SWRU543B January 2019 – June 2025 CC3230S , CC3230SF , CC3235MODS , CC3235MODSF , CC3235S , CC3235SF
The bit field MCSPI_XFERLEVEL[AFL] is required when the buffer is used to receive a SPI word from a slave (MCSPI_CHCONF[FFER] must be set to 1), and defines the Almost Full buffer status. See Figure 8-11.
When the FIFO pointer reaches this level, an interrupt or a DMA request is sent to the local host to enable the system to read AFL+1 bytes from the receive register. AFL+1 must correspond to a multiple value of MCSPI_CHCONF[WL]. When DMA is used, the request is deasserted after the first receive register read. No new request is asserted until it has performed the correct number of read accesses.
Figure 8-11 Buffer Almost Full Level (AFL)