ESP32 Bluetooth Tutorial: Wireless Serial Communication with Arduino IDE

Introduction

The ESP32 has built-in Classic Bluetooth and Bluetooth Low Energy (BLE), making it incredibly versatile for wireless communication. In this tutorial, we use Bluetooth Serial to create a wireless terminal — allowing you to send commands from your phone to control GPIO pins.

What We Will Build

A Bluetooth-controlled LED system. Using a free Android app (Serial Bluetooth Terminal), you will type commands on your phone and the ESP32 will respond by toggling an LED.

No Extra Hardware Needed

Unlike the older HC-05/HC-06 Bluetooth modules, the ESP32 has Bluetooth built directly into the chip — saving you money and simplifying your circuit.

The Code

#include "BluetoothSerial.h"
BluetoothSerial SerialBT;
#define LED_PIN 2
void setup() {
  Serial.begin(115200);
  pinMode(LED_PIN, OUTPUT);
  SerialBT.begin("ESP32_BT"); // Bluetooth device name
  Serial.println("Bluetooth started! Pair with 'ESP32_BT'");
}
void loop() {
  if (SerialBT.available()) {
    String cmd = SerialBT.readStringUntil('\n');
    cmd.trim();
    if (cmd == "ON") {
      digitalWrite(LED_PIN, HIGH);
      SerialBT.println("LED is ON");
    } else if (cmd == "OFF") {
      digitalWrite(LED_PIN, LOW);
      SerialBT.println("LED is OFF");
    } else {
      SerialBT.println("Unknown command. Send ON or OFF.");
    }
  }
}

How to Connect

1. Upload the code to your ESP32.
2. On your Android phone, go to Settings > Bluetooth and pair with “ESP32_BT”.
3. Download Serial Bluetooth Terminal from the Play Store.
4. Connect to ESP32_BT in the app and type ON or OFF.

Conclusion

Bluetooth Serial on the ESP32 is a powerful and cable-free way to control your projects. It is perfect for robotics, smart home gadgets, and any project where you need a quick wireless debugging terminal.