BCM88335 Data Sheet
PCM Interface
Wideband Speech Support
When the host encodes Wideband Speech (WBS) packets in transparent mode, the encoded packets are
transferred over the PCM bus for an eSCO voice connection. In this mode, the PCM bus is typically configured
in master mode for a 4 kHz sync rate with 16-bit samples, resulting in a 64 Kbps bit rate. The BCM88335 also
supports slave transparent mode using a proprietary rate-matching scheme. In SBC-code mode, linear 16-bit
data at 16 kHz (256 Kbps rate) is transferred over the PCM bus.
Multiplexed Bluetooth Over PCM
To support multiple Bluetooth audio streams within the Bluetooth channel, both 16 kHz and 8 kHz streams can
be multiplexed. This mode of operation is only supported when the Bluetooth host is the master. Figure 9 shows
the operation of the multiplexed transport with three simultaneous SCO connections. To accommodate
additional SCO channels, the transport clock speed is increased. To change between modes of operation, the
transport must be halted and restarted in the new configuration.
Figure 9: Functional Multiplex Data Diagram
1 frame
BT SCO 1 Rx
BT SCO 1 Tx
BT SCO 2 Rx
BT SCO 2 Tx
BT SCO 3 Rx
FM right
FM right
FM left
FM left
PCM_OUT
PCM_IN
BT SCO 3 Tx
PCM_SYNC
PCM_CLK
CLK
16 bits per SCO frame
16 bits per frame
16 bits per frame
Each SCO channel duplicates the data 6 times. Each
WBS frame duplicates the data 3 times per frame
Broadcom®
September 23, 2015 • 88335-DS100-R
Page 44
BROADCOM CONFIDENTIAL
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