SPRUJ28E November 2021 – September 2024 AM68 , AM68A , TDA4AL-Q1 , TDA4VE-Q1 , TDA4VL-Q1
The AFIFO may be configured to delay making a receive DMA request to the host until the Read FIFO contains a specified number of words. In this situation, the number of receive DMA requests to the host or DMA controller is reduced. If the Read FIFO contains at least RNUMEVT 32-bit words, it generates a receive DMA request to the host and then waits for a response. Once RNUMEVT 32-bit words have been read from the RFIFO, the RFIFO checks again to see if it contains at least another RNUMEVT words. If it does, it generates another receive DMA request to the host, and so on. In this fashion, the Read FIFO will attempt to stay empty. Note that if receive DMA event pacing is desired, MCASP_RFIFOCTL[15-8] RNUMEVT bit field should be set to a non-zero integer multiple of the value in MCASP_RFIFOCTL[7-0] RNUMDMA bit field. If receive DMA event pacing is not desired, then the value in MCASP_RFIFOCTL[15-8] RNUMEVT bit field should be set equal to the value in MCASP_RFIFOCTL[7-0] RNUMDMA bit field.