Programming Examples
10-52
ADSP-BF537 Blackfin Processor Hardware Reference
completed,
SPI_STAT
is polled to determine when the transmit buffer is
empty. If there is data in the SPI Transmit FIFO, it is loaded as soon as
the
TXS
bit clears. A second consecutive read with the
TXS
bit clear indi-
cates the FIFO is empty and the last word is in the shift register. Finally,
polling for the
SPIF
bit determines when the last bit of the last word has
been shifted out. At that point, it is safe to shut down the SPI port and the
DMA engine.
Listing 10-8. Stopping a Transfer
SPI_DMA_INTERRUPT_HANDLER:
P0.L = lo(DMA7_IRQ_STATUS);
P0.H = hi(DMA7_IRQ_STATUS);
R0 = 1 ;
W[P0] = R0 ;
/* Clear DMA interrupt */
/* Wait for DMA to complete */
P0.L = lo(DMA7_IRQ_STATUS);
P0.H = hi(DMA7_IRQ_STATUS);
R0 = DMA_RUN; /* 0x08 */
CHECK_DMA_COMPLETE:
/* Poll for DMA_RUN bit to clear */
R3 = W[P0] (Z);
R1 = R3 & R0;
CC = R1 == 0;
IF !CC JUMP CHECK_DMA_COMPLETE;
/* Wait for TXS to clear */
P0.L = lo(SPI_STAT);
P0.H = hi(SPI_STAT);
R1 = TXS; /* 0x08 */
Check_TXS:
/* Poll for TXS = 0 */
R2 = W[P0] (Z);
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 ...
Страница 660: ...Programming Examples 10 54 ADSP BF537 Blackfin Processor Hardware Reference ...
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 ...