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# Distance Calculation with Ultrasonic Sensor

Ultrasonic distance sensors are designed to measure distance between the source and target using ultrasonic waves.

BeginnerFull instructions provided1 hour45,379

## Things used in this project

### Hardware components

 Raspberry Pi 3 Model B
×1
 Resistor 330 ohm
×1
 Resistor 475 ohm
×1
×1
 Jumper wires (generic)
×1
 Ultrasonic Sensor - HC-SR04 (Generic)
×1

## Code

### dist-sensor.py

Python
```import RPi.GPIO as GPIO                    #Import GPIO library
import time                                #Import time library
GPIO.setmode(GPIO.BCM)                     #Set GPIO pin numbering

TRIG = 23                                  #Associate pin 23 to TRIG
ECHO = 24                                  #Associate pin 24 to ECHO

print "Distance measurement in progress"

GPIO.setup(TRIG,GPIO.OUT)                  #Set pin as GPIO out
GPIO.setup(ECHO,GPIO.IN)                   #Set pin as GPIO in

while True:

GPIO.output(TRIG, False)                 #Set TRIG as LOW
print "Waitng For Sensor To Settle"
time.sleep(2)                            #Delay of 2 seconds

GPIO.output(TRIG, True)                  #Set TRIG as HIGH
time.sleep(0.00001)                      #Delay of 0.00001 seconds
GPIO.output(TRIG, False)                 #Set TRIG as LOW

while GPIO.input(ECHO)==0:               #Check whether the ECHO is LOW
pulse_start = time.time()              #Saves the last known time of LOW pulse

while GPIO.input(ECHO)==1:               #Check whether the ECHO is HIGH
pulse_end = time.time()                #Saves the last known time of HIGH pulse

pulse_duration = pulse_end - pulse_start #Get pulse duration to a variable

distance = pulse_duration * 17150        #Multiply pulse duration by 17150 to get distance
distance = round(distance, 2)            #Round to two decimal points

if distance > 2 and distance < 400:      #Check whether the distance is within range
print "Distance:",distance - 0.5,"cm"  #Print distance with 0.5 cm calibration
else:
print "Out Of Range"                   #display out of range
```

## Credits

### Arbaz Hussain

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