Bluetooth Core Technology Overview (I): Bluetooth Overview

Keywords: Bluetooth Core Technology Protocol version history
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Download link: Bluetooth profile specifications (basically covering all Bluetooth protocols), buletooth core 2.1-4.0 specification (Core Protocol V2.1 \ V3.0 \ v4.0 of three Bluetooth versions), Bluetooth Core Technology and Application (Bluetooth protocol-related beginners must read, developer reference)

I. Name Origin
The name of Bluetooth comes from a Danish king Harar in the tenth century, and the Harar Bluetooth King blatand can be interpreted as Bluetooth because the King prefers to eat blueberries, the gums are blue every day, so they are called bluetooth.
In the preparatory stage of the industry association, an extremely expressive name is needed to name this high-tech technology. After a night of discussion about Europe's history and future wireless technology development, some people thought it would be appropriate to name blatand. King blatand unified Norway, Sweden, and Denmark. He is articulate and sociable, just like this coming technology, technology will be defined to allow coordination between different industrial fields and maintain good communication between various system fields, such as jobs in the computer, mobile phone, and automotive industries.

Ii. Development History
Developed by Ericsson in 1994;
On April 9, 1997, Ericsson contacted other equipment manufacturers;
In February 1998, a special interest group sig (Special Interest Group) composed of Nokia, apple, and Samsung );
In May 1998, five famous manufacturers, including Ericsson, Nokia, Toshiba, IBM, and Intel, were jointly developed;
In the second half of 1999, mainstream equipment vendors such as Microsoft, Motorola, Samsung, and Lucent widely promoted bluetooth technology applications;
In October 13, 2006, the Bluetooth sig (Bluetooth Technology Alliance) grew to more than 200 member companies and about 6000 application member companies.

Iii. Version Information

There are six versions of Bluetooth: V1.1, 1.2, 2.0, 2.1, 3.0, and 4.0. Download the connection:
1. V1.1
The transfer rate is about 748 ~ Kb/s, because of its early design, the communication quality is easily affected by the interference of products with the same frequency.
2. v1.2
Similarly, only 748 ~ The transmission rate of kb/s, but the anti-interference frequency hopping function is added.
3. V2.0 + EDR version
Is a 1.2 improved version with a transfer rate of about 1.8 MB/S ~ 2.1 Mb/s, supporting duplex mode-one side for voice communication and transmission of file/high-quality images. Version 2.0 also supports stereo.
The most widely used is the thinkth2.0 + EDR standard, which was launched in 2004. Many products that support the Bluetooth 2.0 + EDR standard emerged in 2006. Although the Bluetooth 2.0 + EDR standard has made a lot of technical improvements, the configuration process continued from the 1.x standard is complicated and the power consumption of devices is large.
4. V2.1
Better power-saving performance: the sniffsubrating function is added to Bluetooth 2.1, which saves power consumption by setting the sending interval of mutually confirmed signals between two devices.
5. V3.0 + HS
In April 21, 2009, the Bluetooth Technology Alliance (Bluetooth sig) officially issued a new generation of Standard Specification "Bluetooth Core Specification Version 3.0 high speed" (Bluetooth Core Specification Version 3.0 ), the core of Bluetooth 3.0 is "genericalternate MAC/PHY" (AMP), a new alternating RF technology that allows the Bluetooth protocol stack to dynamically select the correct RF for any task. Technologies originally expected to be used in the new specification include 802.11 and umb, but umb applications are removed from the new specification.
6. v4.0
Bluetooth 4.0 includes three sub-Specifications: Traditional bluetooth technology, high-speed bluetooth technology, and new Bluetooth Low-power technology. The improvement of Bluetooth 4.0 is mainly reflected in three aspects: Battery endurance, energy saving, and device types. With low cost, cross-vendor interoperability, 3 ms low latency, over 100 long distance, AES-128 encryption and many other features, in addition, Bluetooth 4.0 effective transmission distance is also improved. The valid transmission distance of Bluetooth 3.0 is 10 meters (about 32 feet), while that of Bluetooth 4.0 is up to 100 meters (about 328 feet ).
Iv. Technical Features of Bluetooth
Simply put, Bluetooth is a short-range broadband radio technology and a global open standard for wireless voice and data transmission. It uses advanced technologies such as FHSS, TDMA, and CDMA to establish information transmission between multiple communication and information systems in a small scope.
1. Main Technical Features of Bluetooth:
(1) Working Frequency Band: 2.4ghz engineering medical (ISM) frequency band, no license required. Most countries use 79 frequency points. The carrier frequency is (2402 + k) MHz (k =, 2... 78), the carrier frequency interval is 1 MHz. TDD time-division duplex is used.
(2) transmission rate: 1 Mb/s (V2.0 or above)
(3) debugging methods: Bt = 0.5 gfsk modulation, modulation index is 0.28-0.35.
(4) frequency hopping technology:The frequency hopping rate is 1600 hops/second. When the chain is created (including paging and query), it is increased to 3200 hops/second. Bluetooth uses fast frequency hopping and short grouping technology to reduce interference with the same frequency and ensure the reliability of transmission.
(5) Speech modulation method:Continuous Variable Slope incremental modulation (CVSD, continuousvariable slope delta modulation), strong fading resistance, even if the error rate reaches 4%, the voice quality is acceptable.
(6) Support for circuit switching and group switching:Bluetooth supports real-time synchronous and targeted connections (SCO links) and non-real-time asynchronous and non-targeted connections (ACL links). The former transfers real-time information such as voice, and the latter focuses on data packets. Speech and data can be transmitted independently or simultaneously. Bluetooth supports an asynchronous data channel, three concurrent synchronous voice channels, or a channel that simultaneously transmits asynchronous data and synchronous voice. Each voice channel supports synchronous voice at 64 Kbps; asynchronous channels support asymmetric duplex communication at 723.2/57.6kbps or symmetric full duplex communication at 433.9kbps.
(7) support point-to-point and point-to-point communication: A bluetooth device can form two types of networks in a specific way: a micro-Network (piconet) and a distributed network (scatternet). The establishment of a micro-network starts with the connection of the two devices, A maximum of eight devices can be used. In a micro-network, there is only one master device, and the rest are slave devices (slave). Different Master/Slave Device pairs can adopt different connection methods. In one communication, the connection method can also be changed. Several independent micronetworks are linked together in a specific way to form a distributed network. All Bluetooth devices are equal, so there is no base station concept in Bluetooth.
(8) Working Distance:A Bluetooth device has three power levels: 100 MW (20dbm), 2.5 MW (4dbm), and 1 MW (0dbm). The effective working range is as follows: 100, 10, and 1.
5. Bluetooth System Structure

