HCI (Host Controller Interface)

The HCI contents a command interface to the baseband controller and link manager, and access to hardware status and control registers.

The HCI Driver and Firmware communicate via the Host Controller Transport Layer , a definition of the several layers that may exist between the HCI driver on the host system and the HCI firmware in the Bluetooth hardware. These intermediate layers, the Host Controller Transport Layer, should provide the ability to transfer data without intimate knowledge of the data being transferred. Several different Host Controller Layers can be used, of which 3 have been defined initially for Bluetooth : USB , UART and RS232. The Host should receive asynchronous notifications of HCI events independent of which Host Controller Transport Layer is used.