Bluetooth 5.2 enhances the short-range wireless standard by adding Low Power Isochronous Channels (LE Isochronous Channels) functionality to support LE Audio. Here are the specific changes in Bluetooth 5.2.
1. Low Power Bluetooth Isochronous Channels
The Low Power Bluetooth Isochronous Channels feature is important for LE Audio support because it allows time-limited data to be transmitted to one or more devices for time-synchronized processing. This technology extends audio applications as it can be used not only in a single-to-one connection, but also broadcast to multiple devices in a connectionless topology.
The Advanced Audio Distribution Profile (A2DP) is an existing Bluetooth audio profile that defines how Bluetooth can be used for high-quality audio applications, such as streaming music from a smartphone to a set of Bluetooth headphones.The disadvantage of A2DP is that it can support only a single or multiple point-to-point pairing topology, which defines the "playback source" (e.g., a playback device such as a smartphone). The disadvantage of A2DP is that it can only support a single or multiple point-to-point pairing topology, which defines the relationship between a "playback source" (e.g., a playback device such as a smartphone) and a "receiving device" (e.g., a device such as a speaker that broadcasts sound). A2DP is unable to ensure that multiple receivers are playing the audio streams precisely at the same time, making synchronized playback across a series of associated devices difficult. In fact, Bluetooth audio devices using A2DP only operate when connected to a single device.
The low-power synchronization channel provides a mechanism to overcome this shortcoming by ensuring simultaneous playback across multiple receiving devices (e.g., left and right earbud headsets) that receive data from the same source. The data has a time-limited expiration date and expires at the end of this period. Expired data that has not yet been sent is discarded. These mechanisms ensure that the receiving device only receives valid data that meets the wait time and delay rules.
2. Synchronized channels enable many new applications
With the new low-power synchronized channel feature, many new uses, new topologies, and ultimately many new products will be possible. The ability to use low-power Bluetooth for audio is called LE Audio, and one of the most obvious examples of an LE Audio scenario is Personal Audio Sharing. A group of friends can each utilize their own Bluetooth headset to simultaneously enjoy music played on a single smartphone. This is an example of a private group sharing a single audio source. This kind of sound context can be used in a variety of ways in teaching and learning environments, such as individuals and groups grouped together in large lecture halls or industrial production lines to listen to the same content, the same narration, and the same lecture at the same time.
A similar example of use is "public assisted listening," which is the broadcasting of conversations in theater performances that can be clearly heard by those in the audience who have low-power Bluetooth hearing aids. For example, the same technology can be applied to a TV in a gym, where all participants using low-power Bluetooth headphones or earbuds can listen to the TV's audio content. Similarly, when an emergency flight message is broadcast in multiple languages at an airport, passengers on an airplane can connect their headset to the flight information system, specify their preferred language, and listen to the flight message in that language.
3. Enhanced Attribute Protocol
Bluetooth 5.2 introduces the Enhanced Attribute Protocol (EATT), which is an upgraded version of the Generic Attribute Protocol (GATT). The main advantage of EATT is that it can support concurrent event manipulation, allowing packets of ATT-related data from different applications to be logically linked. The main advantage of EATT is that it supports concurrent event operations, allows logical link control and adaptation protocol (L2CAP) packets from different applications associated with the ATT to be interleaved, and allows the size of the ATT's Maximum Transmission Unit (MTU) to be varied during the course of a connection. These enhancements to EATT reduce the risk of multiple applications on a device using the low-power Bluetooth stack temporarily blocking each other, thereby reducing point-to-point latency for one or more applications and improving responsiveness for a better user experience. Enhanced EATT has security advantages over original ATT because it can only be used for encrypted connections.
To support EATT, the revised core specification defines a new L2CAP model. The new mode is called L2CAP Enhanced Credit Based Flow Control Mode, and as the name implies, this mode provides flow control and therefore allows applications to treat the protocol as reliable.
4. Low Power Control
The third major addition to Bluetooth 5.2 is LE PowerControl, which allows devices to dynamically optimize the amount of transmission power used for communication to extend battery life. Low-power Bluetooth receivers can now monitor the signal strength on the transmitting device and request a change in the transmit power, often to balance signal quality and power. This is an important addition, as a particularly strong signal can saturate the receiving device and cause communication to fail; conversely, when the signal strength is too low, the error rate of the receiving device increases, which affects the transmission and ultimately causes it to fail.
The LE Power Control feature allows the Bluetooth controller to monitor and report changes in path loss to the Bluetooth host using the concept of zones. Finally, this feature also allows other wireless devices in the environment that use the 2.4GHz frequency range to improve **** storage.
Specific scenarios for using Bluetooth 5.2
1. Private audio sharing: For example, if you have a favorite piece of music that you want to share with people around you, instead of having to share the link with an easy-to-use cloud, you can just play the music directly from your phone and have people around you connect to your sharing channel.
2. Public **** external device audio reception: For example, in the gym there will be different fitness programs playing on different screens, the sound between each other must have interference, this time the different audio into different groups, by accessing the corresponding grouping you can receive the corresponding audio, reducing noise interference. When it comes to square dancing, a LE Audio Bluetooth headset is a great way to keep the world quiet.
3. Auxiliary reception: In the terminal waiting room in the flight train information are loud speaker mode play, for some hearing impaired people, or the environment is noisy, it is not easy to hear the content, if the flight train information through the LE Audio equipment broadcast, passengers through the Bluetooth headset or the corresponding cell phone APP to receive, you can greatly save time and energy.
4. Multi-language real-time translation: In an environment where people's languages are complex, it is possible to receive translated information by connecting a Bluetooth device to the corresponding language translation channel.
ST17H66 Bluetooth BLE5.2 Chip is the latest 16-pin Bluetooth BLE chip from Lenze Technology, featuring 512KB Flash + (96KB ROM) + 64KB SRAM, Bluetooth stack curing, no more Flash space. 64KB SRAM, partitioned for use. More user data can be saved in standby, high-capacity buffer can be set to support more complex functions. Self-organizing network application in line with SIG specification. Includes multi-node control, and 2 masters and 4 slaves working at the same time.
ST17H66 has 10 x GPIO, -103dBm @BLE 125Kbps. single-ended antenna output, can be no matching circuit. It supports antenna matrix switching and external LNA signal amplification.
The biggest advantage is the reduced power consumption. The previous generation of product Bluetooth receive peak current >13mA; MCU power consumption ~0.5mA/MHz; low power mode average current >40uA. new product Bluetooth receive peak current 8.6mA, MCU power consumption