
ADSP-BF59x Blackfin Processor Hardware Reference
5-33
Direct Memory Access
peripheral are granted as soon as new prefetched data is available in
the DMA FIFO. The peripheral can thus use the
Restart
com-
mand to re-attempt a failed transmission of a work unit.
If a channel programmed for receive (memory write) receives a
Restart
command, the channel stops writing to memory, discards
any data held in its DMA FIFO, and resets its counters and FIFO.
As soon as this initialization is complete, the channel again grants
DMA write requests from the peripheral. The peripheral can thus
use the
Restart
command to abort transfer of received data into a
work unit and re-use the memory buffer for a later data transfer.
•
Finish
The
Finish
command causes the current work unit to terminate
and move on to the next work unit. An interrupt is signalled as
usual, if selected by the
DI_EN
bit. The peripheral can thus use the
Finish
command to partition the DMA stream into work units on
its own, perhaps as a result of parsing the data currently passing
though its supported communication channel, without direct
real-time control by the processor.
If a channel programmed for transmit (memory read) receives a
Finish
command, the channel momentarily pauses while any
pending memory reads initiated prior to the
Finish
command are
completed. During this period of time, the channel does not grant
DMA requests. Once all pending reads have been flushed from the
channel’s pipelines, the channel signals an interrupt (if enabled),
and begins fetching the next descriptor (if any). DMA data requests
from the peripheral are granted as soon as new prefetched data is
available in the DMA FIFO.
If a channel programmed for receive (memory write) receives a
Finish
command, the channel stops granting new DMA requests
while it drains its FIFO. Any DMA data received by the DMA con-
troller prior to the
Finish
command is written to memory. When
Содержание ADSP-BF59x Blackfin
Страница 64: ...Development Tools 1 22 ADSP BF59x Blackfin Processor Hardware Reference...
Страница 74: ...Processor Specific MMRs 2 10 ADSP BF59x Blackfin Processor Hardware Reference...
Страница 204: ...Unique Information for the ADSP BF59x Processor 5 104 ADSP BF59x Blackfin Processor Hardware Reference...
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...
Страница 346: ...Unique Information for the ADSP BF59x Processor 9 10 ADSP BF59x Blackfin Processor Hardware Reference...
Страница 398: ...Unique Information for the ADSP BF59x Processor 11 42 ADSP BF59x Blackfin Processor Hardware Reference...
Страница 622: ...Unique Information for the ADSP BF59x Processor 15 38 ADSP BF59x Blackfin Processor Hardware Reference...
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...