Low-energy Bluetooth is widely recognized in the industry as a key technology for realizing the vision of the Internet of Things (IoT) application. In fact, the extremely low power consumption makes it the ideal wireless communication solution for battery-powered IoT products. Although the current low-power Bluetooth specification is limited to several specific applications, innovative solutions can make this Technology is extended to different application areas, such as multimedia streaming. In this development direction, this article introduces a low-energy Bluetooth device voice streaming application called BlueVoice.
This article introduces the BlueVoice application from the set of extended services required to support voice streaming services, and then evaluates the performance of BlueVoice on actual hardware devices. On selected hardware platforms, the BlueVoice app fully supports voice streaming services while avoiding wasted energy.
I. Preface
Through the rapid growth of the past few decades, the Internet has penetrated almost every aspect of daily life in human society. In the future, the Internet will expand to the Internet of Everything, and billions or even tens of billions of unique "items" will interact with humans and the surrounding environment through wireless communication to perform advanced tasks. In this concept, "items" may be sensors, actuators, appliances, toys, and in general, any virtual or physical item that can be identified. This Internet evolution concept is called the Internet of Things (IoT).
The concept of the Internet of Things is to connect all product devices together to form a global network through standard protocol solutions (ie Internet Protocol) and wireless communication interfaces. Realizing the Internet of Everything, although the existing large number of RF communication technologies can be used, when the IoT product is an autonomous battery-powered device deployed in the field, low-power wireless communication technology is the most suitable communication solution. In this regard, Bluetooth LE [1] technology is considered the most effective IoT communication solution and is being integrated into the Internet world [2].
In today's IoT applications, low-energy Bluetooth solutions are primarily used for life parameter monitoring purposes. In addition to traditional surveillance services, the industry has begun to explore advanced applications based on other technologies in recent years. For example, reference [3] proposes and analyzes the network communication [4] based on IEEE802.15.4. In this respect, the transmission of multimedia data over low-energy Bluetooth is still in its infancy, and the lack of available solutions is mainly due to the fact that these applications were not originally considered (for example, applications such as medical and fitness were initially considered). This article explores how to address these technical limitations by taking the BlueVoice application that supports voice streaming services on Bluetooth devices with low power consumption as an example. Let's take a look at the low-energy Bluetooth technology, then detail the extended service set needed to support the new application concept, then introduce the application design, and finally test the actual performance on the STM32 Nucleo L476 board.
The content of this article is arranged as follows: Chapter 2 introduces the working principle of low-energy Bluetooth, first describes the entire working stack; then introduces the concept of Profiles. The third chapter introduces the application design, describes its low-energy Bluetooth configuration file, and then introduces its design principles, design implementation and actual performance. The fourth chapter is the conclusion.
M. GenTIli and R. Sannino are with AST Audio/Sensors Platforms R&D and Audio SW Ecosystem, STMicroelectronics, Agrate Brianza, Italy (e-mail: [maurizio.genTIlijroberto.sannino]@st.com).
M. Petracca is with Scuola Superiore Sant'Anna di Pisa and NaTIonal Inter-University ConsorTIum for Telecommunications, Pisa, Italy (e-mail:matteo.).
II. Overview of Bluetooth Low Energy Technology
The BLE Low Energy Bluetooth specification was written to the Bluetooth 4.0 core specification in 2010. Although similar to basic Bluetooth, the low energy Bluetooth specification is primarily designed for ultra low power applications. There are very few potential applications for connecting battery-powered devices through low-power Bluetooth technology, and medical, fitness and smart homes are just a few examples.
Figure 1. Low-power Bluetooth protocol stack
As shown in Figure 1, the overall structure of the low-power Bluetooth protocol stack is mainly composed of two parts: the controller and the host. The application software uses the services provided by the protocol of the protocol stack host layer. The host layer is divided into five layers: Logical Link Control and Adaptation Protocol (L2CAP), Attribute Protocol (ATT), Common Attribute Profile (GATT), Security Management Protocol (SM), and Generic Access Profile (GAP). The controller part has only two layers: the physical layer (PHY) and the link layer (LL). As shown in Figure 1, the host-controller (HCI) interface is the communication channel between the controller and the host.
The physical layer is responsible for bit modulation and sends and receives data over the wireless channel. The maximum data rate is 1 Mb/s and the typical communication distance is tens of meters.
The link layer specifies the function of two-way communication between two devices. Low-power Bluetooth nodes have two roles: master and slave. Typically, a master device (eg, a laptop, a smartphone) searches for a slave device (eg, a somatosensory device); if necessary, the slave device transmits data to the master device. The slave device is usually in a sleep state and wakes up at regular intervals to be searched by the master device.
Above the link layer, the Logical Link Control and Adaptation Protocol (L2CAP) has two main functions. The main function of the protocol is to provide multiplexed functions, package and convert top-level multi-protocol data according to the standard low-energy Bluetooth packet data format. Security Management Protocol (SM) and Generic Access Profile (GAP) provide data security and service management capabilities, respectively. In detail, the security management protocol defines how the key is generated, and how to exchange keys between two devices (master and slave devices) to establish a secure encrypted communication channel, while the universal access profile specifies how the two devices are at the bottom. Interworking
Attribute Protocol (ATT) and Common Attribute Profiles are two protocol components that need to be considered when developing new applications. The attribute protocol is a stateless client/server protocol: regardless of whether the underlying role of the device is a master or a slave, each device can be set to a server, client, or client-server. The client requests server data to send data, the server sends data to the client, the data is stored in the server as attributes, each attribute contains GATT managed data, and the data is assigned a Universally Unique Identifier (UUID). Through an L2CAP dedicated channel, the attribute protocol establishes a communication channel between the server properties and the client. The Generic Attribute Profile (GATT) adds a data abstraction model at the attribute protocol layer that is responsible for searching the data held by the attribute protocol and exchanging features between the two devices. Each low-energy Bluetooth device has a set of possible attributes (storage services) and characteristics (properties related to the storage service). If you are creating a new application on a low-power Bluetooth stack, you must define attributes and characteristics. The characteristics, attributes, and underlying specifications of a particular application are collectively referred to as profiles, and standard profiles ensure that products of different brands can be interconnected.
Electronic motors applications.
Multiple Electronic Limits Tubular Motor,Motor Solutions,Intelligent Remote Control Motor Solutions,Electronic Limit Garage Door Motor
GUANGDONG A-OK TECHNOLOGY GRAND DEVELOPMENT CO.,LTD. , https://www.a-okmotor.com