ADVANCE
CYW43570
7.2.4 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 CYW43570 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.
7.2.5 Burst PCM Mode
In this mode of operation, the PCM bus runs at a significantly higher rate of operation to allow the host to duty cycle its operation and
save current. In this mode of operation, the PCM bus can operate at a rate of up to 24 MHz. This mode of operation is initiated with
an HCI command from the host.
7.2.6 PCM Interface Timing
Short Frame Sync, Master Mode
Figure 8. PCM Timing Diagram (Short Frame Sync, Master Mode)
1
2
3
BT_PCM_CLK
4
BT_PCM_SYNC
BT_PCM_OUT
8
HIGH IMPEDANCE
7
5
6
BT_PCM_IN
Table 7. PCM Interface Timing Specifications (Short Frame Sync, Master Mode)
Reference Characteristics Minimum
PCM bit clock frequency
Typical
Maximum
Unit
MHz
1
–
–
–
–
–
–
–
–
–
12
–
2
3
4
5
6
7
8
PCM bit clock LOW
PCM bit clock HIGH
BT_PCM_SYNC delay
BT_PCM_OUT delay
BT_PCM_IN setup
BT_PCM_IN hold
41
41
0
ns
ns
ns
ns
ns
ns
ns
–
25
25
–
0
8
8
–
Delay from rising edge of BT_PCM_BCLK
during last bit period to BT_PCM_OUT
becoming high impedance.
0
25
Document Number: 002-15054 Rev. *I
Page 25 of 94
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