Figure 630. Continuous Sck Timing Diagram (Cont = 0) - STMicroelectronics SPC572L series Reference Manual

RM0400
Clock and transfer attributes for the Continuous SCK mode are set according to the
following rules:
•
When the DSPI is in SPI configuration, CTAR0 is used initially. At the start of each SPI
frame transfer, the CTAR specified by the CTAS for the frame is used.
• When the DSPI is in DSI configuration, the CTAR specified by the DSICTAS field is
used at all times.
•
When the DSPI is in CSI configuration, the CTAR selected by the DSICTAS field is
used initially.
–
–
•
In all configurations, the currently selected CTAR remains in use until the start of a
frame with a different CTAR specified, or the Continuous SCK mode is terminated.
It is recommended to keep the baud rate the same while using the Continuous SCK.
Switching clock polarity between frames while using Continuous SCK can cause errors in
the transfer. Continuous SCK operation is not guaranteed if the DSPI is put into the External
Stop mode or Module Disable mode.
Enabling Continuous SCK disables the PCS to SCK delay and the Delay after Transfer (t
is fixed to one SCK cycle.
When TSB configuration is enabled the t
Figure 630
disabled.
Note: When in Continuous SCK mode, for the SPI transfer CTAR0 should always be used, and
the TXFIFO must be cleared using the MCR[CLR_TXF] field before initiating transfer.
(CPOL = 0)
SCK
SCK (CPOL = 1)
Master SOUT
Master SIN
PCS
If the CONT bit in the TX FIFO entry is set or the DCONT in the DSICR0 is set, PCS
remains asserted between the transfers. Under certain conditions, SCK can continue with
At the start of a SPI frame transfer, the CTAR specified by the CTAS value for the
frame is used.
At the start of a DSI frame transfer, the CTAR specified by the DSICTAS field is
used.
is the timing diagram for Continuous SCK format with Continuous Selection

Figure 630. Continuous SCK timing diagram (CONT = 0)

DocID027809 Rev 4
Deserial Serial Peripheral Interface (DSPI)
is programmable from 1 to 64 SCK cycles.
DT
t
DT
)
DT
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