mc9s12e256 Freescale Semiconductor, Inc, mc9s12e256 Datasheet - Page 275

• Manufacturer Part Number: mc9s12e256
• Description: Hcs12 Microcontrollers 16-bit Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

Chapter 9
Serial Peripheral Interface (SPIV3)
9.1
The SPI module allows a duplex, synchronous, serial communication between the MCU and peripheral
devices. Software can poll the SPI status flags or the SPI operation can be interrupt driven.
9.1.1
The SPIV3 includes these distinctive features:
9.1.2
The SPI functions in three modes, run, wait, and stop.
This is a high level description only, detailed descriptions of operating modes are contained in
“Functional Description.”
Freescale Semiconductor
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Master mode and slave mode
Bidirectional mode
Slave select output
Mode fault error flag with CPU interrupt capability
Double-buffered data register
Serial clock with programmable polarity and phase
Control of SPI operation during wait mode
Run Mode
This is the basic mode of operation.
Wait Mode
SPI operation in wait mode is a configurable low power mode, controlled by the SPISWAI bit
located in the SPICR2 register. In wait mode, if the SPISWAI bit is clear, the SPI operates like in
Run Mode. If the SPISWAI bit is set, the SPI goes into a power conservative state, with the SPI
clock generation turned off. If the SPI is configured as a master, any transmission in progress stops,
but is resumed after CPU goes into Run Mode. If the SPI is configured as a slave, reception and
transmission of a byte continues, so that the slave stays synchronized to the master.
Stop Mode
The SPI is inactive in stop mode for reduced power consumption. If the SPI is configured as a
master, any transmission in progress stops, but is resumed after CPU goes into run mode. If the SPI
is configured as a slave, reception and transmission of a byte continues, so that the slave stays
synchronized to the master.
Introduction
Features
Modes of Operation
MC9S12E256 Data Sheet, Rev. 1.08
Section 9.4,
275