PXD20RM Datasheet, PDF (289/1628 Pages) Freescale Semiconductor, Inc – PXD20 Microcontroller

– RX FIFO is not empty (RFDF)
– FIFO overrun (attempt to transmit with an empty TX FIFO or serial frame received while
RX FIFO is full) (RFOF)
– FIFO under flow (slave only and SPI mode, the slave is asked to transfer data when the TX
FIFO is empty) (TFUF)
• Modified SPI transfer formats for communication with slower peripheral devices
• Continuous serial communications clock (SCK)
10.5 Modes of operation
The DSPI has five modes of operation. These modes can be divided into two categories:
• Module-specific modes such as master, slave, and module disable modes
• MCU-specific modes such as external stop and debug modes
The module-specific modes are entered by host software writing to a register. The MCU-specific modes
are controlled by signals external to the DSPI. The MCU-specific modes are modes that the entire device
may enter, in parallel to the DSPI being in one of its module-specific modes.
10.5.1 Master mode
Master mode allows the DSPI to initiate and control serial communication. In this mode the SCK, and CSn
signals are controlled by the DSPI and configured as outputs. (SOUT is always an output.)
For more information, refer to Section 10.9.1.1, Master Mode.
10.5.2 Slave mode
Slave mode allows the DSPI to communicate with SPI bus masters. In this mode the DSPI responds to
externally controlled serial transfers. The DSPI cannot initiate serial transfers in slave mode. In slave
mode, the SCK signal and the CS0_x signal are configured as inputs and provided by a bus master. CS0_x
must be configured as input and pulled high. If the internal pullup is being used then the appropriate bits
in the relevant SIU_PCR must be set (SIU_PCR [WPE = 1], [WPS = 1]).
• All frames need to be masked when operating in Fast Continuous Mode.(User cannot switch to
continuous mode (delays not masked) and come back to the Fast Continuous Mode when Fast
Continuous Mode of operation is selected).
• CPHA is to be kept "1" when operating in Fast Continuous Mode.
For more information, refer to Section 10.9.1.2, Slave Mode.
10.5.3 Module disable mode
The module disable mode is used for MCU power management. The clock to the non-memory mapped
logic in the DSPI is stopped while in module disable mode. The DSPI enters the module disable mode
when the MDIS bit in DSPIx_MCR is set.
For more information, refer to Section 10.9.1.3, Module Disable Mode.
Freescale Semiconductor
PXD20 Microcontroller Reference Manual, Rev. 1
Preliminary—Subject to Change Without Notice
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