mukeshkp2005
Published © GPL3+

Arduino with Bluetooth to Control an LED!

Tutorial to control an LED with an app using an HC 05 bluetooth module.

BeginnerFull instructions provided22,059
Arduino with Bluetooth to Control an LED!

Things used in this project

Hardware components

Arduino UNO
Arduino UNO
×1
HC-05 Bluetooth Module
HC-05 Bluetooth Module
×1
Resistor 1k ohm
Resistor 1k ohm
×1
Male/Male Jumper Wires
×8
5 mm LED: Red
5 mm LED: Red
×1

Software apps and online services

Arduino IDE
Arduino IDE
MIT App Inventor
MIT App Inventor

Story

Read more

Schematics

HC-05 to Arduino Connections

This is the way a circuit is meant to be formed between an HC-05 and an arduino.

This is the voltage divider circuit between Arduino and HC-05.

Code

The code for HC-05 and Arduino Interfacing

C/C++
This is the code you have to type into the Arduino IDE. The comments are not necessary, but I have commented heavily for better understanding, especially for people just starting out Arduino.
/*Code to control an LED via bluetooth through a phone app.
Project by MukeshArvindh. Code by MukeshArvindh.*/

/*If you are going to copy and paste the code, then do not forget 
to delete the void setup() and void loop() function from the 
sketch you are using before doing so,as the functions already
exist in this sketch. Copy-pasting the comments will not
cause any changes in the outcome or code.*/

/*Note:This code has been compiled and checked multiple times, and has 
proven to be accurate. The product also works as intended.*/

//Bluetooth uses serial communication. So, we use many serial functions 
//in this sketch. 
const int LED = 5;
/*Declaring that there is an LED on pin 5 of the arduino board. We use 
const as we will not change this. You don't have to name it LED. You 
can even put your name instead.*/
char switchstate;
/*declaring that there is a variable called switchstate, which will 
hold a character value. This is due to programming of the app, which
will send  a text value to arduino. If we use 'int' instead of 
'char' the code will not work properly.*/
void setup() {//Here the code only runs once.
Serial.begin(9600);
/*To start serial communication at a rate of 9600 bits per second. This  
is the default rate anyways.*/
pinMode(LED, OUTPUT);
//Declaring that the LED is an output.
}
void loop() {//This code repeats. This is our main code.
while(Serial.available()>0){ 
 //code to be executed only when Serial.available()>0
 /*Serial.available>0 is to check if there is any reading from the 
 HC-05 Bluetooth module.*/ 
switchstate = Serial.read();
/*The character we had declared earlier is now being assigned a value-
the value of whatever Serial.read() is.*/
//Serial.read() is to read the value coming from app.
Serial.print(switchstate);
//This will print the value onto the Serial monitor.
Serial.print("\n");
//This moves to the next line after every new line printed.
delay(15);
/*Gives a break of 15 milliseconds. Delay is for human eye, and for
speed of some computers, as some will crash at high speeds.*/
if(switchstate == '1'){//Checking if the value from app is '1'
 digitalWrite(5, HIGH);
 //If it is, write the component on pin 5(LED) high. 
}
else if(switchstate == '0'){//Else, if the vaue from app is '0',
 digitalWrite(5, LOW);//Write the component on pin 5(LED) low.
}
}
}

Credits

mukeshkp2005

mukeshkp2005

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Related channels and tags
  • Arduino
  • Communication
  • Internet of Things
  • MIT App Inventor