Learning Center

Bluetooth Low Energy

Bluetooth Low Energy (BLE) is the short-range, low-power radio in phones, sensors and wearables. Learn how BLE advertising, GATT, the MTU and the central and peripheral roles work, and what iOS and Android allow apps to do with them.

Start with how BLE works Learning Center

Basics

How does Bluetooth Low Energy work?The radio, advertising and scanning, connections, roles and GATT.Bluetooth Classic vs Bluetooth Low EnergyTwo radios in one standard, and why phone-to-phone apps use the low energy one.What is a BLE beacon?A one-way Bluetooth LE broadcast of an identifier, and what phones do with it.BLE vs NFC vs UWBDiscovery and data, tap to share, or precise ranging, and how the three combine.

How it works

What is BLE advertising?The small broadcast packets that let Bluetooth LE devices find each other.What are GATT services and characteristics?How a Bluetooth LE device lays out its data, and how another device reads it.What is a BLE central and a BLE peripheral?Who advertises, who scans, and why two phones need both roles to talk.What is the BLE MTU, and why does it limit message size?The per-packet size limit on a BLE link, and how apps send longer messages.What is LE Coded PHY (Bluetooth long range)?The Bluetooth LE radio mode that gives up speed for range, and when to use it.How far does Bluetooth Low Energy reach?Why BLE range has no single number, and the factors that decide it.How much battery does BLE use?What drains battery in BLE, from scanning to connection intervals, and how to tune it.What throughput does BLE get in practice?Why apps see far less than the PHY rate, and the settings that decide how much.Is Bluetooth Low Energy encrypted?What BLE encrypts, what it leaves readable, and why pairing type matters.How does Bluetooth Mesh (the SIG standard) work?Provisioning, keys, managed flooding, and the four optional node features.Is a phone mesh over BLE the same as Bluetooth Mesh?A SIG standard for building devices versus an app protocol between phones.

Phones and platforms

Can a BLE app run in the background on iOS?The two background modes, what changes off screen, and how state restoration helps.Bluetooth permissions on Android, explainedThe Android 12 Bluetooth permissions, the location rule before them, and background work.How do two phones find each other over Bluetooth?Advertising, scanning and service UUID filters, and where iOS and Android differ.How do iPhone and Android phones message each other over Bluetooth?The BLE roles, the GATT exchange, and where iOS and Android behave differently.

Building

Can react-native-ble-plx connect two phones directly?Why ble-plx cannot do phone to phone, and what React Native apps use instead.How do you build a Bluetooth mesh chat app in React Native?The native and JavaScript layers behind a phone-to-phone mesh chat app.How do you send data between two phones without internet in React Native?The direct links a React Native app can use, by platform pair, and what each needs.