How to use HC-SR04 Ultrasonic Distance Sensor with Arduino

Overview
In this project, we use
HC-SR04 Ultrasonic Distance Sensor
with
Arduino
for displaying the measured distance on an
LCD screen
. The HC-SR04 sensor operates on the
principle of sonar
, emitting an ultrasonic wave at a specific frequency that reflects off an object and returns to the sensor. The system then calculates the
distance
to the object by measuring the time taken for the
ultrasonic wave
to travel to the object and back.
First we will
interface
the
HC-SR04 Ultrasonic Distance Sensor
with Arduino Code and display the measured distance in
Serial Monitor
. Later, we will add an additional
16×2 I2C LCD Display
to the system which will display the measured distance in Screen. The HC-SR04 Ultrasonic Sensor can be used for a variety of
applications
, such as
obstacle detection systems
, automation projects, and more.
Components Required
For this tutorial I am using the
SunFounder Arduino Starter Kit
which has 90+ components.
Here are the list of components I am using from this Kit.
S.N.
Components
Quantity
Purchase Links

Arduino UNO R4/R3 Board

Amazon
AliExpress

Ultrasonic Sensor HC-SR04

Amazon
AliExpress
SunFounder

16X2 I2C LCD Display

Amazon
AliExpress
SunFounder

Connecting Wires

Amazon
AliExpress
SunFounder

Type C USB Cable

Amazon
AliExpress

Breadboard

Amazon
AliExpress
SunFounder
HC-SR04 Ultrasonic Distance Sensor
The
HC-SR04 ultrasonic sensor
uses sonar to determine the distance to an object like bats do. It offers excellent non-contact
range detection
with high accuracy and
stable readings
in an easy-to-use package.
From
2cm
to
400 cm
or 1” to 13 feet. Its operation is not affected by sunlight or black material like sharp rangefinders are (although acoustically soft materials like cloth can be difficult to detect). It comes complete with the ultrasonic transmitter and a receiver module. A waterproof version of this Ultrasonic Sensor is also available called as
JSN-SR04T/AJ-SR04M
How Does the Ultrasonic Sensor HC-SR04 Work?
Ultrasonic sensors
function by emitting a sequence of short, high-frequency sound waves. These sound waves are produced at
regular intervals
and travel through the air at a consistent speed, known as the
speed of sound
. When these ultrasonic waves encounter any object in their path, they are reflected back toward the sensor, creating an
echo
that is detected by the sensor’s receiver.
The sensor is equipped with the capability to calculate the distance to the object by analyzing the t
ime interval
between the moment the sound pulse is emitted and the moment the echo is received. This time interval is directly related to the
round-trip distance
that the sound waves have traveled.
To convert this time interval into a distance measurement, we use the formula:
S
=(
v
×
t)/2
Where:
S
is the distance to the object (in centimeters),
v
is the speed of sound in air (approximately 340 meters per second or 0.034 centimeters per microsecond),
t
is the time interval measured from when the sound wave is emitted to when the echo is received (in seconds).
It’s important to note that the time measured is the
total time
for the sound wave to travel to the object and back to the sensor. Since we are interested in the distance from the sensor to the object, not the round trip, we divide the
time
by

