Deserial Serial Peripheral Interface (DSPI)MPC5644A Microcontroller Reference Manual, Rev. 61256 Freescale Semiconductor30.6 Modes of operationThe DSPI has four modes of operation that can be divided into two categories: module-specific modes andan MCU-specific mode. Master Mode, Slave Mode and Module Disable Mode are the module-specificmodes, and Debug Mode is the MCU-specific mode.The module-specific modes are entered by host software writing to a register bit. The MCU-specific modeis selected by a signal external to the DSPI. The MCU-specific mode is a mode that MPC5644A may enterin parallel to the DSPI being in one of its module-specific modes.30.6.1 Master modeMaster Mode allows the DSPI to initiate and control serial communication. In this mode the SCK,DSPI_x_PCS and SOUT signals are controlled by the DSPI and configured as outputs.30.6.2 Slave modeSlave Mode allows the DSPI to communicate with SPI/DSI bus masters. In this mode the DSPI respondsto externally controlled serial transfers. The DSPI cannot initiate serial transfers in Slave Mode.30.6.3 Module Disable modeThe Module Disable mode is used for MCU power management. The clock to the non-memory mappedlogic in the DSPI is stopped while in Module Disable Mode. The DSPI enters the Module Disable Modewhen bit DSPI_MCR[MDIS] is set.30.6.4 Debug modeDebug Mode is used for system development and debugging. If the MPC5644AMCU enters Debug Modewhile bit DSPI_MCR[FRZ] is set, the DSPI halts operation on the next frame boundary. If the MPC5644Aenters Debug Mode while the FRZ bit is negated, the DSPI behavior is unaffected and remains dictated bythe module-specific mode and configuration of the DSPI.Table 30-1. DSPI channel frequency supportSystem clock(MHz)DSPI usemodeMax. usablefrequency (MHz) Notes150 LVDS 37.5 Use sysclock /4 divide ratioNon-LVDS 18.75 Use sysclock /8 divide ratio120 LVDS 40 Use sysclock /3 divide ratio. Gives 33/66 duty cycle. Use DSPIconfiguration DBR = 0b1 (double baud rate), BR = 0b0000(scaler value 2) and PBR = 0b01 (prescaler value 3).Non-LVDS 20 Use sysclock /6 divide ratio80 LVDS 40 Use sysclock /2 divide ratioNon-LVDS 20 Use sysclock /4 divide ratio
