MC68HC908AT32 Datasheet, PDF (163/378 Pages) Freescale Semiconductor, Inc – Microcontrollers

Chapter 17
Serial Peripheral Interface Module (SPI)
17.1 Introduction
This section describes the serial peripheral interface (SPI) module, which allows full-duplex, synchronous,
serial communications with peripheral devices.
17.2 Features
Features of the SPI module include:
• 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 with central processor unit (CPU) service:
– SPRF (SPI receiver full)
– SPTE (SPI transmitter empty)
• Mode fault error flag with cpu interrupt capability
• Overflow error flag with cpu interrupt capability
• Programmable wired-OR mode
• I²C (inter-integrated circuit) compatibility
17.3 Pin Name and Register Name Conventions
The generic names of the SPI input/output (I/O) pins are:
• SS (slave select)
• SPSCK (SPI serial clock)
• MOSI (master out slave in)
• MISO (master in slave out)
The SPI shares four I/O pins with a parallel I/O port. The full name of an SPI pin reflects the name of the
shared port pin. Table 17-1 shows the full names of the SPI I/O pins. The generic pin names appear in
the text that follows.
Table 17-1. Pin Name Conventions
SPI Generic Pin Name
Full SPI Pin Name
MISO
PTE5/MISO
MOSI
PTE6/MOSI
SS
PTE4/SS
SPSCK
PTE7/SPSCK
MC68HC908AT32 Data Sheet, Rev. 3.1
Freescale Semiconductor
163