mc68hc08az60 Freescale Semiconductor, Inc, mc68hc08az60 Datasheet - Page 235

• Manufacturer Part Number: mc68hc08az60
• Description: M68hc08 Family Of 8-bit Microcontroller Units Mcus
• Manufacturer: Freescale Semiconductor, Inc

V
Ground)
25-spi
MOTOROLA
SS
(Clock
NOTE:
state of the MODFEN control bit. However, the MODFEN bit can still
prevent the state of the SS from creating a MODF error. (See
and Control Register
A logic 1 voltage on the SS pin of a slave SPI puts the MISO pin in a
high-impedance state. The slave SPI ignores all incoming SPSCK
clocks, even if a transmission already has begun.
When an SPI is configured as a master, the SS input can be used in
conjunction with the MODF flag to prevent multiple masters from driving
MOSI and SPSCK. (See
of the SS pin to set the MODF flag, the MODFEN bit in the SPSCK
register must be set. If the MODFEN bit is low for an SPI master, the SS
pin can be used as a general-purpose I/O under the control of the data
direction register of the shared I/O port. With MODFEN high, it is an
input-only pin to the SPI regardless of the state of the data direction
register of the shared I/O port.
The CPU can always read the state of the SS pin by configuring the
appropriate pin as an input and reading the data register. (See
V
for the port output buffers. To reduce the ground return path loop and
minimize radio frequency (RF) emissions, connect the ground pin of the
slave to the V
X = don’t care
SPE SPMSTR MODFEN
SS
0
1
1
1
Freescale Semiconductor, Inc.
is the ground return for the serial clock pin, SPSCK, and the ground
For More Information On This Product,
Serial Peripheral Interface Module (SPI)
X
0
1
1
Go to: www.freescale.com
SS
pin.
X
X
0
1
Table 5. SPI Configuration
on page 238).
Master without MODF
Mode Fault Error
SPI Configuration
Master with MODF
Not Enabled
Slave
Serial Peripheral Interface Module (SPI)
on page 225). For the state
MC68HC08AZ60 — Rev 1.0
General-Purpose I/O;
General-Purpose I/O;
State of SS Logic
SS Ignored by SPI
SS Ignored by SPI
Input-Only to SPI
Input-Only to SPI
SPI Status
I/O Signals
Table
235
5).