Digital Audio Transmitter
DAX Programming Considerations
MOTOROLA
DSP56367
12-13
5. Enable DAX by setting PC1 bit (and by setting PC0 bit if in slave mode) in the port
control register (PCR); transmission begins.
12.6.2
AUDIO DATA REGISTER EMPTY INTERRUPT HANDLING
When the XDIE bit is set and the DAX is active, an audio data register empty interrupt
(XADE = 1) is generated once at the beginning of every frame transmission. Typically, within
an XADE interrupt, the non-audio data bits of the next frame are stored in XNADR and one
frame of audio data to be transmitted in the next frame is stored in the FIFO by two
consecutive MOVEP instructions to XADR. If the non-audio bits are not changed from frame
to frame, this procedure can be handled within a fast interrupt routine. Storing the next
frame’s audio data in the FIFO clears the XADE bit in the XSTR.
12.6.3
BLOCK TRANSFERRED INTERRUPT HANDLING
An interrupt with the XBLK vector indicates the end of a block transmission and may require
some computation to provide the next non-audio data structures that are to be transmitted
within the next block. Within the routine, the next audio data can be stored in the FIFO by two
consecutive MOVEP instructions to XADR, and the next non-audio data can be stored in the
XNADR. The XBLK interrupt occurs only if the XBIE bit in XCTR is set. If XBIE is cleared,
a XADE interrupt vector will take place.
12.6.4
DAX OPERATION WITH DMA
During DMA transfers, the XDIE bit of the XCTR must be cleared to avoid XADE interrupt
services by the DSP core. The initialization appearing in Section 12.6.1 is relevant for DMA
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: ......