Arduino Ultrasonic Sensor Obstacle detection using Arduino & ”HC SR04

(Last Updated On: February 13, 2020)

Arduino ultrasonic sensor


Arduino Ultrasonic Sensor Project Obstacle detection using Arduino- In this tutorial, you will learn how to use the HC-SR04 ultrasonic sensor with Arduino for Obstacle detection and distance measurement. For the demonstration purposes, I will use an Led which will be controlled depending on the distance of the object from the HC-SR04 Sensor. This LED will be controlled as per the pre-defined value. The Obstacle detection range can be adjusted in the programming.

The same programming can also be used in the Robot for detecting any Obstacle, or it can be used in a security project, or the same idea can also be used in making the touch-less doorbell system. For the Step by Step explanation, you can watch a video tutorial given at the end of this Article.

 This tutorial covers the extreme basics

  1. Ultrasonic sensor Pinout
  2. Circuit Diagram
  3. Ultrasonic Sensor interfacing with Arduino
  4. Ultrasonic Sensor Arduino Programming and finally
  5. Testing

The components and tools used in this project can be purchased from Amazon, the components Purchase links are given below:

Arduino Uno:
Mega 2560:
Nodemcu esp8266 wifi module: Best price
HC-SR04 Ultrasonic Sensor:
LM7805 Voltage Regulator:
330-ohm resistors pack:
5v 2A adaptor:
2n2222 NPN transistors:
10k Resistor:
lm7805 Voltage Regulator:
330-ohm resistors pack:
female DC power jack socket:
470uf capacitors:
5×7 cm Vero board:
female headers:
connection wires:
Super Starter kit for Beginners:
Jumper Wires:
Bread Board:
12v Adaptor:
PCB plate:
Variable Supply:
Digital Multimeter:
Vero Board / stripboard:
Soldering iron kit: “best” You guys should definitely purchase this:
Solder wire:
Wire Stripper:
PCB small portable drill machine:


Please Note: these are affiliate links. I may make a commission if you buy the components through these links. I would appreciate your support in this way!

Features of the Ultrasonic Sensor:

Arduino ultrasonic sensor

Power Supply: +5V DC

Quiescent Current : <2mA

Working Current: 15mA

Effectual Angle: <15°

Ranging Distance : 2cm – 400 cm/1″ – 13ft

Resolution : 0.3 cm

Measuring Angle: 30 degree

Trigger Input Pulse width: 10uS

Dimension: 45mm x 20mm x 15mm

Ultrasonic Sensor HC SR04 Pinout:

As you can see in the Picture above, the HC-SR04  has a total of 4 male headers which are clearly labeled with Vcc, Trig, Echo and GND. As the HC-SR04 needs 5v so this Ultrasonic Sensor can be powered using the Arduino’s 5v.

Circuit Diagram:

Arduino ultrasonic sensor

This schematic is designed in Cadsoft eagle 9.1.0 version, if you want to learn how to make a schematic and PCB then watch my tutorial, the video is given below.

Learn how to make a schematic and PCB using Eagle:


As you can see in the circuit diagram above the HC-SR04 Vcc pin is connected with the Arduino’s 5v, the trigger pin is connected with pin number 4.Tthe echo pin is connected with pin number 2, and the ground pin is connected with the Arduino’s ground. A 330 ohm resistor is connected in series with a 2.5v LED. This is a current limiting resistor. I have a very detailed tutorial on led and how to calculate the current limiting resistor value; you can watch the following tutorial.

LED and how to calculate the current limiting resistor:


The resistor is connected with pin number 13, while the cathode side of the LED is connected with the ground.

HC-SR04 Interfacing:

Arduino ultrasonic sensor

  • Connect the orange wire with the Vcc.
  • Connect a blue wire with the trigger pin.
  • Connect a green wire with the echo pin.
  • Connect a black wire with the ground pin.

After I was done with connecting the male to female type jumper wires with the HC-SR04 then I started connecting these wires with the Arduino Uno.

Arduino ultrasonic sensor

I simply connected the Orange wire with the Vcc.

I connected the black wire with the ground.

I connected the blue wire with pin number 4.

I connected the green wire with pin number 2.   I also connected an LED with pin number 13 through a 330 resistor.

Arduino Programming:

After I uploaded this program into the Arduino Uno, I was able to detect objects and was also able to measure the distance.

Arduino ultrasonic sensor

For the practical Demonstration watch the following video Tutorial.

Watch Video Tutorial:


Other HC-SR04 Sensor Projects:

Safe distance maintaining Car to Avoid accident using Ultrasonic Sensor

Water level monitoring using Ultrasonic Sensor

IOT Water level monitoring using Ultrasonic Sensor

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About the Author: Engr Fahad

My name is Shahzada Fahad and I am an Electrical Engineer. I have been doing Job in UAE as a site engineer in an Electrical Construction Company. Currently, I am running my own YouTube channel "Electronic Clinic", and managing this Website. My Hobbies are * Watching Movies * Music * Martial Arts * Photography * Travelling * Make Sketches and so on...

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