In this article we will use Bluetooth capabilities of ESP32 and connect our phone (or laptop) to ESP32 using Bluetooth, and turn the built in LED on and off.

Requirements

For this project, we'll need:

1. ESP32

By the end of this project, we will be able to connect our phone to ESP32 using Bluetooth and turn the LED on/off using Bluetooth.

Demo

Watch the demo video below.

Code (Explained)

Library

First of all we need to include a library for Bluetooth operations.

#include "BluetoothSerial.h"

Global variables

Then we will need 3 variables for this code.

BluetoothSerial bs;
char command;
int ledPin = 2;

Variable bs is for accessing the BluetoothSerial library functions.

Variable command is used to store the incoming command from phone, which can either be '0' or '1'.

Variable ledPin is used as a constant, to store the value 2. The reason for this variable is that when we use any other module (other than ESP32), then it might have a different pin connected to the LED. So instead of changing everywhere, we can just update here.

setup() function

This function is very easy.

First we start the Bluetooth protocol.

And then we set the pin mode for the LED pin, which is OUTPUT.

void setup() {
  bs.begin("ESP32");
  pinMode(ledPin, OUTPUT);
}

loop() function

This function is also unbelievably simple.

First, we check if any device is connected to the Bluetooth. And read the incoming command if connected.

  if (bs.available()) {
    command = bs.read();
  }

Secondly, if the command is '1' then turn the LED on.

  if (command == '1') {
    digitalWrite(ledPin, HIGH);
  }

Thirdly, if the command is '0' then turn the LED off.

  if (command == '0') {
    digitalWrite(ledPin, LOW);
  }

Finally, add a delay so everything goes smooth.

  delay(20);

Full code

The entire code is as below.

#include "BluetoothSerial.h"


BluetoothSerial bs;
char command;
int ledPin = 2;


void setup() {
  bs.begin("ESP32");
  pinMode(ledPin, OUTPUT);
}

void loop() {
  if (bs.available()) {
    command = bs.read();
  }

  if (command == '1') {
    digitalWrite(ledPin, HIGH);
  }

  if (command == '0') {
    digitalWrite(ledPin, LOW);
  }

  delay(20);
}

That's all, plug the ESP32, compile and upload the code, once ready, connect the phone.

To send command using Bluetooth, we will use a third party application on our phone.

I've android phone, so I am downloading application named Serial Bluetooth Terminal but pretty much any similar application will work.

Thanks for reading.