ESP32 BASICS · LESSON 13
Bluetooth Basics: Classic and BLE
The difference between classic Bluetooth and BLE, and a first look at services and characteristics.
Bluetooth on the ESP32 comes in two distinct flavours that aren't interchangeable: classic Bluetooth, aimed at continuous audio and serial-style links, and Bluetooth Low Energy (BLE), aimed at short, infrequent exchanges of small amounts of data on very little power.
| Classic Bluetooth | BLE | |
|---|---|---|
| Typical use | Audio, serial cable replacement | Sensors, wearables, short data bursts |
| Power use | Higher, continuous | Very low, especially when idle |
| Data model | Stream of bytes | Services made of characteristics |
A first BLE characteristic
ble_basic.ino
#include
#include
#include
#define SERVICE_UUID "12345678-1234-1234-1234-1234567890ab"
#define CHARACTERISTIC_UUID "abcd1234-ab12-cd34-ef56-1234567890ab"
void setup() {
BLEDevice::init("ESP32-Sensor");
BLEServer* server = BLEDevice::createServer();
BLEService* service = server->createService(SERVICE_UUID);
BLECharacteristic* characteristic = service->createCharacteristic(
CHARACTERISTIC_UUID,
BLECharacteristic::PROPERTY_READ
);
characteristic->setValue("hello");
service->start();
server->getAdvertising()->start();
}
void loop() {
} KEY IDEA
Think of a BLE "service" as a folder and its "characteristics" as the individual values inside it that a phone app can read or write.