2-18
DSP56853/854/855/857/858 User’s Manual
MOTOROLA
Preliminary
Power, Ground and Peripheral Signals
2
MOSI
(GPIOF1)
Input / Output(Z)
Input / Output
SPI Master Out / Slave In—This serial data pin is
an output from a master device and an input to a
slave device. The master device places data on
the MOSI line a half-cycle before the clock edge
the slave device uses to latch the data. The driver
on this pin can be configured as an open-drain by
the SPI’s Wired-OR mode (WOM) bit when this pin
is configured for SPI operation.
Port F GPIO 1—This is a General Purpose I/O pin
capable of being independently programmed as an
input or output pin.
11
—
11
SCK
(GPIOF3)
Input / Output
Input / Output
SPI Serial Clock—This bidirectional pin provides
a serial bit rate clock for the SPI. This gated clock
signal is an input to a slave device and is
generated as an output by a master device. Slave
devices ignore the SCK signal unless the SS pin is
active low. In both master and slave SPI devices,
data is shifted on one edge of the SCK signal and
is sampled on the opposite edge, where data is
stable. The driver on this pin can be configured as
an open-drain driver by the SPI’s WOM bit when
this pin is configured for SPI operation. When
using Wired-OR mode, the user must provide an
external pull-up device.
Port F GPIO 2—This is a General Purpose I/O pin
capable of being independently programmed as an
input or output pin.
11
—
11
SS
(GPIOF3)
Input
Input / Output
SPI Slave Select—This input pin selects a slave
device before a master device can exchange data
with the slave device. SS must be low before data
transactions and must stay low for the duration of
the transaction. The SS line of the master must be
held high.
Port F GPIO 3—This is a General Purpose I/O pin
capable of being independently programmed as an
input or output pin.
11
—
11
Table 2-13. Serial Peripheral Interface (Continued)
Signal Name
Signal Type
Signal Description
853
Pins
854
Pins
855
Pins
857
Pins
858
Pins