Description of Operation
18-16
ADSP-BF50x Blackfin Processor Hardware Reference
the slave and accepts new data from the master into its shift register, while
it transmits requested data out of the shift register through its SPI trans-
mit data pin. Multiple processors can take turns being the master device,
as can other microcontrollers or microprocessors. One master device can
also simultaneously shift data into multiple slaves (known as broadcast
mode). However, only one slave may drive its output to write data back to
the master at any given time. This must be enforced in broadcast mode,
where several slaves can be selected to receive data from the master, but
only one slave at a time can be enabled to send data back to the master.
In a multimaster or multidevice environment where multiple processors
are connected through their SPI ports, all
MOSI
pins are connected
together, all
MISO
pins are connected together, and all
SCK
pins are con-
nected together.
For a multislave environment, the processor can make use of up to seven
programmable flags that are dedicated SPI slave select signals for the SPI
slave devices.
At reset, the SPI is disabled and configured as a slave.
Clock Signals
The SCK signal is a gated clock that is only active during data transfers for
the duration of the transferred word. The number of active edges is equal
to the number of bits driven on the data lines. The clock rate can be as
high as one-fourth of the SCLK rate. For master devices, the clock rate is
determined by the 16-bit value in the SPI_BAUD register. For slave
devices, the value in SPI_BAUD is ignored. When the SPI device is a mas-
ter, SCK is an output signal. When the SPI is a slave, SCK is an input
signal. Slave devices ignore the serial clock if the slave select input is
driven inactive (high).
The
SCK
signal is used to shift out and shift in the data driven onto the
MISO
and
MOSI
lines. The data is always shifted out on one edge of the
clock and sampled on the opposite edge of the clock. Clock polarity and
Содержание EZ-KIT Lite ADSP-BF506F
Страница 50: ...Contents l ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 92: ...Development Tools 1 30 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 110: ...Interface Overview 3 12 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 132: ...Unique Information for the ADSP BF50x Processor 4 22 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 236: ...Internal Flash Memory Control Registers 6 92 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 342: ...Unique Information for the ADSP BF50x Processor 7 106 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 484: ...Unique Information for the ADSP BF50x Processor 10 60 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 493: ...ADSP BF50x Blackfin Processor Hardware Reference 11 9 Core Timer Unique Information for the ADSP BF50x Processor None ...
Страница 494: ...Unique Information for the ADSP BF50x Processor 11 10 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 506: ...Unique Information for the ADSP BF50x Processor 12 12 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 544: ...Unique Information for the ADSP BF50x Processor 13 38 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 650: ...Programming Examples 15 56 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 712: ...Unique Information for the ADSP BF50x Processor 16 62 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 804: ...Programming Examples 17 92 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 972: ...Unique Information for the ADSP BF50x Processor 20 38 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 1194: ...Programming Examples 24 90 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 1256: ...ACM Registers A 50 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 1264: ...Boundary Scan Architecture B 8 ADSP BF50x Blackfin Processor Hardware Reference ...