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FM Receiver Subsystem

BCM4354 Data Sheet

BROADCOM CONFIDENTIAL

Broadcom®

October 15, 2014 • 4354-DS109-R

Page 61

Section 8: FM Receiver Subsystem

FM Radio

The BCM4354 includes a completely integrated FM radio receiver with RDS/RBDS covering all FM bands from

65 MHz to 108 MHz. The receiver is controlled through commands on the HCI. FM received audio is available

as stereo or in digital form through I2S or PCM. The FM radio operates from the external clock reference.

Digital FM Audio Interfaces

The FM audio can be transmitted via the shared PCM and I2S pins, and the sampling rate is programmable.

The BCM4354 supports a three-wire PCM or I2S audio interface in either master or slave configuration. The

master or slave configuration is selected using vendor specific commands over the HCI interface. In addition,

multiple sampling rates are supported, derived from either the FM or Bluetooth clocks. In master mode, the clock

rate is either of the following:

• 48 kHz × 32 bits per frame = 1.536 MHz

• 48 kHz × 50 bits per frame = 2.400 MHz

In slave mode, any clock rate is supported up to a maximum of 3.072 MHz.

FM Over Bluetooth

The BCM4354 can output received FM audio onto Bluetooth using one of following three links: eSCO, WBS,

and A2DP. In all of the above modes, once the link has been set up, the host processor can enter sleep mode

while the BCM4354 continues to stream FM audio to the remote Bluetooth device, allowing the system current

consumption to be minimized.

eSCO

In this use case, the stereo FM audio is downsampled to 8 kHz and a mono or stereo stream is then sent through

the Bluetooth eSCO link to a remote Bluetooth device, typically a headset. Two Bluetooth voice connections

must be used to transport stereo.

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