Functional Description
5-28
ADSP-BF537 Blackfin Processor Hardware Reference
the cost of higher latency in the transition. In synchronized transitions,
the DMA FIFO pipeline is drained to the destination or flushed (RX data
discarded) between work units.
L
Work unit transitions for MDMA streams are controlled by the
SYNC
bit of the MDMA source channel’s
DMAx_CONFIG
register. The
SYNC
bit of the MDMA destination channel is reserved and must be
0. In transmit (memory read) channels, the
SYNC
bit of the last
descriptor prior to the transition controls the transition behavior.
In contrast, in receive channels, the
SYNC
bit of the first descriptor
of the next descriptor chain controls the transition.
DMA Transmit and MDMA Source
In DMA transmit (memory read) and MDMA source channels, the
SYNC
bit controls the interrupt timing at the end of the work unit and the han-
dling of the DMA FIFO between the current and next work unit.
If
SYNC = 0
, a continuous transition is selected. In a continuous transition,
just after the last data item is read from memory, these four operations all
start in parallel:
• The interrupt (if any) is signalled.
• The
DMA_DONE
bit in the
DMAx_IRQ_STATUS
register is set.
• The next descriptor begins to be fetched.
• The final data items are delivered from the DMA FIFO to the des-
tination memory or peripheral.
This allows the DMA to provide data from the FIFO to the peripheral
“continuously” during the descriptor fetch latency period.
When
SYNC = 0
, the final interrupt (if enabled) occurs when the last data is
read from memory. This interrupt is at the earliest time that the output
memory buffer may safely be modified without affecting the previous data
transmission. Up to four data items may still be in the DMA FIFO,
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 ...