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MC908AP8CFBE Datasheet, PDF (211/324 Pages) Freescale Semiconductor, Inc – Microcontrollers | |||
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Chapter 13
Serial Peripheral Interface Module (SPI)
13.1 Introduction
This section describes the serial peripheral interface (SPI) module, which allows full-duplex,
synchronous, serial communications with peripheral devices.
13.2 Features
Features of the SPI module include the following:
⢠Full-duplex operation
⢠Master and slave modes
⢠Double-buffered operation with separate transmit and receive registers
⢠Four master mode frequencies (maximum = bus frequency ÷ 2)
⢠Maximum slave mode frequency = bus frequency
⢠Serial clock with programmable polarity and phase
⢠Two separately enabled interrupts:
â SPRF (SPI receiver full)
â SPTE (SPI transmitter empty)
⢠Mode fault error flag with CPU interrupt capability
⢠Overflow error flag with CPU interrupt capability
⢠Programmable wired-OR mode
13.3 Pin Name Conventions and I/O Register Addresses
The text that follows describes the SPI. The SPI I/O pin names are SS (slave select), SPSCK (SPI serial
clock), CGND (clock ground), MOSI (master out slave in), and MISO (master in/slave out). The SPI
shares four I/O pins with four parallel I/O ports.
The full names of the SPI I/O pins are shown in Table 13-1. The generic pin names appear in the text that
follows.
Table 13-1. Pin Name Conventions
SPI Generic
Pin Names:
MISO
Full SPI
Pin Names:
SPI
PTC2/MISO
MOSI
PTC3/MOSI
SS
PTC4/SS
SPSCK
PTC5/SPSCK
CGND
VSS
Figure 13-1 summarizes the SPI I/O registers.
MC68HC908AP Family Data Sheet, Rev. 4
Freescale Semiconductor
209
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