I received the HC-SR04 Module as part of an Arduino Starter Kit I ordered some time ago and thought I would run a few tests over it to see what it could potentially be used for in the future. I was thinking it would make a good addition to the self balancing robot to stop it bumping into things.
The link for the YouTube video is below, take a look at it as it covers off on the circuit, the code and the actual testing.
I have created a quick and dirty datasheet for the device based on information I dug up from the internet and have included it in the link below.
http://www.grumpyoldtech.technology/attachment/HC-SR04 Ultrasonic Module.pdf
The schematic is pretty straight forward as there are only 4 connections to the device. Just connect up the 5V and Ground connections and link the Trigger input to pin 12 on the Arduino and Echo pin to pin 2 on the Arduino. Its all labeled really well on the module.
The Arduino code i used for this test is below, just copy and paste it into a blank Arduino project.
A full description of the code is in the YouTube video (link above):
//
//
// HC_SR04 Ultrasonic Sensor test
//
// Code by: Grumpy Old Tech
//
// Pins
#define trigPin 12
#define echoPin 2
// Variables
long echoDuration;
float distance;
// Setup
void setup() {
pinMode(trigPin, OUTPUT);
pinMode(echoPin, INPUT);
Serial.begin(9600);
}
// Loop
void loop() {
// Create a trigger pulse, ___|_10µS_|˜˜˜˜50µS˜˜˜˜|_____
digitalWrite(trigPin, LOW);
delayMicroseconds(10);
digitalWrite(trigPin, HIGH);
delayMicroseconds(50);
digitalWrite(trigPin, LOW);
// Read the time the pulse is high, this equates the sound wave travel time in microseconds
echoDuration = pulseIn(echoPin,HIGH);
// Calculate the actual distance
// Speed of sound = 340 m/s = 34000 cm/s = 34 cm/ms = 0.034 cm/µs
// time = distance / speed
// distance = time x speed
// distance apart (cm) = time x speed / 2 = time x 0.034 / 2 *** distance is halved as signal goes to the object and back
distance = echoDuration * 0.034 / 2.0;
// send the value to the serial port
Serial.print("Distance (cm): ");
Serial.println(distance);
delay(100);
}