s908ey16g2vfar Freescale Semiconductor, Inc, s908ey16g2vfar Datasheet - Page 196

• Manufacturer Part Number: s908ey16g2vfar
• Description: M68hc08 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

Serial Peripheral Interface (SPI) Module
SPRF — SPI Receiver Full Bit
ERRIE — Error Interrupt Enable Bit
OVRF — Overflow Bit
MODF — Mode Fault Bit
SPTE — SPI Transmitter Empty Bit
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This clearable, read-only flag is set each time a byte transfers from the shift register to the receive data
register. SPRF generates a CPU interrupt request if the SPRIE bit in the SPI control register is set also.
During an SPRF CPU interrupt, the CPU clears SPRF by reading the SPI status and control register
with SPRF set and then reading the SPI data register. Any read of the SPI data register clears the
SPRF bit.
Reset clears the SPRF bit.
This read-only bit enables the MODF and OVRF flags to generate CPU interrupt requests. Reset
clears the ERRIE bit.
This clearable, read-only flag is set if software does not read the byte in the receive data register before
the next byte enters the shift register. In an overflow condition, the byte already in the receive data
register is unaffected, and the byte that shifted in last is lost. Clear the OVRF bit by reading the SPI
status and control register with OVRF set and then reading the SPI data register. Reset clears the
OVRF flag.
This clearable, read-only flag is set in a slave SPI if the SS pin goes high during a transmission. In a
master SPI, the MODF flag is set if the SS pin goes low at any time. Clear the MODF bit by reading
the SPI status and control register with MODF set and then writing to the 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 if the SPTIE bit in the SPI control register is
set also.
For an idle master or idle slave that has no data loaded into its transmit buffer, the SPTE will be set
again within two bus cycles since the transmit buffer empties into the shift register. This allows the user
to queue up a 16-bit value to send. For an already active slave, the load of the shift register cannot
occur until the transmission is completed. This implies that a back-to-back write to the transmit data
register is not possible. The SPTE indicates when the next write can occur.
Reset sets the SPTE bit.
1 = Receive data register full
0 = Receive data register not full
1 = MODF and OVRF can generate CPU interrupt requests
0 = MODF and OVRF cannot generate CPU interrupt requests
1 = Overflow
0 = No overflow
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
Do not write to the SPI data register unless the SPTE bit is high.
MC68HC908EY16A • MC68HC908EY8A Data Sheet, Rev. 1
NOTE
Freescale Semiconductor