SPI and an Audio codec

Bear in mind that the 8-bit limit is only for the Altera HAL SPI driver. If you don't mind talking straight to your SPI hardware, you can use any word size up to 16 bits (set in SOPC Builder).

One other limit to the HAL SPI driver is that it either writes a byte and ignores the byte shifted in, or writes a 0 out and reads the byte shifted in; it can't read and write on the same transaction.

FYI, I have used the SPI peripheral several times, and the HAL driver 0 of those times. It's really a pretty simple peripheral to drive directly; initialize it by setting two or three registers, then read and write when the status bits tell you to.