Before analyzing the Bluetooth circuit in the module, we will briefly introduce the working principle of Bluetooth technology. Bluetooth is a communication protocol that operates within the 2.4GHz range. This radio-frequency range is similar to many other communication protocols like the very popular WiFi protocol.
The structure of Bluetooth communication contains a master device that can connect up to seven slave devices. Each slave communicates serially with the master, and communication between slaves can only be done through the master, which acts as an intermediary. Bluetooth devices can cover a range from 1 cm up to 100 meters. According to the range and energy consumption, Bluetooth devices are divided into three categories, the first category covers the maximum range.
Each Bluetooth device has the ability to maintain a low-power mode while idle, thus reducing energy consumption. For the communication between two Bluetooth devices, they need to exchange their unique code, so communication between them can only be done with user approval.
Multiple resistors are placed across the board as well as capacitors and diodes. There is a voltage regulator, a crystal-based clock, an antenna and two chips. The figure below shows the circuit final product after the assembly of the PCB board. This example is just one of many Bluetooth modules that exist in the transaction.
The general function is simple; the signal that gets from the aerial is dealt with in the chip, and then produce the output again. Depending on the purpose of your Bluetooth device, you can use a series of protocols called Bluetooth profiles to communicate between devices. For example, a serial communication UART is made using a serial port configuration file (SPP).
In order to make the module work properly, especially the assembly of the antenna, a high quality PCB assembly is required.