Simultaneous BLE connection

Question

How to determine maximum number simultaneous BLE connection possible with a Bluetooth Chipset like CSR8510.Where CSR8510 act as a BLE Master and end device act as a BLE slave.

What should all parameter we consider to determine?

Answer 1

There is no HCI protocol message to get this number. You need to create connections with LE Create Connection Command to slaves until you get the HCI error 0x09 (Connection Limit Exceeded).

The CSR8510 can have 5 connections in master mode to slave devices. It can have 1 connection in slave mode to a master device. While it has a connection in slave mode, it cannot have any other connection in master mode. When having a connection in master mode, it cannot start connectable advertising. When having a connection in slave mode, it cannot start initiating a connection as master.

In general, there is a difference between Bluetooth versions. In Bluetooth 4.0 there were these limitations:

• The Link Layer in the Connection State shall not operate in the Master Role and Slave Role at the same time.

• The Link Layer in the Connection State operating in the Slave Role shall have only one connection.

• If the Link Layer is already operating in the Connection State or Initiating State, the Link Layer shall not operate in the Advertising State with a type of advertising that could result in the Link Layer entering the Connection State in the Slave Role.

In Bluetooth 4.1 these limitations were removed. However, controllers are not required to support all combinations of multiple states. What state combinations are supported for a particular controller can be found at https://www.bluetooth.org/tpg/listings.cfm.