MC68HC908QC16_07 Datasheet, PDF (186/274 Pages) Freescale Semiconductor, Inc – Microcontrollers

Serial Peripheral Interface (SPI) Module
15.8.2 SPI Status and Control Register
The SPI status and control register contains flags to signal these conditions:
• Receive data register full
• Failure to clear SPRF bit before next byte is received (overflow error)
• Inconsistent logic level on SS pin (mode fault error)
• Transmit data register empty
The SPI status and control register also contains bits that perform these functions:
• Enable error interrupts
• Enable mode fault error detection
• Select master SPI baud rate
Read:
Write:
Reset:
Bit 7
SPRF
6
ERRIE
5
OVRF
4
MODF
3
SPTE
2
MODFEN
1
SPR1
0
0
0
0
1
0
0
= Unimplemented
Figure 15-14. SPI Status and Control Register (SPSCR)
Bit 0
SPR0
0
SPRF — SPI Receiver Full Bit
This clearable, read-only flag is set each time a byte transfers from the shift register to the receive data
register. SPRF generates a interrupt request if the SPRIE bit in the SPI control register is set also.
During an SPRF interrupt, user software can clear SPRF by reading the SPI status and control register
with SPRF set followed by a read of the SPI data register.
1 = Receive data register full
0 = Receive data register not full
ERRIE — Error Interrupt Enable Bit
This read/write bit enables the MODF and OVRF bits to generate interrupt requests.
1 = MODF and OVRF can generate interrupt requests
0 = MODF and OVRF cannot generate interrupt requests
OVRF — Overflow Bit
This clearable, read-only flag is set if software does not read the byte in the receive data register before
the next full 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 receive data register.
1 = Overflow
0 = No overflow
MODF — Mode Fault Bit
This clearable, read-only flag is set in a slave SPI if the SS pin goes high during a transmission with
MODFEN 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 MODF by reading the SPI status and control register (SPSCR) with MODF set
and then writing to the SPI control register (SPCR).
1 = SS pin at inappropriate logic level
0 = SS pin at appropriate logic level
MC68HC908QC16 • MC68HC908QC8 • MC68HC908QC4 Data Sheet, Rev. 3
186
Freescale Semiconductor