Functional Description
5-36
ADSP-BF537 Blackfin Processor Hardware Reference
Additional information for the control commands includes:
•
Restart
The restart control command causes the current work unit to inter-
rupt processing and start over, using the addresses and counts from
DMAx_START_ADDR
,
DMAx_X_COUNT
, and
DMAx_Y_COUNT
. No interrupt
is signalled.
If a channel programmed for transmit (memory read) receives a
restart control command, the channel momentarily pauses while
any pending memory reads initiated prior to the restart command
are completed.
During this period of time, the channel does not grant DMA
requests. Once all pending reads have been flushed from the chan-
nel’s pipelines, the channel resets its counters and FIFO, and starts
prefetch reads from memory. DMA data requests from the periph-
eral are granted as soon as new prefetched data is available in the
DMA FIFO. The peripheral can thus use the restart command to
re-attempt a failed transmission of a work unit.
If a channel programmed for receive (memory write) receives a
restart control 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 periph-
eral 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 control command causes the current work unit to termi-
nate processing of the current work unit and move on to the next.
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
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 ...