode=viewprofile&u=71930&sid=78c72fd5d7f7c6d39cf3b3ddcc9a0ed5
# See: https://www.raspberrypi.org/forums/viewtopic.php?t=228207#p1399745

# Import required Python libraries
import time
import RPi.GPIO as GPIO

# Use BCM GPIO references
# instead of physical pin numbers
GPIO.setmode(GPIO.BCM)
GPIO.setwarnings(False)

# Define GPIO to use on Pi
GPIO_TRIGGER = 23
GPIO_ECHO    = 24



# Set pins as output and input
GPIO.setup(GPIO_TRIGGER,GPIO.OUT)  # Trigger
GPIO.setup(GPIO_ECHO,GPIO.IN)      # Echo

# Set trigger to False (Low)
GPIO.output(GPIO_TRIGGER, False)

print "Ultrasonic Measurement"

# 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)
distancet = elapsed * 34300

# That was the distance there and back so halve the value
distance = distancet / 2

print "Distance :", distance

print "Elaspsed time :", elapsed

print "Total distance :", distancet


# Reset GPIO settings
GPIO.cleanup()