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In this session, we will see How to use Ultrasonic Sensor with Arduino . Ultrasonic Sensor is used to calculate the distances of the obstacle. It works on the principle of SONAR.
Ultrasonic Sensor senses the distance of an object by sending the ultrasonic sound at 40,000 Hz, which travels through the air and if there is an object or obstacle on its path it will reflect or bounce back to the receiver of the module.
·        The common name of Ultrasonic Sensor is HC-SR04.
·        Operating Voltage of this sensor is +5V.
·        It can measure distance from 2cm to 80cm.

·        It contains 4 pins – VCC, Ground, Echo, Trigger.

·                                Trigger pin is the input pin and it sends the ultrasonic waves.
                  Echo pin is the output pin and it receives the bounced or reflected waves.


Speed of sound: v=340 m/s,   v=0.034cm/μ s

Time = Distance / Speed:

                    t   =   s/v   =   10 / 0.034 =   294 μ s
                    Distance:   s   =   t   *   0.034 / 2


Disclaimer: This blog contains Amazon Affiliate links. Buying product from those links helps us run this blog without any extra charges on you.    

Things we need:

  1. Arduino UNO (Amazon)
  2. Ultrasonic Sensor (Amazon)

 This sensor connection to the ARDUINO is discussed in the following steps:
  • There will be 4 pins present on the ultrasonic sensor.
  •  Initially the VCC pin of the Ultrasonic Sensor is connected to the VCC(5V) pin     of the ARDUINO by using the male to female wire.
  • Then the GROUND pin of the Ultrasonic Sensor is connected to the GND of the   ARDUINO by using the male to female wire.
  •  Finally, the TRIGGER and ECHO pins of the Ultrasonic Sensor is connected to     the Digital pins of the ARDUINO, excepting the 0 and 1 pins since they                 are used for transmission and receiving purpose.
  •  Now the power supply is given to the ARDUINO for the functioning of the         Ultrasonic Sensor and the ARDUINO Development Board.

The complete interfacing of the Ultrasonic Sensor with ARDUINO is done perfectly, the only left over task is to type the program and dump the program into the ARDUINO Development Board.


         // defines pins numbers

const int trigPin = 2;

const int echoPin = 4;

// 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);


// Sets the trigPin on HIGH state for 10 micro seconds

digitalWrite(trigPin, HIGH);


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: ");




After the complete writing of the above program in ARDUINO IDE , you can dump the code into the ARDUINO board.


After the successful dumping of code into the ARDUINO board, the output values of the Ultrasonic Sensor can be visible in the serial monitor in the computer screen. When a obstacle is detected in the path of Ultrasonic Sensor , then the distance of the obstacle from the sensor is displayed on the serial monitor in the ARDUINO IDE software window on the computer screen.


Initially the TRIGGER pin and the ECHO pin is connected to the pins 2 and 4 respectively in the ARDUINO BOARD , this means the ARDUINO board gets the input and output values from the 2 and 4 pins connection of the TRIGGER AND ECHO pins.
·                  The Variables duration and distance are declared.
·        Sets the TRIGGER Pin as an Output and ECHO Pin as an Input.
·        Then establishes the serial communication with baud rate of 9600
·        Then in the loop, TRIGGER pin is kept off (low) for 2 microseconds.
·        Now the TRIGGER pin is kept on (high) for 10 microseconds and then kept off .
·        Then the ECHO pin is kept on (high) to read the time taken by the wave to return           back and is stored in duration.
·        Now finally, the distance is calculated by using the appropriate formulae.
·        And the distance is printed on the Serial Monitor.


The above discussed information about the Ultrasonic Sensor is all about the interfacing and functioning of the Sensor with ARDUINO Development Board. In this way the HC-SR04 component can be connected to the ARDUINO and can be used for wide range of applications in the Autonomous Robotic Projects.

