Spi General Operation - Analog Devices ADSP-BF506F Hardware Reference Manual

SPI General Operation

The SPI can be used in single master as well as multimaster environments.
The ,
MOSI MISO
tions. SPI transmission and reception are always enabled simultaneously,
unless the broadcast mode has been selected. In broadcast mode, several
slaves can be enabled to receive, but only one of the slaves must be in
transmit mode driving the
needed, it can simply be ignored. This section describes the clock signals,
SPI operation as a master and as a slave, and error generation.
Precautions must be taken to avoid data corruption when changing the
SPI module configuration. The configuration must not be changed during
a data transfer. The clock polarity should only be changed when no slaves
are selected. An exception to this is when an SPI communication link con-
sists of a single master and a single slave,
input of the slave is always tied low. In this case, the slave is always
selected and data corruption can be avoided by enabling the slave only
after both the master and slave devices are configured.
In a multimaster or multislave SPI system, the data output pins (
) can be configured to behave as open drain outputs, which prevents
MISO
contention and possible damage to pin drivers. An external pull-up resis-
tor is required on both the
selected.
The bit in the
WOM
and the SPI is configured as a master, the
the data driven out on
three-stated when the driven data is a logic low. Similarly, when
and the SPI is configured as a slave, the
driven out on
MISO
During SPI data transfers, one SPI device acts as the SPI link master,
where it controls the data flow by generating the SPI serial clock and
asserting the SPI device select signal (
ADSP-BF50x Blackfin Processor Hardware Reference
, and the signals are all tied together in both configura-
SCK
line. If the transmit or receive is not
MISO
and
MOSI
register controls this option. When
SPI_CTL
is a logic high. The
MOSI
is a logic high.
SPI-Compatible Port Controller
= 1, and the slave select
CPHA
pins when this option is
MISO
pin is three-stated when
MOSI
pin is not
MOSI
pin is three-stated if the data
MISO
). The other SPI device acts as
SPISS
and
MOSI
is set
WOM
is set
WOM
18-15