Wireless communication has become an invisible bridge in the Internet of Things connection, and Bluetooth, as a mainstream wireless communication technology, plays a vital role in the Internet of Things application. we receive inquiries from customers about the Bluetooth module sometimes, but during the communication process, I found that some engineers are still vague about the concept of the Bluetooth module as the master and slave, but we have a strong curiosity about technology, how can we tolerate the existence of such knowledge What about blind spots?

Generally we call BLE Center “Master mode”, call BLE peripheral “Slave”.

BLE has the following roles: Advertiser, Scanner, Slave, Master, and Initiator, where the master is converted by the initiator and the scanner On the other hand, the slave device is converted by the broadcaster; Bluetooth module communication refers to the communication between two Bluetooth modules or Bluetooth devices. The two parties for data communication are the master and the slave

Master device mode: It works in master device mode and can connect with a slave device. In this mode, you can search for surrounding devices and select the slave devices that need to be connected for connection. 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 between the two roles. It usually works in slave mode and waits for other master devices to connect. When needed, it switches to master mode and initiates 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. After pairing is complete, the call can be initiated directly.

Such as FSC-BT616 TI CC2640R2F BLE 5.0 Module:

Slave device mode: The Bluetooth module working in slave mode can only be searched by the host, and cannot be actively searched. After the slave device is connected to the host, it can also send and receive data with the host device.