Analog Devices ADSP-BF506F Hardware Reference Manual page 260

Functional Description
elements. The high 16 bits of
former value. This supports a shorter, more efficient descriptor
than the large descriptor list model, which is suitable whenever the
application can place the channel's descriptors in the same 64K
byte range of memory.
If
FLOW
32-bit
DMAx_NEXT_DESC_PTR
DMA controller fetches a descriptor from memory into the DMA
registers using the new contents of
ments
DMAx_CURR_DESC_PTR
loaded is a new 32-bit value for the full
lowed by the rest of the descriptor elements. The high 16 bits of
DMAx_NEXT_DESC_PTR
ports a fully flexible descriptor list which can be located anywhere
in internal memory or external memory.
• If it is necessary to link from a descriptor chain whose descriptors
are in one 64K byte area to another chain whose descriptors are
outside that area, only the descriptor containing the link to the new
64K byte range needs to use
the same 64K byte area may use
• If
FLOW
descriptor list, respectively), the DMA controller clears the
bit in the
7-24
= 7 (large descriptor list) the DMA controller copies the
may differ from their former value. This sup-
= 4, 6, or 7 (descriptor array, small descriptor list, or large
DMAx_IRQ_STATUS
ADSP-BF50x Blackfin Processor Hardware Reference
DMAx_NEXT_DESC_PTR
into
DMAx_CURR_DESC_PTR
DMAx_CURR_DESC_PTR
. The first descriptor element that is
DMAx_NEXT_DESC_PTR
= 7. All descriptors that reference
FLOW
= 6.
FLOW
register.
will retain their
. Next, the
, and incre-
, fol-
DFETCH