SPRUI30H November 2015 – May 2024 DRA745 , DRA746 , DRA750 , DRA756
The MCSPI_XFERLEVEL[15:8] AFL bit field is needed when the buffer is used to receive an SPI word from a slave (the MCSPI_CHxCONF[28] FFER bit must be set to 1). It defines the almost-full buffer status. See Figure 24-94.
When the FIFO pointer reaches this level, an interrupt or a DMA request is sent to the MPU to enable the system to read AFL + 1 bytes from the receive register.
AFL + 1 must correspond to a multiple value of the MCSPI_CHxCONF[11:7] WL bit field.
When DMA is used, the request is deasserted after the first receive register read.
No new request is asserted again as long as the system has not performed the correct number of read accesses.
The MCSPI_IRQSTATUS register bits are not available in DMA mode. In DMA mode, the SPIm_DMA_RXx request is asserted on the same conditions as the MCSPI_IRQSTATUS RXx_FULL flag.