1. Radio Frequency Unit (radio ):Responsible for sending and receiving data and voice, featuring short distance and low power consumption. A Bluetooth antenna is generally small in size and light in weight and belongs to a micro-band antenna.
2. baseband or link controller ):Converts RF and digital or voice signals to implement baseband protocols and other underlying connection procedures.
3. Link Manager ):Manages communications between bluetooth devices and establishes, verifies, and configures links.
4. Implementation of the Bluetooth Software protocol:For example, the purple part.

Vi. Bluetooth protocol specifications
Transmission protocol, intermediary protocol, and application protocol;
1. Transmission Protocol
Establishes and manages physical links between bluetooth devices, confirms locations of each other, and establishes and manages physical links between bluetooth devices;
Underlying transmission protocol:
Bluetooth radio frequency (Radio), baseband link management controller (baseband & link Controller), and Link Management Protocol (LMP ). Physical implementation of language and data wireless transmission and networking between bluetooth devices.
High-level transmission protocol:
Logicallink control and Adaptation Protocol L2CAP and Host Control Interface (HCI ). It shields high-level applications from bottom-layer transmission operations such as frequency hopping sequence selection, and provides high-level programs with effective data grouping formats.
2. Intermediary Agreement
It provides necessary support for high-level application protocols or programs to work on the Bluetooth Logical Link and provides different standard interfaces for applications.
Serial Port simulation Protocol: RFCOMM, Service Discovery Protocol: SDP, Interoperability Protocol IrDA, network access protocol: PPP, IP, TCP, UDP, Telephone Control Protocol: TCS, at instruction set.

3. Application Protocol

Applications on the Bluetooth protocol stack and related protocols, such as dial-up Internet access and language functions.

The application framework of Bluetooth is as follows:
(1) General application framework: Query and establish connection services;
(2) Bluetooth phone application framework: Telephone Control and language;
(3) Bluetooth connection application framework: network applications;
(4) object interaction service framework: IrDA and obex;
(5) Bluetooth audio and video control framework.

VII. Hardware Interfaces
Generally, the Bluetooth Chip communicates with the master chip through UART, USB, sdio, I2S, and pccard. As shown in, communicate with the master chip through UART.

8. Bluetooth applications
The Bluetooth Application is on the mobile phone.
Bluetooth is applied on the handheld computer.
Bluetooth is used on other digital devices, such as digital cameras and digital cameras.
The electronic wallet and the electronic lock made up by the basketball technology.
The basketball system is embedded with traditional household appliances such as microwave oven, washing machine, refrigerator, and air conditioner.