9.3.2
Long Frame Sync
Long Frame Sync is the name given to a clocking format that controls the transfer of PCM data words or samples.
In Long Frame Sync, the rising edge of PCM_SYNC indicates the start of the PCM word. When CSR8640 BGA is
configured as PCM master, generating PCM_SYNC and PCM_CLK, then PCM_SYNC is 8 bits long. When
CSR8640 BGA is configured as PCM Slave, PCM_SYNC is from 1 cycle PCM_CLK to half the PCM_SYNC rate.
G-
T
W
-000
0219.2.2
PCM_SYNC
PCM_CLK
PCM_OUT
PCM_IN
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
Undefined
Undefined
Figure 9.11: Long Frame Sync (Shown with 8-bit Companded Sample)
CSR8640 BGA samples PCM_IN on the falling edge of PCM_CLK and transmits PCM_OUT on the rising edge.
PCM_OUT is configurable as high impedance on the falling edge of PCM_CLK in the LSB position or on the rising
edge.
9.3.3
Short Frame Sync
In Short Frame Sync, the falling edge of PCM_SYNC indicates the start of the PCM word. PCM_SYNC is always 1
clock cycle long.
G-
T
W
-000
0220.2.3
PCM_SYNC
PCM_CLK
PCM_OUT
PCM_IN
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16
Undefined
Undefined
Figure 9.12: Short Frame Sync (Shown with 16-bit Sample)
As with Long Frame Sync, CSR8640 BGA samples PCM_IN on the falling edge of PCM_CLK and transmits
PCM_OUT on the rising edge. PCM_OUT is configurable as high impedance on the falling edge of PCM_CLK in the
LSB position or on the rising edge.
9.3.4
Multi-slot Operation
More than 1 SCO connection over the PCM interface is supported using multiple slots. Up to 3 SCO connections
are carried over any of the first 4 slots.
Advance Information
This material is subject to CSR's non-disclosure agreement
© Cambridge Silicon Radio Limited 2011
Page 49 of 110
CS-209182-DSP1
CSR8640 BGA
Data Sheet
