DMA Registers
5-76
ADSP-BF537 Blackfin Processor Hardware Reference
interrupts are still filtered out by the DMA unit. The channel may
be restarted simply by another write to the
DMAx_CONFIG
register
specifying the next work unit, in which the
DMAEN
bit is set to 1.
0x1 - autobuffer mode. In this mode, no descriptors in memory are
used. Instead, DMA is performed in a continuous circular buffer
fashion based on user-programmed DMAx MMR settings. Upon
completion of the work unit, the parameter registers are reloaded
into the current registers, and DMA resumes immediately with
zero overhead. Autobuffer mode is stopped by a user write of 0 to
the
DMAEN
bit in the
DMAx_CONFIG
register.
0x4 - descriptor array mode. This mode fetches a descriptor from
memory that does not include the
NDPH
or
NDPL
elements. Because
the descriptor does not contain a next descriptor pointer entry, the
DMA engine defaults to using the
DMAx_CURR_DESC_PTR
register to
step through descriptors, thus allowing a group of descriptors to
follow one another in memory like an array.
0x6 - descriptor list (small model) mode. This mode fetches a
descriptor from memory that includes
NDPL
, but not
NDPH
. There-
fore, the high 16 bits of the next descriptor pointer field are taken
from the upper 16 bits of the
DMAx_NEXT_DESC_PTR
register, thus
confining all descriptors to a specific 64K page in memory.
0x7 - descriptor list (large model) mode. This mode fetches a
descriptor from memory that includes
NDPH
and
NDPL
, thus allowing
maximum flexibility in locating descriptors in memory.
•
NDSIZE[3:0]
(flex descriptor size). This field specifies the number
of descriptor elements in memory to load. This field must be 0 if in
stop or autobuffer mode. If
NDSIZE
and
FLOW
specify a descriptor
that extends beyond
YMOD
, a DMA error results.
Summary of Contents for Blackfin ADSP-BF537
Page 42: ...Contents xlii ADSP BF537 Blackfin Processor Hardware Reference ...
Page 90: ...Development Tools 1 32 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 138: ...Programming Examples 4 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 340: ...SDC Programming Examples 6 84 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 606: ...Programming Examples 9 94 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 660: ...Programming Examples 10 54 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 720: ...Electrical Specifications 11 60 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 840: ...Programming Examples 13 42 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 876: ...Programming Examples 14 36 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 938: ...Programming Examples 15 62 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 958: ...Programming Examples 17 12 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 986: ...Programming Examples 18 28 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 1162: ...G 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 1218: ...Index I 56 ADSP BF537 Blackfin Processor Hardware Reference ...