Ultrasonic distance measurement project using an HY-SRF05

In this article we create a distance measurement ultrasonic project, we will use an Arduino Uno with an LCD Keypad shield. We will then connect the HY-SFR05 to this shield and display the readings on the LCD. Lets go and look at the ultrasonic sensor

The HY-SRF05 is an ultrasonic emitter/receiver used to measure distance with a precision of ~0.3cm. It sends out a 40 KHz square wave signal that reflects on objects in front of the sensor. This signal is then read back by the sensor and the duration of the received signal is reflected on the ECHO pin.

Features

Supply voltage: 4.5V to 5.5V
Supply current: 10 to 40mA
Trigger pin format: 10 uS digital pulse
Sound frequency: 40 KHz
Echo pin output: 0V-VCC
Echo pin format: digital

How to use

Send a 10Us wide pulse (low to high) to the Trigger pin.
Monitor the ECHO pin.
When the ECHO pin goes HIGH, start a timer.
When the ECHO pin goes LOW, stop the timer and save the elapsed time.
Use the elapsed time in the following formula to get the distance in cm:

Distance (in cm) = (elapsed time * sound velocity (340 m/s)) / 100 / 2

We will see a code example later

Parts List

Layout

arduino and lcd keypad shield and HY-SRF05

Code

[codesyntax lang=”cpp”]

#include <Wire.h>
#include <LiquidCrystal.h>

//setup for the LCD keypad shield
LiquidCrystal lcd(8, 9, 4, 5, 6, 7);
const int TRIG_PIN = 2;
const int ECHO_PIN = 3;

void setup() 
{
  pinMode(TRIG_PIN,OUTPUT);
  pinMode(ECHO_PIN,INPUT);
  //init LCD
  lcd.begin(16,2);
  //line 1 - temperature
  lcd.setCursor(0,0);
  lcd.print("Distance");
}

void loop() 
{
  long duration, distanceCm, distanceIn;
 
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);
  duration = pulseIn(ECHO_PIN,HIGH);
 
  // convert the time into a distance
  distanceCm = duration / 29.1 / 2 ;
  distanceIn = duration / 74 / 2;
  lcd.setCursor(0,0);
  if (distanceCm <= 0)
  {
    lcd.print(distanceCm);
    lcd.print("???");
  }
  else 
  {
    //display readings on lcd  
    lcd.clear();
    lcd.print("Distance: ");
    lcd.print(distanceCm);
    lcd.print("cm");
  }
  lcd.print("");
  delay(500);
}

[/codesyntax]