SPI Transfer Formats
10-26
ADSP-2126x SHARC Processor Hardware Reference
SPI Transfer Formats
The ADSP-2126x SPI supports four different combinations of serial clock
phases and polarity. The application code can select any of these combina-
tions using the
CLKPL
and
CPHASE
bits in the
SPICTL
register.
shows the transfer format when
CPHASE
= 0
where
SPICLK
starts toggling in the middle of the data transfer,
WL
= 0, and
MSBF
= 1.
shows the transfer format when
CPHASE
= 1. Each diagram shows two waveforms for
SPICLK
—one for
CLKPL
= 0 and the other for
CLKPL
= 1. The diagrams may be interpreted as
master or slave timing diagrams since the
SPICLK
,
MISO
, and
MOSI
pins are
directly connected between the master and the slave. The
MISO
signal is the
output from the slave (slave transmission), and the
MOSI
signal is the out-
put from the master (master transmission).
The
SPICLK
signal is generated by the master, and the
SPIDS
signal rep-
resents the slave device select input to the processor from the SPI master.
The diagrams represent 8-bit transfers (
WL
= 0) with MSB first (
MSBF
= 1).
Any combination of the
WL
and
MSBF
bits of the
SPICTL
register is allowed.
For example, a 16-bit transfer with the LSB first is one possible
configuration.
The clock polarity and the clock phase should be identical for the master
device and slave devices involved in the communication link. The transfer
Table 10-2. DMA Chaining Sequence
Address
Register
Description
CPSPI
DMA Start Address
Address in Memory
CPSPI – 1
DMA Address Modifier
Address increment
CPSPI – 2
DMA Word Count
Number of words to transfer
CPSPI – 3
DMA Next TCB
Pointer to address of next TCB
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 ...