Bluetooth chip technology is a short-range wireless communication technology, using Bluetooth technology can effectively simplify the communication between mobile communication terminal devices such as handheld computers, laptops and mobile phones, and can also successfully simplify the communication between these devices and the Internet. This makes data transfer between these modern communication devices and the Internet faster and more efficient and opens the way for wireless communication.
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master-slave relation
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Bluetooth chip technology stipulates that when Bluetooth communication between each pair of devices, one must be the master role and the other is the slave role, so that communication can be carried out, and the communication must be searched by the master end, and after the successful pairing and establishment of the chain, the two sides can send and receive data. In theory, one Bluetooth primary device can communicate with seven Bluetooth secondary devices at the same time. A device with Bluetooth communication can switch between the two roles, usually working in slave mode, waiting for other master devices to connect, and switching to master mode when needed to initiate calls to other devices. When a Bluetooth device initiates a call in the main mode, it needs to know the other party's Bluetooth address, pairing password and other information, and can directly initiate a call after pairing.
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Calling procedure
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The Bluetooth primary device initiates the call, first looks up, and finds out which Bluetooth devices are around to be looked up. After the primary device finds the secondary Bluetooth device, it pairs with the secondary Bluetooth device. In this case, the PIN of the secondary device is required, and some devices do not need to enter the PIN code. After the pair is complete, the secondary Bluetooth device records the trust information of the primary device. In this case, the primary device can initiate a call to the secondary device. The paired device does not need to be re-paired for the next call. A paired device can also initiate a link building request as a secondary Bluetooth headset, but the Bluetooth module for data communication generally does not initiate a call. After a link is successfully established, two-way data or voice communication can be performed between the primary and secondary ends. Both the primary and secondary devices in the communication state can initiate a disconnection and disconnect the Bluetooth link.
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data transmission
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In the application of Bluetooth chip data transmission, one-to-one serial data communication is one of the most common applications, the Bluetooth device is set up in advance of the pairing information between the two Bluetooth devices before the factory, the main end prestores the PIN code, address, etc., the devices at both ends are powered up automatically to build a chain, transparent serial transmission, without peripheral circuit intervention. In a one-to-one application, the secondary device can be set to two types. One is silent, that is, it can only communicate with the specified primary device and is not searched by other Bluetooth devices. The second is the development state, which can be specified by the main end to find and can be found by other Bluetooth devices.
First of all, we should understand the working principle of Bluetooth headphones:
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1. The decoding chip in the mobile phone decodes the music file, generates a digital signal and sends it to the Bluetooth headset via Bluetooth;
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2. Bluetooth headset to receive digital signals;
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3. Through the digital-to-analog conversion chip inside the Bluetooth headset, it can be converted into an analog signal that can be understood by the adult ear;
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4. To amplify the analog signal, it is necessary to use the signal amplifier chip inside the headset to make sound.
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In the process of compression and decompression, some information will inevitably be lost. The amount of loss caused by different Bluetooth encoders is also very different. The main parameters of influence are the sound quality and delay time.