Bluetooth is divided into traditional Bluetooth and Bluetooth low energy. Bluetooth 4.0 and above are called Bluetooth low energy, but the Bluetooth 4.0 standard includes a traditional Bluetooth module and a Bluetooth low energy module. It is a dual-mode standard.
Bluetooth low energy is developed on the basis of traditional Bluetooth, but it is different from traditional modules. The biggest feature is that the cost and power consumption are reduced. It can be quickly searched and connected quickly. It keeps the connection and transmits data with ultra low power .
Structure and configuration of the Bluetooth low energy protocol stack
The Bluetooth low energy protocol stack includes two parts and a total of 8 layers: Host and Controller.
Host includes L2CAP logical link control and adaptive protocol layer, security management layer, ATT attribute protocol layer, GAP universal access profile layer and GATT general attribute profile layer. Controller includes physical layer, link layer and host control interface layer.
Profiles and applications are always based on GAP and GATT; in a single-chip solution, the Controller and Host, profiles, and the application layer are on the same chip; in the network controller mode, the Host and Controller run together. However, applications and profiles are on another device, such as a PC or other microcontroller, and can be operated through UART and USB. In dual-chip mode, the Controller runs on one controller, while the application layer, profiles and Host run on another On a controller.
Flow chart of BLE device connection status:
Application of BLE
Many people's understanding of Bluetooth is also limited to mobile phones, wireless mouse and other fields. In fact, Bluetooth can be applied to more products. Traditional Bluetooth can be used for transmission of relatively large amounts of data, such as voice and music; Bluetooth low energy is used in products with high real-time requirements but low data rates, such as remote control (mouse, keyboard, etc.) and sensors Data transmission from devices (heartbeat belts, sphygmomanometers, temperature sensors, etc.).
The emergence of Bluetooth 5.0 and Bluetooth 5.1 makes the application of Bluetooth low energy technology more extensive and has great potential. Bluetooth modules based on Bluetooth low energy technology can be applied to mobile expansion devices, automotive electronics, health and medical supplies (heartbeat Belt, sphygmomanometer, etc.), positioning applications (indoor positioning, downhole positioning, etc.), close-range data collection (wireless meter reading, wireless telemetry, temperature and humidity sensors, etc.), data transmission (smart home indoor control, Bluetooth dimming, printers, etc. )etc.