NXP Semiconductors PXN2020 - 30.4.11 Peripheral Chip Select Expansion and Deglitching; 30.4.12 DMA and Interrupt Conditions

Deserial – Serial Peripheral Interface (DSPI)
PXN20 Microcontroller Reference Manual, Rev. 1
30-56 Freescale Semiconductor
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.
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 Flag Interrupt DMA
End of queue reached (EOQ) EOQF X
TX FIFO is not full TFFF X X
Transfer of current frame complete TCF X
SCK
PCS
Master SOUT
t
DT
Data Frame 1
Data Frame 2
Invalid
t
DT
Invalid
LSB LSB
Active Phase
Active Phase
0
0
Data Selection Bit
Data Frame = 4 to 32 bits
t
DT
= from 1 to (PDT × DT / Fsys) TSCK
DSPI
PCS0–PCS4
PCSS
PCS0
PCS1
PCS31
5