Calculate Distance Using Ultrasonic Sensor (HC-SR04)

About

In this tutorial we will be using an ultrasonic sensor (HC-SR04). We are going to program our surilli with a basic program so we can calculate distance to an object the way bats do.

Ultrasonic sensor (HC-SR04)

The HC-SR04 Ultrasonic module has 4 pins: Ground, VCC, Trig and Echo. The Ground and the VCC pins of the module needs to be connected to the Ground and the 5 volts pins on the Surilli Board respectively and the trig and echo pins to any Digital I/O pin on the Surilli Board.

Trigger (Transmitter) emits an ultrasound at 40 000 Hz which travels through the air and if there is an object or obstacle on its path it will bounce back to the Echo (Receiver). Considering the travel time and the speed of the sound you can calculate the distance.

STEP 1: Setup Arduino IDE for Surilli

Make sure you have selected the right port, board and processor for the Surilli as shown in the picture below and it is programmable (compile and upload “Blink” from File>Examples>Digital>Blink onto your Surilli to check if every thing is working fine).

STEP 2: The Circuitry

The circuitry is very simple. It's mostly the programming. Follow the figure to setup your hardware.

STEP 3: Upload & Burn Code onto Surilli

• Now you have completed setting up your hardware and Arduino IDE. Copy and paste the Arduino sketch given below into your Arduino IDE and hit upload.

• After it is uploaded, the ultrasonic sensor will start working.

Code:

const int trigPin = 2;
const int echoPin = 16;
// defines variables
long duration;
int distance;
void setup() {
pinMode(trigPin, OUTPUT); // Sets the trigPin as an Output
pinMode(echoPin, INPUT); // Sets the echoPin as an Input
Serial.begin(9600); // Starts the serial communication
}
void loop() {
// Clears the trigPin
digitalWrite(trigPin, LOW);
delay(500);
// Sets the trigPin on HIGH state for 10 micro seconds
digitalWrite(trigPin, HIGH);
delay(500);
digitalWrite(trigPin, LOW);
// Reads the echoPin, returns the sound wave travel time in microseconds
duration = pulseIn(echoPin, HIGH);
// Calculating the distance
distance= duration*0.034/2;
// Prints the distance on the Serial Monitor
Serial.print("Distance: ");
Serial.println(distance);
} 

Play with the program to see how it reacts to different values and logic. This will develop your understanding about ultrasonic sensors so you can use them in your practical application.

If you make something fun and interesting, do share it with our community. :)

That’s all for now. If you have any queries, visit surilli.io or contact our support. Stay connected with the Surilli family for more amazing stuff :)