SPI Transfer Formats
10-28
ADSP-BF535 Blackfin Processor Hardware Reference
SPI Transfer Formats
The ADSP-BF535 SPI supports four different combinations of serial clock
phase and polarity, selectable using the
CPOL
and
CPHA
bits in
SPIx_CTL
.
The SPI transfer protocols shown in
Figure 10-18
and
Figure 10-19
dem-
onstrate the two basic transfer formats as defined by the
CPHA
bit. Two
waveforms are shown for
SCK
: one for
CPOL = 0
and the other for
CPOL =
1
. The diagrams may be interpreted as master or slave timing diagrams
since the
SCK
,
MISO
, and
MOSI
pins are directly connected between the mas-
ter and the slave. The
MISO
signal is the output from the slave (slave
transmission), and the
MOSI
signal is the output from the master (master
transmission). The
SCK
signal is generated by the master, and the
SPISS
signal is the slave device select input to the slave from the master. The dia-
grams represent an 8-bit transfer (
SIZE = 0
) with MSB first (
LSBF = 0
).
Any combination of the
SIZE
and
LSBF
bits of
SPIx_CTL
is allowed. For
example, a 16-bit transfer with LSB first is another possible configuration.
The clock polarity and the clock phase should be identical for the master
device and the slave device involved in the communication link. The
transfer format from the master may be changed between transfers to
adjust to various requirements of a slave device.
SPIx_DESCR_RDY
SPI port DMA
descriptor ready
Write a 1 to bit 0 to reactivate a descriptor
fetch
SPIx_DMA_INT
SPI port interrupt
status
All three Interrupt Status bits are sticky;
write a 1 to the corresponding bit to clear
Table 10-18. SPI Register Mapping (Cont’d)
Register Name
Function
Notes
Summary of Contents for ADSP-BF535 Blackfin
Page 80: ...Development Tools 1 26 ADSP BF535 Blackfin Processor Hardware Reference...
Page 312: ...Working With Memory 6 86 ADSP BF535 Blackfin Processor Hardware Reference...
Page 332: ...System Interfaces 7 20 ADSP BF535 Blackfin Processor Hardware Reference...
Page 360: ...Dynamic Power Management Controller 8 28 ADSP BF535 Blackfin Processor Hardware Reference...
Page 446: ...Beginning and Ending an SPI Transfer 10 40 ADSP BF535 Blackfin Processor Hardware Reference...
Page 522: ...Timing Examples 11 76 ADSP BF535 Blackfin Processor Hardware Reference...
Page 562: ...IrDA Support 12 40 ADSP BF535 Blackfin Processor Hardware Reference...
Page 608: ...PCI I O Issues 13 46 ADSP BF535 Blackfin Processor Hardware Reference...
Page 672: ...References 14 64 ADSP BF535 Blackfin Processor Hardware Reference...
Page 810: ...SDRAM Controller SDC 18 86 ADSP BF535 Blackfin Processor Hardware Reference...
Page 811: ...ADSP BF535 Blackfin Processor Hardware Reference 18 87 External Bus Interface Unit...
Page 812: ...SDRAM Controller SDC 18 88 ADSP BF535 Blackfin Processor Hardware Reference...
Page 860: ...DMA Bus Debug Registers 20 30 ADSP BF535 Blackfin Processor Hardware Reference...