User's Manual

48
PCM_OUT
PCM_IN
PCM_CLK
PCM_SYNC
8kHz
Up to 2048kHz
WT12
WTxx
Figure 25: WT32 as PCM slave
7.4.2 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 WT32 is configured as PCM Master, generating PCM_SYNC and PCM_CLK, then PCM_SYNC
is 8-bits long. When BlueCore4-External is configured as PCM Slave, PCM_SYNC may be from two
consecutive falling edges of PCM_CLK to half the PCM_SYNC rate, i.e. 62.5s long.
WT32 samples PCM_IN on the falling edge of PCM_CLK and transmits PCM_OUT on the rising edge.
PCM_OUT may be configured to be high impedance on the falling edge of PCM_CLK in the LSB
position or on the rising edge.
1
2 3 4 5 6 7 8PCM_OUT
PCM_CLK
PCM_SYNC
1
2 3 4 5 6 7 8
undefined undefined
PCM_IN
Figure 26: Long frame sync (shown with 8-bit companded sample)
7.4.3 Short Frame Sync
In Short Frame Sync
, the falling edge of PCM_SYNC indicates the start of the PCM word. PCM_SYNC
is always one clock cycle long.
1
2 3 4 5 6 7 8PCM_OUT
PCM_CLK
PCM_SYNC
1
2 3 4 5 6 7 8
undefined
PCM_IN
9 10 11 12
13
14 15 16
9 10 11 12
13
14 15 16
undefined
Figure 27: Short frame sync (shown with 16-bit companded sample)