8-12
DSP56012 User’s Manual
MOTOROLA
Digital Audio Transmitter
DAX Internal Architecture
8.5.6
DAX Non-Audio Data Buffer (XNADBUF)
The XNADBUF is a 3-bit register that temporarily holds Channel B non-audio data
(XVB, XUB and XCB) for the current transmission while the Channel A data is being
transmitted. This mechanism provides programmers more instruction cycles to store
the next frame’s non-audio data to the XCB, XUB, XVB, XCA, XUA and XVA bits in
the XCTR. The data in the XNADBUF register is transferred to the XADSR along with
the contents of the XADBUF register at the beginning of Channel B transmission.
Note:
The XNADBUF register is not directly accessible by DSP instructions.
8.5.7
DAX Parity Generator (PRTYG)
The PRTYG generates the parity bit for the sub-frame being transmitted. The
generated parity bit ensures that sub-frame bits four to thirty-one will carry an even
number of 1s and 0s.
8.5.8
DAX Biphase Encoder
The DAX biphase encoder encodes each audio and non-audio bit into its biphase
mark format, and shifts this encoded data out to the ADO output pin synchronous to
the biphase clock.
8.5.9
DAX Preamble Generator
The DAX preamble generator automatically generates one of three preambles in the
8-bit preamble shift register at the beginning of each sub-frame transmission, and
shifts it out. The generated preambles always start with “0”. Bit patterns of
preambles generated in the preamble generator are shown in
Table 8-4
. The
preamble bits are already in the biphase mark format.
Table 8-4
Preamble Bit Patterns
Preamble
Bit Pattern
Channel
X
00011101
A
Y
00011011
B
Z
00010111
A (first in block)
Summary of Contents for DSP56012
Page 12: ...xii Motorola ...
Page 20: ...xx Motorola ...
Page 21: ...MOTOROLA DSP56012 User s Manual 1 1 SECTION 1 OVERVIEW ...
Page 40: ...1 20 DSP56012 User s Manual MOTOROLA Overview DSP56012 Architectural Overview ...
Page 41: ...MOTOROLA DSP56012 User s Manual 2 1 SECTION 2 SIGNAL DESCRIPTIONS ...
Page 61: ...SECTION 3 MEMORY OPERATING MODES AND INTERRUPTS ...
Page 81: ...MOTOROLA DSP56012 User s Manual 4 1 SECTION 4 PARALLEL HOST INTERFACE ...
Page 148: ...4 68 DSP56012 User s Manual MOTOROLA Parallel Host Interface Host Interface HI ...
Page 149: ...MOTOROLA DSP56012 User s Manual 5 1 SECTION 5 SERIAL HOST INTERFACE ...
Page 179: ...MOTOROLA DSP56012 User s Manual 6 1 SECTION 6 SERIAL AUDIO INTERFACE ...
Page 205: ...MOTOROLA DSP56012 User s Manual 7 1 SECTION 7 GPIO ...
Page 210: ...7 6 DSP56012 User s Manual MOTOROLA GPIO GPIO Register GPIOR ...
Page 211: ...MOTOROLA DSP56012 User s Manual 8 1 SECTION 8 DIGITAL AUDIO TRANSMITTER ...
Page 226: ...8 16 DSP56012 User s Manual MOTOROLA Digital Audio Transmitter DAX Programming Considerations ...
Page 233: ...MOTOROLA DSP56012 User s Manual B 1 APPENDIX B PROGRAMMING REFERENCE ...