NXP Semiconductors K22F series - Page 1139

SPIx_CTARn field descriptions (continued)
Field Description
Table 45-3. Delay Scaler Encoding (continued)
Field Value Delay Scaler Value
0011 16
0100 32
0101 64
0110 128
0111 256
1000 512
1001 1024
1010 2048
1011 4096
1100 8192
1101 16384
1110 32768
1111 65536
Refer PCS to SCK Delay (t
CSC
) for more details.
11–8
ASC
After SCK Delay Scaler
Selects the scaler value for the After SCK Delay. This field is used only in master mode. The After SCK
Delay is the delay between the last edge of SCK and the negation of PCS. The delay is a multiple of the
protocol clock period, and it is computed according to the following equation:
t
ASC
= (1/f
P
) x PASC x ASC
See Delay Scaler Encoding table in CTARn[CSSCK] bit field description for scaler values. Refer After SCK
Delay (t
ASC
) for more details.
7–4
DT
Delay After Transfer Scaler
Selects the Delay after Transfer Scaler. This field is used only in master mode. The Delay after Transfer is
the time between the negation of the PCS signal at the end of a frame and the assertion of PCS at the
beginning of the next frame.
In the Continuous Serial Communications Clock operation, the DT value is fixed to one SCK clock period,
The Delay after Transfer is a multiple of the protocol clock period, and it is computed according to the
following equation:
t
DT
= (1/f
P
) x PDT x DT
See Delay Scaler Encoding table in CTARn[CSSCK] bit field description for scaler values.
BR Baud Rate Scaler
Selects the scaler value for the baud rate. This field is used only in master mode. The prescaled protocol
clock is divided by the Baud Rate Scaler to generate the frequency of the SCK. The baud rate is computed
according to the following equation:
SCK baud rate = (f
P
/PBR) x [(1+DBR)/BR]
The following table lists the baud rate scaler values.
Table continues on the next page...
Chapter 45 Serial Peripheral Interface (SPI)
K22F Sub-Family Reference Manual, Rev. 4, 08/2016
NXP Semiconductors 1139