
Modes of Operation
5-16
ADSP-BF59x Blackfin Processor Hardware Reference
DMAx_CURR_Y_COUNT
registers are reloaded between the descriptor fetch and
the start of DMA operation.
Table 5-1
shows the offsets for descriptor elements in the three modes
described above. Note the names in the table describe the descriptor ele-
ments in memory, not the actual MMRs into which they are eventually
loaded. For more information regarding descriptor element acronyms, see
Table 5-6 on page 5-63
.
Note that every descriptor fetch consumes bandwidth from either the
DCB bus or the DEB bus and the external memory interface, so it is best
to keep the size of descriptors as small as possible.
Mixing Flow Modes
The
FLOW
mode of a DMA is not a global setting. If the DMA configura-
tion word is reloaded with a descriptor fetch, the
FLOW
and
NDSIZE
bit
fields can also be altered. A small descriptor might be used to loop back to
the first descriptor if a descriptor array is used in an endless manner. If the
Table 5-1. Parameter Registers and Descriptor Offsets
Descriptor Offset Descriptor Array Mode Small Descriptor List Mode Large Descriptor List
Mode
0x0
SAL
NDPL
NDPL
0x2
SAH
SAL
NDPH
0x4
DMACFG
SAH
SAL
0x6
XCNT
DMACFG
SAH
0x8
XMOD
XCNT
DMACFG
0xA
YCNT
XMOD
XCNT
0xC
YMOD
YCNT
XMOD
0xE
YMOD
YCNT
0x10
YMOD
Содержание ADSP-BF59x Blackfin
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Страница 74: ...Processor Specific MMRs 2 10 ADSP BF59x Blackfin Processor Hardware Reference...
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Страница 244: ...Programming Examples 6 40 ADSP BF59x Blackfin Processor Hardware Reference...
Страница 345: ...ADSP BF59x Blackfin Processor Hardware Reference 9 9 Core Timer Unique Information for the ADSP BF59x Processor None...
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Страница 700: ...Programming Examples 16 78 ADSP BF59x Blackfin Processor Hardware Reference...
Страница 738: ...Boundary Scan Architecture B 8 ADSP BF59x Blackfin Processor Hardware Reference...