The host controller interface (HCI) layer is a thin layer which transports commands and events between the host and controller elements of the Bluetooth protocol stack. In a pure network processor application, the HCI layer is implemented through a transport protocol such as SPI or UART.

HCI Interface

The communication between a Host (a computer or an MCU) and a Host Controller (the actual Bluetooth chipset) follows the Host Controller Interface (HCI).

HCI defines how commands, events, asynchronous and synchronous data packets are exchanged. Asynchronous packets (ACL) are used for data transfer, while synchronous packets (SCO) are used for Voice with the Headset and the Hands-Free Profiles.

How does Bluetooth HCI work?

The HCI provides a command interface to the baseband controller and link manager, and access to hardware status and control registers. Essentially this interface provides a uniform method of accessing the Bluetooth baseband capabilities.The HCI exists across 3 sections, the Host – Transport Layer – Host Controller. Each of the sections has a different role to play in the HCI system.

Feasycom currently has modules that support Bluetooth HCI: