Digital Audio Transmitter
DAX Internal Architecture
MOTOROLA
DSP56367
12-11
preamble generator are shown in Table 12-4. The preamble bits are already in the biphase
mark format.
There is no programmable control for the preamble selection. The first subframe to be
transmitted (immediately after the DAX is enabled) is the beginning of a block, and therefore
it has a “Z” preamble. This is followed by the second subframe, which has an “Y” preamble.
After that, “X” and “Y” preambles are transmitted alternately until the end of the block
transfer (192 frames transmitted). See Figure 12-4 for an illustration of the preamble
sequence.
Figure 12-4 Preamble sequence
12.5.11
DAX CLOCK MULTIPLEXER
The DAX clock multiplexer selects one of the clock sources and generates the biphase clock
(128
×
Fs) and shift clock (64
×
Fs). The clock source can be selected from the following
options (see also Section 12.5.6.4, “DAX Clock Input Select (XCS[1:0])—Bits 3–4”).
•
The internal DSP core clock—assumes 1024
×
Fs
•
DAX clock input pin (ACI)—512
×
Fs
•
DAX clock input pin (ACI)—384
×
Fs
•
DAX clock input pin (ACI)—256
×
Fs
Table 12-4 Preamble Bit Patterns
Preamble
Bit Pattern
Channel
X
00011101
A
Y
00011011
B
Z
00010111
A (first in block)
DAX
Enabled
Here
First Block (384 subframes)
Second Block
Z
Y
X
Y
X
Y
X
Y
Z
Y
X
Y
AA0609k
Summary of Contents for DSP56367
Page 16: ...xvi MOTOROLA CONTENTS Paragraph Number Title Page Number ...
Page 22: ...xxii MOTOROLA List of Figures Figure Number Title Page Number ...
Page 26: ...xxvi MOTOROLA List of Tables Table Number Title Page Number ...
Page 148: ...4 6 DSP56367 MOTOROLA Design Considerations PLL Performance Issues ...
Page 248: ...9 30 DSP56367 MOTOROLA Serial Host Interface SHI Programming Considerations ...
Page 306: ...10 58 DSP56367 MOTOROLA Enhanced Serial Audio Interface ESAI ESAI Initialization Examples ...
Page 389: ...Bootstrap ROM Contents MOTOROLA DSP56367 A 15 end ...
Page 390: ...A 16 DSP56367 MOTOROLA Bootstrap ROM Contents ...
Page 432: ...C 8 DSP56367 MOTOROLA JTAG BSDL ...
Page 484: ...D 52 DSP56367 MOTOROLA Programmer s Reference ...
Page 490: ...E 6 DSP56367 MOTOROLA Power Consumption Benchmark ...
Page 516: ...F 26 DSP56367 MOTOROLA IBIS Model ...
Page 522: ...Index 6 MOTOROLA Index ...
Page 523: ......