Deserial Serial Peripheral Interface (DSPI)MPC5566 Microcontroller Reference Manual, Rev. 2Freescale Semiconductor 20-5120.4.5 Combined Serial Interface (CSI) ConfigurationIn master mode, the CSI configuration of the DSPI is used to support SPI and DSI functions on a frame byframe basis. CSI configuration allows interleaving of DSI data frames from the parallel input signals(from the eTPU or eMIOS) with SPI commands and data from the TX FIFO. The data returned from thebus slave is either used to drive the parallel output signals (to the eTPU or eMIOS) or is stored in the RXFIFO. CSI configuration allows serialized data and configuration or diagnostic data to be transferred to aslave device using only one serial link. The DSPI is in CSI configuration when the DCONF field in theDSPIx_MCR is 0b10. Figure 20-29 shows an example of how a DSPI can be used with a deserializingperipheral that supports SPI control for control and diagnostic frames.Figure 20-29. Example of System using DSPI in CSI ConfigurationIn CSI configuration the DSPI transfers DSI data based on Section 20.4.4.5, “DSI Transfer InitiationControl.” When there are SPI commands in the TX FIFO, the SPI data has priority over the DSI frames.When the TX FIFO is empty, DSI transfer resumes.Two peripheral chip select signals indicate whether DSI data or SPI data is transmitted. You must configurethe DSPI so the CTARs for the DSI data and SPI data assert different peripheral chip select signals denotedin the figure as PCSx and PCSy. The CSI configuration is only supported in master mode.Data returned from the external slave while a DSI frame is transferred is placed on the parallel outputsignals. Data returned from the external slave while an SPI frame is transferred is moved to the RX FIFO.The TX FIFO and RX FIFO are fully functional in CSI mode.20.4.5.1 CSI SerializationSerialization in the CSI configuration is similar to serialization in DSI configuration. The transferattributes for SPI frames are determined by the DSPIx_CTAR selected by the CTAS field in the SPIcommand halfword. The transfer attributes for the DSI frames are determined by the DSPIx_CTARselected by the DSICTAS field in the DSPIx_DSICR. Figure 20-30 shows the CSI serialization logic.SPIDSPI MasterDSIShift registerTX FIFOTXprioritycontrolSINxSOUTxSCKxPCSxPCSy SPIExternal Slave DeserializerShift registerframeFrameselectlogicSOUTxSINxSCKxSSxSSy DSIframe
