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DMA Registers
5-78
ADSP-BF537 Blackfin Processor Hardware Reference
•
WNR
(DMA direction). This bit specifies DMA direction—memory
read (0) or memory write (1).
•
DMAEN
(DMA channel enable). This bit specifies whether to enable
a given DMA channel.
L
When a peripheral DMA channel is enabled, interrupts from the
peripheral denote DMA requests. When a channel is disabled, the
DMA unit ignores the peripheral interrupt and passes it directly to
the interrupt controller. To avoid unexpected results, take care to
enable the DMA channel before enabling the peripheral, and to
disable the peripheral before disabling the DMA channel.
DMAx_IRQ_STATUS/MDMA_yy_IRQ_STATUS Registers
The interrupt status register (
DMAx_IRQ_STATUS/MDMA_yy_IRQ_STATUS
),
, contains bits that record whether the DMA channel:
• Is enabled and operating, enabled but stopped, or disabled.
• Is fetching data or a DMA descriptor.
• Has detected that a global DMA interrupt or a channel interrupt is
being asserted.
• Has logged occurrence of a DMA error.
Note the
DMA_DONE
interrupt is asserted when the last memory access (read
or write) has completed.
L
For a memory transfer to a peripheral, there may be up to four data
words in the channel’s DMA FIFO when the interrupt occurs. At
this point, it is normal to immediately start the next work unit. If,
however, the application needs to know when the final data item is
actually transferred to the peripheral, the application can test or
poll the
DMA_RUN
bit. As long as there is undelivered transmit data
in the FIFO, the
DMA_RUN
bit is 1.
Содержание Blackfin ADSP-BF537
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Страница 90: ...Development Tools 1 32 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 138: ...Programming Examples 4 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 340: ...SDC Programming Examples 6 84 ADSP BF537 Blackfin Processor Hardware Reference ...
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Страница 720: ...Electrical Specifications 11 60 ADSP BF537 Blackfin Processor Hardware Reference ...
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Страница 986: ...Programming Examples 18 28 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 1162: ...G 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 1218: ...Index I 56 ADSP BF537 Blackfin Processor Hardware Reference ...