PXN20RM Datasheet, PDF (982/1376 Pages) Freescale Semiconductor, Inc – PXN20 Microcontroller

Deserial – Serial Peripheral Interface (DSPI)
SCK
Master SOUT
PCS
Data Frame 1
Active Phase
Data Frame 2
Active Phase
0 LSB
Invalid
0 LSB
t_DT
Invalid
t_DT
t_DT = from 1 to (PDT × DT / Fsys) TSCK ^{Data Selection Bit}
Data Frame = 4 to 32 bits
Figure 30-41. TSB Data Frame Format
30.4.11 Peripheral Chip Select Expansion and Deglitching
The DSPI supports as many as 64 peripheral chip select signals with the use of an external demultiplexer.
As many as 32 peripheral chip select signals can be used if deglitching is desired. The PCSS signal
provides the appropriate timing to enable and disable the demultiplexer for the PCS[0:4] signals.
Figure 30-42 shows how an external 5-to-32 demultiplexer (decoder) can be connected to the DSPI.
DSPI
PCSS
5
PCS0–PCS4
PCS0
PCS1
PCS31
Figure 30-42. DSPI PCS Expansion and Deglitching
30.4.12 DMA and Interrupt Conditions
The DSPI has six conditions that can generate interrupt requests only and two conditions that can generate
interrupt or DMA request. Table 30-34 lists the conditions. The X indicates which signals are connected.
Table 30-34. DSPI Interrupt and DMA Request Conditions
Condition
End of queue reached (EOQ)
TX FIFO is not full
Transfer of current frame complete
Flag
EOQF
TFFF
TCF
Interrupt
X
X
X
DMA
X
30-56
PXN20 Microcontroller Reference Manual, Rev. 1
Freescale Semiconductor