SWRU543B January 2019 – June 2025 CC3230S , CC3230SF , CC3235MODS , CC3235MODSF , CC3235S , CC3235SF
FIFO peripherals contain a FIFO of data to be sent and a FIFO of data that has been received. The µDMA controller transfers data between these FIFOs and system memory. For example, when a UART FIFO contains one or more entries, a single transfer request is sent to the µDMA for processing. If this request has not been processed and the UART FIFO reaches the interrupt FIFO level, another interrupt is sent to the µDMA which is higher priority than the single-transfer request. In this instance, an ARBSIZ transfer is performed as configured in the DMACHCTL register. After the transfer is complete, the µDMA sends a receive or transmit complete interrupt to the UART register.
If the SETn bit of the FIFO peripheral is set in the DMA Channel Useburst Set (DMAUSEBURSTSET) register, then the µDMA controller only performs transfers defined by the ARBSIZ bit field in the DMACHCTL register for better bus use. For peripherals that tend to transmit and receive in bursts, such as the UART, TI recommends against the use of this configuration because it could cause the tail end of transmissions to stick in the FIFO.