Bluetooth module data transmission principle

- Mar 06, 2020-

The upgrade of intelligent products is increasingly dependent on the wireless module of the Internet of Things. There are two ways to make the product performance better. Optimize the product design and optimize the wireless module selection. Based on the wireless connection and data transmission market, Feasycom have BLE v4.2 and v5.0 Bluetooth module products. The following are some of the data transmission principles for Bluetooth communication.


Bluetooth module

 

Bluetooth communication refers to the establishment of a connection between two Bluetooth devices, which is equivalent to making a call, one person and one mobile phone for communication;

 

Host: refers to the party that can search for others and actively creates a connection. For example, I make a initiative call to a friend;

 

Slave: Refers to the fact that you cannot take the initiative call to create a connection, you can only wait for others to connect you, and have been listening (waiting for others to call);

 

The current status of a module can only be one of them, either on the master or the slave.

 

Master-slave integration refers to the ability to switch between master and slave modes. You can choose to work in master mode or slave mode.

 

The principle of Bluetooth transmission:

 

1. Master-slave relationship:

 

Bluetooth technology stipulates that for Bluetooth communication between each pair of devices, one must be the master role and the other is the slave role in order to communicate. When communicating, the master must search and initiate pairing. After connection successful, both parties can send and receive data. In theory, one Bluetooth master device can communicate with 7 Bluetooth slave devices at the same time.

 

A device with Bluetooth communication function can switch freely between two roles. It usually works in slave mode and waits for other master devices to connect. When necessary, it switches to master mode and initiates calls to other devices. When a Bluetooth device initiates a call in the master mode, it needs to know the other party's Bluetooth address, pairing password, and other information. After pairing is complete, the call can be initiated directly.

 

2. Calling process:

 

When a Bluetooth master device initiates a call, the first step is to find out which Bluetooth devices are around to be found. After the master device finds the slave Bluetooth device, pair it with the slave Bluetooth device. At this time, you need to enter the PIN code of the slave device, and some devices do not need to enter the PIN code.

 

After the 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. The paired device no longer needs to be re-paired on the next call. A paired device, as a slave Bluetooth headset, can also initiate a chain establishment request, but a Bluetooth module for data communication generally does not initiate a call.

 

After the connection is established successfully, two-way data or audio communication can be performed between the master and slave ends. In the communication state, both the master and slave devices can initiate a disconnection and disconnect the Bluetooth.

 

Data transmission

 

In Bluetooth data transmission applications, one-to-one serial data communication is the main application. Before the Bluetooth device leaves the factory, the pairing information between the two Bluetooth devices is set in advance. The master device stores the PIN code of the slave device, Addresses, etc., devices at both ends will automatically set a connection and transparent serial port transmission, without the intervention of peripheral circuits.

 

In one-to-one applications, the slave device can be set two types. One is the default state, that is, it can only communicate with the designated master and not be searched by other Bluetooth devices; another type is development status ,it can be searched by the designated master or by other Bluetooth devices.

 

BLE module is one of Feasycom’s main product lines. The FSC-BT630 is a BLE module and based on the NRF52832 chipset, it has some advanced features such as BLE 5.0, small size, one-to-one connection, multiple connections, Mesh network. For more details, feel free to reach out to Feasycom!