master:
P9.25           hclk input or 24.576 MHz output
P9.31           clk output
P9.29           fs output
P9.30           data in or out
P9.41           data in or out
P9.28 or P9.41  data in or out

slave:
P9.31           clk input
P9.29           fs input
P9.30           data in or out
P9.41           data in or out
P9.28 or P9.41  data in or out
P9.25           data in or out