ADSP-2126x SHARC Processor Hardware Reference
10-21
Serial Peripheral Interface Port
3. Disable the SPI Port by setting the
SPIEN
bit, (bit 0) in the
SPICTL
register, to zero.
When performing transmit DMA transfers, data moves through a four
deep SPI DMA FIFO, then into the
TXSPI
buffer, 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 still six words
left to be fully transmitted (four in the FIFO, one in the
TXSPI
buffer, and
one being shifted out of the Shift register). To disable the SPI port after a
DMA transmit operation, use these steps:
1. Wait for DMA FIFO to empty. This is done when the
SPISx
bits
(bits 13–12) in the
SPIDMAC
register become zero.
2. Wait for the
TXSPI
register to empty. This is done when the
TXS
bit
(bit 3) in the
SPISTAT
register becomes zero.
3. Wait for the SPI Shift register to finish transferring the last word.
This is done when the
SPIF
bit, (bit 0) of the
SPISTAT
register,
becomes one.
4. Disable the SPI Port by setting the
SPIEN
bit, (bit 0) of the
SPICTL
register, to zero.
Switching From Transmit To Receive DMA
The following sequence details the steps for switching from transmit to
receive DMA.
With disabling the SPI:
1. Write 0x00 to the
SPICTL
register to disable SPI. Disabling the SPI
also clears the
RXSPI
/
TXSPI
registers and the buffer status.
2. Disable DMA by writing 0x00 to the
SPIDMAC
register.
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 ...