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Digital Audio Transmitter
DAX Programming Considerations
operation. DMA transfers can be performed with or without changing non-audio bits from
frame to frame. Table 12-5 describes two examples of DMA configuration.
Table 12-5 Examples of DMA configuration
Register
DCR2
DE=1; Enable DMA channel.
DIE=1; Enable DMA interrupt.
DTM[2:0]=010; Line transfer mode.
D3D=0; Not 3D.
DAM[5:3]=000; 2D mode.
DAM[2:0]=101; post increment by 1.
DDS[1:0]=00; X memory space.
DRS[4:0]=01010; DAX is DMA request source.
Other bits are application dependent.
DCO2
DCOH=number of frames in block - 1
DCOL=$002; 3 destination registers
DSR2
first memory address of the block
DDR2
XNADR address (base address + $1)
DOR0
$FFFFFE; offset=-2
The memory organization employed for DMA transfers depends on whether or not non-audio
data changes from frame to frame as shown in Figure 12-6.
12-14
Non-audio data bits change
DSP56367
Non-audio data bits do not change
DE=1; Enable DMA channel.
DIE=1; Enable DMA interrupt.
DTM[2:0]=010; Line transfer mode.
D3D=0; Not 3D.
DAM[5:3]=000; 2D mode.
DAM[2:0]=101; post increment by 1.
DDS[1:0]=00; X memory space.
DRS[4:0]=01010; DAX is DMA request source.
Other bits are application dependent.
DCOH=number of frames in block - 1
DCOL=$001; 2 destination registers
first memory address of the block
XADR address (base address + $2)
$FFFFFF; offset=-1
MOTOROLA
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