MC68HC08AS32 Datasheet, PDF (204/280 Pages) Motorola, Inc – M68HC08 Family of 8-bit microcontroller units (MCUs)

14.4 Functional Description
Figure 14-3 summarizes the SPI I/O registers and Figure 14-2 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
SPMSTR SPE
CLOCK
SELECT
SPR1 SPR0
SHIFT REGISTER
76543210
RECEIVE DATA REGISTER
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 14-2. SPI Module Block Diagram
Data Sheet
204
MC68HC08AS32 — Rev. 4.1
Freescale Semiconductor