CC256X Datasheet, PDF (22/51 Pages) Texas Instruments – Bluetooth® Smart Ready Controller

CC256x
SWRS121C – JULY 2012 – REVISED OCTOBER 2013
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Figure 3-14 shows the operation of a falling-edge-clock type of codec. The codec is the master of the bus.
The frame-sync signal is updated (by the codec) on the falling edge of the clock and is therefore sampled
(by the CC256x device) on the next rising clock. The data from the codec is sampled (by the CC256x
device) on the falling edge of the clock.
PCM FSYNC
PCM CLK
PCM DATA IN
D7 D6 D5 D4 D3 D2 D1 D0
CC256x
SAMPLE TIME
Figure 3-14. Negative Clock Edge Operation
SWRS121-004
3.5.3.6 Two-Channel Bus Example
Figure 3-15 shows a 2-channel bus in which the two channels have different word sizes and arbitrary
positions in the bus frame. (FT stands for frame timer.)
Clock
FT
127 0 1 2 3 4 5 6 7 8 9
42 43 44
...
... _{127 0}
Fsync
Data_Out
MSB
LSB
bit bit bit bit bit bit bit bit bit bit bit
0 1 2 3 4 5 6 7 8 9 10
MSB
LSB
bit bit bit bit bit bit bit bit
...
0123 4567
Data_In
bit bit bit bit bit bit bit bit bit bit bit
0 1 2 3 4 5 6 7 8 9 10
bit bit bit bit bit bit bit bit
...
0123 4567
PCM_data_window
CH1 data start FT = 0
CH1 data length = 11
CH2 data
start FT = 43
Figure 3-15. Two-Channel Bus Timing
CH2 data
length = 8
Fsync period = 128
Fsync length = 1
twochpcm_swrs064
3.5.3.7 Improved Algorithm For Lost Packets
The CC256x device features an improved algorithm to improve voice quality when received voice data
packets are lost. There are two options:
• Repeat the last sample: possible only for sample sizes up to 24 bits. For sample sizes larger than 24
bits, the last byte is repeated.
• Repeat a configurable sample of 8 to 24 bits (depending on the real sample size) to simulate silence
(or anything else) in the bus. The configured sample is written in a specific register for each channel.
The choice between those two options is configurable separately for each channel.
3.5.3.8 Bluetooth and Codec Clock Mismatch Handling
In Bluetooth RX, the CC256x device receives RF voice packets and writes them to the codec interface. If
the CC256x device receives data faster than the codec interface output allows, an overflow occurs. In this
case, the Bluetooth has two possible behavior modes:
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Detailed Description
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