
Chapter 14 Serial Peripheral Interface (SPIV3) Block Description
410
MC9S12Q128
Freescale Semiconductor
Rev 1.10
14.1.3
Block Diagram
Figure 14-1 gives an overview on the SPI architecture. The main parts of the SPI are status, control, and
data registers, shifter logic, baud rate generator, master/slave control logic, and port control logic.
Figure 14-1. SPI Block Diagram
14.2
External Signal Description
This section lists the name and description of all ports including inputs and outputs that do, or may, connect
off chip. The SPIV3 module has a total of four external pins.
14.2.1
MOSI — Master Out/Slave In Pin
This pin is used to transmit data out of the SPI module when it is congured as a master and receive data
when it is congured as slave.
SPI Control Register 1
SPI Control Register 2
SPI Baud Rate Register
SPI Status Register
SPI Data Register
Shifter
Port
Control
Logic
MOSI
SCK
Interrupt Control
SPI
MSB
LSB
LSBFE=1
LSBFE=0
LSBFE=1
data in
LSBFE=1
LSBFE=0
data out
8
Baud Rate Generator
Prescaler
Bus Clock
Counter
Clock Select
SPPR
3
SPR
Baud Rate
Phase +
Polarity
Control
Master
Slave
SCK in
SCK out
Master Baud Rate
Slave Baud Rate
Phase +
Polarity
Control
CPOL
CPHA
2
BIDIROE
SPC0
2
MODF
SPIF
SPTEF
SPI
Request
Interrupt
SS
Shift
Clock
Sample
Clock