SPRUIE9D May 2017 – May 2024 DRA74P , DRA75P , DRA76P , DRA77P
In store and controlled transmission (SCT) mode, the MPU starts writing data to the TX FIFO. Then, after writing a part of a frame (for a bigger frame) or an entire frame (a small frame; that is, a supervisory frame), the MPU writes 1 to the UART3.UART_ACREG[2] SCTX_EN bit (deferred TX start) to start transmission.
SCT mode is enabled by setting the UART3.UART_MDR1[5] SCT bit to 1. This transmission method differs from normal mode, in which data transmission starts immediately after data is written to the TX FIFO. SCT mode is useful for sending short frames without TX underrun.