Bluetooth technology is a communication protocol for wireless data and voice communication. It is a low-cost, short-range wireless connection technology used to monitor communication environments for fixed and mobile devices. Bluetooth technology enables today’s portable mobile devices and computers to be linked to each other without lines, and can access the Internet wirelessly.
Working principle of Bluetooth module
1.Bluetooth module master-slave relationship:
Bluetooth technology stipulates that when each pair of devices communicate via Bluetooth, one Bluetooth module must be the primary role and the other Bluetooth module must be the secondary role in order to communicate. During communication, the primary end must search, initiate pairing, and successfully establish a link. After that, both parties can send and receive data. In theory, a Bluetooth master device can communicate with seven Bluetooth slave devices simultaneously. A device with Bluetooth communication function that can switch between two roles, usually working in slave mode, waiting for other master devices to connect, and when needed, switching to master mode to initiate calls to other devices. When a Bluetooth device initiates a call in master mode, it needs to know the other party’s Bluetooth address, pairing password, and other information. After pairing is completed, the call can be directly initiated.
2.Bluetooth module call process:
When a Bluetooth host device initiates a call, the first step is to search for Bluetooth devices in the surrounding area that can be searched. After the master device finds the slave Bluetooth device, it pairs with the slave Bluetooth device. At this time, the PIN code of the slave device needs to be entered, and some devices do not need to enter the PIN code.
After pairing is completed, the slave Bluetooth device will record the trust information of the master device. At this time, the master can initiate a call to the slave device, and the paired device no longer needs to be re paired for the next call. Paired devices can also initiate link building requests as Bluetooth earphones on the slave end, but Bluetooth modules for data communication generally do not initiate calls.
After the link is successfully established, bidirectional data or voice communication can be carried out between the master and slave ends. In communication mode, both the master and slave devices can initiate disconnection and disconnect the Bluetooth link.
3.Bluetooth data transmission
In Bluetooth data transmission applications, one-to-one serial data communication is one of the most common applications. The Bluetooth module sets the pairing information between the two Bluetooth modules in advance before leaving the factory. The master end pre stores the PIN code, address, etc. of the slave end device, and the two end devices automatically establish a link when powered on, with transparent serial transmission and no need for peripheral circuit intervention.
In one-on-one applications, the slave devices can be set to two types: silent state, which means they can only communicate with the designated master and are not searched by other Bluetooth devices; The second is the development status, which can be searched by designated hosts or by other Bluetooth devices to establish links.
How to connect Bluetooth earphones to a mobile phone
- First, press and hold the power button on the Bluetooth earphones for about ten seconds until you see the signal light flashing
- Turn on Bluetooth on your phone
- Turn on Bluetooth and search for nearby Bluetooth devices
- Find the Bluetooth name of the Bluetooth headset, click connect, and once connected successfully, you can use it
