MC68HC908AS32A Datasheet, PDF (207/280 Pages) Freescale Semiconductor, Inc – Microcontrollers

Functional Description
16.4 Functional Description
Figure 16-2 shows the structure of the SPI module.
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. All SPI interrupts can be serviced by the CPU.
The following paragraphs describe the operation of the SPI module.
INTERNAL BUS
TRANSMIT DATA REGISTER
BUS CLOCK
÷2
CLOCK ^{÷ 8}
DIVIDER _{÷ 32}
÷ 128
SHIFT REGISTER
76543210
RECEIVE DATA REGISTER
SPMSTR SPE
CLOCK
SELECT
SPR1 SPR0
CLOCK
LOGIC
PIN
CONTROL
LOGIC
M
S
SPMSTR CPHA CPOL
MISO
MOSI
SPSCK
SS
TRANSMITTER CPU INTERRUPT REQUEST
RECEIVER/ERROR CPU INTERRUPT REQUEST
SPI
CONTROL
MODFEN
ERRIE
SPTIE
SPRIE
SPWOM
SPE
SPRF
SPTE
OVRF
MODF
Figure 16-2. SPI Module Block Diagram
MC68HC908AS32A Data Sheet, Rev. 2.0
Freescale Semiconductor
207