With the continuous progress and development of technology, the IoT technology continues to spread; Bluetooth communication technology as a wireless transmission method, the application is extensive.
Bluetooth is mainly divided into Bluetooth 2.0, Bluetooth 3.0, Bluetooth 4.0,
Bluetooth 2.0 is the traditional Bluetooth, the transmission of the ordinary data stream, compatible with the mainstream Android version but not compatible with the IOS system.
Bluetooth 3.0 (SPP for short) can transmit large-capacity data, commonly used in the audio part of the transmission, compatible with the mainstream Android version, not compatible with the IOS system, the general working current is 20mA, and each manufacturer is slightly different.
Bluetooth 4.0 (BLE) low-power Bluetooth. This version of Bluetooth is not compatible with Bluetooth 3.0 and 2.0, so only compatible with Android 5.0 and above versions to have BLE. It is working current in 3-5mA, such as Bluetooth LED controller.
Bluetooth 5.0 was the Bluetooth technology alliance in 2016; the expected design can use Bluetooth networking and, combined with wifi, can achieve indoor positioning function; this function is not yet popular on the market.
In the Bluetooth module selection, combined with the following points for selection
- Bluetooth version.
- Bluetooth and terminal compatibility, such as Android system, IOS system, Bluetooth module terminal, etc.
- Bluetooth, whether it is data transmission or command control, it is recommended to choose transmission + command mode, the usual data using data transmission, the need for Bluetooth name, Bluetooth PIN, Bluetooth MAC, and other parameters for operation, and command operation.
- Bluetooth transmission can be divided into active and passive two modes.
Active mode means that when the Bluetooth module remembers the Bluetooth terminal MAC, only the Bluetooth of this MAC is open; it can be actively searched by the Bluetooth module and actively connected to this Bluetooth terminal. The data will be transmitted to the Bluetooth terminal; this mode can only one-way transmission. And the whole process of implementation needs MCU to Bluetooth module command operation, compared to the passive data transmission mode, which is more complex.
In passive mode, the Bluetooth module is open and broadcast its signal to the surrounding; when the surrounding Bluetooth terminal scan search for the Bluetooth module signal, there is a Bluetooth terminal active link Bluetooth module, match and establish a link through the MAC or agreed Bluetooth name to distinguish and identify. MCU and Bluetooth module for data transmission, the development of simple and convenient, usually we use the Bluetooth headset, and Bluetooth Speaker is generally passive.
The advantages and disadvantages of Bluetooth are based on the frequency 2.4G wireless transmission method, which is a one-to-one, point-to-point data transmission method. So it is relatively single.
In the hardware test, you also need to pay attention to the PCBA board on the impact of Bluetooth signal strength; the general requirements of the 10-meter range can be properly transmitted.
Bluetooth communication for APP requirements in IOS needs to be compatible with BLE; the IOS system also only supports BLE (iPhone 4S and above support).
In Android 5.0 and above version is only compatible with BLE, also includes the basic classic Bluetooth.
In the development of the Bluetooth part of the Android system, although the major Android smartphone manufacturers are based on Google Android, each brand for the original Android system has deep customization and optimization, and incompatibility needs to be considered and integrated.
In the development and design process, combine their own needs and select the suitable module for Bluetooth function.
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