BCM4354 Data Sheet
FM Receiver Subsystem
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.
Broadcom®
October 15, 2014 • 4354-DS109-R
Page 61
BROADCOM CONFIDENTIAL
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