SPI Transfer Formats
10-28
ADSP-2126x SHARC Processor Hardware Reference
Beginning and Ending an SPI Transfer
An SPI transfer’s defined start and end depend on the following: whether
the device is configured as a master or a slave, whether the
CPHASE
mode is
selected, and whether the transfer initiation mode is (
TIMOD
) selected. For
a master SPI with
CPHASE
= 0, a transfer starts when either the
TXSPI
regis-
ter is written or the
RXSPI
register is read, depending on the
TIMOD
selection. At the start of the transfer, the enabled slave-select outputs are
driven active (
LOW
). However, the
SPICLK
starts toggling after a delay equal
to one-half the
SPICLK
period. For a slave with
CPHASE
= 0, the transfer
starts as soon as the
SPIDS
input transitions to low.
For
CPHASE
= 1, a transfer starts with the first active edge of
SPICLK
for
both slave and master devices. For a master device, a transfer is considered
complete after it sends and simultaneously receives the last data bit. A
transfer for a slave device is complete after the last sampling edge of
SPICLK
.
Figure 10-7. SPI Transfer Protocol for CPHASE = 1
1
CLO CK CYCLE
NUMBER
SPICLK
CLKPL=0
MOSI
FROM MASTER
MISO
FROM SLAVE
SPIDS
TO SLAVE
SPICLK
CLKPL=1
2
3
4
5
6
7
8
*
6
6
5
4
3
5
4
3
2
1
LSB
*
2
1
LSB
MSB
MSB
* = UNDEF INED
*
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 ...