I am using a FRDM-K64 board to receive I2S data from an audio codec. I use the KSDK 1.1.0 SAI driver in I2S stereo mode with 32 bit words and eDMA to write the received data into a large buffer. In general this works fine, but sometimes I see that some received words are shifted by one bit. When I look at the I2S signals with an oscilloscope, they look fine. The bit clock has low to high transitions in the middle of the data bits and the frame sync signal switches polarity one data bit before a new word begins.
Does anyone have an idea what can cause such bit shifts?