BCM43455 Preliminary Data Sheet
FM Receiver Subsystem
Section 8: FM Receiver Subsystem
FM Radio
The BCM43455 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
2
in analog form or in digital form through I S or PCM. The FM radio operates from the external clock reference.
Digital FM Audio Interfaces
2
The FM audio can be transmitted via the shared PCM and I S pins, and the sampling rate is programmable.
2
The BCM43455 supports a three-wire PCM or I S 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 x 32 bits per frame = 1.536 MHz
48 kHz x 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 BCM43455 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 BCM43455 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®
November 5, 2015 • 43455-DS109-R
Page 60
BROADCOM CONFIDENTIAL
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