Figure 6.5 Rotating Priority Example (Adsp-21060 & Adsp-21062) - Analog Devices ADSP-2106x SHARC User Manual

The external port channel priorities do not change relative to the serial
port and link port channel priorities. At reset, the DCPR bit is cleared
and rotating priority is disabled.
Highest
Priority
6
One transfer occurs
on Channel 7, which
Lowest
9 7
then rotates into the
Priority
lowest priority slot.
8
Figure 6.5 Rotating Priority Example (ADSP-21060 & ADSP-21062)
Note: Even though the external port channel DMA priority can rotate,
the interrupt priorities of all DMA channels are fixed.
When using fixed priority for the external port DMA channels, the
highest priority of the four is assigned to Channel 6 and the lowest
priority is assigned to Channel 9 (as shown in Table 6.13) for the
ADSP-21060 and ADSP-21062. The lowest priority channel on the
ADSP-21061 is channel 7. This order of priority can be redefined by
assigning one of the other channels the highest priority. To change the
fixed priority sequence of the external port DMA channels, use the
following procedure:
1) Disable all external port DMA channels except the one which is to have
lowest priority.
2) Select rotating priority.
3) Cause at least one transfer to occur on the enabled channel.
4) Disable rotating priority and re-enable all of the external port DMA
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DMA
Highest
Priority
8
Lowest
7 9
Priority
6
6
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