Deserial Serial Peripheral Interface (DSPI)
MPC5510 Microcontroller Family Reference Manual, Rev. 1
23-12
Freescale Semiconductor
Preliminary
CPOL
Clock Polarity. Selects the inactive state of the serial communications clock (SCK). This bit is used in both master
and slave mode. For successful communication between serial devices, the devices must have identical clock
polarities. When the continuous selection format is selected (CONT = 1 or DCONT = 1), switching between clock
polarities without stopping the DSPI can cause errors in the transfer due to the peripheral device interpreting the
switch of clock polarity as a valid clock edge. For more information on continuous selection format, refer to
Section 23.4.8.5, “Continuous Selection Format
.”
0 The inactive state value of SCK is low
1 The inactive state value of SCK is high
CPHA
Clock Phase. Selects which edge of SCK causes data to change and which edge causes data to be captured.
This bit is used in both master and slave mode. For successful communication between serial devices, the
devices must have identical clock phase settings.
0 Data is captured on the leading edge of SCK and changed on the following edge
1 Data is changed on the leading edge of SCK and captured on the following edge
LSBFE
LSB First Enable. Selects if the LSB or MSB of the frame is transferred first. This bit is only used in master mode.
0 Data is transferred MSB first
1 Data is transferred LSB first
PCSSCK
PCS to SCK Delay Prescaler. Selects the prescaler value for the delay between assertion of PCS and the first
edge of the SCK. This field is only used in master mode. The table below lists the prescaler values. The
description for bitfield CSSCK in
details how to compute the PCS to SCK delay.
PASC
After SCK Delay Prescaler. Selects the prescaler value for the delay between the last edge of SCK and the
negation of PCSx. This field is only used in master mode. The table below lists the prescaler values. The
description for bitfield ASC in
details how to compute the after SCK delay.
Table 23-4. DSPI_CTARn Field Description (continued)
Field
Description
PCSSCK
PCS to SCK Delay
Prescaler Value
00
1
01
3
10
5
11
7
PASC
After SCK Delay
Prescaler Value
00
1
01
3
10
5
11
7