MC9S12G FREESCALE [Freescale Semiconductor, Inc], MC9S12G Datasheet - Page 604

• Manufacturer Part Number: MC9S12G
• Description: Ignores external trigger. Performs one conversion sequence and stops.
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

Serial Peripheral Interface (S12SPIV5)
19.1.3
The SPI functions in three modes: run, wait, and stop.
For a detailed description of operating modes, please refer to
19.1.4
Figure 19-1
data registers, shifter logic, baud rate generator, master/slave control logic, and port control logic.
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This document is valid for the S12G96 and the S12G128 device. All information related to other devices is preliminary.
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 data 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 data continues, so that the slave stays
synchronized to the master.
Modes of Operation
Block Diagram
gives an overview on the SPI architecture. The main parts of the SPI are status, control and
MC9S12G Family Reference Manual,
Section 19.4.7, “Low Power Mode
Rev.1.01
Freescale Semiconductor
Options”.