Programming Model
10-32
ADSP-BF537 Blackfin Processor Hardware Reference
TXE
is set). If
SZ = 1
, the device repeatedly transmits 0s on the
MOSI
pin. If
SZ = 0
, it repeatedly transmits the contents of the
SPI_TDBR
register. The
TXE
underrun condition cannot generate an error interrupt in this mode.
For transmit DMA operations, the master SPI initiates a word transfer
only when there is data in the DMA FIFO. If the DMA FIFO is empty,
the SPI waits for the DMA engine to write to the DMA FIFO before start-
ing the transfer. All aspects of SPI receive operation should be ignored
when configured in transmit DMA mode, including the data in the
SPI_RDBR
register, and the status of the
RXS
and
RBSY
bits. The
RBSY
over-
run conditions cannot generate an error interrupt in this mode. The
TXE
underrun condition cannot happen in this mode (master DMA
TX
mode),
because the master SPI will not initiate a transfer if there is no data in the
DMA FIFO.
Writes to the
SPI_TDBR
register during an active SPI transmit DMA opera-
tion should not occur because the DMA data will be overwritten. Writes
to the
SPI_TDBR
register during an active SPI receive DMA operation are
allowed. Reads from the
SPI_RDBR
register are allowed at any time.
DMA requests are generated when the DMA FIFO is not empty (when
TIMOD = 10
), or when the DMA FIFO is not full (when
TIMOD = 11
).
Error interrupts are generated when there is an
RBSY
overflow error condi-
tion (when
TIMOD = 10
).
A master SPI DMA sequence may involve back-to-back transmission
and/or reception of multiple DMA work units. The SPI controller sup-
ports such a sequence with minimal core interaction.
Slave Mode DMA Operation
When enabled as a slave with the DMA engine configured to transmit or
receive data, the start of a transfer is triggered by a transition of the
SPISS
signal to the active-low state or by the first active edge of
SCK
, depending
on the state of
CPHA
.
Содержание Blackfin ADSP-BF537
Страница 42: ...Contents xlii ADSP BF537 Blackfin Processor Hardware Reference ...
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 ...
Страница 606: ...Programming Examples 9 94 ADSP BF537 Blackfin Processor Hardware Reference ...
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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 ...