Combined Serial Interface (Csi) Configuration - STMicroelectronics SPC572L series Reference Manual

Deserial Serial Peripheral Interface (DSPI)
DSPI_DSICR0 bits
46.5.3.5.1 Continuous control
For continuous control, a new DSI frame shifts out when the previous transfer cycle has
completed and the delay after transfer (t
46.5.3.5.2 Change in data control
For change in data control, a transfer is initiated when the data to be serialized has changed
since the transfer of the last DSI frame. A copy of the previously transferred DSI data is
stored in the DSPI_COMPR0/1. When the data selected for the transfer from the
DSPI_SDR0/1 and DSPI_ASDR0/1 registers is different from the data in the
DSPI_COMPR0/1 a new DSI frame is transmitted.
46.5.3.5.3 Change in data control
For change in data control, initiation of a transfer is controlled by the detection of a change
in data to be serialized.
It is not advisable to configure a DSPI Slave with the combination DSICR0[DCONT] = 1,
DSICR0[CID] = 1; since the following statement then holds true:
Once slave select is asserted, there is a very small window (of up to three module
clocks) after every SOF (Start of Frame) during which if a write on ASDR/SDR registers
occurs, the next frame to be transmitted would be loaded into the shift register. Since it
is not feasible that such a write is initiated and completed within this short span of time,
the data transmitted by DSPI slave would lag by one data frame.
46.5.4

Combined Serial Interface (CSI) configuration

The CSI Configuration of the DSPI is used to support SPI and DSI functions on a frame by
frame basis.
CSI Configuration allows interleaving of DSI data frames from the parallel input signals with
SPI data frames from the TX FIFO. The data returned from the bus slave is either used to
drive the Parallel Output signals or it is stored in the RX FIFO. The CSI Configuration allows
serialized data and configuration or diagnostic data to be transferred to a slave device using
only one serial link. The DSPI is in CSI Configuration when the DCONF field in the
DSPI_MCR is 0b10.
deserializing peripheral that supports SPI control for control and diagnostic frames.
1188/2058
Table 642. DSI data transfer initiation control
CID
0 Continuous
1 Change in Data
0 Triggered
1 Triggered or Change in Data
Figure 616
DocID027809 Rev 4
Transfer initiation control
) has elapsed.
DT
shows an example of how a DSPI can be used with a
RM0400