Modes of Operation
5-14
ADSP-BF537 Blackfin Processor Hardware Reference
should clear the
DMAEN
enable bit to disable a paused channel. Stop mode
is entered if the
FLOW
bit field in the DMA channel’s
DMAx_CONFIG
register
is 0. The
NDSIZE
field must always be 0 in this mode.
For receive (memory write) operation, the
DMA_RUN
bit functions almost
the same as the inverted
DMA_DONE
bit. For transmit (memory read) opera-
tion, however, the two bits have different timing. Refer to the description
of the
SYNC
bit for details.
Autobuffer Mode
In autobuffer mode, the DMA operates repeatedly in a circular manner. If
all data words have been transferred, the address pointer
DMAx_CURR_ADDR
is reloaded automatically by the
DMAx_START_ADDR
value. An interrupt may
also be generated.
Autobuffer mode is entered if the
FLOW
field in the
DMAx_CONFIG
register
is 1. The
NDSIZE
bit must be 0 in autobuffer mode.
Two-Dimensional DMA Operation
Register-based and descriptor-based DMA can operate in one-dimensional
mode or two-dimensional mode.
In two-dimensional (2D) mode the
DMAx_X_COUNT
register is accompanied
by the
DMAx_Y_COUNT
register, supporting arbitrary row and column sizes
up to 64 K x 64 K elements, as well as arbitrary
DMAx_X_MODIFY
and
DMAx_
Y_MODIFY
values up to ±32 K bytes. Furthermore,
DMAx_Y_MODIFY
can be
negative, allowing implementation of interleaved datastreams. The
DMAx_
X_COUNT
and
DMAx_Y_COUNT
values specify the row and column sizes, where
DMAx_X_COUNT
must be 2 or greater.
The start address and modify values are in bytes, and they must be aligned
to a multiple of the DMA transfer word size (
WDSIZE[1:0]
in
DMAx_CON-
FIG
). Misalignment causes a DMA error.
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 ...