The working principle of the Bluetooth module
The Bluetooth module is a PCBA board with integrated Bluetooth function, used for short-distance wireless communication, and is divided into Bluetooth data module and Bluetooth voice module according to function. The Bluetooth module refers to a collection of basic circuits of chips that integrate Bluetooth functions. It is used for wireless network communication and can be roughly divided into three types: data transmission module, Bluetooth audio module, Bluetooth audio + data two-in-one module, and so on. Generally, the module has the properties of a semi-finished product and has been processed on the basis of the chip to make subsequent applications easier.
1. The working principle of the Bluetooth module
As a short-distance wireless communication technology that replaces data cables, Bluetooth supports point-to-point and point-to-multipoint communication, wirelessly connecting various data and voice devices in the home or office into a piconet, and several piconets can be further Realize interconnection and form a distributed network (scatter-net), so as to realize fast and convenient communication between these connected devices. This article introduces the realization of the Bluetooth interface on the embedded digital signal processor OMAP5910. The DSP samples the analog signal and processes the digital signal after A/D conversion, and transmits it to the receiving end through the Bluetooth interface. Similarly, the DSP receives Bluetooth The received digital signal undergoes D/A conversion and becomes an analog signal.
The BlueTooth signal is sent and received by the BlueTooth module. This Bluetooth module is a wireless signal transceiver chip recently launched by the company that follows the Bluetooth V1.1 standard. The main features are on-chip digital wireless processor DRP, numerical control oscillator, on-chip RF transceiver switch, built-in ARM7 embedded processor Wait. When receiving a signal, the transceiver switch is set to the receiving state, and the radio frequency signal is received from the antenna and is directly transmitted to the baseband signal processor through the Bluetooth transceiver. Baseband signal processing includes down-conversion and sampling, using a zero-IF structure. The digital signal is stored in RAM (32KB incapacity) for the ARM7 processor to call and process. ARM7 outputs the processed data from the encoding interface to other devices. The signal transmission process is the reverse process of signal reception. In addition, it also includes a clock and power management module and multiple general I/O ports for different peripherals. Its host interface can provide a duplex universal serial port, which can easily communicate with the RS232 of the PC and can also communicate with the buffered serial port of the DSP.
2. Bluetooth module pin description
1. RDX: Receiver
2. TXD: sender
3. AT: Set working mode
1) Working mode: automatic connection, also known as transparent mode (transparent communication)
2) AT command setting mode: order-response, also known as AT mode (AT mode)
4. VCC: Module power supply positive (5V)
5. GND: Module power supply negative
6. EN: Enable terminal, connect 3.3V when you need to enter AT mode.
3. The role of the Bluetooth module
Bluetooth module, generally speaking, is a chip that integrates Bluetooth function, and the most important thing is IC. Divided into two kinds of data transmission and audio module. Audio transmission is mainly used in devices such as Bluetooth speakers and Bluetooth headsets. But this thing is only a semi-finished product and cannot be used directly. It must be assembled and processed by the Bluetooth speaker manufacturer.
1. Medical field: low-frequency massager, thermometer, blood pressure meter, electronic scale, etc.;
2. Sports field: smart wearable devices, sports equipment, heart rate monitoring instruments, etc.;
3. Industrial field: material tracking, asset management, etc.;
4. Smart home field: smart locks, curtains, small appliances, etc.;
5. Other fields: beacons, tire pressure monitoring, mobile payment, etc.
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