22.4.2.4 Frame Error/LRCK Errors

The SPI module provides detection of frame/LRCK errors for debugging. The frame/LRCK error occurs when the LRCK edge that is defining a channel start happens before the correct number of bits (as defined by MODE[32,16]).

The SPI module immediately sets the FRMERR bit (SPIxSTAT[12]), pushes data in from the SPIxRXSR register into the SPIxRXB register and pops data from the SPIxTXB register into the SPIxTXSR register. The module can be configured to detect frame/LRCK related errors by setting the FRMERREN bit (SPIxIMSK[12]).

Note: In Audio Protocol mode, both the BCLK (on the SCKx pin) and the LRCK (on the SSx pin) are free running, meaning they are continuous. Normally, the LRCK is a fixed number of BCLKs long. In all cases, the SPI module will realign to the new frame edge and will set the FRMERR bit. If operating in a Non-PCM mode, the SPI module will also push the abbreviated data onto the FIFO when the frame is too short.