CYW4343X
Figure 39. I2S Receiver Timing
T
tLC > 0.35T
tHC > 0.35
VH = 2.0V
VL = 0.8V
SCK
tsr > 0.2T
thr > 0
SD and WS
T = Clock period
Tr = Minimum allowed clock period for transmitter
T > Tr
11. FM Receiver Subsystem
11.1 FM Radio
The CYW4343X 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 a stereo analog output or in digital
form through I2S or PCM. The FM radio operates from the external clock reference.
11.2 Digital FM Audio Interfaces
The FM audio can be transmitted via the shared PCM and I2S pins, and the sampling rate is programmable. The CYW4343X sup-
ports a three-wire PCM or I2S audio interface in either a 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, clock rates up to 3.072 MHz are supported.
11.3 Analog FM Audio Interfaces
The demodulated FM audio signal is available as line-level analog stereo output, generated by twin internal high SNR audio DACs.
11.4 FM Over Bluetooth
The CYW4343X can output received FM audio onto Bluetooth using one of following three links: eSCO, WBS, or A2DP. For all link
types, after a link has been established, the host processor can enter sleep mode while the CYW4343X streams FM audio to the
remote Bluetooth device, thus minimizing system current consumption.
11.5 eSCO
In this use case, the stereo FM audio is downsampled to 8 kHz and a mono or stereo stream is sent through the Bluetooth eSCO link
to a remote Bluetooth device, typically a headset. Two Bluetooth voice connections must be used to transport stereo.
11.6 Wideband Speech Link
In this case, the stereo FM audio is downsampled to 16 kHz and a mono or stereo stream is sent through the Bluetooth wideband
speech link to a remote Bluetooth device, typically a headset. Two Bluetooth voice connections must be used to transport stereo.
Document No. 002-14797 Rev. *H
Page 56 of 128
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