Datasheet

Functional Description
MC68HC908QB8 Data Sheet, Rev. 3
Freescale Semiconductor 157
15.3 Functional Description
The SPI module allows full-duplex, synchronous, serial communication between the MCU and peripheral
devices, including other MCUs. Software can poll the SPI status flags or SPI operation can be interrupt
driven.
The following paragraphs describe the operation of the SPI module.
Figure 15-2. SPI Module Block Diagram
TRANSMITTER INTERRUPT REQUEST
RECEIVER/ERROR INTERRUPT REQUEST
76543210
SPR1
SPMSTR
TRANSMIT DATA REGISTER
SHIFT REGISTER
SPR0
CLOCK
SELECT
÷ 2
CLOCK
DIVIDER
÷ 8
÷ 32
÷ 128
CLOCK
LOGIC
CPHA CPOL
SPI
SPRIE
SPE
SPWOM
SPRF
SPTE
OVRF
M
S
PIN
CONTROL
LOGIC
RECEIVE DATA REGISTER
SPTIE
SPE
INTERNAL BUS
BUSCLK
MODFEN
ERRIE
CONTROL
MODF
SPMSTR
MOSI
MISO
SPSCK
SS