The best way to predict the future is to invent it.
As shown in Figure 3–1, the Host Controller Interface (HCI) is the interface between the host and the controller. It is responsible for two main functions: It sends commands to the controller and receives events back, and it sends and receives data from a peer device.
Typically, the host interface is both a physical and logical interface between devices. The logical interface defines a number of packet formats for commands, events, and data. The physical interface then defines how these packets can be transported between the host and controller.
There are four defined physical interfaces in the Bluetooth ...