mc68hc711k4 Freescale Semiconductor, Inc, mc68hc711k4 Datasheet - Page 170

• Manufacturer Part Number: mc68hc711k4
• Description: Hcmos Microcontroller Unit
• Manufacturer: Freescale Semiconductor, Inc

Serial Peripheral Interface (SPI)
8.4 SPI Signal Descriptions
8.4.1 Master In Slave Out (MISO)
8.4.2 Master Out Slave In (MOSI)
8.4.3 Serial Clock (SCK)
Technical Data
170
The four basic SPI signals (MISO, MOSI, SCK, and SS) are discussed
for both the master and slave modes in the following paragraphs.
Every SPI output line must have its corresponding port D data direction
register (DDRD) bit set. If this bit is clear, the line is disconnected from
the SPI logic and becomes a general-purpose input line. SPI input lines
are not affected by the data direction register.
The MISO is one of two unidirectional serial data lines in the SPI. It
functions as an input in a master device and as an output in a slave
device. The MISO line of a slave device is placed in the high-impedance
state if the slave is not selected.
This unidirectional serial data line is an output in a master device and an
input in a slave device.
The serial clock (SCK) synchronizes data movement both in and out of
all devices. Master and slave devices exchange a byte of information
simultaneously during a sequence of eight clock cycles. SCK is
generated by the master device so its SCK pin functions as an output.
Slave devices receive this signal through their SCK pins, which are
configured as inputs.
The SPI clock rate select bits in the master device determine the SCK
clock rate. These bits are SPR[1:0] in the serial peripheral control
register (SPCR) and SPR2 in the system configuration options 2 register
(OPT2). These bits have no effect in a slave device.
Freescale Semiconductor, Inc.
For More Information On This Product,
Serial Peripheral Interface (SPI)
Go to: www.freescale.com
M68HC11K Family
MOTOROLA