What is BLE ?

• Bluetooth Low Energy (BLE), is a light-weight subset of classic Bluetooth and was introduced as part of the Bluetooth 4.0 specification
• BLE is a close-range, wireless technology that is prevalent in connecting low-power/battery consumer IoT devices including wearables, phones and tablet PCs
• Compared to the full Bluetooth protocol, BLE is focused on delivering small amounts of data at low speeds
• BLE devices define both a General Access Profile (GAP) and a Generic Attribute Profile (GATT). The GAP controls the connections and visibility of devices, while the GATT defines how two devices transfer data via BLE Services and Characteristics. GATT-based data flow occurs after two devices are connected based on the GAP advertising and discovery process
• BLE devices are categorized into 2 types: peripheral (GATT Server) devices, such as heart rate monitors or proximity tags, are the small, low-power, resource-constrained devices that connect to a much more powerful central (GATT Client) device such as a phone, tablet or gateway. A peripheral can only be connected to a single central device at a time, so once connected, a peripheral will stop advertising itself