The BM64 is a Bluetooth 4.2 Stereo Module that supports classic A2DP, AVRCP, HFP, HSP, and SPP protocols, as well as Bluetooth Low Energy (BLE). 

The BM64 streams I2S audio at up to 24-bit and 96 kHz, and uses a UART to receive commands from the host microcontroller and send events back over the same interface. 

Protocols supported by the BM64 include A2DP, AVRCP, HFP, HSP, SPP, and BLE. However, this version of the driver only supports A2DP, AVRCP, HFP, and BLE. 

The BM64 can be connected to a microphone (for HFP) and also has line-input; however, the latter is not supported by this driver. The multi-speaker modes of the BM64 are also not handled by this driver. 

A typical interface of BM64 to a Microchip microcontroller is provided in the following diagram:

BM64 to MCU Interface

An example demonstration application using this library to interface with the BM64 for BLE functionality is BM64_ble_comm, which is used to send a string of characters to a smartphone when the push button is pressed on the SAM E70 Xplained Ultra board, and to receive a string of characters from the smartphone causing one of the LEDs to turn on and off, both using the "Transparent Service" feature of the BM64.