By using this formula, the ultrasonic sensor can provide a precise measurement of the distance to an object, which can be utilized in various applications such as collision avoidance systems, robotics, level sensing, and more.
Specifications of HC-SR04 Ultrasonic Distance Sensor
The specifications of the HC-SR04 Ultrasonic Distance Sensor are below:
Minimum measuring range – 2 cm
Maximum measuring range: 400 cm or 4 meter
Accuracy : 3 mm
Operating Voltage: +5V
Operating Current: 15mA
Working Frequency: 40 KHz
Trigger Input signal: 10us pulse
Measuring angle: 15 degrees
Pinout of HC-SR04
The HC-SR04 ultrasonic sensor has 4 Pins.
VCC (Power)
: This pin powers the sensor, typically with +5V from the microcontroller board.
Trig (Trigger)
: This pin is used to initiate the ultrasonic pulse. A short pulse of 10 microseconds sent to this pin starts the ultrasonic burst.
Echo (Echo Pulse)
: This pin outputs a pulse from the sensor. The duration of this pulse is proportional to the time taken for the ultrasonic wave to travel to the object and back to the sensor.
GND (Ground)
: This pin is connected to the ground of the circuit.
Interfacing HC-SR04 Ultrasonic Distance Sensor with Arduino
Now lets interface the HC-SR04 Ultrasonic Distance Sensor with Arduino. Here is the simple connection diagram.
Hardware Connection
VCC
connects to the 5V output on the Arduino.
Trig
connects to a D2 pin on the Arduino.
Echo
connects to D3 pin on the Arduino.
GND
connects to the ground pin on the Arduino.
You can use a breadboard and jumper wires for connection.
Source Code/Program
Here is the simple code for reading the distance value from HC-SR04 Ultrasonic Sensor using the Arduino Code.

/*
Read data from an ultrasonic sensor connected to the Arduino board
and print the distance measurement in centimeters
through the serial communication.
Board: Arduino Uno R4 (or R3)
Component: Ultrasonic distance Sensor(HC-SR04)
*/
// Define the pin numbers for the ultrasonic sensor
const
int
echoPin
=

;
const
int
trigPin
=

;
void
setup
(
)
{
Serial
begin
(
9600
)
;
// Start serial communication with a baud rate of 9600
pinMode
(
echoPin
INPUT
)
;
// Set echo pin as input
pinMode
(
trigPin
OUTPUT
)
;
// Set trig pin as output
Serial
println
(
"Ultrasonic sensor:"
)
;
// Print a message indicating the ultrasonic sensor is ready
}
void
loop
(
)
{
float
distance
=
readDistance
(
)
;
// Call the function to read the sensor data and get the distance
if
(
distance
>

)
{
// Check if the distance is greater than 400 cm
Serial
println
(
"Out of Range"
)
;
// Print "Out of Range"
}
else
{
Serial
(
distance
)
;
// Print the distance value
Serial
println
(
" cm"
)
;
// Print " cm" to indicate the unit of measurement
}
delay
(

)
;
// Delay for 400 milliseconds before repeating the loop
}
// Function to read the sensor data and calculate the distance
float
readDistance
(
)
{
digitalWrite
(
trigPin
LOW
)
;
// Set trig pin to low to ensure a clean pulse
delayMicroseconds
(

)
;
// Delay for 2 microseconds
digitalWrite
(
trigPin
HIGH
)
;
// Send a 10 microsecond pulse by setting trig pin to high
delayMicroseconds
(

)
;
digitalWrite
(
trigPin
LOW
)
;
// Set trig pin back to low
// Measure the pulse width of the echo pin and calculate the distance value
float
pulse_duration
=
pulseIn
(
echoPin
HIGH
)
;
// Read pulse duration
float
distance
=
pulse_duration
/
58.00
;
// Calculate the distance
return
distance
;
// Return the calculated distance
}
To upload the code to the Arduino Board, Select the Arduino UNO Board from Tools Menu and also select the COM port. Then upload the code by clicking on upload button.
Testing & Results
The device is ready for testing after the code uploading is done.
Place some solid flat object in front of the Ultrasonic Sensor.
Then open the Serial Monitor on the Arduino IDE. The Serial Monitor will show the measured distance.
To test it further place the obstacle at far distance from the Sensor.
Observe the distance on the Serial Monitor. The Serial Monitor will show the measured distance again.
You can increase or decrease the distance between 2cm to 400cm and measurement will be shown in Serial Monitor.
Interfacing HC-SR04 Ultrasonic Sensor with Arduino & LCD Display
Now lets add an extra component to the above circuit for distance visualization. We can use 16×2 I2C LCD Display with the Arduino UNO.
Hardware Connection
Here is a connection between Arduino and 16×2 I2C LCD Disp