mcf51ac256a Freescale Semiconductor, Inc, mcf51ac256a Datasheet - Page 428

• Manufacturer Part Number: mcf51ac256a
• Description: Mcf51ac Flexis
• Manufacturer: Freescale Semiconductor, Inc

8-Bit Serial Peripheral Interface (SPIV3)
19.1.1
Features of the SPI module include:
19.1.2
This section includes block diagrams showing SPI system connections, the internal organization of the SPI
module, and the SPI clock dividers that control the master mode bit rate.
19.1.2.1
Figure 19-1
device initiates all SPI data transfers. During a transfer, the master shifts data out (on the MOSI pin) to the
slave while simultaneously shifting data in (on the MISO pin) from the slave. The transfer effectively
exchanges the data that was in the SPI shift registers of the two SPI systems. The SPSCK signal is a clock
output from the master and an input to the slave. The slave device must be selected by a low level on the
slave select input (SS pin). In this system, the master device has configured its SS pin as an optional slave
select output.
The most common uses of the SPI system include connecting simple shift registers for adding input or
output ports or connecting small peripheral devices such as serial A/D or D/A converters. Although
19-2
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Master or slave mode operation
Full-duplex or single-wire bidirectional option
Programmable transmit bit rate
Double-buffered transmit and receive
Serial clock phase and polarity options
Slave select output
Selectable msb-first or lsb-first shifting
Features
Block Diagrams
shows the SPI modules of two MCUs connected in a master-slave arrangement. The master
7
SPI System Block Diagram
6
5
MCF51AC256 ColdFire Integrated Microcontroller Reference Manual, Rev. 5
SPI Shifter
Generator
Master
Clock
4
3
2
1
0
Figure 19-1. SPI System Connections
MOSI
MISO
SPSCK
SS
SPSCK
MOSI
MISO
SS
7
Slave
6
5
SPI Shifter
4
3
Freescale Semiconductor
2
1
0