Quad Serial Peripheral Interface (QuadSPI)
MPC5606S Microcontroller Reference Manual, Rev. 7
Freescale Semiconductor 1053
• TBUF—TX Buffer Underrun, enabled by TBU_IE
• RBOF—RX Buffer Overflow, enabled by RBO_IE
• ABOF—AHB Buffer Overflow, enabled by ABO_IE
The Transmit Buffer Underrun indicates that an underrun condition in the TX Buffer has occurred. It is
generated when the TX Buffer is empty, a transfer to the serial flash is initiated and the
QSPI_SPIRSER[TFUF_IE] bit is set.
The Receive Buffer Overflow indicates that an overflow condition in the RX Buffer has occurred. It is
generated when the RX Buffer is full, an additional read transfer attempts to write into the RX Buffer and
the QSPI_SFMRSER[RBO_IE] bit is set.
The AHB Buffer Overflow indicates that an overflow condition in the AHB Buffer has occurred. It is
generated when the AHB Buffer is full, an additional read transfer attempts to write into the AHB Buffer
and the QSPI_SFMRSER[ABO_IE] bit is set.
The data from the transfers that generated the individual overflow conditions are ignored.
30.5.3.5.4 Serial Flash Communication Error Interrupt Request
The IPAEF, IPIEF or ICEF flags in the QSPI_SFMSR and the related interrupt enable bits in the
QSPI_SFMRSER determine the assertion of the SFMERRIRQ interrupt line.
30.5.3.5.5 Transaction Finished Interrupt Request
The Transaction Finished IRQ indicates the completion of the current command. It is masked by the
QSPI_SFMSR[TF_IE] bit.
30.5.3.6 TX Buffer Operation
The TX Buffer provides the data used for page programming. For proper operation it is required to provide
at least one entry in the TX Buffer prior to starting the execution of the page programming command. The
application must ensure that the required number of data bytes is written into the TX Buffer fast enough
as long as the command is executed without a TX Buffer overflow or underrun.
The QuadSPI module sets the QSPI_SFMFR[TBFF] flag initially when entering the SFM mode and
subsequently as long as the TX Buffer can accept more data to be written into.
When the QuadSPI module tries to pull data out of an empty TX Buffer the TX Buffer underrun is signaled
by the QSPI_SFMFR[TBUF] flag and the current instruction is terminated without further write access to
the serial flash and consequently no further assertions of the QSPI_SFMFR[TBFF] flag.
The TX Buffer overflow isn’t signaled explicitly, but the TX Buffer fill level can be monitored by the
QSPI_TBSR[TRBFL] field.
Refer to Section 30.4.3.16, TX Buffer Status Register (QSPI_TBSR), and Section 30.4.3.20, Serial Flash
Mode Flag Register (QSPI_SFMFR), for details about the TX Buffer related registers and to
Section 30.5.3.5.1, Transmit buffer fill interrupt request, for details about the usage of the associated
interrupt.
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