PXS20RM Datasheet, PDF (359/1368 Pages) Freescale Semiconductor, Inc – PXS20 Microcontroller

Deserial Serial Peripheral Interface (DSPI)
sys clk
PCS
SIN
SCK
SOUT
DSPI samples SIN
Tvd_sl
Tsu_ms
D0
D1
D2
Slave samples SOUT
Tcsc
Thd_ms
Tsu_sl
Thd_sl
D0
D1
D2
Tasc
Dn
Dn
Figure 16-29. DSPI Modified Transfer Format (MTFE=1, CPHA=1, f_sck = f_sys/3)
sys clk
PCS
SIN
SCK
SOUT
DSPI samples SIN
Tvd_sl
D0
D1
Slave samples SOUT
Tcsc
Tsu_ms
D2
Thd_ms
Thd_sl
Tsu_sl
D0
D1
D2
Tasc
Dn
Dn
Figure 16-30. DSPI Modified Transfer Format (MTFE=1, CPHA=1, f_sck = f_sys/4)
16.4.4.5 Continuous selection format
Some peripherals must be deselected between every transfer. Other peripherals must remain selected
between several sequential serial transfers. The Continuous Selection Format provides the flexibility to
handle both cases. The Continuous Selection Format is enabled for the SPI Configuration by setting the
CONT bit in the SPI command.
When the CONT bit = 0, the DSPI drives the asserted Chip Select signals to their idle states in between
frames. The idle states of the Chip Select signals are selected by the PCSISn bits in the DSPI_MCR.
Figure 16-31 shows the timing diagram for two four-bit transfers with CPHA = 1 and CONT = 0.
Freescale Semiconductor
PXS20 Microcontroller Reference Manual, Rev. 1
16-39