Bluetooth protocol stack architecture

1. Bluetooth core protocol architecture

The Bluetooth core protocol includes Baseband Protocol (Baseband), Link Management Protocol (LMP), Link Control Protocol (LCP), Logical Link Control and Adaptation Protocol (L2CAP), Service Discovery Protocol (SDP) and Serial Port Emulation Protocol (RFCOMM ). Among them, the baseband and link controller and the link management protocol belong to the low-level transmission protocol. Their functions focus on the physical realization of voice and data wireless transmission and the connection and networking between Bluetooth devices. These functions are integrated in the Bluetooth hardware module. , application developers for high-level protocols do not need to care about the details of these low-level protocols; Logical Link Control and Adaptation Protocol and Host Control Interface (HCI) belong to high-level transmission protocols, which shield high-level application profiles such as frequency hopping sequences Select and other low-level transmission operations, and provide high-level applications with more beneficial and more effective data packet formats; based on the TS07.10 standard of the European Telecommunications Standards Institute (ETSI), the serial port emulation protocol (RFCOMM) has been formulated; this protocol uses In order to simulate the working environment of the serial port, the traditional application based on the serial port can directly run on the protocol layer without any modification or only a small amount of modification; the Service Discovery Protocol (SDP) is used to realize the mutual query between Bluetooth devices and Ability to access services provided by the other party.

2. Bluetooth upper layer application framework

The Bluetooth application protocol profile refers to the application software located on the upper layer of the Bluetooth protocol stack and the protocols involved, including the development of Bluetooth applications that drive functions such as voice communication and dial-up Internet access. All kinds of Bluetooth products have developed corresponding application frameworks for them by SIG. The application framework mainly defines some common functions or the protocols used to realize specific Bluetooth products, the interoperability requirements of each Bluetooth protocol, and the realization functions of each function.

Bluetooth application frameworks can be divided into five categories:

(1) Application framework: The application framework in the general application model is the basis of all other application frameworks. They specify the application frameworks in other application models and are the functional processes commonly used by all other application frameworks, such as device query, connection Establish and discover services, etc.; (2) Bluetooth phone application framework: application framework related to voice applications and phone control; (3) Bluetooth networking application framework: use Bluetooth devices to provide users with the establishment of personal local area networks and wireless access Public switched telephone network; (4) Object exchange application class framework: used to realize interoperability applications of different types of data objects, such as files, electronic business cards, images, etc.; (5) Bluetooth audio and video application framework: based on network applications audio and video transmission, control, and distribution applications.

3. Bluetooth networking technology

Bluetooth technology is a short-distance wireless communication technology that supports point-to-point or point-to-multipoint data and voice services. The Bluetooth system adopts a flexible networking method without a base station, so that a Bluetooth device can be connected to other multiple Bluetooth devices at the same time, thus forming a Bluetooth piconet (Piconet); a Bluetooth piconet can be just two connected devices (such as As shown in Figure 2.12a), such as a laptop and a mobile phone, or multiple devices connected together (as shown in Figure 2.12b); the Bluetooth piconet adopts a master-slave When the network was first built, one of the Bluetooth devices was defined as the master device, and the rest were slave devices; a master device can communicate with up to seven slave devices at the same time, and the slave devices here are called active slave devices (ActiveSlave); but at the same time There can be multiple dormant (Parked) slave devices belonging to the master device; these dormant slave devices do not perform actual effective data transmission and reception, but still maintain clock synchronization with the master device so that they can quickly join the piconet in the future. Regardless of the state of the device, whether it is a dormant slave device or an active slave device, the master device of the piconet controls the parameters of the channel. In the piconet, the master device communicates with all active slave devices through a certain polling method, and uses methods such as designated time slots to enhance the communication between the master and the slave and the communication between the slave and the slave.

Bluetooth Scatternet (Scatternet) is formed by interconnecting multiple piconets. As shown in Figure 2.12c/2.13, a scatternet is a bluetooth network with a larger coverage area than a piconet composed of overlapping piconets. The slave device can join different piconets through the time division multiplexing mechanism, and the master device of one piconet can become the slave device of another piconet. Each piconet has its own frequency hopping sequence, and there is no frequency hopping synchronization between them, which reduces the interference of the same frequency.

The above are the details of the Bluetooth protocol stack architecture and networking technology introduced by Shenzhen Zuchuang Microelectronics Co., Ltd. If you have Bluetooth product design and development needs, you can trust us. We have rich experience in custom development of smart electronic products. We can evaluate the development cycle and IC price as soon as possible, and can also calculate the PCBA quotation. We are a number of chip agents at home and abroad: Songhan, Yingguang, Jieli, Ankai, Quanzhi, realtek, with MCU, voice IC, BLE Bluetooth IC, dual-mode Bluetooth module, wifi module. We have hardware design and software development capabilities. Covering circuit design, PCB design, single-chip microcomputer development, software custom development, APP custom development, WeChat official account development, voice recognition technology, Bluetooth development, wifi technology, etc. It can also undertake the research and development of smart electronic products, the design of household appliances, the development of beauty equipment, the development of Internet of Things applications, the design of smart home solutions, the development of TWS earphones, the development of Bluetooth earphone speakers, the development of children's toys, and the research and development of electronic education products.