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Interface Overview
10-12
ADSP-BF537 Blackfin Processor Hardware Reference
When using DMA for SPI transmit, the
DMA_DONE
interrupt signi-
fies that the DMA FIFO is empty. However, at this point there
may still be data in the SPI DMA FIFO waiting to be transmitted.
Therefore, software needs to poll
TXS
in the
SPI_STAT
register until
it goes low for 2 successive reads, at which point the SPI DMA
FIFO will be empty. When the
SPIF
bit subsequently goes low, the
last word has been transferred and the SPI can be disabled or
enabled for another mode.
Internal Interfaces
The SPI has dedicated connections to the processor’s PAB and DAB.
The low-latency PAB bus is used to map the SPI resources into the system
MMR space through the PAB bus. For the PAB accesses to SPI MMRs,
the primary performance criteria is latency, not throughput. Transfer
latencies for both read and write transfers on the PAB are 2
SCLK
cycles.
The DAB bus provides a means for DMA SPI transfers to gain access to
on-chip and off-chip memory with little or no degradation in core band-
width to memory. The SPI peripheral, as a DMA master, is capable of
sourcing DMA accesses. A single arbiter supports a programmable priority
arbitration policy for access to the DAB.
default arbitration priority.
DMA Functionality
The SPI has a single DMA engine which can be configured to support
either an SPI transmit channel or a receive channel, but not both simulta-
neously. Therefore, when configured as a transmit channel, the received
data will essentially be ignored.
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 660: ...Programming Examples 10 54 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 720: ...Electrical Specifications 11 60 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 840: ...Programming Examples 13 42 ADSP BF537 Blackfin Processor Hardware Reference ...
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Страница 958: ...Programming Examples 17 12 ADSP BF537 Blackfin Processor Hardware Reference ...
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 ...