Hi Tom,
The SPI ports on the OMAP-L13x parts don't seem to have an RX fifo. If using them to interface to the ADS8556 (and DMAing RX data directly to memory) I am concerned about missing samples if there is bus priority contention in the OMAP.
The McBSP does have an RX fifo which would ensure no missed samples. do you have any examples of interfaceing to the ADS8556 from interfaces other than the SPI?
Thanks, Al...