SPRUIE9D May 2017 – May 2024 DRA74P , DRA75P , DRA76P , DRA77P
In start-bit mode, an extended bit is added before the SPI word to indicate whether the next SPI word must be handled as a command or as data. This feature is available only in master mode. Start-bit mode cannot be used at the same time as turbo mode and/or force SPIEN[x] mode. In this case, only one channel can be used; round-robin arbitration is not possible.
This mode is programmable per channel by setting the MCSPI_CHxCONF[23] SBE bit to 1. The polarity of the extended bit is programmable per channel. When the MCSPI_CHxCONF[24] SBPOL bit is set to 0, the SPI word must be handled as a command. When the MCSPI_CHxCONF[24] SBPOL bit is set to 1, the SPI word must be handled as data. Moreover, start-bit polarity can be changed dynamically during start-bit transfer without disabling the channel for reconfiguration; in this case, users must configure the MCSPI_CHxCONF[24] SBPOL bit before writing the SPI word to be transmitted to the TX register.