MC68HC908GR4 MOTOROLA [Motorola, Inc], MC68HC908GR4 Datasheet - Page 326

• Manufacturer Part Number: MC68HC908GR4
• Description: Microcontrollers
• Manufacturer: MOTOROLA [Motorola, Inc]

Serial Peripheral Interface (SPI)
Technical Data
326
NOTE:
MODF — Mode Fault Bit
SPTE — SPI Transmitter Empty Bit
Do not write to the SPI data register unless the SPTE bit is high.
MODFEN — Mode Fault Enable Bit
Freescale Semiconductor, Inc.
This clearable, read-only flag is set in a slave SPI if the SS pin goes
high during a transmission with the MODFEN bit set. In a master SPI,
the MODF flag is set if the SS pin goes low at any time with the
MODFEN bit set. Clear the MODF bit by reading the SPI status and
control register (SPSCR) with MODF set and then writing to the SPI
control register (SPCR). Reset clears the MODF bit.
This clearable, read-only flag is set each time the transmit data
register transfers a byte into the shift register. SPTE generates an
SPTE CPU interrupt request or an SPTE DMA service request if the
SPTIE bit in the SPI control register is set also.
During an SPTE CPU interrupt, the CPU clears the SPTE bit by
writing to the transmit data register.
Reset sets the SPTE bit.
This read/write bit, when set to 1, allows the MODF flag to be set. If
the MODF flag is set, clearing the MODFEN does not clear the MODF
flag. If the SPI is enabled as a master and the MODFEN bit is low,
then the SS pin is available as a general-purpose I/O.
If the MODFEN bit is set, then this pin is not available as a general-
purpose I/O. When the SPI is enabled as a slave, the SS pin is not
available as a general-purpose I/O regardless of the value of
MODFEN. See
If the MODFEN bit is low, the level of the SS pin does not affect the
operation of an enabled SPI configured as a master. For an enabled
SPI configured as a slave, having MODFEN low only prevents the
MODF flag from being set. It does not affect any other part of SPI
operation. See
For More Information On This Product,
1 = SS pin at inappropriate logic level
0 = SS pin at appropriate logic level
1 = Transmit data register empty
0 = Transmit data register not empty
Serial Peripheral Interface (SPI)
Go to: www.freescale.com
Mode Fault
SS (Slave
Select).
Error.
MC68HC908GR8 — Rev 4.0
MOTOROLA