15:     Start conversation
             0 - do nothing
             1 - start conversation

    14-13:  Channel selection
            00 - channel 0
            01 - channel 1
            11 - both channels

    12-11: Pin selection
            00 - no pin
            01 - pin 1
            11 - pin 2

    10-8:   Unused (Don't care bits)

    7-0:    Data