Deserial Serial Peripheral Interface (DSPI)
MPC5510 Microcontroller Family Reference Manual, Rev. 1
Freescale Semiconductor
23-31
Preliminary
transfer attributes are set in the DSPI
x
_CTAR1. In slave mode, for both SPI and DSI configurations, data
is transferred MSB first. The LSBFE field of the associated CTAR is ignored.
23.4.1.3
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 DSPI
x
_MCR is set. See
Section 23.4.12, “Power Saving Features
on the module disable mode.
23.4.1.4
Halt Mode
When the appropriate bit in the SIU_HLT register is set, a request to enter halt mode will be made to the
DSPI. The DSPI will not acknowledge the request to enter halt mode until it has reached a frame boundary.
When the DSPI has reached a frame boundary it will halt all operations and indicate that it is ready to have
its clocks shut off. The DSPI exits halt mode and resumes normal operation once the clocks are turned on.
Serial communications or register accesses made while in halt mode are ignored even if the clocks have
not been shut off yet. See
Section 23.4.12, “Power Saving Features
,”for more details on the halt mode.
23.4.1.5
Debug Mode
The debug mode is used for system development and debugging. If the MCU enters debug mode while the
FRZ bit in the DSPI
x
_MCR is set, the DSPI stops all serial transfers and enters a stopped state. If the MCU
enters debug mode while the FRZ bit is negated, the DSPI behavior is unaffected and remains dictated by
the module-specific mode and configuration of the DSPI. The DSPI enters debug mode when a debug
request is asserted by an external controller. See
23.4.2
Start and Stop of DSPI Transfers
The DSPI has two operating states: stopped and running. The states are independent of DSPI
configuration. The default state of the DSPI is stopped. In the stopped state no serial transfers are initiated
in master mode and no transfers are responded to in slave mode. The stopped state is also a safe state for
writing the various configuration registers of the DSPI without causing undetermined results. The TXRXS
bit in the DSPI
x
_SR is negated in this state. In the running state, serial transfers take place. The TXRXS
bit in the DSPI
x
_SR is asserted in the running state.
shows a state diagram of the start and
stop mechanism. The transitions are described in
Figure 23-16. DSPI Start and Stop State Diagram
Running
TXRXS = 1
Stopped
TXRXS = 0
Reset
Power-on-Reset
0
1
2