Datasheet

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SLES105B − FEBRUARY 2004 − REVISED NOVEMBER 2006
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49
58 BCK
Command FieldDID
LRCK
BCK
DI
DCO1
DCI2
Device ID = 1
Device ID = 2
DCO1
DCO2
DCI3
DCO29
DCI30
Device ID = 3
Device ID = 30
•
•
•
•
•
•
Figure 57. Device ID Determination Sequence
TDMCA Frame
In general, the TDMCA frame consists of the command field, extended command (EMD) field, and audio data
fields. All of them are 32 bits in length, but the lowest byte has no meaning. The MSB is transferred first for each
field. The command field is always transferred as the first packet of the frame. The EMD field is transferred if
the EMD flag of the command field is HIGH. If any EMD packets are transferred, no audio data follows the EMD
packets. This frame is for quick system initialization. All devices of a daisy chain should respond to the command
field and extended command field. The PCM1792A has two audio channels that can be selected by OPE
(register 19). If this OPE bit is not set to HIGH, those audio channels are transferred. Figure 58 shows the
general TDMCA frame. If some DACs are enabled, but corresponding audio data packets are not transferred,
the analog outputs are unpredictable.
LRCK
BCK
DI
CMD
EMD
EMD
EMD CMD
Don’t
Care
EMD
EMD
DO
Ch1
Ch(m)
Ch2
CMD
CMD
Ch2
Ch3
Ch(n) CMD
Ch1
Ch4
DI
Ch3 Ch4
[For Initialization]
[For Operation]
32 Bits
DO
CMD CMD CMD CMD CMD
CMD
1/f
S
Don’t
Care
Figure 58. General TDMCA Frame