1 baud rate generator, 2 cs to sck delay (tcsc), 3 after dspisck delay (tasc) – Freescale Semiconductor MCF5480 User Manual
Page 841: 4 delay after transfer (tdt), Baud rate generator -23, Cs to sck delay (tcsc), After dspisck delay (tasc), Delay after transfer (t, Section 27.7.3.2, “cs to sck delay (tcsc), Section 27.7.3.3, “after dspisck delay (tasc)

Functional Description
MCF548x Reference Manual, Rev. 3
Freescale Semiconductor
27-23
27.7.3.1
Baud Rate Generator
The baud rate is the frequency of the DSPI serial communication clock (DSPISCK). The system clock f
sys
is divided by a prescaler (PBR) and scaler (BR) to produce DSPISCK. The PBR and BR fields in the
DCTARn registers select the frequency of DSPISCK by the formula below:
shows an example of how to compute the baud rate.
27.7.3.2
CS to SCK Delay (t
CSC
)
The CS to SCK delay is the length of time from assertion of the DSPICSn signal to the first DSPISCK
for an illustration of the CS to SCK delay. The PCSSCK and CSSCK fields in the
DCTARn registers select the CS to SCK delay by the formula below:
Eqn. 27-5
shows an example of how to compute the CS to SCK delay.
27.7.3.3
After DSPISCK Delay (t
ASC
)
The after DSPISCK delay is the length of time between the last edge of DSPISCK and the negation of
DSPICSn. See
for illustrations of the after DSPISCK delay. The PASC and
ASC fields in the DCTARn registers select the after DSPISCK delay by the formula below:
Eqn. 27-6
shows an example of how to compute the after DSPISCK delay.
27.7.3.4
Delay after Transfer (t
DT
)
The delay after transfer is the length of time between negation of the DSPICSn signal for a frame and the
assertion of the DSPICSn signal for the next frame. See
for an illustration of the delay after
transfer. The PDT and DT fields in the DCTARn registers select the delay after transfer by the formula
below:
Table 27-15. Baud Rate Computation Example
PBR
Prescaler
BR
Scaler
Fsys
Baud Rate
0b00
2
0b0000
2
100 MHz
25 Mb/s
Table 27-16. PCS to DSPISCK Delay Computation Example
PCSSCK
Prescaler
CSSCK
Scaler
Fsys
PCS to DSPISCK
Delay
0b01
3
0b0100
32
100 MHz
0.96 us
Table 27-17. After DSPISCK Delay Computation Example
PASC
Prescaler
ASC
Scaler
Fsys
After DSPISCK Delay
0b01
3
0b0100
32
100 MHz
0.96 us
DSPISCK baud rate
=
PBR
× BR
f
sys
t
CSC
1
f
sys
--------
PCSSCK CSSCK
Ч
Ч
=
t
ASC
1
f
sys
--------
PASC
×
ASC
Ч
=