NXP Semiconductors freescale KV4 Series, Reference Manual

Page: 1222 / 1359

Table 44-44. Interrupt and DMA request conditions (continued)
Condition Flag Interrupt DMA
RX FIFO Drain RFDF Yes Yes
RX FIFO Overflow RFOF Yes -
Each condition has a flag bit in the module Status Register (SR) and a Request Enable bit
in the DMA/Interrupt Request Select and Enable Register (RSER). Certain flags (as
shown in above table) generate interrupt requests or DMA requests depending on
configuration of RSER register.
The module also provides a global interrupt request line, which is asserted when any of
individual interrupt requests lines is asserted.
44.5.7.1 End Of Queue interrupt request
The End Of Queue (EOQ) interrupt request indicates that the end of a transmit queue is
reached. The module generates the interrupt request when EOQ interrupt requests are
enabled (RSER[EOQF_RE]) and the EOQ bit in the executing SPI command is 1.
The module generates the interrupt request when the last bit of the SPI frame with EOQ
bit set is transmitted.
44.5.7.2 Transmit FIFO Fill Interrupt or DMA Request
The Transmit FIFO Fill Request indicates that the TX FIFO is not full. The Transmit
FIFO Fill Request is generated when the number of entries in the TX FIFO is less than
the maximum number of possible entries, and the TFFF_RE bit in the RSER is set. The
TFFF_DIRS bit in the RSER selects whether a DMA request or an interrupt request is
generated.
NOTE
TFFF flag clears automatically when DMA is used to fill TX
FIFO.
To clear TFFF when not using DMA, follow these steps for
every PUSH performed using CPU to fill TX FIFO:
1. Wait until TFFF = 1.
2. Write data to PUSHR using CPU.
3. Clear TFFF by writing a 1 to its location. If TX FIFO is not
full, this flag will not clear.
Functional description
KV4x Reference Manual, Rev. 2, 02/2015
1222
Preliminary
Freescale Semiconductor, Inc.