SWCU195A December 2024 – May 2025 CC2744R7-Q1 , CC2745P10-Q1 , CC2745R10-Q1 , CC2745R7-Q1 , CC2755R10
SPI includes a feature to reset the TX and RX FIFO pointers to flush FIFOs. This must be triggered when no SPI transactions are in progress. If a FIFO flush is triggered when a transaction is in progress, then a second FIFO flush is needed when no operations are ongoing, before restarting new SPI transfers.
The FIFO flush operation is atomic. When the CPU writes into SPI.CTL0[11] FIFORST register bit, the SPI hardware internally ensures that TX and RX FIFO pointers are set to zero, and auto-clears the FIFORST bit after four CLKSVT clock cycles. The CPU can poll the FIFORST bit to identify when the FIFO pointer reset operation has completed.