PRELIMINARY
CYW20710
Table 3. PCM Interface Time Slotting Scheme
Audio Sample Rate
Time Slotting Scheme
8 kHz
The number of slots depends on the selected interface rate, as follows:
Interface rate Slot
128
1
256
2
512
4
1024
2048
8
16
16 kHz
The number of slots depends on the selected interface rate, as follows:
Interface rate Slot
256
512
1024
2048
1
2
4
8
Transmit and receive PCM data from an SCO channel is always mapped to the same slot. The PCM data output driver tri-states its
output on unused slots to allow other devices to share the same PCM interface signals. The data output driver tri-states its output
after the falling edge of the PCM clock during the last bit of the slot.
5.1.3 Wideband Speech
The CYW20710 provides support for Wideband Speech (WBS) in two ways:
■
Transparent mode The host encodes WBS packets and the encoded packets are transferred over the PCM bus for SCO or eSCO
voice connections. In Transparent 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.
■
On-chip SmartAudio® technologyThe CYW20710 can perform Subband-Codec (SBC) encoding and decoding of linear 16 bits
at 16 kHz (256 kbps rate) transferred over the PCM bus.
5.1.4 Frame Synchronization
The device supports both short and long frame synchronization types in both master and slave configurations. In short frame synchro-
nization mode, the frame synchronization signal is an active-high pulse at the 8 kHz audio frame rate (which is a single bit period in
width) and synchronized to the rising edge of the bit clock. The PCM slave expects PCM_SYNC to be high on the falling edge of the
bit clock and the first bit of the first slot to start at the next rising edge of the clock. In the long frame synchronization mode, the frame
synchronization signal is an active-high pulse at the 8 kHz audio frame rate. However, the duration is 3-bit periods and the pulse starts
coincident with the first bit of the first slot.
5.1.5 Data Formatting
The device can be configured to generate and accept several different data formats. The device uses 13 of the 16 bits in each PCM
frame. The location and order of these 13 bits is configurable to support various data formats on the PCM interface. The remaining
three bits are ignored on the input, and may be filled with zeros, ones, a sign bit, or a programmed value on the output. The default
format is 13-bit two’s complement data, left justified, and clocked most significant bit first.
Document No. 002-14804 Rev. *H
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