ST SPC560P34 - Table 222. Baud Rate Computation Example; Table 223. CS to SCK Delay Computation Example; Table 224. after SCK Delay Computation Example

RM0046 Deserial Serial Peripheral Interface (DSPI)
Doc ID 16912 Rev 5 467/936
Equation 21
Table 222 shows an example of a computed baud rate.
CS to SCK delay (t
CSC
)
The CS_x to SCK_x delay is the length of time from assertion of the CS_x signal to the first
SCK_x edge. Refer to Figure 220 for an illustration of the CS
_x to SCK_x delay. The
PCSSCK and CSSCK fields in the DSPIx_CTARn registers select the CS
_x to SCK_x delay,
and the relationship is expressed by the following formula:
Equation 22
Table 223 shows an example of the computed CS
to SCK_x delay.
After SCK delay (t
ASC
)
The after SCK_x delay is the length of time between the last edge of SCK_x and the
deassertion of CS
_x. Refer to Figure 220 and Figure 221 for illustrations of the after SCK_x
delay. The PASC and ASC fields in the DSPIx_CTARn registers select the after SCK delay.
The relationship between these variables is given in the following formula:
Equation 23
Table 224 shows an example of the computed after SCK delay.
SCK baud rate
f
SYS
PBRPrescalerValue
----------------------------------------------------------
1DBR+
BRScalerValue
--------------------------------------------
=
Table 222. Baud rate computation example
f
SYS
PBR Prescaler value BR Scaler value DBR value Baud rate
100 MHz 0b00 2 0b0000 2 0 25 Mbit/s
20 MHz 0b00 2 0b0000 2 1 10 Mbit/s
t
CSC
=
f
SYS
CSSCK

PCSSCK
1

Table 223. CS to SCK delay computation example
PCSSCK Prescaler value CSSCK Scaler value f
SYS
CS to SCK delay
0b01 3 0b0100 32 100 MHz 0.96 s
t
ASC
=
f
SYS
ASC

PASC
1

Table 224. After SCK delay computation example
PASC Prescaler value ASC Scaler value f
SYS
After SCK delay
0b01 3 0b0100 32 100 MHz 0.96 s