ESP32 - Classic Bluetooth and Bluetooth Low Energy

Overview

This tutorial demonstrates how to implement wireless communication between the ESP32 and the DIYables Bluetooth App using either Classic Bluetooth or Bluetooth Low Energy (BLE). The ESP32 features integrated Bluetooth capabilities, eliminating the need for external Bluetooth modules.

The ESP32 provides native support for both Classic Bluetooth and BLE protocols, enabling direct connectivity to the DIYables Bluetooth App on Android and iOS devices without additional hardware requirements.

Key Information: The ESP32 supports dual Bluetooth modes — both Classic Bluetooth and BLE (Bluetooth Low Energy). The DIYables Bluetooth App provides full support for Classic Bluetooth and BLE on Android platforms, with BLE support on iOS. Users can select the appropriate protocol based on their platform requirements and project specifications.

ESP32 Bluetooth Tutorial - Classic Bluetooth and BLE with DIYables Bluetooth App

Features

Dual Protocol Support: Implements both Classic Bluetooth and BLE protocols for maximum compatibility
Wireless Range: Provides wireless communication up to 10 metres
Multi-Platform Compatibility: Supports both Android and iOS operating systems
Flexible Connection Methods: Classic Bluetooth uses traditional pairing; BLE offers automatic connection
Comprehensive Widget Library: Includes sliders, joystick, monitor, plotter, gauge, temperature display, chat, table, rotator, and additional interface components
Power Efficiency Options: BLE mode optimized for low-power applications; Classic Bluetooth provides broader device compatibility
Simple Integration: Single library installation manages all communication protocols

Hardware Used In This Tutorial

1	×	ESP-WROOM-32 Dev Module
1	×	Alternatively, ESP32 Uno-form board
1	×	Alternatively, ESP32 S3 Uno-form board
1	×	USB Cable Type-A to Type-C (for USB-A PC)
1	×	USB Cable Type-C to Type-C (for USB-C PC)
1	×	Recommended: Screw Terminal Expansion Board for ESP32
1	×	Recommended: Breakout Expansion Board for ESP32
1	×	Recommended: Power Splitter for ESP32

Or you can buy the following kits:

1	×	DIYables ESP32 Starter Kit (ESP32 included)
1	×	DIYables Sensor Kit (30 sensors/displays)
1	×	DIYables Sensor Kit (18 sensors/displays)

Disclosure: Some of the links in this section are Amazon affiliate links, meaning we may earn a commission at no additional cost to you if you make a purchase through them. Additionally, some links direct you to products from our own brand, DIYables .

Software Setup

Quick Instructions

Follow these procedures to configure the development environment:

For initial ESP32 setup, consult the ESP32 getting started guide.
Connect the ESP32 board to the computer via USB cable.
Launch the Arduino IDE.
Select the ESP32 board and corresponding COM port.

Install Board Core

Navigate to Tools Board Boards Manager...
Search for "esp32"
Install esp32 by Espressif Systems

Install DIYables Bluetooth Library

Access the Libraries icon in the Arduino IDE left sidebar.
Search for "DIYables Bluetooth" and locate the DIYables Bluetooth library by DIYables
Click Install to add the library

When prompted, install the required library dependencies
Click Install All to complete the installation.

Mobile App

Install the DIYables Bluetooth App: Android | iOS

Platform Compatibility: The DIYables Bluetooth App supports both Classic Bluetooth and BLE on Android platforms, with BLE support on iOS. The ESP32's dual-mode capability allows protocol selection based on platform requirements. Android devices support both Classic Bluetooth and BLE modes. iOS devices require BLE mode. BLE connections establish automatically without manual pairing procedures.

Launch the DIYables Bluetooth App
Grant the following permissions when requested:

Nearby Devices permission (Android 12+) / Bluetooth permission (iOS) - Required for Bluetooth device scanning and connection
Location permission (Android 11 and below only) - Required by Android system for Bluetooth device scanning

Verify Bluetooth is enabled in device settings
Tap the Connect button on the home screen to initiate device scanning.

DIYables Bluetooth App - Home Screen with Scan Button

Select the ESP32 device from the scan results to establish connection.

Examples

The ESP32 supports both Classic Bluetooth and BLE protocols. Select the appropriate implementation based on project requirements. All examples are compatible with ESP32 hardware.

Classic Bluetooth Examples (Android Only) and BLE Examples (Android & iOS)

ESP32 - Bluetooth Slider - Control slider values
ESP32 - Bluetooth Pin Control - Control digital output pins
ESP32 - Bluetooth Monitor - Wireless serial communication
ESP32 - Bluetooth Plotter - Real-time data visualization
ESP32 - Bluetooth Analog Gauge - Analog gauge display
ESP32 - Bluetooth Temperature - Temperature and humidity monitoring
ESP32 - Bluetooth Joystick - 2D joystick input
ESP32 - Bluetooth Rotator - Rotary control input
ESP32 - Bluetooth Chat - Text message communication
ESP32 - Bluetooth Table - Tabular data display
ESP32 - Bluetooth RTC - Real-time clock synchronization
ESP32 - Bluetooth Multiple Apps - Multiple widget integration

Troubleshooting

Symptom	Probable Cause	Resolution
Device not visible during app scanning	Incorrect Bluetooth mode or firmware not running	Verify code uses correct Bluetooth mode (Classic or BLE) and ESP32 is executing
SerialBT.begin() or BLE.begin() fails	Board core or library incompatibility	Install ESP32 board core by Espressif Systems via Boards Manager
Connection established but no data transfer	Outdated DIYables library	Update DIYables Bluetooth library to latest version via Library Manager
Compile error	BluetoothSerial.h or BLEDevice.h not found	DIYables Bluetooth library not installed	Install DIYables Bluetooth library via Library Manager
Compile errors related to board selection	Incorrect board selected or core missing	Select ESP32 board and install esp32 core by Espressif Systems
Connection drops immediately after establishment	Interference or power supply issues	Ensure stable USB power supply and maintain device proximity within 10 metres
Classic Bluetooth fails on iOS	iOS does not support Classic Bluetooth profile	Use BLE mode for iOS device compatibility

Notes

For ESP32 implementation, use Esp32Bluetooth_ examples for Classic Bluetooth or Esp32BLE_ examples for BLE. ArduinoBLE_ examples are designed for different hardware platforms (e.g., Arduino Uno R4).
Classic Bluetooth requires manual pairing through device Bluetooth settings prior to app connection (Android only).
BLE establishes automatic connections without manual pairing procedures and supports both Android and iOS platforms.
Maintain continuous power supply (USB or external) to ensure persistent Bluetooth advertisement and device discoverability.
IOS compatibility requires BLE mode as iOS does not support Classic Bluetooth for accessory devices.

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