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DMA Serial Peripheral Interface (DSPI)
Freescale Semiconductor
31-3
– FIFO overrun (logical OR of RX overflow and TX underflow interrupts)
– General DSPI interrupt (logical OR of the seven above conditions)
•
Modified SPI transfer formats for communication with slower peripheral devices
•
Continuous serial communications clock (DSPI_SCK)
31.1.4
Modes of Operation
The DSPI module has four available distinct modes:
•
Master mode
•
Slave mode
•
Module disable mode
•
Debug mode
Master, slave, and module disable modes are module-specific modes while debug mode is a
device-specific mode.
Bits in the DSPI_MCR register determine the module-specific modes. Debug mode is a mode that the
entire device can enter in parallel with the DSPI being configured in one of its module-specific modes.
31.1.4.1
Master Mode
In master mode, the DSPI can initiate communications with peripheral devices. The DSPI operates as bus
master when the DSPI_MCR[MSTR] bit is set. The serial communications clock (DSPI_SCK) is
controlled by the master DSPI.
Master mode transfer attributes are controlled by the SPI command in the current TX FIFO entry. The
CTAS field in the SPI command selects which of the eight DSPI_CTARs sets the transfer attributes.
Transfer attribute control is on a frame by frame basis. See
Section 31.4.2, “Serial Peripheral Interface
” for more details.
31.1.4.2
Slave Mode
In slave mode, the DSPI responds to transfers initiated by an SPI master. The DSPI operates as bus slave
when the DSPI_MCR[MSTR] bit is cleared. A bus master selects the DSPI slave by having the slave’s
DSPI_SS signal asserted. In slave mode, the bus master provides DSPI_SCK. The bus master controls all
transfer attributes, but clock polarity, clock phase, and numbers of bits to transfer must be configured in
the DSPI slave for proper communications.
In slave mode, data transfers MSB first. The LSBFE field of the associated CTAR register is ignored.
31.1.4.3
Module Disable Mode
The module disable mode is used for MCU power management. The clock to the non-memory mapped
logic in the DSPI stops while in module disable mode. The DSPI enters the module disable mode when
the DSPI_MCR[MDIS] bit is set. See
Section 31.4.7, “Power Saving Features
module disable mode.
Summary of Contents for MCF54455
Page 33: ...xxviii Freescale Semiconductor ...
Page 67: ...Freescale Semiconductor 1 ...
Page 125: ...Freescale Semiconductor 1 ...
Page 145: ...Enhanced Multiply Accumulate Unit EMAC 5 21 Freescale Semiconductor ...
Page 173: ...Cache 6 28 Freescale Semiconductor ...
Page 179: ...Static RAM SRAM 7 6 Freescale Semiconductor ...
Page 207: ...Power Management 9 16 Freescale Semiconductor ...
Page 323: ...Reset Controller Module 13 8 Freescale Semiconductor ...
Page 389: ...Pin Multiplexing and Control 16 44 Freescale Semiconductor ...
Page 575: ...PCI Bus Controller 22 58 Freescale Semiconductor ...
Page 600: ...Advanced Technology Attachment ATA Freescale Semiconductor 23 25 ...
Page 601: ...Freescale Semiconductor 1 ...
Page 842: ...I2 C Interface Freescale Semiconductor 33 16 ...
Page 843: ...Freescale Semiconductor 1 ...
Page 921: ...Revision History A 6 Freescale Semiconductor ...