BCM4339 Preliminary Data Sheet
I2S Interface
I2S Interface
The BCM4339 supports two independent I2S digital audio ports: one for Bluetooth audio, and one for high-
fidelity FM audio. The I2S interface for FM audio supports both master and slave modes. The I2S signals are:
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•
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I2S clock: I2S SCK
I2S Word Select: I2S WS
I2S Data Out: I2S SDO
I2S Data In: I2S SDI
I2S SCK and I2S WS become outputs in master mode and inputs in slave mode, while I2S SDO always stays
as an output. The channel word length is 16 bits and the data is justified so that the MSB of the left-channel data
is aligned with the MSB of the I2S bus, per the I2S specification. The MSB of each data word is transmitted one
bit clock cycle after the I2S WS transition, synchronous with the falling edge of bit clock. Left-channel data is
transmitted when I2S WS is low, and right-channel data is transmitted when I2S WS is high. Data bits sent by
the BCM4339 are synchronized with the falling edge of I2S_SCK and should be sampled by the receiver on the
rising edge of I2S_SSCK.
The clock rate in master mode 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
The master clock is generated from the input reference clock using a N/M clock divider.
In the slave mode, any clock rate is supported to a maximum of 3.072 MHz.
Broadcom®
November 17, 2014 • 4339-DS106-R
Page 61
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