NXP Semiconductors K22F series, Reference Manual, Page: 1173 / 1407

45.4.7.3 Transfer Complete Interrupt Request
The Transfer Complete Request indicates the end of the transfer of a serial frame. The
Transfer Complete Request is generated at the end of each frame transfer when the
TCF_RE bit is set in the RSER.
45.4.7.4 Transmit FIFO Underflow Interrupt Request
The Transmit FIFO Underflow Request indicates that an underflow condition in the TX
FIFO has occurred. The transmit underflow condition is detected only for the module
operating in Slave mode and SPI configuration . The TFUF bit is set when the TX FIFO
of the module is empty, and a transfer is initiated from an external SPI master. If the
TFUF bit is set while the TFUF_RE bit in the RSER is set, an interrupt request is
generated.
45.4.7.5 Receive FIFO Drain Interrupt or DMA Request
The Receive FIFO Drain Request indicates that the RX FIFO is not empty. The Receive
FIFO Drain Request is generated when the number of entries in the RX FIFO is not zero,
and the RFDF_RE bit in the RSER is set. The RFDF_DIRS bit in the RSER selects
whether a DMA request or an interrupt request is generated.
45.4.7.6 Receive FIFO Overflow Interrupt Request
The Receive FIFO Overflow Request indicates that an overflow condition in the RX
FIFO has occurred. A Receive FIFO Overflow request is generated when RX FIFO and
shift register are full and a transfer is initiated. The RFOF_RE bit in the RSER must be
set for the interrupt request to be generated.
Depending on the state of the ROOE bit in the MCR, the data from the transfer that
generated the overflow is either ignored or shifted in to the shift register. If the ROOE bit
is set, the incoming data is shifted in to the shift register. If the ROOE bit is cleared, the
incoming data is ignored.
45.4.8 Power saving features
The module supports following power-saving strategies:
Chapter 45 Serial Peripheral Interface (SPI)
K22F Sub-Family Reference Manual, Rev. 4, 08/2016
NXP Semiconductors 1173