mc68hc908as60 Freescale Semiconductor, Inc, mc68hc908as60 Datasheet - Page 273

• Manufacturer Part Number: mc68hc908as60
• Description: Mc68hc908as60 Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

18.7.2 Mode Fault Error
MC68HC908AS60 — Rev. 1.0
NOTE:
NOTE:
For the MODF flag (in SPSCR) to be set, the mode fault error enable bit
(MODFEN in SPSCR) must be set. Clearing the MODFEN bit does not
clear the MODF flag but does prevent MODF from being set again after
MODF is cleared.
MODF generates a receiver/error CPU interrupt request if the error
interrupt enable bit (ERRIE in SPSCR) is also set. The SPRF, MODF,
and OVRF interrupts share the same CPU interrupt vector. MODF and
OVRF can generate a receiver/error CPU interrupt request. (See
Figure
generate a receiver/error CPU interrupt request. However, leaving
MODFEN low prevents MODF from being set.
In a master SPI with the mode fault enable bit (MODFEN) set, the mode
fault flag (MODF) is set if SS goes to logic 0. A mode fault in a master
SPI causes the following events to occur:
To prevent bus contention with another master SPI after a mode fault
error, clear all data direction register (DDR) bits associated with the SPI
shared port pins.
Setting the MODF flag (SPSCR) does not clear the SPMSTR bit.
Reading SPMSTR when MODF = 1 will indicate a MODE fault error
occurred in either master mode or slave mode.
When configured as a slave (SPMSTR = 0), the MODF flag is set if SS
goes high during a transmission. When CPHA = 0, a transmission begins
when SS goes low and ends once the incoming SPSCK returns to its idle
level after the shift of the eighth data bit. When CPHA = 1, the
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If ERRIE = 1, the SPI generates an SPI receiver/error CPU
interrupt request.
The SPE bit is cleared.
The SPTE bit is set.
The SPI state counter is cleared.
The data direction register of the shared I/O port regains control of
port drivers.
18-9.) It is not possible to enable only MODF or OVRF to
Serial Peripheral Interface (SPI)
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Serial Peripheral Interface (SPI)
Error Conditions
Technical Data