Freescale Semiconductor MC68HC908MR32 - Manual (Page 197)

Functional Description
MC68HC908MR32 • MC68HC908MR16 Data Sheet, Rev. 6.1
Freescale Semiconductor 197
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.
Figure 15-2. SPI Module Block Diagram
TRANSMITTER CPU INTERRUPT REQUEST
RECEIVER/ERROR CPU INTERRUPT REQUEST
7 6 5 4 3 2 1 0
SPR1
SPMSTR
TRANSMIT DATA REGISTER
SHIFT REGISTER
SPR0
CGMOUT ÷ 2
CLOCK
SELECT
÷ 2
CLOCK
DIVIDER
ч 8
ч 32
ч 128
CLOCK
LOGIC
CPHA CPOL
SPI
SPRIE
SPE
SPWOM
SPRF
SPTE
OVRF
M
S
PIN
CONTROL
LOGIC
RECEIVE DATA REGISTER
SPTIE
SPE
INTERNAL BUS
(FROM SIM)
MODFEN
ERRIE
CONTROL
MODF
SPMSTR
MOSI
MISO
SPSCK
SS