Typically when setting up TX and RX SPI DMA transfers (on K20 for example), I would use dedicated (or separate) source numbers for TX and RX DMAs. For the K22, I can only use this approach for SPI0 but not for SPI1 and SPI2 because the DMA source numbers on both peripherals appear to be a share resource where I can only do either TX or RX (see below):
How can I still implement SPI DMAs (TX and RX) on SPI channels with shared DMA source numbers? Any examples?
If not possible, then will I have to set up the transfers such that one transfer is interrupt controlled (likely TX) while the other is DMA controlled (RX)?