Deserial Serial Peripheral Interface (DSPI)
MPC5510 Microcontroller Family Reference Manual, Rev. 1
23-32
Freescale Semiconductor
Preliminary
State transitions from running to stopped occur on the next frame boundary if a transfer is in progress, or
on the next system clock cycle if no transfers are in progress.
23.4.3
Serial Peripheral Interface (SPI) Configuration
The SPI configuration transfers data serially using a shift register and a selection of programmable transfer
attributes. The DSPI is in SPI configuration when the DCONF field in the DSPI
x
_MCR is 0b00. The SPI
frames can be from four to 16 bits long. The data to be transmitted can come from queues stored in RAM
external to the DSPI. Host software or an eDMA controller can transfer the SPI data from the queues to a
first-in first-out (FIFO) buffer. The received data is stored in entries in the receive FIFO (RX FIFO) buffer.
Host software or an eDMA controller transfers the received data from the RX FIFO to memory external
to the DSPI. The FIFO buffer operations are described in
Section 23.4.3.4, “Transmit First-In First-Out
Section 23.4.3.5, “Receive First-In First-Out (RX FIFO)
.” The interrupt and DMA request conditions are described in
.”
shows an example of how a master DSPI connects to a SPI slave in SPI Configuration.
Figure 23-17. DSPI Connections for SPI and DSI Transfers
The SPI configuration supports two module-specific modes: master mode and slave mode. The FIFO
operations are similar for the master mode and slave mode. The main difference is that in master mode the
DSPI initiates and controls the transfer according to the fields in the SPI command field of the TX FIFO
Table 23-16. State Transitions for Start and Stop of DSPI Transfers
Transition #
Current State
Next State
Description
0
Reset
Stopped
Generic power-on-reset transition
1
Stopped
Running
The DSPI is started (DSPI transitions to running) when all of the
following conditions are true:
• EOQF bit is clear
• Debug mode is unselected or the FRZ bit is clear
• HALT bit is clear
2
Running
Stopped
The DSPI stops (transitions from running to stopped) after the
current frame for any one of the following conditions:
• EOQF bit is set
• Debug mode is selected and the FRZ bit is set
• HALT bit is set
DSPI Master
Shift Register
Baud Rate Generator
SPI/DSI Slave
Shift Register
SOUT
SIN
SOUT
SIN
SCK
SCK
PCS
x
SS