Dax Programming Model - Motorola DSP56367 User Manual

Digital Audio Transmitter

DAX Programming Model

biphase encoder to the ADO pin at the last two time slots. This is the end of the first (channel
A) subframe transmission.
The second subframe transmission (channel B) starts with the preamble generator generating
the channel B preamble (Y-preamble). At the same time, channel B audio and non-audio data
is transferred to the XADSR shift-register from the XADBUFB and XNADBUF registers.
The generated Y-preamble is output immediately after the channel A parity and is followed by
the audio and non-audio data in the XADSR, which is in turn followed by the calculated parity
for channel B. This completes a frame transmission. When the channel B parity is sent, the
audio data for the next frame, stored in XADBUFA and the non-audio data bits from the
XNADR, are uploaded to XADSR.
12.4 DAX PROGRAMMING MODEL
The programmer-accessible DAX registers are shown in Figure 12-2. The registers are
described in the following subsections. The Interrupt Vector table for the DAX is shown in
Table 12-1. The internal interrupt priority is shown in Table 12-2.
Condition
XAUR
XADE & XBLK
XADE
Priority
highest
lowest
12-4
Table 12-1 DAX Interrupt Vectors
Address
VBA:$28
VBA:$2A
VBA:$2E
Table 12-2 DAX Interrupt Priority
DAX transmit underrun error
DAX block transferred
DAX audio data register empty
DSP56367
Description
DAX transmit underrun error
DAX block transferred
DAX audio data register empty
Interrupt
MOTOROLA