SPRUIM2H May 2020 – October 2023 AM2431 , AM2432 , AM2434 , AM6411 , AM6412 , AM6421 , AM6422 , AM6441 , AM6442
In start-bit mode, an extended bit is added before the MCSPI word to indicate whether the next MCSPI word must be handled as a command or as data. This feature is available only in controller mode. Start-bit mode cannot be used at the same time as turbo mode and/or force SPIEN[i] 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_CHCONF_0/1/2/3[23] SBE bit to 1. The polarity of the extended bit is programmable per channel. When the MCSPI_CHCONF_0/1/2/3[24] SBPOL bit is set to 0, the MCSPI word must be handled as a command. When the MCSPI_CHCONF_0/1/2/3[24] SBPOL bit is set to 1, the MCSPI 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_CHCONF_0/1/2/3[24] SBPOL bit before writing the MCSPI word to be transmitted to the TX register.