Previously we learnt how to decode IR signals using Arduino and how to use  these signals to control LEDs. It was pretty basic setup and a good project to get started. Today we will use that knowledge to build a simple robot car which will be controlled using an IR remote. I suggest you check out "Everything you need to know about motor drivers" article to get a better understanding on how to control the motors.

Without any further ado, let's get right into it.

Disclaimer: This blog contains Amazon Affiliate links. Buying product from those links helps us run this blog without any extra charges on you.


For any projects we need some materials. Here I have listed all the hardware and software requirements for this project.


  1. Arduino Uno   (Amazon Link)
  2. Arduino Motor Shield v1.0   (Amazon Link)
  3. 2 x Geared Motor   (Amazon Link)
  4. 2 x Wheels   (Amazon Link)
  5. Caster Wheel   (Amazon Link)
  6. 2WD Chassis   (Amazon Link)
  7. 1838 IR Receiver   (Amazon Link)
  8. 3 x Female Headers   (Amazon Link)
  9. 4 x 3.7v Li-ion batteries   (Amazon Link)
  10.  Li-ion Battery Holder   (Amazon Link)
  11. LM2596 5v Voltage Regulator   (Amazon Link)
  12. DC Power Jack   (Amazon Link)
  13. IR Remote   (Amazon Link)
NOTE: Make sure you use the same IR receiver as I have used here. Also The 2WD chassis are not required if you will make your own platform as I have.


  1. Arduino IDE: For writing and uploading code
  2. SketchUp : For designing Chassis  
That's all the things we need for this project, now lets move on to next step, designing chassis.

Building Chassis:

Building chassis is an optional part here, you can just skip this step and get yourself a 2WD robot chassis. I have built myself one using foamboard, The design is pretty simple you can find a SketchUp file below:

arduino robot

You can make your own design as you want, just make sure all the components fit in properly.

IR Robot CAD File

Making Circuit: 

The circuit is pretty straight forward, The motor shield is placed on top of the Arduino board and the IR receiver is connected to A0 pin. Refer the following image.

1838 IR receiver

Here I have soldered the pins of the receiver directly to female headers. Which can be connected to the motor shield directly as shown below:

arduino motor shield

Note:-  If you are not familiar with 1838 IR receiver, check out this article.

Now about the power supply, we need two. One for Arduino (9-12v) another for Motorshield (12-30v). For our motor requirements we need atleast 12v so we will use a 4cell 18650 battery pack. 4x3.7 will give us 14.5v which is enough for motor drive.

But now the problem is about arduino, we cannot power the microcontroller with more than 12v. To solve this problem I have used a DC to DC voltage regulator. 
Check the power supply circuit diagram given below for better understanding.

This is pretty simple circuit and needs no further explanation. But before you connect the output to arduino, use a multi meter to check if the voltage is between 9-12v. You can adjust the voltage by adjusting the screw on the trimmer. 


Now we can write the code to control our robot. 
First get any IR remote you wish to use and decode its IR signals. If you have no idea how to do that, check out this article

Once you have successfully decoded the IR signals of the buttons on your remote, you should have some hex numbers as: 20DF02FD, 20DFE01F, etc. 

We will use these codes in the script below:

Note: Make sure that you have the ""IRremote" and "AFMotor" libraries installed in IDE.



int RECV_PIN = A0; //data out of IR receiver connects to pin A0 

AF_DCMotor motor1(3); 

AF_DCMotor motor2(4);

IRrecv irrecv(RECV_PIN); 

decode_results results; 

void setup() 



 irrecv.enableIRIn(); // start the receiver 




void loop() 


 if (irrecv.decode(&results)) 

{ Serial.println(results.value, HEX); 

 irrecv.resume(); // Receive the next value 

 if (results.value==0x20DF02FD)

{ //Go Forward 






if (results.value==0x20DF827D)

{ //Go Backward 






 if (results.value==0x20DFE01F)

{ //turn left 






if (results.value==0x20DF609F)

{ //turn right 






 if (results.value==0x20DF22DD)

{ //stop








In the above codes just replace the codes with yours and make sure to put the '0x' prefix.
Now you can power up the robot and start controlling it with your IR remote.

