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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.
46.4.7.3 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.
46.4.7.4 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 a DSPI 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.
46.4.7.5 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.
46.4.7.6 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.
Chapter 46 Serial Peripheral Interface (SPI)
K20 Sub-Family Reference Manual, Rev. 1.1, Dec 2012
Freescale Semiconductor, Inc.
Preliminary
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