PXD10RM Datasheet, PDF (314/1332 Pages) Freescale Semiconductor, Inc – PXD10 Microcontroller

11.8.4.3 After SCK Delay (t_ASC)
The after SCK_x delay is the length of time between the last edge of SCK_x and the negation of CS_x.
Refer to Figure 11-14 and Figure 11-15 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:
t_ASC =
1
 PASC
f_SYS
 ASC
Table 11-21 shows an example of the computed after SCK delay.
Table 11-21. After SCK Delay Computation Example
PASC
0b01
Prescaler
Value
3
ASC
0b0100
Scaler
Value
32
f_SYS
100 MHz
After SCK Delay
0.96 s
11.8.4.4 Delay after Transfer (t_DT)
The delay after transfer is the length of time between negation of the CSx signal for a frame and the
assertion of the CSx signal for the next frame. The PDT and DT fields in the DSPIx_CTARn registers
select the delay after transfer.
Refer to Figure 11-14 for an illustration of the delay after transfer.
The following formula expresses the PDT/DT/delay after transfer relationship:
t_DT =
1
f_SYS ^{ PDT  DT}
Table 11-22 shows an example of the computed delay after transfer.
Table 11-22. Delay after Transfer Computation Example
PDT
0b01
Prescaler
Value
3
DT
0b1110
Scaler
Value
32768
f_SYS
Delay after Transfer
100 MHz
0.98 ms
When in non-continuous clock mode the t_DT delay is configurable as outlined in the DSPI_CTARx
registers. When in continuous clock mode and TSB is not enabled the delay is fixed at 1 SCK period. When
in TSB and continuous mode the delay is programmed as outlined in the DSPI_CTARx registers but in the
event that the delay does not coincide with an SCK period in duration the delay is extended to the next
SCK active edge. Table 11-23 shows an example of how to compute the Delay after Transfer with the clock
period of SCK defined as T_SCK. The values calculated assume 1 TSCK period = 4 ipg_clk.
11-32
PXD10 Microcontroller Reference Manual, Rev. 1
Preliminary—Subject to Change Without Notice
Freescale Semiconductor