mc68hc08az60 Freescale Semiconductor, Inc, mc68hc08az60 Datasheet - Page 234

• Manufacturer Part Number: mc68hc08az60
• Description: M68hc08 Family Of 8-bit Microcontroller Units Mcus
• Manufacturer: Freescale Semiconductor, Inc

Serial Peripheral Interface Module (SPI)
MC68HC08AZ60 — Rev 1.0
234
MOSI (Master
Out/Slave In)
SPSCK (Serial
Clock)
SS (Slave Select)
MOSI is one of the two SPI module pins that transmit serial data. In full
duplex operation, the MOSI pin of the master SPI module is connected
to the MOSI pin of the slave SPI module. The master SPI simultaneously
transmits data from its MOSI pin and receives data on its MISO pin.
When enabled, the SPI controls data direction of the MOSI pin
regardless of the state of the data direction register of the shared I/O
port.
The serial clock synchronizes data transmission between master and
slave devices. In a master MCU, the SPSCK pin is the clock output. In a
slave MCU, the SPSCK pin is the clock input. In full duplex operation,
the master and slave MCUs exchange a byte of data in eight serial clock
cycles.
When enabled, the SPI controls data direction of the SPSCK pin
regardless of the state of the data direction register of the shared I/O
port.
The SS pin has various functions depending on the current state of the
SPI. For an SPI configured as a slave, the SS is used to select a slave.
For CPHA = 0, the SS is used to define the start of a transmission. (See
Transmission Formats.) Since it is used to indicate the start of a
transmission, the SS must be toggled high and low between each byte
transmitted for the CPHA = 0 format. However, it can remain low
throughout the transmission for the CPHA = 1 format. See
When an SPI is configured as a slave, the SS pin is always configured
as an input. It cannot be used as a general-purpose I/O regardless of the
MASTER SS
MISO/MOSI
SLAVE SS
SLAVE SS
CPHA = 0
CPHA = 1
Freescale Semiconductor, Inc.
For More Information On This Product,
Serial Peripheral Interface Module (SPI)
Go to: www.freescale.com
BYTE 1
Figure 10. CPHA/SS Timing
BYTE 2
BYTE 3
Figure
MOTOROLA
10.
24-spi