Final Note:

Here is a look at the robot I made, you can go ahead and make your own design. 

arduino robot

Also you might like to increase the speed of the robot, to so that just increase the number in the setSpeed() function. It can be anywhere between 0-255, where 0 will stop the motors completely and 255 will set the highest speed as per the motor.

With that been said, you can now make robot and play around. If you have any questions or doubts, feel free to comment down below.
Previously we learned how to control DC motors using arduino. We used a motor driver IC named L293D for the purpose. Although it does get the job done, it isn't the best way to do it. The IC can get hot rather quickly and there is no filtering of motor noise which could cause problems in RF communications and data transfer. 

To avoid these problems we can use a motor drive board/module. Motor drive boards have a driver IC as the heart with a heat sink and some other electronic components to reduce the motor noise. Let's see what a motor driver is, how it works and how to use it for our projects.

Disclaimer: This blog contains Amazon Affiliate links. Buying product from those links helps us run this blog without any extra charges on you.

What is a Motor Driver Board?

A module with a motor driver IC which helps us control speed and direction of DC motors is called a motor driver board. There are a variety of motor driver boards in the market. Most popular being L298N and L293D based motor drivers. 

These boards are compatible with all arduino, esp and similar microcontrollers. In this article we will perticulerly look into 2 very popular motor drivers, The L298N Driver and L293D based motor controller shield.

So let's see these boards in more detail:

L298N Motor Driver:

This board is very popular in the makers community for its smaller size and power. The IC has a heat sink already which makes the board highly efficient. 

L298N motor driver board
L298N is dual H-bridge IC, which means we can control 2 motors uisng this IC.
Here is a list of specification of the driver:

  • Dual H-Bridge Drive Chip: L298N
  • Logical Voltage: 5V
  • Drive Voltage: 5V-35V
  • Logical Current: 0-36mA
  • Drive current: 2A (MAX single bridge)
  • Max Power: 25W
  • Dimensions: 43 x 43 x 26mm
  • Weight: 26g
Using this motor driver we can control 12v-30v motor with max current of 2A. Using driver is pretty similar to using bare IC. Check out this tutorial for more information about that.

L293D Motor Shield:

Shields are something you use with Arduino. These boards stack on top of arduino and we can use them with libraries. It reduces the mess created by wires and saves a lot of space.
Here we will see the popular Arduino Motor Shield V1. 

arduino motor shield motor driver
This motor shield has two L293D ICs which control two DC motors each, hence we can control four DC motors or two stepper motors using this shield. Along with that we can also control two servo motors with this shield.

  • Double H Bridge Drive Chip: L293D
  • Logical Voltage: 5V
  • Drive Voltage: 5V-36V
  • Logical Current: 0-36mA
  • Drive current: 1.2A (MAX single bridge)
  • Max Power: 25W
  • Dimensions: 69 x 53 x 14.3mm
This motor shield just stacks on top of arduino and using a library called AFMotor.h we can easily control motors and servos using it. 

How To Use Motor Shield?

Motor shield can be stacked upon our Arduino uno. Before coding, we need to install the library.
To install library first open the IDE and goto >> Tools >> Manage Libraries
In the search box type "Adafruit Motor Shield" and install the first library.

After the library is installed, goto >> Files >> Examples >> Adafruit Motor Shield Library >> Motor Test. 

Next connect the Arduino to PC and upload the code. Now connect a DC motor to the M4 terminal and see how the motor works. You will notice that the motor slowly spin in one direction gradually gaining speed and then it does same in other direction. 

That's all for this article, now you know how to control a motor using a motor shield. You can use this for testing different codes in the example and learn more. In future we will use this to create an arduino based robot. Till then keep experimenting.

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