Programming Model
10-50
ADSP-2126x SHARC Processor Hardware Reference
Stopping DMA Transfers
When performing transmit DMA transfers, data moves through a four
deep SPI DMA FIFO, then into the
TXSPIx
buffers, and finally into the
shift register. DMA interrupts are latched when the I/O processor moves
the last word from memory to the peripheral. For the SPI, this means that
the SPI “DMA complete” interrupt is latched when there are six words
remaining to be transmitted (four in the FIFO, one in the
TXSPIx
buffers,
and one being shifted out of the shift register). To disable the SPI port
after a DMA transmit operation, use the following steps:
1. Wait for the DMA FIFO to empty. This is done when the
SPISx
bits (bits 13–12 in the
SPIDMACx
registers) become zero.
2. Wait for the
TXSPIx
registers to empty. This is done when the
TXS
bit, (bit 3) in the
SPISTATx
registers becomes zero.
When stopping receive DMA transfers, it is recommended that
programs follow the SPI disable steps provided in
Receive to Receive/Transmit DMA”
below.
3. Wait for the SPI shift register to finish transferring the last word.
This is done when the
SPIF
bit (bit 0) of the
SPISTATx
registers
becomes one.
4. Disable the SPI ports by setting the
SPIEN
bit (bit 0) of the
SPICTLx
registers to zero.
Switching from Transmit To Transmit/Receive DMA
The following sequence details the steps for switching from transmit to
receive DMA.
Summary of Contents for ADSP-21261 SHARC
Page 30: ...Contents xxx ADSP 2126x SHARC Processor Hardware Reference ...
Page 40: ...Register Diagram Conventions xl ADSP 2126x SHARC Processor Hardware Reference ...
Page 58: ...Differences From Previous SHARCs 1 18 ADSP 2126x SHARC Processor Hardware Reference ...
Page 112: ...Secondary Processing Element PEy 2 54 ADSP 2126x SHARC Processor Hardware Reference ...
Page 178: ...Summary 3 66 ADSP 2126x SHARC Processor Hardware Reference ...
Page 204: ...DAG Instruction Summary 4 26 ADSP 2126x SHARC Processor Hardware Reference ...
Page 322: ...Setting Up DMA 7 32 ADSP 2126x SHARC Processor Hardware Reference ...
Page 436: ...SPORT Programming Examples 9 86 ADSP 2126x SHARC Processor Hardware Reference ...
Page 521: ...ADSP 2126x SHARC Processor Hardware Reference 11 31 Input Data Port rts IDP_ISR end ...
Page 522: ...Input Data Port Programming Example 11 32 ADSP 2126x SHARC Processor Hardware Reference ...
Page 590: ...Timer Programming Examples 14 20 ADSP 2126x SHARC Processor Hardware Reference ...
Page 796: ...I O Processor Registers A 174 ADSP 2126x SHARC Processor Hardware Reference ...
Page 800: ...B 4 ADSP 2126x SHARC Processor Core Manual ...
Page 846: ...Index I 36 ADSP 2126x SHARC Processor Hardware Reference ...