MC908MR32CFUE Datasheet, PDF (197/282 Pages) Freescale Semiconductor, Inc – Microcontrollers

Functional Description
15.4 Functional Description
Figure 15-2 shows the structure of the SPI module and Figure 15-3 shows the locations and contents of
the SPI I/O registers.
The SPI module allows full-duplex, synchronous, serial communication between the microcontroller unit
(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.
INTERNAL BUS
CGMOUT ÷ 2
(FROM SIM)
÷2
CLOCK ^{÷ 8}
DIVIDER _{÷ 32}
÷ 128
TRANSMIT DATA REGISTER
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
SPE
SPWOM
SPRF
SPTE
OVRF
MODF
Figure 15-2. SPI Module Block Diagram
MC68HC908MR32 • MC68HC908MR16 Data Sheet, Rev. 6.1
Freescale Semiconductor
197