M68HC16 Z SERIES
MULTICHANNEL COMMUNICATION INTERFACE
USER’S MANUAL
10-5
Figure 10-2 SPI Block Diagram
Clock control logic allows a selection of clock polarity and a choice of two clocking pro-
tocols to accommodate most available synchronous serial peripheral devices. When
the SPI is configured as a master, software selects one of 254 different bit rates for the
serial clock.
During an SPI transfer, data is simultaneously transmitted (shifted out serially) and re-
ceived (shifted in serially). A serial clock line synchronizes shifting and sampling of the
information on the two serial data lines. A slave-select line allows individual selection
of a slave SPI device. Slave devices which are not selected do not interfere with SPI
bus activities. On a master SPI device the slave-select line can optionally be used to
indicate a multiple-master bus contention.
MCCI SPI BLOCK
PRINT CONTROL LOGIC
S
M
M
S
M
S
MISO
PMC0
MOSI
PMC1
SCK
PMC2
SS
PMC3
SPI CONTROL
WOMP
SPE
MSTR
SHIFT
CONTROL
LOGIC
CLOCK
SPI CONTROL REGISTER
SPIE
SPE
WOMP
MSTR
CPHA
CPOL
LSBF
SIZE
BAUD
SELECT
BAUD
SPI CLOCK (MASTER)
CLOCK
SPI STATUS REGISTER
SPIF
WCOL
MODF
MSTR
SPE
SPI INTERRUPT
INTERNAL
DATA BUS
REQUEST
LOGIC
8/16-BIT SHIFT REGISTER
READ DATA BUFFER
MSB
LSB
MODULUS
COUNTER
INTERNAL
MCU CLOCK
F
re
e
sc
a
le
S
e
m
ic
o
n
d
u
c
to
r,
I
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
n
c
.
..