GS2971A Datasheet, PDF (83/152 Pages) Gennum Corporation – Integrated audio clock generator

4.19.2 Serial Audio Data Format Support
The GS2971A supports the following serial audio data formats:
• I²S (default)
• AES/EBU
• Serial Audio Left Justified, MSB First
• Serial Audio Left Justified, LSB First
• Serial Audio Right Justified, MSB First
• Serial Audio Right Justified, LSB First (this mode is not supported in SD)
By default (at power up or after system reset) I²S is selected. The other data formats are
selectable via the host interface using the AMA/AMB[1:0] bits.
Table 4-17:Audio Output Formats
AMA/AMB[1:0]
00
01
10
11
Audio Output Format
AES/EBU audio output
Serial audio output: Left Justified; MSB first
Serial audio output: Right Justified; MSB first
I²S (Default)
The serial audio output formats may use LSB first according to the settings of the control
bits LSB_FIRSTA, LSB_FIRSTB, LSB_FIRSTC, and LSB_FIRSTD. When in I²S mode, these
control bits must all be set LOW (default).
When I²S format is desired, both groups must be set to I²S (i.e. AMA = AMB = 11). This is
because they share the same WCLK.
WCLK
ACLK
Channel A (Left)
AOUT[8/7:2/1] 23 22
MSB
6 5 43 2 10
LSB
Figure 4-37:I²S Audio Output Format
Channel B (Right)
23 22
MSB
65 4 32 10
LSB
WCLK
Channel A (Left)
ACLK
AOUT[8/7:2/1] 0 1 2 3 4
Preamble
56
AUX
78
LSB
Channel B (Right)
27 28 29 30 31 0 1 2 3 4 5 6 7 8
MSB V U C P
Preamble
AUX
LSB
Figure 4-38:AES/EBU Audio Output Format
27 28 29 30 31
MSB V U C P
GS2971A 3Gb/s, HD, SD SDI Receiver
Data Sheet
54311 - 2
September 2012
83 of 152