BLE 서비스 알리기

Before a phone can connect, your ESP32 must announce itself. This shouting into the air is called advertising. 📣

Advertising broadcasts tiny packets with your device name and what it offers, so nearby phones can list it without connecting yet.

The Arduino core gives you a BLE library. Include it once, then everything for advertising and connecting becomes a few clean calls.

First you initialize BLE and give your board a friendly name. That name is what users will tap in their phone's Bluetooth list.

Your board acts as a BLE server: it holds the data, and the phone is the client that asks for it. Create the server next.

A service is a labeled group of related data, like all the values for one sensor. A device can offer several services at once.

Each service is identified by a UUID, a long unique code. The phone uses this exact id to find the right service among many.

Short UUIDs like 180F are official standard ones. For your own data, generate a long custom UUID so it never clashes with others.

Once the service is defined, you must start it. Until you do, the phone cannot actually use any of its data.

Finally, tell the radio to advertise. Now the board broadcasts its name and service so phones nearby can discover it.

Open a scanner app like nRF Connect and you should see Smart-Sensor appear. Seeing your name means advertising works.

You wrote a service but the phone shows no data inside it.

Init BLE, name the board, make a server, add a service with a UUID, start it, then advertise. Now your device is discoverable. ✨